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165 KiB

Open AccessAbstract

Carbon Dots as a Fluorescence pH Nanosensor by Application of an Active Surface Preservation Strategy

by Ana Carolina P. Afonso and Luís Pinto da Silva

Chem. Proc. 2021, 5(1), 2; https://doi.org/10.3390/CSAC2021-10638 - 7 Jul 2021

Viewed by 1095

Abstract

In the environmental, industrial, and biomedical fields, pH monitorization is of the upmost importance. However, the most used type of pH sensors, glass pH-electrodes, still present limitations in their application in low volume samples and in cellular pH sensing, due to their size [...] Read more.

In the environmental, industrial, and biomedical fields, pH monitorization is of the upmost importance. However, the most used type of pH sensors, glass pH-electrodes, still present limitations in their application in low volume samples and in cellular pH sensing, due to their size and invasive nature. Fluorescence-based sensors present a solution to such issues, providing a non-invasive solution to pH sensing. Herein, we report the rational development of carbon dots (CDs) as a pH nanosensor via an active surface preservation (ASP) method. Carbon dots (CDs) are carbon-based fluorescent nanoparticles with valuable properties such as high aqueous solubility, low cost and good biocompatibility, with remarkable fluorescence performance, been increasingly used as fluorescent nanosensors. Namely, these nanomaterials present advantages over molecular probes in terms of (photo)stability and water solubility, among others. By employing ASP strategies, the CDs will be prepared by using precursors with known active functional features. The ASP method allows the nanoparticles to retain the structural features of precursors, thus retaining their properties, without the need for costly and time-consuming post-synthesis functionalization procedures. In this work, we intend to provide a proof-of-concept of this type of strategy by utilizing the known pH-sensitivity of fluorescein to provide a pH-based response to CDs. The resulting CDs presented reversible response by fluorescence enhancement in the range of pH from 4 to 12. The nanoparticles exhibited excellent photostability, in different pH solutions. The studied CDs were also unaffected by, either variation of ionic strength or the presence of interferent species, while being compatible with human cancer cells. Finally, CDs were able to determine the pH of real samples. Thus, a selective pH fluorescent CDs-based nanosensor was developed. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

166 KiB

Open AccessAbstract

Eucalyptus Biochar as a Sustainable Nanomaterial for Electrochemical Sensors

by Annalisa Scroccarello, Flavio Della Pelle, Qurat Ul Ain Bukhari, Filippo Silveri, Daniele Zappi, Enrico Cozzoni and Dario Compagnone

Chem. Proc. 2021, 5(1), 13; https://doi.org/10.3390/CSAC2021-10618 - 6 Jul 2021

Cited by 3 | Viewed by 1836

Abstract

Carbonaceous-based nanomaterials (C-NMs) are the pillar of myriad sensing and catalytic electrochemical applications. In this field, the search for environmentally sustainable C-NMs from renewable sources became a duty in the development of nano-sensors. Herein, water-soluble carbon nanofibers (CF) were produced from eucalyptus scraps-based [...] Read more.

Carbonaceous-based nanomaterials (C-NMs) are the pillar of myriad sensing and catalytic electrochemical applications. In this field, the search for environmentally sustainable C-NMs from renewable sources became a duty in the development of nano-sensors. Herein, water-soluble carbon nanofibers (CF) were produced from eucalyptus scraps-based biochar (BH) through an ultrasound treatment, assisted by sodium cholate used as a stabilizing agent. Noteworthy, thanks to the use of the bio-stabilizing agent, the nanofibers were dispersed in water avoiding the use of organic solvents. The BH-CF was investigated as sensing material onto commercial screen-printed electrodes via drop-casting (BH-SPE) and as thin-film fully integrated into a lab-made flexible electrode. The thin film was produced via BH-CF vacuum filtration followed by the film transferring to a thermo-adhesive plastic substrate through thermal lamination. This approach gave rise to a conductive BH-CF film (BH-Film) easily embodied in a lab-made electrode produced with office-grade instrumentation (i.e., craft-cutter machine, thermal laminator) and materials (i.e., laminating pouches, stencil). The BH-CF amount was optimized and the resulting film morphologically characterized, then, the electrochemical performances were studied. The BH-CF electrochemical features were investigated towards a broad range of analytes containing phenol moieties, discrimination between orto- and mono-phenolic structures were achieved for all the studied compounds. As proof of applicability, the BH-CF-based sensors were challenged for simultaneous determination of mono-phenols and ortho-diphenols in olive oil extracts. LODs ≤ 0.5 μM and ≤ 3.8 μM were obtained for hydroxytyrosol (o-diphenol reference standard) and Tyrosol (m-phenols reference standard), respectively. Moreover, a high inter-sensors precision (RSD calibration-slopes ≤ 7%, n = 3) and quantitative recoveries in sample analysis (recoveries 91–111%, RSD ≤ 6%) were obtained. Here, a solvent-free strategy to obtain water-soluble BH-CF was proposed, and their usability to sensor fabrication and modification proved. This work demonstrated as cost-effective and sustainable renewable sources, rationally used, can lead to obtain useful nanomaterials. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

168 KiB

Open AccessAbstract

Graphene Nanoflakes Incorporating Natural Phytochemicals Containing Catechols as Functional Material for Sensors

by Filippo Silveri, Flavio Della Pelle, Daniel Rojas and Dario Compagnone

Chem. Proc. 2021, 5(1), 14; https://doi.org/10.3390/CSAC2021-10619 - 6 Jul 2021

Viewed by 949

Abstract

Phytochemical products start to be employed to assist 2D nanomaterials exfoliation. However, a lack of studies regarding the molecules involved and their capacity to give rise to functional materials is evident. In this work, a novel green liquid-phase exfoliation strategy (LPE) is proposed, [...] Read more.

Phytochemical products start to be employed to assist 2D nanomaterials exfoliation. However, a lack of studies regarding the molecules involved and their capacity to give rise to functional materials is evident. In this work, a novel green liquid-phase exfoliation strategy (LPE) is proposed, wherein a flavonoid namely catechin (CT) exclusively assists the exfoliation of bulk graphite in conductive water-soluble graphene nanoflakes (GF). Physicochemical and electrochemical methods have been employed to characterize the morphological, structural, and electrochemical features of the GF-CT. Surprisingly, the obtained GF-CT integrates well-defined electroactive quinoid adducts. The resulting few-layers graphene flakes intercalated with CT aromatic skeleton ensure strict electrical contact among graphene sheets, whereas the fully reversible quinoid electrochemistry (ΔE = 28 mV, Ip, a/Ip, c = ~1) is attributed to the residual catechol moieties, which work as an electrochemical mediator. The GF-CT intimate electrochemistry is generated directly during the LPE of graphite, not requiring any modification or electro-polymerization steps, resulting in stable (8 months) and reproducible material. The electrocatalytic activity has been proven towards hydrazine (HY) and β-nicotinamide adenine dinucleotide (NADH), a pollutant and a coenzyme, respectively. High sensitivity in extended linear ranges (HY: LOD = 0.1 µM, L.R. 0.5–150 µM; NADH: LOD = 0.6 µM, L.R. 2.5–200 µM) at low overpotential (+0.15 V) was obtained using amperometry, avoiding electrode-fouling. Improved performances, compared with graphite commercial electrodes and graphene exfoliated with a conventional surfactant, were obtained. The GF-CT was successfully used to perform the detection of HY and NADH (recoveries 94–107%, RSD ≤ 8%) in environmental and biological matrices, proving the material exploitability even in challenging analytical applications. On course studies aim to combine the intrinsic conductivity of the GF-CT with flexible substrates, in order to construct flexible electrodes/devices able to house GF-CT-exclusively composed conductive films. In our opinion, the proposed GF-CT elects itself as a cost-effective and sustainable material, particularly captivating in the (bio)sensoristics scenario. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

176 KiB

Open AccessAbstract

Validation of Spent Coffee Grounds as Precursors for the Development of Sustainable Carbon Dot-Based for Fe³⁺ Optical Sensing

by Diana M. A. Crista, Joaquim C. G. Esteves da Silva and Luís Pinto da Silva

Chem. Proc. 2021, 5(1), 17; https://doi.org/10.3390/CSAC2021-10452 - 30 Jun 2021

Viewed by 916

Abstract

Carbon dots (CDs) are fluorescence carbon-based nanomaterials that possess several properties such as photoluminescence, biocompatibility and good water solubility. They can be fabricated from a large variety of precursors; however, most available organic molecules are still expensive and their use or synthesis can [...] Read more.

Carbon dots (CDs) are fluorescence carbon-based nanomaterials that possess several properties such as photoluminescence, biocompatibility and good water solubility. They can be fabricated from a large variety of precursors; however, most available organic molecules are still expensive and their use or synthesis can lead to significant challenges to the environment and human health. It has become desirable to use biomass waste as alternative precursors in the synthesis of CDs, given that biomass waste material is ubiquitous, nontoxic, cheap and renewable. Spent coffee grounds (SCGs) are the residues of the treatment of coffee powder can be a potential carbon source to a more environmentally sustainable synthesis route. In this work, we fabricated SCG-based CDs via one-pot and solvent-free carbonization at 200 °C of solid samples generating particles with sizes between 2.1 and 3.9 nm. These carbon nanoparticles exhibited blue fluorescence and excitation-dependent emission of carbon dots with moderate quantum yields (2.9–5.8%). The presence of heavy metals in water resources, such as Fe³⁺, can lead to adverse health effects. SCG-based CDs showed potential for being used as optical Fe³⁺ optical sensors, with Life Cycle Assessment (LCA) studies validating the SCGs as more sustainable precursors than classical precursors, both considering a weight- or function-based functional unit. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

165 KiB

Open AccessAbstract

Voltammetric Detection of Mercury Ions at Poly(azulene-EDTA)-like Screen Printed Modified Electrodes

by George-Octavian Buica, Georgiana-Luiza Tatu (Arnold), Eleonora-Mihaela Ungureanu and Gabriela Geanina Vasile

Chem. Proc. 2021, 5(1), 23; https://doi.org/10.3390/CSAC2021-10630 - 7 Jul 2021

Viewed by 975

Abstract

In recent years, many applications have been developed for the detection of different toxic metals (As, Cd, Cu, Hg, Ni, Pb) in water samples. The classic analytical methods (ICP-MS, AAS with graphite furnace, ICP-EOS with ultrasonic nebulizer) not only require a longer analysis [...] Read more.

In recent years, many applications have been developed for the detection of different toxic metals (As, Cd, Cu, Hg, Ni, Pb) in water samples. The classic analytical methods (ICP-MS, AAS with graphite furnace, ICP-EOS with ultrasonic nebulizer) not only require a longer analysis time (pretreatment of the sample and analysis), but also the costs involved are higher as a result of expensive equipment, costs associated with the method validation process and qualified staff. The use of modified electrodes for trace metals analysi from wastewater samples represents a modern approach which can provide accurate, fast results with selectivity and sensitivity. Thus, here we present the development of the previously obtained glassy carbon-modified electrodes based on poly(2,2′-(ethane-1,2-diylbis(2-(azulen-2-ylamino)-2-oxoethyl)azanediyl))diacetic acid, (polyL) in laboratory-scale studies. In order to analyze Hg(II) ion content from aqueous samples, an assembly system made of carbon screen-printed modified electrodes (SPEs) modified with polyL selective complexing polymeric films coupled with a portable potentiostat was used. The detection of Hg(II) ions was accomplished by chemical accumulation in an open circuit followed by anodic stripping using the differential pulse voltammetry technique. The calibration curve of the analytical method was situated in the range of 20 ppb to 150 ppb (y = 0.0051x + 0.123, R² = 0.9951), with a detection limit of 6 ppb. The precision value for the lower limit of the calibration curve was 20%, while for the upper limit, the value was 10.5%. The novelty of the method consists not only of the low cost of the analysis, but also of the possibility to provide real-time reliable information about the Hg(II) concentration in wastewater using a small and portable device. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

202 KiB

Open AccessAbstract

Electrochemical Immunosensor for Simultaneous Determination of Emerging Autoimmune Disease Biomarkers in Human Serum

by Esther Sánchez-Tirado, Sara Guerrero, Araceli González-Cortés, Lourdes Agüí, Paloma Yáñez-Sedeño and José Manuel Pingarrón

Chem. Proc. 2021, 5(1), 24; https://doi.org/10.3390/CSAC2021-10437 - 30 Jun 2021

Viewed by 706

Abstract

Rheumatoid arthritis is an autoimmune disorder characterized by persistent erosive synovitis, systemic inflammation and the presence of autoantibodies, which play an important role in inducing inflammation and joint damage, releasing pro-inflammatory cytokines from monocytes and macrophages [¹,²]. Likewise, neutrophil [...] Read more.

Rheumatoid arthritis is an autoimmune disorder characterized by persistent erosive synovitis, systemic inflammation and the presence of autoantibodies, which play an important role in inducing inflammation and joint damage, releasing pro-inflammatory cytokines from monocytes and macrophages [¹,²]. Likewise, neutrophil activating protein-2 (CXCL7) is a platelet-derived growth factor belonging to the CXC chemokine subfamily, which is expressed in serum, synovial fluid and synovial tissue of patients developing rheumatoid arthritis during the first twelve weeks, being useful to reflect local pathological changes [³]. Besides, matrix metalloproteinase-3 (MMP-3), which is induced by inflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-α) in rheumatoid synovium, degrades several extracellular matrix components of cartilage and plays central roles in rheumatoid joint destruction [⁴]. Therefore, monitoring serum CXCL7 and MMP-3 levels is useful for predicting the disease activity in rheumatoid arthritis. In this work, the construction and analytical performance of a dual electrochemical platform for the simultaneous determination of CXCL7 and MMP-3 is described. After the optimization of experimental variables involved in the preparation and implementation of the biosensor, the analytical usefulness of the developed configuration was demonstrated by its application to the determination of these biomarkers in serum samples from healthy individuals and patients with rheumatoid arthritis. To carry out the simultaneous determination of CXCL7 and MMP3 in human serum, just a fifty-fold sample dilution in PBS of pH 7.4 was required. In addition, the results obtained using the dual immunosensor were compared with those provided by the respective ELISA immunoassays, yielding no significant differences between the two methods. It is important to highlight that reagents consumption, four times smaller using the dual immunosensor than that required in the ELISA protocol, and an assay time of 2 h 50 min versus almost 5 h, counted in both cases after incubation of the capture antibody, are advantageous features of the dual immunosensor [⁵]. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

165 KiB

Open AccessAbstract

From Single Nanowires to Smart Systems: Different Ways to Assess Food Quality

by Matteo Tonezzer, Franco Biasioli and Flavia Gasperi

Chem. Proc. 2021, 5(1), 29; https://doi.org/10.3390/CSAC2021-10605 - 5 Jul 2021

Viewed by 872

Abstract

Recently, low-dimensional (1D, 2D) nanostructured materials have been attracting more and more interest as building blocks for innovative systems. Metal oxide nanowires are one of the most widely used materials for solid-state gas sensors, as they are simple to make, inexpensive, and sensitive [...] Read more.

Recently, low-dimensional (1D, 2D) nanostructured materials have been attracting more and more interest as building blocks for innovative systems. Metal oxide nanowires are one of the most widely used materials for solid-state gas sensors, as they are simple to make, inexpensive, and sensitive to a wide range of gases and volatiles. Unfortunately, their broad sensitivity has a price to pay, which is very low selectivity. Fortunately, this flaw is not a problem for all applications. Where the boundary conditions are defined and “simple” (only the presence of a target gas is expected, without any interfering gases), a single traditional chemiresistor may be the best choice, while in cases where the variables are many, it is better to use an intelligent system. In this paper, we will show a resistive sensor based on a single SnO₂ nanowire which, working at three temperatures (200, 250, and 300 °C), is able to detect tens of ppb of ammonia (30 ppb at 300 °C). The limit of detection (LoD) was calculated as 3 N/S, where N is the standard deviation of the sensor signal in air and S is the sensor sensitivity. We will show that the performance of this nanosensor is excellent and can be used in various applications, including agri-food quality monitoring. We will demonstrate that the SnO₂ nanowire in a thermal gradient can act as a nano-electronic nose thanks to machine learning algorithms. The single nanowire-based sensor can estimate the total viable count with an error of 2.32% on mackerel fish samples stored at room temperature (25 °C) and in a fridge (4 °C). The integration of such a small (less than one square mm) and cheap device into the food supply chain would greatly reduce waste and the frequency of food poisoning. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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160 KiB

Open AccessAbstract

Core Modulation of Porphyrins for Chemical Sensing

by Karolis Norvaiša and Mathias Otto Senge

Chem. Proc. 2021, 5(1), 32; https://doi.org/10.3390/CSAC2021-10417 - 30 Jun 2021

Viewed by 836

Abstract

The inner core system of metal-free (‘free base’) porphyrins has continually served as a ligand for various metal ions, but it was only recently studied in organocatalysis due its highly tunable basicity. Highly conjugated porphyrin systems offer spectrophotometric sensitivity toward geometrical and/or electronic [...] Read more.

The inner core system of metal-free (‘free base’) porphyrins has continually served as a ligand for various metal ions, but it was only recently studied in organocatalysis due its highly tunable basicity. Highly conjugated porphyrin systems offer spectrophotometric sensitivity toward geometrical and/or electronic changes and, thus, utilizing the porphyrin core for the selective detection of substrates in solution offers significant potential for a multitude of applications. However, solvation and dilution drastically affect weak interactions by dispersing the binding agent to its surroundings. Thus, the spectroscopic detection of N–H···X-type binding in porphyrin solutions is almost impossible without especially designing the binding pocket. Here, we present the first report on the spectroscopic detection of N–H···X-type interplay in porphyrins formed by weak interactions. Protonated 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(2-aminophenyl) porphyrin contains coordination sites for the selective binding of charge-bearing analytes, revealing characteristic spectroscopic responses. While electronic absorption spectroscopy proved to be a particularly useful tool for the detection of porphyrin–analyte interactions in the supramolecular complexes, X-ray crystallography helped to pinpoint the orientation, flexibility, and encapsulation of substrates in the corresponding atropisomers. This charge-assisted complexation of analytes in the anion-selective porphyrin inner core system is ideal for the study of atropisomers using high-resolution NMR, since it reduces the proton exchange rate, generating static proton signals. Therefore, we were able to characterize all four rotamers of the nonplanar 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(2-aminophenyl) porphyrin by performing 1D and 2D NMR spectroscopic analyses of host-guest systems consisting of benzenesulfonic acid (BSA) and each porphyrin atropisomer. Lastly, a detailed assignment of the symmetry operations that are unique to porphyrin atropisomers allowed us to accurately identify the rotamers using NMR techniques only. Overall, the N–H···X-type interplay in porphyrins formed by weak interactions that form restricted H-bonding complexes is shown to be the key to unravelling the atropisomeric enigma. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

164 KiB

Open AccessAbstract

Plasmonic Hydrogel Nanocomposites with Combined Optical and Mechanical Properties for Biochemical Sensing

by Bruno Miranda, Rosalba Moretta, Selene De Martino, Principia Dardano, Ilaria Rea, Carlo Forestiere and Luca De Stefano

Chem. Proc. 2021, 5(1), 34; https://doi.org/10.3390/CSAC2021-10467 - 30 Jun 2021

Viewed by 956

Abstract

Localized surface plasmon resonance (LSPR) and metal-enhanced-fluorescence (MEF)-based optical biosensors exhibit unique properties compared to other sensing devices that can be exploited for the design point-of-care (POC) diagnostic tools [1]. Plasmonic devices exploit the capability of noble-metal nanoparticles of absorbing light at a [...] Read more.

Localized surface plasmon resonance (LSPR) and metal-enhanced-fluorescence (MEF)-based optical biosensors exhibit unique properties compared to other sensing devices that can be exploited for the design point-of-care (POC) diagnostic tools [1]. Plasmonic devices exploit the capability of noble-metal nanoparticles of absorbing light at a well-defined wavelength. The increasing request for wearable, flexible and easy-to-use diagnostic tools has brought to the development of plasmonic nanocomposites, whose peculiar performances arise from the combination of the optical properties of plasmonic nanoparticles and mechanical properties of the polymeric matrix in which they are embedded [2,3]. An optical platform based on spherical gold nanoparticles (AuNPs) embedded in high molecular weight poly-(ethylene glycol) diacrylate (PEGDA) hydrogel is proposed. PEGDA hydrogel represents a biocompatible, flexible, transparent polymeric network to design wearable, 3D, plasmonic biosensors for the detection of targets with different molecular weights for the early diagnosis of disease. The swelling capability of PEGDA is directly correlated to the plasmonic decoupling of AuNPs embedded within the matrix. A study on the effect of swelling on the optical response of the PEGDA/AuNPs composites was investigated by using a biorecognition layer/target model system. Specifically, after the in situ chemical modification of the AuNPs within the hydrogel, the interaction biotin-streptavidin is monitored within the 3D hydrogel network. Additionally, metal-enhanced fluorescence is observed within the PEGDA/AuNPs nanocomposites, which can be exploited to achieve an ultra-low limit of detection. LSPR signal was monitored via transmission mode customized setup and MEF signal was detected via fluorescence and confocal microscopes. Label-free (LSPR-based) and fluorescence (MEF-based) signals of a high molecular weight target analyte were successfully monitored with relatively high resolutions and low limits of detection compared to the standard polymeric optical platforms available in the literature. The optimized platform could represent a highly reproducible and low-cost novel biosensor to be applied as a POC diagnostic tool in healthcare and food monitoring applications. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

155 KiB

Open AccessAbstract

Conductive Electrospun Nanofibers for Multifunctional Portable Devices

by Antonio Fotia, Patrizia Frontera, Lucio Bonaccorsi and Angela Malara

Chem. Proc. 2021, 5(1), 37; https://doi.org/10.3390/CSAC2021-10634 - 7 Jul 2021

Viewed by 781

Abstract

The need to perform in situ sensing measurements lead to the development of innovative and smart field-portable devices. The advantages of such systems are remarkable since they are mainly battery-powered, lightweight and easy to carry and keep. Moreover, field-portable devices are easy to [...] Read more.

The need to perform in situ sensing measurements lead to the development of innovative and smart field-portable devices. The advantages of such systems are remarkable since they are mainly battery-powered, lightweight and easy to carry and keep. Moreover, field-portable devices are easy to use and are able to give fast sensing responses. In the last few years, many efforts have been made in the development of new performing systems and the advantageous use of nanofibrous materials was assessed. To this purpose, the electrospinning has been recognized as the most powerful and facile technique for generating uniform nanofibers with controlled dimension and morphology. When conductive polymers are electrospun, very interesting electrical properties can be obtained along with the well-known ones that are typical of nanofibers. Among these polymers, polyaniline has been extensively used. In this work, an innovative hybrid material based on polyaniline/polyvinyl acetate/graphene oxide nanofibers was developed and tested as a sensor toward the detection of contaminants in aqueous media. Nanofibers, in the form of a compact mat, were deposited onto a support with suitable electrical contacts. Measurements were performed exploiting the excellent electrical properties of the realized nanofibers in both direct and alternating currents. When a direct current was used, the change in the nanofibers’ resistance value was registered upon exposure to contaminated aqueous solutions and used to determine the presence or absence of contaminants, whereas when tests were performed with an alternating current, the quantitative determination of single species in contaminated solutions was also possible. In this way, by integrating the two different measurement methodologies, an opportunely designed multifunctional portable device will be developed for both qualitative and quantitative contaminants determinations. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

451 KiB

Open AccessAbstract

Optical Characterization of Acetone-Sensitive Thin Films of poly(vinyl alcohol)-g-poly(methyl acrylate)

by Katerina Lazarova, Silvia Bozhilova, Sijka Ivanova, Darinka Christova and Tsvetanka Babeva

Chem. Proc. 2021, 5(1), 41; https://doi.org/10.3390/CSAC2021-10416 - 30 Jun 2021

Viewed by 838

Abstract

Organic solvents are widely used as reaction media and/or for the separation and purification of synthetic products in chemical and pharmaceutical industries [...] Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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173 KiB

Open AccessAbstract

The Inhibition Study of Cytochrome bd Oxidase Using the Enzyme-Based Electrochemical Sensor

by Iryna Makarchuk, Anton Nikolaev, Alexander Thesseling, Lisa Dejon, Daniel Lamberty, Laura Stief, Thorsten Friedrich, Petra Hellwig, Hamid R. Nasiri and Frederic Melin

Chem. Proc. 2021, 5(1), 45; https://doi.org/10.3390/CSAC2021-10555 - 1 Jul 2021

Viewed by 1067

Abstract

Membrane proteins that participate in multiple vital functions of every living organism such as transport, signaling and respiration, provide 80 to 90% of the relevant targets for the pharmaceutical industries. The family of cytochrome bd oxidase enzymes is of great interest for the [...] Read more.

Membrane proteins that participate in multiple vital functions of every living organism such as transport, signaling and respiration, provide 80 to 90% of the relevant targets for the pharmaceutical industries. The family of cytochrome bd oxidase enzymes is of great interest for the development of future antibiotics as they are found only in the respiratory chain of the prokaryotes and they are believed to be involved in bacterial adaptability mechanisms. They catalyze the reduction of molecular oxygen in water and oxidation of quinols and contribute to the proton motive force required for ATP synthesis. Due to their hydrophobic nature, membrane proteins are more difficult to handle than soluble proteins. Protein film voltammetry is a very convenient technique, because it allows for working at a very low concentration and for optimizing the electrode surface to the nature of the enzyme. Here, we have developed a biosensor for the study of terminal oxidases based on their immobilization on gold nanoparticles modified with a self-assembled monolayer of thiols. The stability of the protein films can be optimized by varying the nature of thiols and amount of lipids. This enzyme-based electrochemical sensor was successfully used for the inhibition screening of a target-focused library of 34 compounds which belong to the families of quinones, naphthoquinones, phenols, quinolones, coumarins and flavonoids against cytochrome bd oxidase. Moreover, the developed device was applied for the study of the catalytic reaction of the enzyme with small gaseous signaling molecules. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

160 KiB

Open AccessAbstract

Europium-Doped Ceria Nanocrystals as Nanozyme Fluorescent Probes for Biosensing

by Ali Othman, Akhtar Hayat and Silvana Andreescu

Chem. Proc. 2021, 5(1), 53; https://doi.org/10.3390/CSAC2021-10549 - 1 Jul 2021

Viewed by 889

Abstract

Molecular nanoprobes with intrinsic enzyme-like activity represent a new wave of technology for rapid and sensitive detection of molecular targets. This work reports synthesis and characterization of novel and well-dispersed europium-doped ceria nanocrystals (EuCe NCs) with self-integrated catalytic and fluorescence sensing functions. The [...] Read more.

Molecular nanoprobes with intrinsic enzyme-like activity represent a new wave of technology for rapid and sensitive detection of molecular targets. This work reports synthesis and characterization of novel and well-dispersed europium-doped ceria nanocrystals (EuCe NCs) with self-integrated catalytic and fluorescence sensing functions. The NCs have an average size of ∼5 nm and exhibit bright and stable fluorescence for more than 6 months in aqueous media. Their dual cooperative function as both a catalyst and fluorescent probe was explored to develop a universally applicable fluorescence-based biosensing method to monitor enzyme reactions and quantitatively measure clinically relevant molecules. Sensing capabilities are demonstrated for detection of H₂O₂, glucose/glucose oxidase, lactate/lactate oxidase, phosphatase activity, and the catecholamine neurotransmitter, dopamine. Results indicate that EuCe NCs not only provide high enzyme-mimetic activity, but also impart direct fluorescence sensing ability enabling all-in-one recognition, catalytic amplification, and the detection of biomolecular targets. The EuCe nanozyme offers a stable alternative to the more complex systems based on the combined use of natural enzymes and fluorescent dyes. The high stability and fluorescence detection capabilities demonstrate that EuCe NCs have the potential to be used as a generic platform in chemical and biological sensing and bioimaging applications. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

156 KiB

Open AccessAbstract

Antimony Tin Oxide—Prussian Blue Screen-Printed Electrodes for Electrochemical Sensing of Potassium Ions

by Cecilia Lete, Mariana Marin, Francisco Javier del Campo, Ioana Diaconu and Stelian Lupu

Chem. Proc. 2021, 5(1), 59; https://doi.org/10.3390/CSAC2021-10639 - 1 Jul 2021

Viewed by 825

Abstract

In this work, the characterization and the electro-analytical applications of antimony tin oxide (ATO)–Prussian blue (PB) screen printed electrodes (SPE) are presented. The ATO conducting particles have been used recently in the development of screen-printed electrodes due to their excellent spectroelectrochemical properties. PB [...] Read more.

In this work, the characterization and the electro-analytical applications of antimony tin oxide (ATO)–Prussian blue (PB) screen printed electrodes (SPE) are presented. The ATO conducting particles have been used recently in the development of screen-printed electrodes due to their excellent spectroelectrochemical properties. PB is a transition metal hexacyanoferrate with high electrocatalytic properties towards various biologically active compounds like hydrogen peroxide, besides its outstanding electrochromic properties. A combination of ATO and PB ingredients into a screen-printing paste provided a versatile and cost-effective way in the development of novel electrode materials for electrochemical sensing. The ATO-PB electrode material displayed good electrochemical properties demonstrated by means of cyclic voltammetry and electrochemical impedance measurements. In addition, the PB provided a high selectivity towards potassium ions in solution due to its zeolitic structures and excellent redox behavior. The cyclic voltammetric responses recorded at the ATO-PB-SPE device in the presence of potassium ions revealed a linear dependence of the cathodic peak current and cathodic peak potential of the Prussian blue/Everitt’s salt redox system on the potassium concentrations ranging from 0.1 to 10 mM. This finding could be exploited in the development of an electrochemical sensor for electro-inactive chemical species. The potential application of the ATO-PB electrode in the electrochemical sensing of electro-active species like caffeic acid was also studied. An increase of the anodic peak current of the PB/ES redox wave in the presence of caffeic acid was observed. These results point out to the potential analytical applications of the ATO-PB electrode in the sensing of both electro-active and electro-inactive species. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

178 KiB

Open AccessAbstract

Determination of Chemical Oxygen Demand (COD) Using Nanoparticle-Modified Voltammetric Sensors and Electronic Tongue Principles

by Qing Wang and Manel del Valle

Chem. Proc. 2021, 5(1), 81; https://doi.org/10.3390/CSAC2021-10442 - 30 Jun 2021

Viewed by 1012

Abstract

Chemical Oxygen Demand (COD) is a widely used parameter in analyzing and controlling the degree of pollution in water. COD is defined as the amount of molecular oxygen (in milligrams of O₂) required to decompose all the organic compounds in 1 [...] Read more.

Chemical Oxygen Demand (COD) is a widely used parameter in analyzing and controlling the degree of pollution in water. COD is defined as the amount of molecular oxygen (in milligrams of O₂) required to decompose all the organic compounds in 1 L of aqueous solution to carbon dioxide and water. There are many methods reported for COD determination, such as the conventional dichromate titration method. Electro-oxidizing the organic contaminants to completely transform them into CO₂ and H₂O using sensors is considered the best method for COD estimation. Increasing attention has been paid to electrochemical methods because they are highly sensitive, time-saving, low-cost, and easy to operate. In this sense, copper electrodes have been reported based on the fact that copper in alkaline media acts as a powerful electrocatalyst for the oxidation of aminoacids and carbohydrates, which are believed to be the major culprits for organic pollution. Cyclic voltammetry was the technique used to obtain the voltammetric responses. It is common for different organic compounds to show different cyclic voltammogram shapes and current intensities in different concentrations. In this work, four kinds of electrodes modified with copper (Cu)/copper oxide (CuO)/nickel copper alloy (Ni Cu alloy) nanoparticles were studied for COD analysis; this was done by employing the cyclic voltammetry technique, which involved a Nafion film-covered electrodeposited CuO/Cu nanoparticle electrode (E1), a Cu nanoparticle–graphite composite electrode (E2), a CuO nanoparticle–graphite composite electrode (E3), and a Ni Cu alloy nanoparticle–graphite composite electrode (E4). The COD values were determined via the plotted calibration of COD values vs. the current intensity. Glucose, glycine, potassium hydrogen phthalate (KHP), and ethylene glycol—which show different reducibilities—were chosen as the standard substances to play the role of organic contaminants with different degradation difficulties. From the obtained cyclic voltammograms, we can see that glucose is very easily oxidized by those four electrodes, with electrode E1 displaying the best performance, with a linear range of 19.2~1120.8 mg/L and limit of detection of 27.5 mg/L (calculated based on the formula 3σ/k). In contrast, it is very difficult for the compound KHP to be oxidized by these four electrodes. Nevertheless, the obtained voltammetric profiles presented different shapes with the tested organic compounds, suggesting these four electrodes can compose an electronic tongue array for multivariate analysis. As a result, the main component of river samples—whose degradation could be easy or difficult—can be evaluated via the PCA technique. This evaluation is very helpful for the accuracy of COD detection. The resulting sensor-based method demonstrates great potential not only for estimating the precise value of COD, but for predicting the difficulty of its degradation; this represents a simple, fast, and clean methodology, which is perfectly suited to the present demands of green techniques. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

169 KiB

Open AccessAbstract

Detection of Indoor Air Pollutants Using Reactive Sputtering/GLAD of Tin Oxide Thin Films

by Achraf El Mohajir, Jean-Baptiste Sanchez, Mohammad Arab Pour Yazdi, Olivier Heintz and Nicolas Martin

Chem. Proc. 2021, 5(1), 89; https://doi.org/10.3390/CSAC2021-10548 - 1 Jul 2021

Viewed by 751

Abstract

Indoor air quality is a topic of major importance for public health. Among the numerous chemical compounds that can be found in indoor air, BTEX (i.e., benzene, toluene, ethylbenzene, and xylene) is considered one of the most toxic volatile organic compounds (VOCs). The [...] Read more.

Indoor air quality is a topic of major importance for public health. Among the numerous chemical compounds that can be found in indoor air, BTEX (i.e., benzene, toluene, ethylbenzene, and xylene) is considered one of the most toxic volatile organic compounds (VOCs). The present contribution is focused on the use of an original approach to produce nanostructured materials based on tin oxide with unexplored features, especially for gas sensors. In this work, we combine two physical vapor deposition techniques based, first, on a pulsing injection of the reactive gas during the deposition and second focused on the glancing angle deposition (GLAD) technique, which enables the structuring of various architectures. These active layers are deposited on a micro-hotplate to produce micro-chemical gas sensors for the detection of BTEX. Here, we have demonstrated the utility of using the GLAD deposition technique and the role of sputtering pressure in obtaining porous sensitive thin films. In particular, we established relationships between deposition parameters and gas sensing performances. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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186 KiB

Open AccessAbstract

Intrinsically Coloured Red Aromatic Polyamides

by Patricia Peredo-Guzmán, Miriam Trigo-López, Saúl Vallejos, Félix García and José Miguel García

Chem. Proc. 2021, 5(1), 91; https://doi.org/10.3390/CSAC2021-10421 - 30 Jun 2021

Cited by 1 | Viewed by 723

Abstract

Aromatic polyamides or aramids are materials with exceptional thermal and mechanical properties. For this reason, they are considered high-performance materials with many applications in fields such as civil security (bullet-proof body armour or fire, chemical, and saw protection suits), transport (automotive and aerospace), [...] Read more.

Aromatic polyamides or aramids are materials with exceptional thermal and mechanical properties. For this reason, they are considered high-performance materials with many applications in fields such as civil security (bullet-proof body armour or fire, chemical, and saw protection suits), transport (automotive and aerospace), and civil engineering, among many others. The remarkable properties arise from the high cohesive energy due to their chemical structure, including the rigidity of the main chain due to the wholly aromatic structure conjugated with the amide groups, the high average bond energy, and a strong and highly directional interchain hydrogen bonds between the amide moieties. Although the natural yellowish colour of the fibres is used, generally, most of the applications require coloured fibres. However, aramid fibres have poor dyeing properties for the same reasons that make them thermally and mechanically resistant, and traditional dyeing methods, such as dope dyeing, are inefficient and aggressive, which impairs the fibres’ properties. The ideal colour fastness of fibres is achieved by intrinsically, inherently, or self-coloured polymers by introducing a dye motif or chromophore monomer in the chemical structure of the polymer. In addition, the colour hue can be controlled by tuning the chromophore monomer molar content in the final composition. In previous research, we successfully obtained inherently blue-coloured aramids, with blue chromophore motifs unable to migrate and evenly distribute along the polymer chain and maintain their high-performance properties, and our aim now is to obtain red-coloured aramids prepared in the same fashion. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1798 KiB

Open AccessProceeding Paper

Sensitive and Selective Voltammetric Sensors for the Simultaneous Quantification of Natural Phenolic Antioxidants in Cognac and Brandy

by Guzel Ziyatdinova and Ekaterina Guss

Chem. Proc. 2021, 5(1), 1; https://doi.org/10.3390/CSAC2021-10420 - 30 Jun 2021

Viewed by 1025

Abstract

Aged distilled beverages (cognac and brandy) contain phenolic antioxidants as their quality markers. Voltammetric sensors based on the carbon nanotubes and electropolymerized pyrocatechol violet (PCV) or p-aminobenzoic acid (ABA) were developed for the simultaneous determination of the phenolic antioxidants in cognac and [...] Read more.

Aged distilled beverages (cognac and brandy) contain phenolic antioxidants as their quality markers. Voltammetric sensors based on the carbon nanotubes and electropolymerized pyrocatechol violet (PCV) or p-aminobenzoic acid (ABA) were developed for the simultaneous determination of the phenolic antioxidants in cognac and brandy. The polymerization conditions of PCV and ABA were optimized. Sensors allow for the simultaneous sensitive determination of gallic and ellagic acids as well as syringaldehyde and vanillin. The analytical characteristics are improved vs. other modified electrodes. The sensors show selectivity in the presence of typical interferences and other natural phenolics. The sensors that were developed were tested on cognac and brandy samples. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1755 KiB

Open AccessProceeding Paper

Simultaneous Quantification of Four Principal NSAIDs through Voltammetry and Artificial Neural Networks Using a Modified Carbon Paste Electrode in Pharmaceutical Samples

by Guadalupe Yoselin Aguilar-Lira, Prisciliano Hernandez, Giaan Arturo Álvarez-Romero and Juan Manuel Gutiérrez

Chem. Proc. 2021, 5(1), 3; https://doi.org/10.3390/CSAC2021-10450 - 30 Jun 2021

Cited by 2 | Viewed by 1192

Abstract

This work describes the development of a novel and low-cost methodology for the simultaneous quantification of four main nonsteroidal anti-inflammatory drugs (NSAIDs) in pharmaceutical samples using differential pulse voltammetry coupled with an artificial neural network model (ANN). The working electrode used as a [...] Read more.

This work describes the development of a novel and low-cost methodology for the simultaneous quantification of four main nonsteroidal anti-inflammatory drugs (NSAIDs) in pharmaceutical samples using differential pulse voltammetry coupled with an artificial neural network model (ANN). The working electrode used as a detector was a carbon paste electrode (CPE) modified with multi-wall carbon nanotubes (MWCNT-CPE). The specific voltammetric determination of the drugs was performed by cyclic voltammetry (CV). Some characteristic anodic peaks were found at potentials of 0.446, 0.629, 0.883 V related to paracetamol, diclofenac, and aspirin. For naproxen, two anodic peaks were found at 0.888 and 1.14 V and for ibuprofen, an anodic peak was not observed at an optimum pH of 10 in 0.1 mol L⁻¹ Britton–Robinson buffer. Since these drug’s oxidation process turned out to be irreversible and diffusion-controlled, drug quantification was carried out by differential pulse voltammetry (DPV). The Box Behnken design technique’s optimal parameters were: step potential of 5.85 mV, the amplitude of 50 mV, period of 750 ms, and a pulse width of 50 ms. A data pretreatment was carried out using the Discrete Wavelet Transform using the db4 wavelet at the fourth decomposition level applied to the voltammetric records obtained. An ANN was built to interpret the obtained approximation coefficients of voltammograms generated at different drug concentrations to calibrate the system. The ANN model’s architecture is based on a Multilayer Perceptron Network (MLP) that employed a Bayesian regularization training algorithm. The trained MLP achieves significant R values for the test data to simultaneous quantification of the four drugs in the presence of aspirin. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1498 KiB

Open AccessProceeding Paper

An Inkjet-Printed Amperometric H₂S Sensor for Environmental Applications

by Franc Paré, Rebeca Castro, Xavier Guimera, Gemma Gabriel and Mireia Baeza

Chem. Proc. 2021, 5(1), 4; https://doi.org/10.3390/CSAC2021-10462 - 30 Jun 2021

Viewed by 1141

Abstract

Hydrogen sulfide (H₂S) is a highly toxic chemical capable of causing severe health issues. Due to its environmental impact, it is critical to create effective methods for its monitoring. Inkjet printing technology has become an alternative for sensor fabrication because it [...] Read more.

Hydrogen sulfide (H₂S) is a highly toxic chemical capable of causing severe health issues. Due to its environmental impact, it is critical to create effective methods for its monitoring. Inkjet printing technology has become an alternative for sensor fabrication because it is an economic, fast, and reproducible method for mass producing micro-electrodes. Herein, a miniaturized 25 mm² inkjet-printed amperometric sensor is presented. A gold electrode coupled with a silver track was modified with two inks: single-walled carbon nanotubes (SWCNTs) and a mixture of SCWCNTs and poly(vinyl alcohol) (PVA). Morphological and electrochemical properties were studied, as well as H₂S sensor performance. This approach is a suitable option for environmental H₂S tracking. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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611 KiB

Open AccessProceeding Paper

Molecular Emitters as a Tunable Light Source for Optical Multisensor Systems

by Anastasiia Surkova, Aleksandra Paderina, Andrey Legin, Elena Grachova and Dmitry Kirsanov

Chem. Proc. 2021, 5(1), 5; https://doi.org/10.3390/CSAC2021-10611 - 6 Jul 2021

Viewed by 1031

Abstract

In this study, optical multisensor systems based on molecular emitters as a light source are introduced. To obtain such light sources, cyclometalated Ir(III) complexes and Cu(I)-based complexes were synthetized and investigated. Since each complex has its own emission spectrum in the visible range, [...] Read more.

In this study, optical multisensor systems based on molecular emitters as a light source are introduced. To obtain such light sources, cyclometalated Ir(III) complexes and Cu(I)-based complexes were synthetized and investigated. Since each complex has its own emission spectrum in the visible range, it is possible to choose an appropriate set of emitters for specific analytical tacks. The developed analytical device was successfully applied for fluoride and phosphate quantification in surface water. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1532 KiB

Open AccessProceeding Paper

Gold Nanoparticles Functionalized with Mercaptosuccinic Acid as a Means for Detecting Fe(III) Ions

by Nadezhda S. Komova, Ksenya V. Serebrennikova, Anna N. Berlina, Svetlana M. Pridvorova, Anatoly V. Zherdev and Boris B. Dzantiev

Chem. Proc. 2021, 5(1), 6; https://doi.org/10.3390/CSAC2021-10624 - 7 Jul 2021

Viewed by 1464

Abstract

The application of mercaptosuccinic acid-capped gold nanoparticles as a sensing probe for the colorimetric detection of Fe(III) is reported. The well-dispersed gold nanoparticles (AuNPs) with a diameter of around 20 nm were obtained by a one-step reaction of tetrachloroauratic acid with mercaptosuccinic acid [...] Read more.

The application of mercaptosuccinic acid-capped gold nanoparticles as a sensing probe for the colorimetric detection of Fe(III) is reported. The well-dispersed gold nanoparticles (AuNPs) with a diameter of around 20 nm were obtained by a one-step reaction of tetrachloroauratic acid with mercaptosuccinic acid (MSA) as a reducing and capping agent, respectively. Fe(III) reportedly causes the aggregation of prepared MSA-capped AuNPs followed by a change in color and a shift to long wavelengths in the absorbance spectra. The resulting method allows for a visual and spectrophotometric Fe(III) determination with detection limits of 30 ng/mL and 23 ng/mL, respectively. MSA-capped AuNPs have been used as sensing probes for the detection of Fe(III) in drinking water samples with a detection limit that is much lower than the maximum permissible level of Fe(III) specified by official regulations (300 ng/mL). Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1207 KiB

Open AccessProceeding Paper

Implementation of Metallic Film Electrodes for Catalytic Adsorptive Stripping Voltammetric Determination of Germanium(IV)

by Agnieszka Królicka, Jerzy Zarębski and Andrzej Bobrowski

Chem. Proc. 2021, 5(1), 7; https://doi.org/10.3390/CSAC2021-10484 - 30 Jun 2021

Viewed by 953

Abstract

In the present work, it has been shown that bismuth film electrodes deposited on screen-printed carbon supports could be successfully used to provide well-shaped, sensitive and reproducible catalytic adsorptive stripping signals of Ge(IV) in the presence of catechol and V(IV)-HEDTA (HEDTA-N-hydroxyethyl-ethylene diamine-triacetic acid) [...] Read more.

In the present work, it has been shown that bismuth film electrodes deposited on screen-printed carbon supports could be successfully used to provide well-shaped, sensitive and reproducible catalytic adsorptive stripping signals of Ge(IV) in the presence of catechol and V(IV)-HEDTA (HEDTA-N-hydroxyethyl-ethylene diamine-triacetic acid) complex. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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2231 KiB

Open AccessProceeding Paper

Tunable Electrochemical Sensors Based on Carbon Nanocomposite Materials towards Enhanced Determination of Cadmium, Lead and Copper in Water

by Laia L. Fernández, Julio Bastos-Arrieta, Cristina Palet and Mireia Baeza

Chem. Proc. 2021, 5(1), 8; https://doi.org/10.3390/CSAC2021-10456 - 30 Jun 2021

Viewed by 1048

Abstract

Many carbon materials are well-known conductive materials, widely used in the fabrication of composite electrodes. In this work, diverse allotropic forms of carbon such as graphite, MWCNTs and rGO were tested. Furthermore, these materials allow the construction of cheaper, smaller, portable, reliable and [...] Read more.

Many carbon materials are well-known conductive materials, widely used in the fabrication of composite electrodes. In this work, diverse allotropic forms of carbon such as graphite, MWCNTs and rGO were tested. Furthermore, these materials allow the construction of cheaper, smaller, portable, reliable and easy-to-use devices, which can be easily modified. The above-mentioned composite electrodes were developed for metal analysis in water such as Cu, Cd and Pb that, at a high concentration, can have consequences on human health. SWASV is the selected technique. It would be ideal to exploit the potential properties of mercury for metal detection by tuning the electrode’s surface. Due to mercury’s hazardous properties and to reduce the amount of this substance used in polarography, the use of nanoparticles is a good option due to their properties. Mercury nanoparticles were used to modify the surface of the composite electrodes to improve electroanalytical sensor response. For this reason, using these modified composite electrodes can lower detection limits and widen the linear range that can be achieved for Cd (0.05–1 mg·L⁻¹) and Pb (0.045–1 mg·L⁻¹). However, for Cu (0.114–1.14 mg·L⁻¹), meaningful variations were not observed compared to the bare electrode. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1081 KiB

Open AccessProceeding Paper

Colorimetric Determination of Nitrate after Reduction to Nitrite in a Paper-Based Dip Strip

by Amer Charbaji, Hojat Heidari-Bafroui, Nasim Rahmani, Constantine Anagnostopoulos and Mohammad Faghri

Chem. Proc. 2021, 5(1), 9; https://doi.org/10.3390/CSAC2021-10459 - 30 Jun 2021

Cited by 2 | Viewed by 3957

Abstract

Paper-based microfluidic technology is a relatively new field of research that provides low-cost platforms and sensors for point-of-care diagnostics. While the majority of research in this field has been for biomedical applications, more and more paper-based devices and platforms are being designed and [...] Read more.

Paper-based microfluidic technology is a relatively new field of research that provides low-cost platforms and sensors for point-of-care diagnostics. While the majority of research in this field has been for biomedical applications, more and more paper-based devices and platforms are being designed and developed for environmental applications, such as water quality monitoring and assessment. One such application is the detection of nitrate in water samples. Colorimetric detection of nitrate by paper-based devices using the Griess assay requires the reduction of nitrate to nitrite before undergoing the reaction. In this paper, we measured the performance of a paper-based dip strip for detecting nitrate and nitrite by calculating its limit of detection and limit of quantification. We also calculated the reduction efficiency of vanadium (III) chloride in the dip strip for detecting nitrate. Our results show that the reduction time of nitrate via vanadium (III) chloride is much longer than that when using zinc microparticles. Our results also show that the performance of the dip strip using vanadium (III) chloride for nitrate detection is not as good as more intricate paper-based devices that have a separate reaction zone with zinc microparticles. The limits of detection and quantification calculated were 3.352 and 7.437 ppm, and the nitrate reduction efficiency varied over the range of nitrate concentrations tested. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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792 KiB

Open AccessProceeding Paper

A Voltammetric Nanodiamond-Coated Screen-Printed Immunosensor for The Determination of a Peanut Allergen in Commercial Food Products

by André Carvalho, Maria Freitas, Henri P. A. Nouws and Cristina Delerue-Matos

Chem. Proc. 2021, 5(1), 10; https://doi.org/10.3390/CSAC2021-10458 - 30 Jun 2021

Cited by 1 | Viewed by 1148

Abstract

A voltammetric immunosensor was developed to quantify a major peanut allergen, Ara h 1, using screen-printed carbon electrodes (SPCE) as transducers. A sandwich-type immunoassay was performed on nanodiamond-coated SPCEs using an alkaline phosphatase-labeled detection antibody and a mixture containing an enzymatic substrate (3-indoxyl [...] Read more.

A voltammetric immunosensor was developed to quantify a major peanut allergen, Ara h 1, using screen-printed carbon electrodes (SPCE) as transducers. A sandwich-type immunoassay was performed on nanodiamond-coated SPCEs using an alkaline phosphatase-labeled detection antibody and a mixture containing an enzymatic substrate (3-indoxyl phosphate) and silver nitrate. The immunological interaction was detected through the (linear sweep) voltammetric stripping of the enzymatically deposited silver. The immunosensor’s applicability was evaluated by analyzing breakfast cereals, cookies, and energy and cereal bars. Ara h 1 was successfully tracked in these commercial food products. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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895 KiB

Open AccessProceeding Paper

Thermal Desorption of Explosives Vapour from Organic Fluorescent Sensors

by Edward B. Ogugu, Ross N. Gillanders and Graham A. Turnbull

Chem. Proc. 2021, 5(1), 11; https://doi.org/10.3390/CSAC2021-10559 - 1 Jul 2021

Viewed by 1253

Abstract

Organic semiconductors can be used as highly sensitive fluorescent sensors for the detection of trace-level vapours of nitroaromatic explosives. This involves fluorescence quenching of the sensors and indicates the presence of explosives in the surrounding environment. However, for many organic fluorescent sensors, the [...] Read more.

Organic semiconductors can be used as highly sensitive fluorescent sensors for the detection of trace-level vapours of nitroaromatic explosives. This involves fluorescence quenching of the sensors and indicates the presence of explosives in the surrounding environment. However, for many organic fluorescent sensors, the quenching of fluorescence is irreversible and imposes a limitation in terms of the reusability of the sensors. Here, we present a study of thermal desorption of 2,4-DNT from thin-film explosives sensors made from the commercial fluorescent polymers Super Yellow and poly(9-vinyl carbazole). Thermal cycling of the sensor results in recovery of fluorescence, thereby making them reusable. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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3107 KiB

Open AccessProceeding Paper

Ternary Oxidized Carbon Nanohorns/TiO₂/PVP Nanohybrid as Sensitive Layer for Chemoresistive Humidity Sensor

by Bogdan-Catalin Serban, Octavian Buiu, Marius Bumbac, Roxana Marinescu, Niculae Dumbravescu, Viorel Avramescu, Cornel Cobianu, Cristina Mihaela Nicolescu, Mihai Brezeanu, Cristiana Radulescu and Florin Comanescu

Chem. Proc. 2021, 5(1), 12; https://doi.org/10.3390/CSAC2021-10616 - 6 Jul 2021

Cited by 2 | Viewed by 1177

Abstract

The relative humidity (RH) sensing response of a chemoresistive sensor using a novel ternary hybrid nanocomposite film as a sensing element is presented. The sensitive layer was obtained by employing the drop-casting technique for depositing a thin film of nanocomposite between the electrodes [...] Read more.

The relative humidity (RH) sensing response of a chemoresistive sensor using a novel ternary hybrid nanocomposite film as a sensing element is presented. The sensitive layer was obtained by employing the drop-casting technique for depositing a thin film of nanocomposite between the electrodes of an interdigitated (IDT) structure. The sensing support structure consists of an IDT dual-comb structure fabricated on a oSi-SiO₂ substrate. The IDT comprises chromium, as an adhesion layer (10 nm thickness), and a gold layer (100 nm thickness). The sensing capability of a novel thin film based on a ternary hybrid made of oxidated carbon nanohorns–titanium dioxide–polyvinylpyrrolidone (CNHox/TiO₂/PVP) nanocomposite was investigated by applying a direct current with known intensity between the two electrodes of the sensing structure, and measuring the resulting voltage difference, while varying the RH from 0% to 100% in a humid nitrogen atmosphere. The ternary hybrid-based thin film’s resistance increased when the sensors were exposed to relative humidity ranging from 0 to 100%. It was found that the performance of the new chemoresistive sensor is consistent with that of the capacitive commercial sensor used as a benchmark. Raman spectroscopy was used to provide information on the composition of the sensing layer and on potential interactions between constituents. Several sensing mechanisms were considered and discussed, based on the interaction of water molecules with each component of the ternary nanohybrid. The sensing results obtained lead to the conclusion that the synergic effect of the p-type semiconductor behavior of the CNHox and the PVP swelling process plays a pivotal role in the overall resistance decrease of the sensitive film. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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4049 KiB

Open AccessProceeding Paper

Numerical and Experimental Modeling of Paper-Based Actuators

by Ashutosh Kumar, Hojat Heidari-Bafroui, Amer Charbaji, Nasim Rahmani, Constantine Anagnostopoulos and Mohammad Faghri

Chem. Proc. 2021, 5(1), 15; https://doi.org/10.3390/CSAC2021-10468 - 30 Jun 2021

Cited by 8 | Viewed by 2149 | Correction

Abstract

Microfluidic paper-based analytical devices (μPADs) have witnessed a great extent of innovation over the past decade, developing new components and materials assisting the diagnosis of different diseases and sensing of a wide range of biological, chemical, optical, and electrochemical phenomena. The novel paper-based [...] Read more.

Microfluidic paper-based analytical devices (μPADs) have witnessed a great extent of innovation over the past decade, developing new components and materials assisting the diagnosis of different diseases and sensing of a wide range of biological, chemical, optical, and electrochemical phenomena. The novel paper-based cantilever (PBC) actuator is one the major components that allows autonomous loading and control of multiple fluid reagents required for the accurate operation of paper-based microfluidic devices. This paper provides an extensive overview of numerical and experimental modeling of fluidically controlled PBC actuators for automation of the paper-based assay. The PBC model undergoing hygro-expansion utilizes quasi-static 2D fluid loaded structure governed by the Euler–Bernoulli beam theory for small and moderately large deflections. The solution for the model can avail the response of paper-based actuators for response deflection θ, within 0° to 10° under the assumption of insignificant cross-sectional deformation. The actuation of PBC obtained using a quasi-static theory shows that our results are consistent with quantitative experiments demonstrating the adequacy of models. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1138 KiB

Open AccessProceeding Paper

Study of Gas-Sensing Properties of Titania Nanotubes for Health and Safety Applications

by Vardan Galstyan, Nicola Poli and Elisabetta Comini

Chem. Proc. 2021, 5(1), 16; https://doi.org/10.3390/CSAC2021-10625 - 7 Jul 2021

Cited by 1 | Viewed by 1104

Abstract

We studied the preparation and gas-sensing performance of a hybrid nanomaterial based on titania nanotubes and graphene derivatives. We fabricated the hybrid structure with tunable chemical-sensing properties, achieved by tailoring the structure and composition of graphene oxide and coupling it with titania nanotubes. [...] Read more.

We studied the preparation and gas-sensing performance of a hybrid nanomaterial based on titania nanotubes and graphene derivatives. We fabricated the hybrid structure with tunable chemical-sensing properties, achieved by tailoring the structure and composition of graphene oxide and coupling it with titania nanotubes. The parameters of manufactured sensing structures were investigated for hydrogen and ammonia. Our experimental findings indicate that this research may demonstrate an efficient way to enhance the gas-sensing properties of metal oxide nanomaterials for health and safety applications. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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667 KiB

Open AccessProceeding Paper

Unravelling Plant-Pathogen Interactions: Proximal Optical Sensing as an Effective Tool for Early Detect Plant Diseases

by Mafalda Reis-Pereira, Rui C. Martins, Aníbal Filipe Silva, Fernando Tavares, Filipe Santos and Mário Cunha

Chem. Proc. 2021, 5(1), 18; https://doi.org/10.3390/CSAC2021-10560 - 1 Jul 2021

Cited by 2 | Viewed by 1559

Abstract

This study analyzed the potential of proximal optical sensing as an effective approach for early disease detection. A compact, modular sensing system, combining direct UV–Vis spectroscopy with optical fibers, supported by a principal component analysis (PCA), was applied to evaluate the modifications promoted [...] Read more.

This study analyzed the potential of proximal optical sensing as an effective approach for early disease detection. A compact, modular sensing system, combining direct UV–Vis spectroscopy with optical fibers, supported by a principal component analysis (PCA), was applied to evaluate the modifications promoted by the bacteria Xanthomonas euvesicatoria in tomato leaves (cv. cherry). Plant infection was achieved by spraying a bacterial suspension (10⁸ CFU mL⁻¹) until run-off occurred, and a similar approach was followed for the control group, where only water was applied. A total of 270 spectral measurements were performed on leaves, on five different time instances, including pre- and post-inoculation measurements. PCA was then applied to the acquired data from both healthy and inoculated leaves, which allowed their distinction and differentiation, three days after inoculation, when unhealthy plants were still asymptomatic. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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981 KiB

Open AccessProceeding Paper

Development of a Gas Sensor for Eucalyptol Supervision: A Supporting Tool for Extreme Wildfire Management

by Cátia Magro, Marcelo Morais, Paulo A. Ribeiro, Susana Sério, Pedro Vieira and Maria Raposo

Chem. Proc. 2021, 5(1), 19; https://doi.org/10.3390/CSAC2021-10432 - 30 Jun 2021

Viewed by 1206

Abstract

Recent research on volatile organic compounds (VOC) released by the heated vegetation has shown that, under specific conditions (e.g., extreme heat, humidity, wind, and topography), VOC might foster wildfire ignition sources and explain sudden changes in fire behavior, particularly in the most susceptible [...] Read more.

Recent research on volatile organic compounds (VOC) released by the heated vegetation has shown that, under specific conditions (e.g., extreme heat, humidity, wind, and topography), VOC might foster wildfire ignition sources and explain sudden changes in fire behavior, particularly in the most susceptible and flammable forests (eucalypt forests). This work aims to develop an electronic nose (e-nose) based on a sensor’s array to monitor the concentration of eucalyptol, the major VOC compound of the Eucalyptus globulus tree. The detection of this target compound was achieved by measuring the impedance spectra of layer-by-layer developed thin films based on polyethyleneimine, poly(allylamine hydrochloride), and graphene oxide, by injecting the analyte into a custom-made vacuum chamber system. The obtained results were analyzed by the principal component analysis method. The developed e-nose sensor was able to distinguish different concentrations in a range from 411 to 1095 ppm. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1056 KiB

Open AccessProceeding Paper

Bioactive Compound Profiling and Nutritional Composition of Three Species from the Amaranthaceae Family

by Bernabe Nuñez-Estevez, Tiane C. Finimundy, Maria Carpena, Marta Barral-Martinez, Ricardo Calhelha, Tânia C. S. P. Pires, Paz Otero, Pascual Garcia-Perez, Jesus Simal-Gandara, Isabel C. F. R. Ferreira, Miguel A. Prieto and Lillian Barros

Chem. Proc. 2021, 5(1), 20; https://doi.org/10.3390/CSAC2021-10563 - 1 Jul 2021

Cited by 3 | Viewed by 1705

Abstract

In this work, the chemical and nutritional composition of three Amaranthaceae species (Alternanthera sessilis, Dicliptera chinensis, and Dysphania ambrosioides) was studied. The results showed a differential flavonoid content in the three species: A. sessilis and D. ambrosioides showed similar [...] Read more.

In this work, the chemical and nutritional composition of three Amaranthaceae species (Alternanthera sessilis, Dicliptera chinensis, and Dysphania ambrosioides) was studied. The results showed a differential flavonoid content in the three species: A. sessilis and D. ambrosioides showed similar flavonoid contents (15.1 ± 0.6 and 15.1 ± 0.1 mg/g extract, respectively), followed by D. chinensis (11.4 ± 0.1 mg/g extract). On the other hand, the nutritional results showed a high protein content in all species (16.9–13.9 ± 0.1 g/100 g dw) and revealed the presence of organic acids, such as oxalic and succinic acid. Therefore, bioactive compounds, together with protein and organic acids, could be of great value to the food industry. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Development of a Pattern Recognition Tool for the Classification of Electronic Tongue Signals Using Machine Learning

by Edgar G. Mendez-Lopez, Jersson X. Leon-Medina and Diego A. Tibaduiza

Chem. Proc. 2021, 5(1), 21; https://doi.org/10.3390/CSAC2021-10447 - 30 Jun 2021

Viewed by 1180

Abstract

Electronic tongue type sensor arrays are made of different materials with the property of capturing signals independently by each sensor. The signals captured when conducting electrochemical tests often have high dimensionality, which increases when performing the data unfolding process. This unfolding process consists [...] Read more.

Electronic tongue type sensor arrays are made of different materials with the property of capturing signals independently by each sensor. The signals captured when conducting electrochemical tests often have high dimensionality, which increases when performing the data unfolding process. This unfolding process consists of arranging the data coming from different experiments, sensors, and sample times, thus the obtained information is arranged in a two-dimensional matrix. In this work, a description of a tool for the analysis of electronic tongue signals is developed. This tool is developed in Matlab^® App Designer, to process and classify the data from different substances analyzed by an electronic tongue type sensor array. The data processing is carried out through the execution of the following stages: (1) data unfolding, (2) normalization, (3) dimensionality reduction, (4) classification through a supervised machine learning model, and finally (5) a cross-validation procedure to calculate a set of classification performance measures. Some important characteristics of this tool are the possibility to tune the parameters of the dimensionality reduction and classifier algorithms, and also plot the two and three-dimensional scatter plot of the features after reduced the dimensionality. This to see the data separability between classes and compatibility in each class. This interface is successfully tested with two electronic tongue sensor array datasets with multi-frequency large amplitude pulse voltammetry (MLAPV) signals. The developed graphical user interface allows comparing different methods in each of the mentioned stages to find the best combination of methods and thus obtain the highest values of classification performance measures. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Electronic Nose for Bladder Cancer Detection

by Heena Tyagi, Emma Daulton, Ayman S. Bannaga, Ramesh P. Arasaradnam and James A. Covington

Chem. Proc. 2021, 5(1), 22; https://doi.org/10.3390/CSAC2021-10438 - 30 Jun 2021

Cited by 1 | Viewed by 1255

Abstract

This study outlines the use of an electronic nose as a method for the detection of VOCs as biomarkers of bladder cancer. Here, an AlphaMOS FOX 4000 electronic nose was used for the analysis of urine samples from 15 bladder cancer and 41 [...] Read more.

This study outlines the use of an electronic nose as a method for the detection of VOCs as biomarkers of bladder cancer. Here, an AlphaMOS FOX 4000 electronic nose was used for the analysis of urine samples from 15 bladder cancer and 41 non-cancerous patients. The FOX 4000 consists of 18 MOS sensors that were used to differentiate the two groups. The results obtained were analysed using s MultiSens Analyzer and RStudio. The results showed a high separation with sensitivity and specificity of 0.93 and 0.88, respectively, using a Sparse Logistic Regression and 0.93 and 0.76 using a Random Forest classifier. We conclude that the electronic nose shows potential for discriminating bladder cancer from non-cancer subjects using urine samples. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Advances in Visual Immunoassays for Sensitive Detection of Mycotoxins in Food—A Review

by Meijuan Liang, Qi Zhang and Peiwu Li

Chem. Proc. 2021, 5(1), 25; https://doi.org/10.3390/CSAC2021-10443 - 30 Jun 2021

Cited by 2 | Viewed by 1835

Abstract

Mycotoxins are the toxic secondary metabolites naturally produced by fungi; their contamination in agricultural products and food severely threatens food safety and public health worldwide. The reliable, efficient, and sensitive quantification of mycotoxins in food has become increasingly challenging to tackle due to [...] Read more.

Mycotoxins are the toxic secondary metabolites naturally produced by fungi; their contamination in agricultural products and food severely threatens food safety and public health worldwide. The reliable, efficient, and sensitive quantification of mycotoxins in food has become increasingly challenging to tackle due to the complexity of food matrices and their low level. Visual detection has emerged as a popular trend toward miniaturization and simplification of mycotoxins assays yet is constrained with their limited sensitivity. This review mainly focuses on the various sensitive visual immunoassays for signal amplified detection of mycotoxins. These signal amplified immunoassays for the improved sensitivity of mycotoxins detection in food through nanomaterials for encapsulation enzyme, enzyme-mediated nanomaterials as the amplified signal readout, and nanozyme. Furthermore, the underlying principle and the advantages of visual immunoassays for mycotoxins have been proposed. And the challenges and perspectives have been proposed to develop improved efficient visual immunoassays for mycotoxins in food. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Reproductivity Study of Metal Oxide Gas Sensors Using Two Different Temperature Setups

by Giulia Zambotti and Andrea Ponzoni

Chem. Proc. 2021, 5(1), 26; https://doi.org/10.3390/CSAC2021-10613 - 6 Jul 2021

Cited by 1 | Viewed by 982

Abstract

The use of the electronic nose as a screening device is of great interest in various types of applications, including food quality control and environmental monitoring. It is an easy-to-use device and produces a much faster response than that obtained by classical chemical [...] Read more.

The use of the electronic nose as a screening device is of great interest in various types of applications, including food quality control and environmental monitoring. It is an easy-to-use device and produces a much faster response than that obtained by classical chemical and microbiological techniques. The reproductivity of nominally identical electronic noses and sensors is critical. Four identical MOX sensors were compared using two different working methods, namely, the temperature modulation mode and isothermal mode. Each sensor was tested with two standard compounds, water and lactic acid, often identified in food matrices, which are potential applications of the electronic nose. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

First Principles Investigation of the Optoelectronic Properties of Molybdenum Dinitride for Optical Sensing Applications

by Amall A. Ramanathan

Chem. Proc. 2021, 5(1), 27; https://doi.org/10.3390/CSAC2021-10429 - 30 Jun 2021

Cited by 2 | Viewed by 1018

Abstract

The electronic and optical properties of the newly synthesized molybdenum dinitride (MoN₂) in the hypothetical 2H structure analogous to MoS₂ is investigated using the density functional theory (DFT) full potential linearized augmented plane wave (FP-LAPW) method and the modified Becke–Johnson [...] Read more.

The electronic and optical properties of the newly synthesized molybdenum dinitride (MoN₂) in the hypothetical 2H structure analogous to MoS₂ is investigated using the density functional theory (DFT) full potential linearized augmented plane wave (FP-LAPW) method and the modified Becke–Johnson (mBJ) approximation. The aim is to investigate the optoelectronic properties of this compound for potential optical sensing applications and compare with the capabilities of MoS₂ in this field. As compared to MoS₂, which is a semiconductor, MoN₂ is found to be a semi metal from the band structure plots. The dielectric function, optical conductivity and the optical constants, namely, the refractive index, the reflectivity, the extinction and absorption coefficients, are evaluated and compared with those of MoS₂ and discussed with reference to the sensing performance. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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556 KiB

Open AccessProceeding Paper

Essential Oils as Possible Candidates to Be Included in Active Packaging Systems and the Use of Biosensors to Monitor the Quality of Foodstuff

by Anton Soria-Lopez, Maria Carpena, Bernabe Nuñez-Estevez, Paula Garcia-Oliveira, Nicolas Collazo, Paz Otero, Pascual Garcia-Perez, Hui Cao, Jianbo Xiao, Márcio Carocho, Lillian Barros, Jesus Simal-Gandara and Miguel A. Prieto

Chem. Proc. 2021, 5(1), 28; https://doi.org/10.3390/CSAC2021-10485 - 30 Jun 2021

Cited by 2 | Viewed by 1268

Abstract

Active packaging has gained interest in recent years. As well as protecting food from the environment, it can incorporate agents with specific properties to extend the shelf life of the food. As a requirement, it is essential that the active agent has a [...] Read more.

Active packaging has gained interest in recent years. As well as protecting food from the environment, it can incorporate agents with specific properties to extend the shelf life of the food. As a requirement, it is essential that the active agent has a greater affinity for the food than for the packaging material and, in this sense, essential oils (EOs) are potential candidates to be included in this new packaging system. The use of EOs can add to food matrix antimicrobial and antioxidant properties, reduce the permeability of the packaging to water vapor and extend the shelf life of food products. However, their use has been limited because they can produce a strong flavor by interacting with other compounds present in the food matrix and modify the organoleptic characteristics. Although the nanoencapsulation of EOs can provide chemical stability and minimize the impact of the Eos on the organoleptic properties by decreasing their volatilization, some physical modifications have still been observed, such as plasticizing effects and color variations. In this sense, the quality of the food products and consumer safety can be increased by using sensors. This technology indicates when food products are degrading and informs us if specific packaging conditions have changed. This work focuses on highlighting the use of biosensors as a new methodology to detect undesirable changes in the food matrix in a short period of time and the use of nanotechnology to include EOs in active films of natural origin. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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782 KiB

Open AccessProceeding Paper

Silver Nanomaterials as Electron Mediators in a Bio-Electronic Tongue Dedicated to the Analysis of Milks. The Role of the Aspect Ratio of Nanoparticles vs. Nanowires

by Coral Salvo-Comino, Clara Perez-Gonzalez, Fernando Martin-Pedrosa, Cristina Garcia-Cabezon and Maria Luz Rodriguez-Mendez

Chem. Proc. 2021, 5(1), 30; https://doi.org/10.3390/CSAC2021-10554 - 1 Jul 2021

Viewed by 875

Abstract

The integration of silver nanomaterials as electron mediators in electrochemical biosensors can be crucial to improve the affinity with biomolecules and the electrochemical response. In this work, two voltammetric bioelectronics tongues (bioET) formed by biosensors based on the combination of enzymes with silver [...] Read more.

The integration of silver nanomaterials as electron mediators in electrochemical biosensors can be crucial to improve the affinity with biomolecules and the electrochemical response. In this work, two voltammetric bioelectronics tongues (bioET) formed by biosensors based on the combination of enzymes with silver nanoparticles (AgNPs) (bioET-1) or silver nanowires (AgNWs) (bioET-2) have been developed and used to analyze milks. Each array was formed by four biosensors formed by enzymes (glucose oxidase, galactose oxidase, β-galactosidase and a blank), capable to detect compounds usually found in milks. Principal component analysis (PCA) has revealed the ability of both biosensor systems to discriminate between milk samples with different fat contents, but with some differences, attributed to the structure employed in the detection. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Development of a Bioelectronic Tongue Modified with Gold Nanoparticles for Dairy Analysis

by Clara Pérez-González, Coral Salvo-Comino, Fernando Martin-Pedrosa, Cristina García-Cabezón and María Luz Rodríguez Méndez

Chem. Proc. 2021, 5(1), 31; https://doi.org/10.3390/CSAC2021-10553 - 1 Jul 2021

Viewed by 954

Abstract

The objective of this work was to create an all-solid-state potentiometric bioelectronic tongue with an array of polymeric membrane-based sensors, which could then be used in the dairy sector. Membranes were modified with gold nanoparticles, and enzymes were covalently linked to the sensor’s [...] Read more.

The objective of this work was to create an all-solid-state potentiometric bioelectronic tongue with an array of polymeric membrane-based sensors, which could then be used in the dairy sector. Membranes were modified with gold nanoparticles, and enzymes were covalently linked to the sensor’s surface to create an array of sensors with greater sensitivity. The responses of the sensors modified with gold nanoparticles and covalently associated enzymes, showed higher sensitivities. Moreover, the developed bioelectronic tongue was able to perform the discrimination of milks with different nutritional characteristics by applying principal component analysis. In addition, the results obtained showed that by applying partial least squares analysis, the system could be used as a prediction system for different chemical parameters (such as acidity, proteins, lactose, etc.). Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1996 KiB

Open AccessProceeding Paper

Nanostructured Bismuth Electrodes for Non-Enzymatic Paracetamol Sensing: Development, Testing, and Computational Approach

by Mallikarjun Madagalam, Federica Catania, Mattia Bartoli, Alberto Tagliaferro and Sandro Carrara

Chem. Proc. 2021, 5(1), 33; https://doi.org/10.3390/CSAC2021-10427 - 30 Jun 2021

Cited by 2 | Viewed by 1134

Abstract

In this work, new Screen Printed Carbon-paste Electrodes (SPCEs) were developed through deposition of nanostructures of HO–BiONO₃ synthesized with or without surfactant additions. We performed a cyclic voltammetry study showing the improvement in performance of bismuth tailored electrodes for paracetamol sensing compared [...] Read more.

In this work, new Screen Printed Carbon-paste Electrodes (SPCEs) were developed through deposition of nanostructures of HO–BiONO₃ synthesized with or without surfactant additions. We performed a cyclic voltammetry study showing the improvement in performance of bismuth tailored electrodes for paracetamol sensing compared with bare SPCE. A computation study was also performed for investigating the interaction between paracetamol and bismuth species during the electron transfer process enlighten the preferential sites of interaction on the surface of modified SPEs. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Statistical Analysis for Selective Identifications of VOCs by Using Surface Functionalized MoS₂ Based Sensor Array

by Uttam Narendra Thakur, Radha Bhardwaj and Arnab Hazra

Chem. Proc. 2021, 5(1), 35; https://doi.org/10.3390/CSAC2021-10451 - 30 Jun 2021

Cited by 2 | Viewed by 1338

Abstract

Disease diagnosis through breath analysis has attracted significant attention in recent years due to its noninvasive nature, rapid testing ability, and applicability for patients of all ages. More than 1000 volatile organic components (VOCs) exist in human breath, but only selected VOCs are [...] Read more.

Disease diagnosis through breath analysis has attracted significant attention in recent years due to its noninvasive nature, rapid testing ability, and applicability for patients of all ages. More than 1000 volatile organic components (VOCs) exist in human breath, but only selected VOCs are associated with specific diseases. Selective identification of those disease marker VOCs using an array of multiple sensors are highly desirable in the current scenario. The use of efficient sensors and the use of suitable classification algorithms is essential for the selective and reliable detection of those disease markers in complex breath. In the current study, we fabricated a noble metal (Au, Pd and Pt) nanoparticle-functionalized MoS₂ (Chalcogenides, Sigma Aldrich, St. Louis, MO, USA)-based sensor array for the selective identification of different VOCs. Four sensors, i.e., pure MoS₂, Au/MoS₂, Pd/MoS₂, and Pt/MoS₂ were tested under exposure to different VOCs, such as acetone, benzene, ethanol, xylene, 2-propenol, methanol and toluene, at 50 °C. Initially, principal component analysis (PCA) and linear discriminant analysis (LDA) were used to discriminate those seven VOCs. As compared to the PCA, LDA was able to discriminate well between the seven VOCs. Four different machine learning algorithms such as k-nearest neighbors (kNN), decision tree, random forest, and multinomial logistic regression were used to further identify those VOCs. The classification accuracy of those seven VOCs using KNN, decision tree, random forest, and multinomial logistic regression was 97.14%, 92.43%, 84.1%, and 98.97%, respectively. These results authenticated that multinomial logistic regression performed best between the four machine learning algorithms to discriminate and differentiate the multiple VOCs that generally exist in human breath. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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476 KiB

Open AccessProceeding Paper

Evaluation of the Effect of Extracted Time Conditions on the Phenolic Content of Olive Pastes from cv. Arbequina and Discrimination Using a Lab-Made Potentiometric Electronic Tongue

by Ítala M. G. Marx, Nuno Rodrigues, Ana C. A. Veloso, José A. Pereira and António M. Peres

Chem. Proc. 2021, 5(1), 36; https://doi.org/10.3390/CSAC2021-10556 - 1 Jul 2021

Viewed by 984

Abstract

The present study investigated the effect of malaxation times (Mt) (0, 15, 30, 45 and 60 min), during the industrial extraction of cv. Arbequina oils at 25 °C on total phenolic content of olive pastes. Additionally, the possibility of applying a lab-made [...] Read more.

The present study investigated the effect of malaxation times (Mt) (0, 15, 30, 45 and 60 min), during the industrial extraction of cv. Arbequina oils at 25 °C on total phenolic content of olive pastes. Additionally, the possibility of applying a lab-made potentiometric electronic tongue (E-tongue), comprising 40 lipid/polymer sensor membranes with cross sensitivity, to discriminate the olive pastes according to the Mt, was evaluated. The results pointed out that the olive pastes’ total phenolic contents significantly decreased (p-value < 0.001, one-way ANOVA) with the increase of the Mt (from 2.21 ± 0.02 to 1.99 ± 0.03 g gallic acid equivalents/kg olive paste), there being observed a linear decreasing trend (R-Pearson = −0.910). These findings may be tentatively attributed to the migration of the phenolic compounds from the olive pastes to the extracted oil and water phases, during the malaxation process. Finally, the E-tongue signals, acquired during the analysis of the olive pastes’ methanolic extracts (methanol:water, 80:20 v/v), together with a linear discriminant analysis (LDA), coupled with a simulated annealing (SA) algorithm, allowed us to establish a successful classification model. The E-tongue-LDA-SA model, based on 11 selected non-redundant sensors, allowed us to correctly discriminate all the studied olive pastes according to the Mt (sensitivities of 100% for training and leave-one-out cross-validation). The satisfactory performance of the E-tongue could be tentatively explained by the known capability of lipid/polymeric sensor membranes to interact with phenolic compounds, through electrostatic interactions and/or hydrogen bonds, which total content depended on the Mt. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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6 pages, 853 KiB

Open AccessProceeding Paper

Polysaccharide-Based Organic Frameworks with Embedded Nanoparticles: Advanced SPR Study on the Antiviral Activity of Gold Composites Derived from Glucuronoxylomannan

by Praskoviya Boltovets, Sergii Kravchenko, Oleksiy Kovalenko and Borys Snopok

Chem. Proc. 2021, 5(1), 38; https://doi.org/10.3390/CSAC2021-10475 - 15 Dec 2021

Viewed by 1337

Abstract

The nanosized composites based on the natural polysaccharides and nanoparticles of noble metals are promising candidates for efficient antiviral drugs. However, the complexity of such objects, their diversity and novelty necessitate the development of new analytical methods for investigation of such supramolecular architectures. [...] Read more.

The nanosized composites based on the natural polysaccharides and nanoparticles of noble metals are promising candidates for efficient antiviral drugs. However, the complexity of such objects, their diversity and novelty necessitate the development of new analytical methods for investigation of such supramolecular architectures. In this work, which was recently developed for SPR-based instrumentation, the concept of variative refraction (DViFA, density variations in fixed architectures) was used to elucidate the mechanism of the antiviral action of a polysaccharide with gold nanoparticles grown in it. The SPR data were confirmed by direct biological tests: the effect of the native polysaccharide glucuronoxylomannan (GXM) obtained from the fungus Ganoderma adspersum and gold nanocomposites thereon on the infection of Datura stramonium with tobacco mosaic virus (TMV) was investigated. Both drugs suppress the development of viral infections. However, if for high concentrations the characteristic activity of the composite is somewhat lower than for GXM, then with an increase in dilution, the effectiveness of the composite increases significantly, up to a twofold excess. It has been reasonably suggested that the mechanism of antiviral action is associated with the formation of clusters of viruses that are no longer capable of infecting cells. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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379 KiB

Open AccessProceeding Paper

Metal–Peptide Complexes—A Novel Class of Molecular Receptors for Electrochemical Phosphate Sensing

by Aleksandra Tobolska, Nina E. Wezynfeld, Urszula E. Wawrzyniak, Wojciech Bal and Wojciech Wróblewski

Chem. Proc. 2021, 5(1), 39; https://doi.org/10.3390/CSAC2021-10449 - 30 Jun 2021

Viewed by 1021

Abstract

Amyloid-β (Aβ) peptides are crucial in the pathology of Alzheimer’s disease. On the other hand, their metal complexes possess distinctive coordination properties that could be of great importance in the selective recognition of (bio)analytes, such as anions. Here, we report a novel group [...] Read more.

Amyloid-β (Aβ) peptides are crucial in the pathology of Alzheimer’s disease. On the other hand, their metal complexes possess distinctive coordination properties that could be of great importance in the selective recognition of (bio)analytes, such as anions. Here, we report a novel group of molecular receptors for phosphate anions recognition: metal–peptide complexes of Aβ peptides, which combine features of synthetic inorganic ligands and naturally occurring binding proteins. The influence of the change in the metal ion center on the coordination and redox properties of binary Cu(II)/Ni(II)-Aβ complexes, as well as the affinity of these complexes towards phosphate species, were analyzed. This approach offers the possibility of fine-tuning the receptor affinity for desired applications. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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879 KiB

Open AccessProceeding Paper

Evaluation of Olive Oil Quality Grade Using a Portable Battery-Operated Sensor System

by Marco Grossi, Enrico Valli, Alessandra Bendini, Tullia Gallina Toschi and Bruno Riccò

Chem. Proc. 2021, 5(1), 40; https://doi.org/10.3390/CSAC2021-10614 - 6 Jul 2021

Viewed by 1234

Abstract

Olive oil quality is normally assessed by chemical analysis as well as sensory analysis to detect the presence of organoleptic defects. Two of the most important parameters that define the quality of olive oil are the free acidity and the peroxide index. These [...] Read more.

Olive oil quality is normally assessed by chemical analysis as well as sensory analysis to detect the presence of organoleptic defects. Two of the most important parameters that define the quality of olive oil are the free acidity and the peroxide index. These chemical parameters are usually determinated by manual titration procedures that must be carried out in a laboratory by trained personnel. In this paper, a portable sensor system to evaluate the quality grade of olive oil is presented. The system is battery operated and characterized by small dimensions, a light weight and quick measurement response. The working principle is based on the measurement of the electrical conductance of an emulsion between a hydro-alcoholic solution and the olive oil sample. Tests have been carried out on a set of 17 olive oil samples. The results have shown how for fresh olive oil samples, the olive oil’s free acidity can be estimated from the electrical conductance of the emulsion. In the case of oxidized olive oil, the measured electrical conductance is also the function of the oxidation level, and a conductance threshold can be set to discriminate between extra virgin olive oils and lower-quality grade oils. The proposed system can be a low-cost alternative to standard laboratory analysis to evaluate the quality grade of olive oil. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1704 KiB

Open AccessProceeding Paper

Characterization and Comparison of the Relative Humidity Response of Hydromorphic Polymers in Long-Period Fiber Grating Structures

by Bernardo Dias, João P. Mendes, José M. M. M. de Almeida and Luís C. C. Coelho

Chem. Proc. 2021, 5(1), 42; https://doi.org/10.3390/CSAC2021-10461 - 30 Jun 2021

Cited by 1 | Viewed by 1382

Abstract

Relative humidity monitorization is of extreme importance on scientific and industrial applications, and fiber optics-based sensors may provide solutions where other types of sensors have limitations. In this work, fiber optics’ sensors were fabricated by combining Long-Period Fiber Gratings with three different humidity-responding [...] Read more.

Relative humidity monitorization is of extreme importance on scientific and industrial applications, and fiber optics-based sensors may provide solutions where other types of sensors have limitations. In this work, fiber optics’ sensors were fabricated by combining Long-Period Fiber Gratings with three different humidity-responding polymers, namely Poly(vinyl alcohol), Poly(ethylene glycol) and Hydromed™ D4. The performance of the multiple sensors was experimentally tested and crossed with numerical simulations, which provide a comparison with the expected response given the optical properties of the materials. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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383 KiB

Open AccessProceeding Paper

Identification, Quantification, and Method Validation of Anthocyanins

by Paula Garcia-Oliveira, Antia G. Pereira, Maria Fraga-Corral, Catarina Lourenço-Lopes, Franklin Chamorro, Aurora Silva, Pascual Garcia-Perez, Fatima Barroso, Lillian Barros, Isabel C. F. R. Ferreira, Jesus Simal-Gandara and Miguel A. Prieto

Chem. Proc. 2021, 5(1), 43; https://doi.org/10.3390/CSAC2021-10680 - 14 Jul 2021

Cited by 2 | Viewed by 4188

Abstract

Nowadays, anthocyanins have gained scientific and industrial attention due to their biological activities and coloring properties. In this regard, anthocyanins have been proposed for use in the development of new nutraceutical foods to replace synthetic additives as well as to be value-added ingredients. [...] Read more.

Nowadays, anthocyanins have gained scientific and industrial attention due to their biological activities and coloring properties. In this regard, anthocyanins have been proposed for use in the development of new nutraceutical foods to replace synthetic additives as well as to be value-added ingredients. The aim of this study was to evaluate current data on identification and quantification techniques and the validation process of such methods. Our results showed that anthocyanins have been identified by different methods, including nuclear magnetic resonance and chromatography-based techniques. Although problems have been described in this validation, most of the reports showed positive results on the validation parameters, suggesting that the current analytical technology offers a satisfactory identification and quantification of anthocyanins. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1960 KiB

Open AccessProceeding Paper

Portable Electrochemical Detection of Illicit Drugs in Smuggled Samples: Towards More Secure Borders

by Marc Parrilla, Amorn Slosse, Robin Van Echelpoel, Noelia Felipe Montiel, Filip Van Durme and Karolien De Wael

Chem. Proc. 2021, 5(1), 44; https://doi.org/10.3390/CSAC2021-10612 - 6 Jul 2021

Cited by 1 | Viewed by 1976

Abstract

Illicit drug consumption is posing critical concerns in our society causing health issues, crime-related activities and the disruption of the border trade. The smuggling of illicit drugs urges the development of new tools for rapid on-site identification in cargos. Current methods used by [...] Read more.

Illicit drug consumption is posing critical concerns in our society causing health issues, crime-related activities and the disruption of the border trade. The smuggling of illicit drugs urges the development of new tools for rapid on-site identification in cargos. Current methods used by law enforcement offices rely on presumptive color tests and portable spectroscopic techniques. However, these methods sometimes exhibit inaccurate results due to commonly used cutting agents or because the drugs are smuggled (hidden or mixed) in colored samples. Interestingly, electrochemical sensors can deal with these specific problems. Herein, it is presented an electrochemical device that uses low-cost screen-printed electrodes for the electrochemical detection of illicit drugs by square-wave voltammetry (SWV) profiling. A library of electrochemical profiles is built upon pure and mixtures of illicit drugs with common cutting agents. This library allows the design of a tailor-made script that shows the identification of each drug through a user-friendly interface. Finally, the results obtained from the analysis of different samples from confiscated cargos at an end-user laboratory present a promising alternative to current methods offering low-cost and rapid testing in the field. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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6 pages, 1895 KiB

Open AccessProceeding Paper

Electrochemical Measurement System for Chlorides in Drinking and Wastewater

by Diana A. Toriz-Gutiérrez, Humberto Ramírez-Gasca, Luis E. Cárdenas-Galindo and Eloisa Gallegos-Arellano

Chem. Proc. 2021, 5(1), 46; https://doi.org/10.3390/chemproc2021005046 - 17 Dec 2021

Viewed by 1267

Abstract

This paper presents a system for the measurement of chlorides in drinking and wastewater, based on an electrochemical process using a selective electrode as a transducer, which was developed by this group. The measurement for the concentration is carried out by introducing the [...] Read more.

This paper presents a system for the measurement of chlorides in drinking and wastewater, based on an electrochemical process using a selective electrode as a transducer, which was developed by this group. The measurement for the concentration is carried out by introducing the implemented electrode (considered as reference) in the sample that will be analyzed; then a current is passed producing a potential difference in the system. Different aqueous solutions of sodium chloride (NaCl) were used, ranging between 35 and 3546 µg of chloride ions (Cl⁻). As a data acquisition and monitoring system for the analysis, an ATmega 328P microcontroller was used as the main capture element for subsequent interpretation through graphics. The experimental results show that it was possible to detect a potential difference in the electrochemical measurement system that corresponded to 35 µg of chloride ions (Cl⁻), making clear the detection process and the selectivity of chloride ions. It is important to mention that with this measurement system and the applied methodology, results are obtained in real time using a small sample volume and without generate ng extra liquid waste, compared to the application of the traditional analytical titrimetric method. Finally, this chloride measurement system is inexpensive and can be used in drinking and wastewater measurements. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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939 KiB

Open AccessProceeding Paper

Poly(bromocresol purple)-Based Voltammetric Sensor for the Simultaneous Quantification of Ferulic Acid and Vanillin

by Anastasiya Zhupanova and Guzel Ziyatdinova

Chem. Proc. 2021, 5(1), 47; https://doi.org/10.3390/CSAC2021-10441 - 30 Jun 2021

Viewed by 1011

Abstract

Natural phenolic antioxidants are extensively studied compounds due to their positive health effect and wide distribution in human diets. The simultaneous occurrence in samples requires selective methods for their determination. Electrochemical sensor based on the polyaminobenzene sulfonic acid functionalized single-walled carbon nanotubes (f-SWCNT) [...] Read more.

Natural phenolic antioxidants are extensively studied compounds due to their positive health effect and wide distribution in human diets. The simultaneous occurrence in samples requires selective methods for their determination. Electrochemical sensor based on the polyaminobenzene sulfonic acid functionalized single-walled carbon nanotubes (f-SWCNT) and electropolymerized bromocresol purple has been developed for the simultaneous quantification of ferulic acid and vanillin. The electrode has been characterized by scanning electron microscopy (SEM) and electrochemical methods, and the effectivity of the developed modifier has been confirmed. Thus, the novel sensitive voltammetric sensor is simple to fabricate, reliable, cost-effective, and can be applied for foodstuff screening. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1315 KiB

Open AccessProceeding Paper

Label-Free Anti-Human IgG Biosensor Based on Chemical Modification of a Long Period Fiber Grating Surface

by João P. Mendes, Luís C. C. Coelho, Viviana P. Pereira, Manuel A. Azenha, Pedro A. S. Jorge and Carlos M. Pereira

Chem. Proc. 2021, 5(1), 48; https://doi.org/10.3390/CSAC2021-10454 - 30 Jun 2021

Viewed by 1107

Abstract

This work introduces a method specially developed to produce a biorecognition element based on modified Stöber silica nanoparticles by the covalent immobilization of the human IgG. The sensing structure is based on long period fiber gratings (LPFG), specially developed to allow the interaction [...] Read more.

This work introduces a method specially developed to produce a biorecognition element based on modified Stöber silica nanoparticles by the covalent immobilization of the human IgG. The sensing structure is based on long period fiber gratings (LPFG), specially developed to allow the interaction of the electromagnetic wave with the target analytes through its evanescent field. The surface was modified by the immobilization of the IgG-modified nanoparticles serving has recognition elements for specific target molecules. The resulting configuration was tested in the presence of anti-human IgG, recording the refractometric response of the modified LPFG in contact with different amounts of analyte. The selectivity of the sensor was also assessed. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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7 pages, 3503 KiB

Open AccessProceeding Paper

Precipitation of Iron Oxide in Hydrogel with Superparamagnetic and Stimuli-Responsive Properties

by Alice Mieting, Sitao Wang, Mia Schliephake, Daniela Franke, Margarita Guenther, Stefan Odenbach and Gerald Gerlach

Chem. Proc. 2021, 5(1), 49; https://doi.org/10.3390/chemproc2021005049 - 17 Dec 2021

Viewed by 1547

Abstract

In this work, we present a template-based preparation of iron oxide-containing hydrogels (ferrogels) with ionic sensitive and superparamagnetic properties. The influence of the cross-linked template polyacrylamide and the concentration of the iron salts and sodium hydroxide on the precipitation of the iron oxide [...] Read more.

In this work, we present a template-based preparation of iron oxide-containing hydrogels (ferrogels) with ionic sensitive and superparamagnetic properties. The influence of the cross-linked template polyacrylamide and the concentration of the iron salts and sodium hydroxide on the precipitation of the iron oxide particles is investigated with respect to the stability of the ferrogels. Scanning electron microscope images show cubic particles, which can be semiquantitatively classified in three groups of particle size with respect to the dilution level. Magnetic hysteresis curves reveal a sigmoidal shape without remanence and coercivity for all samples. The higher cross-linked ferrogels, in comparison with the lower cross-linked ferrogels, possess a steady-state degree of swelling in ultrapure water and a stimuli-sensitive deswelling over a wide range of varying ionic strengths. Thus, they are suitable candidates for applications in sensing and microfluidics. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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234 KiB

Open AccessProceeding Paper

Critical Variables Influencing the Ultrasound-Assisted Extraction of Bioactive Compounds—A Review

by Anxo Carreira-Casais, Maria Carpena, Antia G. Pereira, Franklin Chamorro, Anton Soria-Lopez, Pascual Garcia Perez, Paz Otero, Hui Cao, Jianbo Xiao, Jesus Simal-Gandara and Miguel A. Prieto

Chem. Proc. 2021, 5(1), 50; https://doi.org/10.3390/CSAC2021-10562 - 1 Jul 2021

Cited by 6 | Viewed by 2017

Abstract

Ultrasound-assisted extraction (UAE) is a novel methodology, belonging to the so-called “Green Chemistry”, which has gained interest in recent years due to the potential to recover bioactive compounds, especially those from plant matrices. It is widely recognized that the extraction of molecules by [...] Read more.

Ultrasound-assisted extraction (UAE) is a novel methodology, belonging to the so-called “Green Chemistry”, which has gained interest in recent years due to the potential to recover bioactive compounds, especially those from plant matrices. It is widely recognized that the extraction of molecules by UAE gives rise to higher or similar yields than those obtained by traditional extraction methods. UAE has certain advantages inherent to Green Chemistry extraction methods, such as short extraction time and low solvent consumption. The aim of this review is to critically present the different variables and parameters that can be modified in UAE, such as ultrasound power, time, temperature, solvent, and solid to solvent ratio that influence yield and extraction performance. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

1033 KiB

Open AccessProceeding Paper

Plants of the Family Asteraceae: Evaluation of Biological Properties and Identification of Phenolic Compounds

by Marta Barral-Martinez, Paula Garcia-Oliveira, Bernabe Nuñez-Estevez, Aurora Silva, Tiane C. Finimundy, Ricardo Calhelha, Marija Nenadic, Marina Sokovic, Fatima Barroso, Jesus Simal-Gandara, Isabel C. F. R. Ferreira, Lillian Barros and Miguel A. Prieto

Chem. Proc. 2021, 5(1), 51; https://doi.org/10.3390/CSAC2021-10486 - 30 Jun 2021

Cited by 5 | Viewed by 1940

Abstract

The present study focused on the biological analysis of five plants: Achillea millefolium, Arnica montana, Calendula officinalis, Chamaemelum nobile and Taraxacum officinale. The results indicated that A. montana extracts showed the highest content of phenolic compounds. Regarding the biological [...] Read more.

The present study focused on the biological analysis of five plants: Achillea millefolium, Arnica montana, Calendula officinalis, Chamaemelum nobile and Taraxacum officinale. The results indicated that A. montana extracts showed the highest content of phenolic compounds. Regarding the biological properties, A. millefolium had outstanding antioxidant activity, while C. officinalis had the highest rate of antimicrobial and antifungal activity. The anti-inflammatory and cytotoxic activities reflected that C. nobile showed the highest effect. In enzyme assays, C. nobile and C. officinalis extracts showed the highest inhibitory effects on acetylcholinesterase and butyrylcholinesterase enzymes. Overall, this study provides scientific evidence for the evaluation of the potential of medicinal plant extracts for the development of new products. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1920 KiB

Open AccessProceeding Paper

Characterization of Unpleasant Odors in Poultry Houses Using Metal Oxide Semiconductor-Based Gas Sensor Arrays and Pattern Recognition Methods

by Mohammed Moufid, Carlo Tiebe, Nezha El Bari, Matthias Bartholmai and Benachir Bouchikhi

Chem. Proc. 2021, 5(1), 52; https://doi.org/10.3390/CSAC2021-10481 - 30 Jun 2021

Viewed by 1233

Abstract

In this study, the ability of an electronic nose developed to analyze and monitor odor emissions from three poultry farms located in Meknes (Morocco) and Berlin (Germany) was evaluated. Indeed, the potentiality of the electronic nose (e-nose) to differentiate the concentration fractions of [...] Read more.

In this study, the ability of an electronic nose developed to analyze and monitor odor emissions from three poultry farms located in Meknes (Morocco) and Berlin (Germany) was evaluated. Indeed, the potentiality of the electronic nose (e-nose) to differentiate the concentration fractions of hydrogen sulfide, ammonia, and ethanol was investigated. Furthermore, the impact change of relative humidity values (from 15% to 67%) on the responses of the gas sensors was reported and revealed that the effect remained less than 0.6%. Furthermore, the relevant results confirmed that the developed e-nose system was able to perfectly classify and monitor the odorous air of poultry farms. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1399 KiB

Open AccessProceeding Paper

Electrode Modified with Tin(IV) Oxide Nanoparticles and Surfactants as Sensitive Sensor for Hesperidin

by Elvira Yakupova and Guzel Ziyatdinova

Chem. Proc. 2021, 5(1), 54; https://doi.org/10.3390/CSAC2021-10615 - 6 Jul 2021

Viewed by 1539

Abstract

Tin(IV) oxide nanoparticles in combination with surfactants were used as a sensitive layer in a sensor for hesperidin. The effect of the surfactant’s nature and concentration on the hesperidin response was evaluated. The best parameters were registered in the case of 500 µM [...] Read more.

Tin(IV) oxide nanoparticles in combination with surfactants were used as a sensitive layer in a sensor for hesperidin. The effect of the surfactant’s nature and concentration on the hesperidin response was evaluated. The best parameters were registered in the case of 500 µM cetylpyridinium bromide (CPB) as a dispersive agent. The SEM and electrochemical data confirmed the increase in sensor surface effective area and electron transfer rate. The sensor gave a linear response to hesperidin in the ranges of 0.10–10 and 10–75 µM with a detection limit of 77 nM. The approach was successfully tested on orange juices and validated using ultra-HPLC. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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535 KiB

Open AccessProceeding Paper

Optical Biosensor for the Detection of Hydrogen Peroxide in Milk

by Helena Vasconcelos, Ana Matias, Pedro Jorge, Cristina Saraiva, João Mendes, João Araújo, Bernardo Dias, Paulo Santos, José M. M. M. Almeida and Luís C. C. Coelho

Chem. Proc. 2021, 5(1), 55; https://doi.org/10.3390/CSAC2021-10466 - 30 Jun 2021

Cited by 3 | Viewed by 1354

Abstract

Over the years, the food industry’s concern to provide safe food that does not cause harm or illness to consumers has increased. The growing demand for the detection of compounds that can contaminate food is increasingly important. Hydrogen peroxide is frequently used as [...] Read more.

Over the years, the food industry’s concern to provide safe food that does not cause harm or illness to consumers has increased. The growing demand for the detection of compounds that can contaminate food is increasingly important. Hydrogen peroxide is frequently used as a substance to control the growth of microorganisms in milk, thus increasing its shelf life. Here, a strategy is presented for the detection of hydrogen peroxide as a milk adulterant, using a single shot membrane sensor. The lowest concentration measured with this technique was 0.002% w/w of H₂O₂ in semi-fat milk. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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956 KiB

Open AccessProceeding Paper

Locally Linear Embedding as Nonlinear Feature Extraction to Discriminate Liquids with a Cyclic Voltammetric Electronic Tongue

by Jersson X. Leon-Medina, Maribel Anaya and Diego A. Tibaduiza

Chem. Proc. 2021, 5(1), 56; https://doi.org/10.3390/CSAC2021-10426 - 30 Jun 2021

Viewed by 1288

Abstract

Electronic tongues are devices used in the analysis of aqueous matrices for classification or quantification tasks. These systems are composed of several sensors of different materials, a data acquisition unit, and a pattern recognition system. Voltammetric sensors have been used in electronic tongues [...] Read more.

Electronic tongues are devices used in the analysis of aqueous matrices for classification or quantification tasks. These systems are composed of several sensors of different materials, a data acquisition unit, and a pattern recognition system. Voltammetric sensors have been used in electronic tongues using the cyclic voltammetry method. By using this method, each sensor yields a voltammogram that relates the response in current to the change in voltage applied to the working electrode. A great amount of data is obtained in the experimental procedure which allows handling the analysis as a pattern recognition application; however, the development of efficient machine-learning-based methodologies is still an open research interest topic. As a contribution, this work presents a novel data processing methodology to classify signals acquired by a cyclic voltammetric electronic tongue. This methodology is composed of several stages such as data normalization through group scaling method and a nonlinear feature extraction step with locally linear embedding (LLE) technique. The reduced-size feature vector input to a k-Nearest Neighbors (k-NN) supervised classifier algorithm. A leave-one-out cross-validation (LOOCV) procedure is performed to obtain the final classification accuracy. The methodology is validated with a data set of five different juices as liquid substances.Two screen-printed electrodes voltametric sensors were used in the electronic tongue. Specifically the materials of their working electrodes were platinum and graphite. The results reached an 80% classification accuracy after applying the developed methodology. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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894 KiB

Open AccessProceeding Paper

Applied Voltage Effect in Lbl Sensors While Detecting 17α-Ethinylestradiol in Water Samples

by Paulo M. Zagalo, Cátia Magro, Paulo A. Ribeiro and Maria Raposo

Chem. Proc. 2021, 5(1), 57; https://doi.org/10.3390/CSAC2021-10460 - 30 Jun 2021

Cited by 2 | Viewed by 954

Abstract

The effect of the applied voltage on impedance spectra, measured on sensors based on solid supports with interdigitated electrodes (IDE) that are either covered or not with a layer-by-layer film prepared with polyethylenimine and poly (sodium 4-styrenesulfonate), was analyzed to detect 17α-ethinylestradiol(EE2) in [...] Read more.

The effect of the applied voltage on impedance spectra, measured on sensors based on solid supports with interdigitated electrodes (IDE) that are either covered or not with a layer-by-layer film prepared with polyethylenimine and poly (sodium 4-styrenesulfonate), was analyzed to detect 17α-ethinylestradiol(EE2) in mineral water and tap water. The results show that the sensor response is strongly affected by the applied voltage, the presence of film, and the water matrix, meaning that electrochemical reactions develop near the IDE. However, for low values of applied voltage, the sensor response is reproducible with negligible electrochemical reactions, allowing us to conclude that 25 mV is the appropriate voltage. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1392 KiB

Open AccessProceeding Paper

Smart Sensing for Antibiotic Monitoring in Mineral and Surface Water: Development of an Electronic Tongue Device

by Cátia Magro, Tiago Moura, Paulo A. Ribeiro, Maria Raposo and Susana Sério

Chem. Proc. 2021, 5(1), 58; https://doi.org/10.3390/CSAC2021-10606 - 5 Jul 2021

Cited by 2 | Viewed by 997

Abstract

Sensors are considered the future monitoring tools, since, compared to traditional sampling and analysis techniques, they provide fast response on the output data in a timely, continuous, safe, and cost-effective fashion. Antibiotics are important pharmaceuticals with a large variety of applications. However, the [...] Read more.

Sensors are considered the future monitoring tools, since, compared to traditional sampling and analysis techniques, they provide fast response on the output data in a timely, continuous, safe, and cost-effective fashion. Antibiotics are important pharmaceuticals with a large variety of applications. However, the overconsumption of these drugs is under the spotlight, since traces of antibiotics are being found in aquatic ecosystems and may lead to the development of antibiotic resistance. Thus, in this work, sensors consisting of ceramic or glass BK7 solid supports with interdigitated gold electrodes coated with five bilayers of polyethyleneimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS) thin films were developed and able to distinguish clarithromycin concentrations between 10⁻¹⁵ M and 10⁻⁵ M in mineral and surface water matrices. In mineral water, the ceramic support sensors have shown high reproducibility, whereas glass support sensors are not reproducible for this matrix. For the surface water matrix, both types of sensors proved to be reproducible. The surface water’s principal component analysis, obtained for an electronic tongue composed of the aforementioned sensors, demonstrated the concept’s ability to discriminate between different concentrations of the target compound, although no significant pattern of trend was achieved. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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799 KiB

Open AccessProceeding Paper

Towards Low Temperature VOCs Chemoresistors: Graphene Oxide Versus Porphyrin-Based Materials

by Eleonora Pargoletti, Francesca Tessore, Gabriele Di Carlo, Gian Luca Chiarello and Giuseppe Cappelletti

Chem. Proc. 2021, 5(1), 60; https://doi.org/10.3390/CSAC2021-10418 - 30 Jun 2021

Cited by 1 | Viewed by 933

Abstract

The sensing of gas molecules is of fundamental importance for environmental monitoring, the control of chemical processes, and non-invasive medical diagnostics based on breath analysis in humans. Herein, the synthesis of hybrid materials (SnO₂/graphene oxide-GO and SnO₂/porphyrins composites) with [...] Read more.

The sensing of gas molecules is of fundamental importance for environmental monitoring, the control of chemical processes, and non-invasive medical diagnostics based on breath analysis in humans. Herein, the synthesis of hybrid materials (SnO₂/graphene oxide-GO and SnO₂/porphyrins composites) with ad hoc properties led to chemoresistors able to reduce the acetone sensing temperature, guaranteeing acceptable LOD values. As such, boosted potentialities, especially in terms of tuned selectivity and low water interference, may be obtained. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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510 KiB

Open AccessProceeding Paper

Field Nitrogen Dioxide and Ozone Monitoring Using Electrochemical Sensors with Partial Least Squares Regression

by Rachid Laref, Etienne Losson, Alexandre Sava and Maryam Siadat

Chem. Proc. 2021, 5(1), 61; https://doi.org/10.3390/CSAC2021-10622 - 6 Jul 2021

Viewed by 1530

Abstract

Low-cost gas sensors detect pollutants gas at the parts-per-billion level and may be installed in small devices to densify air quality monitoring networks for the spread analysis of pollutants around an emissive source. However, these sensors suffer from several issues such as the [...] Read more.

Low-cost gas sensors detect pollutants gas at the parts-per-billion level and may be installed in small devices to densify air quality monitoring networks for the spread analysis of pollutants around an emissive source. However, these sensors suffer from several issues such as the impact of environmental factors and cross-interfering gases. For instance, the ozone (O₃) electrochemical sensor senses nitrogen dioxide (NO₂) and O₃ simultaneously without discrimination. Alphasense proposes the use of a pair of sensors; the first one, NO2-B43F, is equipped with a filter dedicated to measure NO₂. The second one, OX-B431, is sensitive to both NO₂ and O₃. Thus, O₃ concentration can be obtained by subtracting the concentration of NO₂ from the sum of the two concentrations. This technique is not practical and requires calibrating each sensor individually, leading to biased concentration estimation. In this paper, we propose Partial Least Square regression (PLS) to build a calibration model including both sensors’ responses and also temperature and humidity variations. The results obtained from data collected in the field for two months show that PLS regression provides better gas concentration estimation in terms of accuracy than calibrating each sensor individually. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1066 KiB

Open AccessProceeding Paper

Tropomyosin Analysis in Foods Using an Electrochemical Immunosensing Approach

by Ricarda Torre, Maria Freitas, Estefanía Costa-Rama, Henri P. A. Nouws and Cristina Delerue-Matos

Chem. Proc. 2021, 5(1), 62; https://doi.org/10.3390/CSAC2021-10471 - 30 Jun 2021

Cited by 1 | Viewed by 1036

Abstract

A screen-printed carbon electrode was used as the transducer for the development of an electrochemical immunosensor for the determination of tropomyosin (a major shrimp allergen) in food samples. Monoclonal and polyclonal antibodies were used in a sandwich-type immunoassay. The analytical signal was electrochemically [...] Read more.

A screen-printed carbon electrode was used as the transducer for the development of an electrochemical immunosensor for the determination of tropomyosin (a major shrimp allergen) in food samples. Monoclonal and polyclonal antibodies were used in a sandwich-type immunoassay. The analytical signal was electrochemically obtained using an alkaline phosphatase-labelled secondary antibody and a 3-indoxyl phosphate/silver nitrate substrate. The total assay time was 2 h 50 min and allowed the quantification of tropomyosin between 2.5 and 20 ng mL⁻¹, with a limit of detection of 1.7 ng mL⁻¹ The immunosensor was successfully applied to the analysis of commercial food products. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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3546 KiB

Open AccessProceeding Paper

Simultaneous Sensing of Codeine and Diclofenac in Water Samples Using an Electrochemical Bi-MIP Sensor and a Voltammetric Electronic Tongue

by Hafsa El Youbi, Alassane Diouf, Benachir Bouchikhi and Nezha El Bari

Chem. Proc. 2021, 5(1), 63; https://doi.org/10.3390/CSAC2021-10483 - 30 Jun 2021

Viewed by 1113

Abstract

Codeine and diclofenac overdoses have been widely reported. Here, a biomimetic sensor (bi-MIP) was devised, and an electronic tongue was used to analyze water samples simultaneously containing both these drugs. The bi-MIP sensor limits of detection for diclofenac and codeine taken individually were [...] Read more.

Codeine and diclofenac overdoses have been widely reported. Here, a biomimetic sensor (bi-MIP) was devised, and an electronic tongue was used to analyze water samples simultaneously containing both these drugs. The bi-MIP sensor limits of detection for diclofenac and codeine taken individually were 0.01 µg/mL and 0.16 µg/mL, respectively. Due to a cross-reactivity effect when using the bi-MIP sensor, the electronic tongue was shown to differentiate samples containing both analytes. The results confirm the feasibility of simultaneous detection of two target analytes via a bi-MIP sensor. Additionally, they demonstrate the ability of a multi-sensor to classify different water samples. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Electrochemical Detection of Fenthion Insecticide in Olive Oils by a Sensitive Non-Enzymatic Biomimetic Sensor Enhanced with Metal Nanoparticles

by Youssra Aghoutane, Nezha El Bari, Zoubida Laghrari and Benachir Bouchikhi

Chem. Proc. 2021, 5(1), 64; https://doi.org/10.3390/CSAC2021-10773 - 17 Aug 2021

Cited by 2 | Viewed by 1786

Abstract

Fenthion, an organophosphate insecticide, is a cholinesterase inhibitor and is highly toxic. An electrochemical sensor based on molecularly imprinted polymer is developed here for its detection. For this purpose, 2-aminothiophenol mixed with gold nanoparticles was immobilized on screen-printed gold electrodes. The FEN pattern [...] Read more.

Fenthion, an organophosphate insecticide, is a cholinesterase inhibitor and is highly toxic. An electrochemical sensor based on molecularly imprinted polymer is developed here for its detection. For this purpose, 2-aminothiophenol mixed with gold nanoparticles was immobilized on screen-printed gold electrodes. The FEN pattern was then fixed before being covered with 2-aminothiophenol. Cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy methods were used for the electrochemical characterization. The low detection limit was 0.05 mg/Kg over a range of 0.01–17.3 µg/mL. The sensor was successfully applied for the determination of FEN in olive oil samples with high recovery values. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Spectroscopic Ellipsometry Detection of Prostate Cancer Bio-Marker PCA3 Using Specific Non-Labeled Aptamer: Comparison with Electrochemical Detection

by Sarra Takita, Alexei Nabok, David Smith and Anna Lishchuk

Chem. Proc. 2021, 5(1), 65; https://doi.org/10.3390/CSAC2021-10453 - 30 Jun 2021

Cited by 3 | Viewed by 1489

Abstract

The most common prostate cancer (PCa) diagnostics, which are based on detection of prostate-specific antigens (PSA) in blood, have specificity limitations often resulting in both false-positive and false-negative results; therefore, improvement in PCa diagnostics using more specific PCa biomarkers is of high importance. [...] Read more.

The most common prostate cancer (PCa) diagnostics, which are based on detection of prostate-specific antigens (PSA) in blood, have specificity limitations often resulting in both false-positive and false-negative results; therefore, improvement in PCa diagnostics using more specific PCa biomarkers is of high importance. Studies have shown that the long noncoding RNA Prostate Cancer Antigen 3 (lncPCA3) that is over-expressed in the urine of prostate cancer patients is an ideal biomarker for non-invasive early diagnostics of PCa. Geno-sensors based on aptamer bioreceptors (aptasensors) offer cost- and time-effective, and precise diagnostic tools for detecting PCa biomarkers. In this study, we report on further developments of RNA-based aptasensors exploiting optical (spectroscopic ellipsometry) measurements in comparison with electrochemical (CV and IS) measurements published earlier. These sensors were made by immobilization of thiolated CG-3 RNA aptamers on the surface of gold. Instead of a redox-labelled aptamer used previously in electrochemical measurements, a non-labelled aptamer was used here in a combination with total internal reflection ellipsometry (TIRE) measurements. The results obtained by these two methods were compared. The method of TIRE is potentially highly sensitive and comparable in that respect with electrochemical methods capable of detection of PCA3 in sub-pM levels of concentration. The required selectivity is provided by the high affinity of PCA3-to-aptamer binding with K_D in the 10⁻⁹ M range. The spectroscopic ellipsometry measurements provided additional information on the processes of PCA3 to aptamer binding. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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3261 KiB

Open AccessProceeding Paper

Titanium Based Materials for High-Temperature Gas Sensor in Harsh Environment Application

by Roussin Lontio Fomekong and Bilge Saruhan

Chem. Proc. 2021, 5(1), 66; https://doi.org/10.3390/CSAC2021-10480 - 30 Jun 2021

Cited by 2 | Viewed by 1250

Abstract

Gas selective sensors that are capable of sensing at hot-gas environment are increasingly gaining importance for the monitoring of combustion and thermal processes releasing NO, NO₂ and H₂ containing hot gases at temperatures exceeding 600 °C. Despite some drawbacks, TiO₂ [...] Read more.

Gas selective sensors that are capable of sensing at hot-gas environment are increasingly gaining importance for the monitoring of combustion and thermal processes releasing NO, NO₂ and H₂ containing hot gases at temperatures exceeding 600 °C. Despite some drawbacks, TiO₂ is capable of operating as a gas sensor above 500 °C. In this context, Ni-doped TiO₂, Co-doped TiO₂ and Rh-doped BaTiO₃ have been prepared by oxalate coprecipitation route and fully characterized. Co-doping of TiO₂ promotes p-type behavior exhibiting good sensing properties to NO₂ while Ni-doping displays the maintenance of n-type behavior and better H₂-sensing properties at 600 °C. Rh-doped BaTiO₃ shows excellent NO sensing properties at 900 °C. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Nutritional Composition of the Atlantic Seaweeds Ulva rigida, Codium tomentosum, Palmaria palmata and Porphyra purpurea

by Javier Echave, Catarina Lourenço-Lopes, Anxo Carreira-Casais, Franklin Chamorro, Maria Fraga-Corral, Paz Otero, Pascual Garcia-Perez, Sergio Baamonde, Fermín Fernández-Saa, Hui Cao, Jianbo Xiao, Miguel A. Prieto and Jesus Simal-Gandara

Chem. Proc. 2021, 5(1), 67; https://doi.org/10.3390/CSAC2021-10681 - 14 Jul 2021

Cited by 7 | Viewed by 2262

Abstract

Macroalgae are regarded as a healthy food due to their composition and nutritional properties. In this work, nutritional composition of two green (Ulva rigida, Codium tomentosum) and two red (Palmaria palmata, Porphyra purpurea) edible seaweed was studied. [...] Read more.

Macroalgae are regarded as a healthy food due to their composition and nutritional properties. In this work, nutritional composition of two green (Ulva rigida, Codium tomentosum) and two red (Palmaria palmata, Porphyra purpurea) edible seaweed was studied. Total lipids were measured gravimetrically as evaporated mass after petroleum-ether Soxhlet extraction of samples. In addition, fatty acid profile was determined by gas chromatography coupled to a flame ionization detector (GC-FID). Results showed that all studied species were accounted for very low levels of lipids (<1% dw), but levels of unsaturated fatty acids oleic, linoleic, and linolenic acids were present at high concentrations, with P. palmata displaying the highest quantities (>200 mg C18:1/g extract). In parallel, proteins were quantified following the macro-Kjeldahl method. In this analysis, red algae, especially P. purpurea, showed significant protein content up to 30% DW. Total organic acids were found by ultra-filtration liquid-chromatography coupled to an amperometry detector (UFLC-PAD) after an acid extraction, P. purpurea being the algae with the higher organic acid content (10.61% dw). Minerals were identified and quantified by inductively coupled plasma atomic emission spectroscopy (ICP-OES), suggesting that both algae groups are rich in K and Mg (>15 g/kg), but U. rigida also displayed a remarkable iron content (>1 g Fe/kg). Other detected minerals in minor concentrations were Ca, P or F. Altogether, results corroborate that these edible algae are a good source of nutrients in accordance with literature. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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7 pages, 567 KiB

Open AccessProceeding Paper

Drift Compensation of the Electronic Nose in the Development of Instruments for Out-of-Laboratory Analysis

by Anastasiia Shuba, Tatiana Kuchmenko and Dariya Menzhulina

Chem. Proc. 2021, 5(1), 68; https://doi.org/10.3390/CSAC2021-10464 - 1 Jan 2022

Cited by 1 | Viewed by 1535

Abstract

A technique was developed to evaluate and compensate for the drift of eight mass-sensitive sensors in an open detection cell in order to estimate the influence of external factors (temperature, changes in the chemical composition of the background) on the out-of-laboratory analysis of [...] Read more.

A technique was developed to evaluate and compensate for the drift of eight mass-sensitive sensors in an open detection cell in order to estimate the influence of external factors (temperature, changes in the chemical composition of the background) on the out-of-laboratory analysis of biosamples. The daily internal standardization of the system is an effective way to compensate for the sensor signal drift when the sorption properties of sensitive coatings change during their long-term, intensive operation. In this study, distilled water was proposed as a standard for water matrix-based biosamples (blood, exhaled breath condensate, urine, etc.). Further, internal standardization was based on daily calculation of the specific sensor signals by dividing the sensor signals for the biosample according to the corresponding averaged values obtained from three to five standard measurements. The stability of the sensor array operation was estimated using the theory of statistical process control (exponentially weighted moving average control charts) based on the specific signal of the sensor array. The control limits for the statistical quantity of the central tendency for each sensor and the whole array, as well as the variations of the sensor signals, were determined. The average times required for signal and run lengths, for the purpose of statistically substantiated monitoring of the electronic nose’s stability, were calculated. Based on an analysis of the tendency and variations in sensor signals during 3 months of operation, a technique was formulated to control the stability of the sensor array for the out-of-laboratory analysis of the biosamples. This approach was successfully verified by classifying the results of the analysis of the blood and water samples obtained for this period. The proposed technique can be introduced into the software algorithm of the electronic nose, which will improve decision-making during the long-term monitoring of health conditions in humans and animals. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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388 KiB

Open AccessProceeding Paper

The Performance of Organophosphate Pesticides Determination Using Biosensor Based on Small Device Potentiometer as a Transducer

by Mashuni Mashuni, Halimahtussaddiyah Ritonga, Muhammad Jahiding, La Ode Ahmad Nur Ramadhan, Desy Kurniawati and Fitri Handayani Hamid

Chem. Proc. 2021, 5(1), 69; https://doi.org/10.3390/CSAC2021-10604 - 5 Jul 2021

Cited by 1 | Viewed by 1401

Abstract

The need to control pesticide residues in foodstuffs in a fast and straightforward analysis for the field scale is required. Therefore, this research develops a transducer-based biosensor with a small device potentiometer (SDP) to produce a fast and accurate pesticide detection tool. The [...] Read more.

The need to control pesticide residues in foodstuffs in a fast and straightforward analysis for the field scale is required. Therefore, this research develops a transducer-based biosensor with a small device potentiometer (SDP) to produce a fast and accurate pesticide detection tool. The biosensor based on Au electrodes by immobilizing the acetylcholinesterase (AChE) enzyme coated membrane cellulose acetate (CA) 15% (w/v) cross-linked glutaraldehyde (GA) 25% (v/v) and SDP as a transducer that produces a potential value. The biosensor testing results on the organophosphate pesticide class, namely diazinon and profenofos, showed the sensitivity of 21.204 and 20.035 mV decade⁻¹, Limit of Detection (LoD) 10⁻⁷ mg L⁻¹, selectivity coefficient −1 < K_i,j < 1 and accuracy of 99.497 and 94.765%, respectively. The results showed that the biosensor connected to an SDP transducer had an excellent performance in determining the presence of organophosphate pesticides. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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277 KiB

Open AccessProceeding Paper

Optimization of Bioactive Compounds with Antioxidant Activity of Himanthalia elongata by Microwave-Assisted Extraction Using Response Surface Methodology

by Franklin Chamorro, Lucia Cassani, Catarina Lourenço-Lopes, Anxo Carreira-Casais, Maria Carpena, Javier Echave, Sergio Baamonde, Fermin Fernández-Saa, Paz Otero, Pacual Garcia-Perez, Jesus Simal-Gandara and Miguel Angel Prieto

Chem. Proc. 2021, 5(1), 70; https://doi.org/10.3390/CSAC2021-10478 - 30 Jun 2021

Cited by 2 | Viewed by 1332

Abstract

Himanthalia elongata is a brown alga used in applications in the food, pharmaceutical and nutraceutical industries due to its biological properties, such as antioxidant, anti-inflammatory, and antimicrobial, among others. These effects are attributed to the high content of nutrients and secondary metabolites, especially [...] Read more.

Himanthalia elongata is a brown alga used in applications in the food, pharmaceutical and nutraceutical industries due to its biological properties, such as antioxidant, anti-inflammatory, and antimicrobial, among others. These effects are attributed to the high content of nutrients and secondary metabolites, especially phenolic compounds. The objective of this study is to optimize the microwave-assisted extraction method to recover phenolic compounds and flavonoids, considering three extraction parameters: the concentration of ethanol in water, the extraction time and pressure. The total phenolic content and the total flavonoid content were evaluated, and two biological tests were performed to assess the antioxidant properties. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

201 KiB

Open AccessProceeding Paper

Semiconductor Oxide Gas Sensors: Correlation between Conduction Mechanisms and Their Sensing Performances

by Ambra Fioravanti, Sara Morandi and Maria Cristina Carotta

Chem. Proc. 2021, 5(1), 71; https://doi.org/10.3390/CSAC2021-10472 - 30 Jun 2021

Viewed by 855

Abstract

In this work, a variety of semiconducting oxides were prepared and principally characterized by means of spectroscopic techniques (absorbance FT-IR, diffuse reflectance UV-Vis-NIR) to shed light on the electronic properties and defects involved at the roots of gas sensing capabilities. The thick films [...] Read more.

In this work, a variety of semiconducting oxides were prepared and principally characterized by means of spectroscopic techniques (absorbance FT-IR, diffuse reflectance UV-Vis-NIR) to shed light on the electronic properties and defects involved at the roots of gas sensing capabilities. The thick films were obtained by screen printing technology on which electrical characterization and gas sensing measurements were performed. From the cross analysis of the results, a description of the specific sensing mechanism for each material is proposed. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

387 KiB

Open AccessProceeding Paper

Cross-Sensitive Potentiometric Sensors Based on Anti-Crown (C₆HgF₄)₃

by Ekaterina Yuskina, Kirill Tugashov, Vladimir B. Shur, Irina A. Tikhonova, Vasily Babain and Dmitry Kirsanov

Chem. Proc. 2021, 5(1), 72; https://doi.org/10.3390/CSAC2021-10424 - 30 Jun 2021

Cited by 1 | Viewed by 1355

Abstract

In this work, we explore the possibility of using anti-crown ether (C₆HgF₄)₃ as a membrane-active component for potentiometric cross-sensitive sensors. Anti-crown ligands have already been employed as ionophores in plasticized polymeric membranes; however, the results of these studies [...] Read more.

In this work, we explore the possibility of using anti-crown ether (C₆HgF₄)₃ as a membrane-active component for potentiometric cross-sensitive sensors. Anti-crown ligands have already been employed as ionophores in plasticized polymeric membranes; however, the results of these studies are contradictory. In order to clarify the electrochemical sensitivity patterns of anti-crown-based sensors, we have studied plasticized polymeric membranes containing cation and anion-exchanging additives and various solvent-plasticizers. We explored the electrochemical sensitivity of these membranes in a wide variety of aqueous solutions of inorganic salts. Alkaline, alkaline-earth, and d-element salts with different anions were studied. It was found that the sensors based on anti-crown (C₆HgF₄)₃ exhibit cationic sensitivity, and no considerable anionic responses were observed. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1743 KiB

Open AccessProceeding Paper

An Optical Fiber Sensor for Hg²⁺ Detection Based on the LSPR of Silver and Gold Nanoparticles Embedded in a Polymeric Matrix as an Effective Sensing Material

by María Elena Martínez-Hernández, Xabier Sandua, Pedro J. Rivero, Javier Goicoechea and Francisco J. Arregui

Chem. Proc. 2021, 5(1), 73; https://doi.org/10.3390/CSAC2021-10633 - 7 Jul 2021

Cited by 3 | Viewed by 1290

Abstract

In this work, an optical fiber sensor based on the localized surface plasmon resonance (LSPR) phenomenon is presented as a powerful tool for the detection of heavy metals (

{Hg}^{2 +}

). The resultant sensing film was fabricated using a nanofabrication process, [...] Read more.

In this work, an optical fiber sensor based on the localized surface plasmon resonance (LSPR) phenomenon is presented as a powerful tool for the detection of heavy metals (

{Hg}^{2 +}

). The resultant sensing film was fabricated using a nanofabrication process, known as layer-by-layer embedding (LbL-E) deposition technique. In this sense, both silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized using a synthetic chemical protocol as a function of a strict control of three main parameters: polyelectrolyte concentration, loading agent, and reducing agent. The use of metallic nanostructures as sensing materials is of great interest because well-located absorption peaks associated with their LSPR are obtained at 420 nm (AgNPs) and 530 nm (AuNPs). Both plasmonic peaks provide a stable real-time reference that can be extracted from the spectral response of the optical fiber sensor, giving a reliable monitoring of the Hg²⁺ concentration. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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2306 KiB

Open AccessProceeding Paper

Development of Graphene-Doped TiO₂-Nanotube Array-Based MIM-Structured Sensors and Its Application for Methanol Sensing at Room Temperature

by Teena Gakhar and Arnab Hazra

Chem. Proc. 2021, 5(1), 74; https://doi.org/10.3390/CSAC2021-10620 - 6 Jul 2021

Viewed by 1143

Abstract

This work concerns the development of a good quality graphene doped TiO₂ nanotube array sensor for efficient detection of methanol. A pure and graphene doped TiO₂ nanotube array was synthesized by electrochemical anodization. Morphological, structural and optical characterizations were performed to [...] Read more.

This work concerns the development of a good quality graphene doped TiO₂ nanotube array sensor for efficient detection of methanol. A pure and graphene doped TiO₂ nanotube array was synthesized by electrochemical anodization. Morphological, structural and optical characterizations were performed to study the samples. Both the nanotube samples were produced in Au/TiO₂ nanotube/Ti type MIM-structured devices. Pure and graphene-doped TiO₂ nanotubes offered a response magnitude of 20% and 28% to 100 ppm of methanol at room temperature, respectively. Response/Recovery time was fast for the graphene doped TiO₂ nanotube array (34 s/40 s) compared to a pure TiO₂ nanotube array (116 s/576 s) at room temperature. This study confirmed the notable enhancement in methanol sensing due to the formation of local heterojunctions between graphene and TiO₂ in the hybrid sample. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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870 KiB

Open AccessProceeding Paper

Morphological Effects in SnO₂ Chemiresistors for Ethanol Detection: A Systematic Statistical Analysis of Results Published in the Last 5 Years

by Andrea Ponzoni

Chem. Proc. 2021, 5(1), 75; https://doi.org/10.3390/CSAC2021-10474 - 30 Jun 2021

Viewed by 943

Abstract

SnO₂ is one of the most studied materials in gas sensing. Among the many strategies adopted to optimize its sensing properties, the fine tuning of the morphology in nanoparticles, nanowires, and nanosheets, as well as their eventual hierarchical organization, has become an [...] Read more.

SnO₂ is one of the most studied materials in gas sensing. Among the many strategies adopted to optimize its sensing properties, the fine tuning of the morphology in nanoparticles, nanowires, and nanosheets, as well as their eventual hierarchical organization, has become an active field of research. In this work, results published in the literature over the last five years are systematically analyzed focusing on response intensities recorded with chemiresistors based on pure SnO₂ for ethanol detection in dry air. Results indicate that no morphology clearly outperforms others, while a few individual sensors emerge as remarkable outliers with respect to the whole dataset. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1145 KiB

Open AccessProceeding Paper

Review of the Recent Advances in Nano-Biosensors and Technologies for Healthcare Applications

by Maha Wajeeh Aqra and Amall Ahmed Ramanathan

Chem. Proc. 2021, 5(1), 76; https://doi.org/10.3390/CSAC2021-10473 - 30 Jun 2021

Cited by 2 | Viewed by 1387

Abstract

The growing human population and the discovery of new diseases and emerging pandemics have increased the need for healthcare treatments and medications with innovative designs. The emergence of nanotechnology provides a platform for novel diagnostic and therapeutic in vivo non-invasive detection and treatment [...] Read more.

The growing human population and the discovery of new diseases and emerging pandemics have increased the need for healthcare treatments and medications with innovative designs. The emergence of nanotechnology provides a platform for novel diagnostic and therapeutic in vivo non-invasive detection and treatment of ailments. It is now the era of the Internet of things (IoT), and data acquisition and interpretation from various parts of the human body in real time is possible with interconnected sensors and information transfer devices. Miniaturization, low power consumption and price with compatibility to existing network circuits are essential requirements in the IoT. Biosensors made of nanostructured materials are the ideal choice due to the unique structural, chemical and electronic properties of these materials with the advantage of a large surface-to-volume ratio, which makes them very successful for use as sensors for the detection of diseases, drug carriers, filters, fillers and reaction catalysts in healthcare applications. In this paper, we reviewed the recent progress made in the research and applications of biosensors in health and preventive medicine. The focus of the paper is biosensors made of nanostructured layered materials such as graphene and its structural analogs molybdenum disulphide (MoS₂) and boron nitride (BN). We discussed and highlighted the present capabilities of the different nano-forms of these materials in the detection and analysis of diseases. Their efficiencies in terms of the detection limit, the sensitivity and the adaptability to different environments were be discussed. In addition, the challenges and future perspectives of using nano-biosensors to develop efficient diagnostic, therapeutic and cost-effective monitoring devices with smart technologies were explored. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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596 KiB

Open AccessProceeding Paper

Feasibility of Total White Blood Cells Counts by Visible-Near Infrared Spectroscopy

by Teresa Guerra Barroso, Lénio Ribeiro, Hugo Gregório, Filipe Santos and Rui Costa Martins

Chem. Proc. 2021, 5(1), 77; https://doi.org/10.3390/CSAC2021-10434 - 30 Jun 2021

Viewed by 2412

Abstract

Total white blood cells (WBC) count is an important indication for infection diagnosis, in both human and veterinary medicine. State-of-the-art WBC counts are performed by flow cytometry combined with light scattering or impedance measurements, in the clinical analysis laboratory. These technologies are complex [...] Read more.

Total white blood cells (WBC) count is an important indication for infection diagnosis, in both human and veterinary medicine. State-of-the-art WBC counts are performed by flow cytometry combined with light scattering or impedance measurements, in the clinical analysis laboratory. These technologies are complex and difficult to be miniaturized into a portable point-of-care (POC) system. Spectroscopy is one of the most powerful technologies for POC miniaturization due to its capacity to analyze low sample quantities, little to no sample preparation, and ‘real-time’ results. WBC is in the proportion of 1:1000 to red blood cells (RBC), and the latter dominate visible-near infrared (Vis-NIR) information due to their large quantities and hemoglobin absorbance. WBC are difficult to be detected by traditional spectral analysis because their information is contained within the interference of hemoglobin bands. Herein, we perform a feasibility study for the direct detection of WBC counts in canine blood by Vis-NIR spectroscopy for veterinary applications, benchmarking current chemometrics techniques with self-learning artificial intelligence—a new advanced method for high-accuracy quantification from spectral information. Results show that total WBC counts can be detected by Vis-NIR spectroscopy to an average detection limit of 7.8

\times 10^{9}

cells/L, with an R

^{2}

of 0.9880 between impedance flow cytometry analysis and spectral quantification. This result opens new possibilities for reagent-less POC technology in infection diagnosis. As WBC counts in dogs range from 5 to 45

\times 10^{9}

cells/L, the detection limit obtained in this research allows concluding that the combined use of spectroscopy with this SL-AI new algorithm is a step towards the existence of portable and miniaturized Spectral POC hemogram analysis. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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517 KiB

Open AccessProceeding Paper

Visible–Near-Infrared Platelets Count: Towards Thrombocytosis Point-of-Care Diagnosis

by Teresa Guerra Barroso, Lénio Ribeiro, Hugo Gregório, Filipe Santos and Rui Costa Martins

Chem. Proc. 2021, 5(1), 78; https://doi.org/10.3390/CSAC2021-10435 - 30 Jun 2021

Cited by 1 | Viewed by 1823

Abstract

Thrombocytosis is a disorder with an excessive number of platelets in the blood, where total platelet counts (TPC) are crucial for diagnosis. This condition predisposes to blood vessels clotting and diseases such as stroke or heart attack. TPC is generally performed at the [...] Read more.

Thrombocytosis is a disorder with an excessive number of platelets in the blood, where total platelet counts (TPC) are crucial for diagnosis. This condition predisposes to blood vessels clotting and diseases such as stroke or heart attack. TPC is generally performed at the laboratory by flow cytometry with laser scattering or impedance detection. Due to the limited capacity of automated hematology in performing TPC quantification, a manual microscopy count is a very common quality assurance measure undertaken by clinical pathologists. Monitoring coagulation risk is key in many health conditions, and point-of-care platforms would simplify this procedure by taking platelet counts to the bedside. Spectroscopy has high potential for reagent-less point-of-care miniaturized technologies. However, platelets are difficult to detect in blood by standard spectroscopy analysis, due to their small size, low number when compared to red blood cells, and low spectral contrast to hemoglobin. In this exploratory research, we show that it is possible to perform TPC by advanced spectroscopy analysis, using a new processing methodology based on self-learning artificial intelligence. The results show that TPC can be measured by visible–near-infrared spectroscopy above the standard error limit of 61.19 × 10

^{9}

cells/L (R

^{2}

= 0.7016), tested within the data range of 53 × 10

^{9}

to 860 × 10

^{9}

cells/L of dog blood. These results open the possibility for using spectroscopy as a diagnostic technology for the detection of high levels of platelets directly in whole blood, towards the rapid diagnosis of thrombocytosis and stroke prevention. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1460 KiB

Open AccessProceeding Paper

Development of an Integrated In-Vehicle Driver Breath Ethanol System Based on α-Fe₂O₃ Sensing Material

by Roberto Di Chio, Monica Galtieri, Nicola Donato and Giovanni Neri

Chem. Proc. 2021, 5(1), 79; https://doi.org/10.3390/CSAC2021-10476 - 30 Jun 2021

Cited by 2 | Viewed by 1045

Abstract

Alcohol abuse is the dominant cause of fatal car accidents (about 25% of all road deaths in Europe). The large-scale implementation of systems aimed at the realization of in-vehicle driver breath ethanol detection is therefore in high demand. For this reason, we devoted [...] Read more.

Alcohol abuse is the dominant cause of fatal car accidents (about 25% of all road deaths in Europe). The large-scale implementation of systems aimed at the realization of in-vehicle driver breath ethanol detection is therefore in high demand. For this reason, we devoted our attention to the design of an inexpensive and reliable breath alcohol sensor for use in an Advanced Driver Assistance System (ADAS). The main challenge in the development of this sensor is related to the complexity of breath composition and its high humidity content, coupled with the high dilution of breath reaching the sensor. In this work, a simple α-Fe₂O₃ film-based sensor was developed and validated in laboratory tests. Tests were also performed by placing the ethanol sensor within the casing of the upper steering column of a car to simulate real driving conditions. Using an array provided with the developed ethanol sensor and humidity, temperature and CO₂ sensors, it was possible to differentiate the signal of a driver’s breath before and after alcohol consumption. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Developing an Electrochemical Biosensor for the Detection of Hemagglutinin Protein of Influenza A Virus Subtype H1N1 in Artificial Saliva

by Carlos Torres-Méndez, Jayendra Ellamathy, Maria Ines Mascarenhas, Yifan Liu, Georgia-Vasiliki Gkountana, Patrizia Kühne, Javier Sebastián, Ivana Jovanovic, David Bern, Sharmilee Nandi, Maike Lüftner, Viktoria Langwallner, Maria Lysandrou, Sam Taylor, Klara Martinovic, Abdul-Raouf Atif, Ehsan Manouchehri Doulabi, Masood Kamali-Moghaddam and Gemma Mestres

Chem. Proc. 2021, 5(1), 80; https://doi.org/10.3390/CSAC2021-10477 - 30 Jun 2021

Viewed by 2151

Abstract

Influenza A virus belongs to the Orthomyxoviridae family and, to date, is one of the most important pathogens causing acute respiratory infections, such as the recent pandemic of 2009. Hemagglutinin (HA) is one of the surface proteins of the virus that allow it [...] Read more.

Influenza A virus belongs to the Orthomyxoviridae family and, to date, is one of the most important pathogens causing acute respiratory infections, such as the recent pandemic of 2009. Hemagglutinin (HA) is one of the surface proteins of the virus that allow it to interact with cellular molecules. Due to the fact that it is the most abundant protein in the virus capsule, it is the best target in the detection of the Influenza A H1N1 virus through biosensing devices. Our aim is to develop an electrochemical biosensor to detect H1 by modifying carbon screen-printed electrodes (CSPE) with gold nanoparticles and to add further functionalization with monoclonal antibodies that are specific to this protein. The electrodes were characterized by the means of cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. Our preliminary results suggest that the selected monoclonal antibodies have acceptable affinity and bind effectively to the H1 protein and that the electrodes have a wide potential window in the presence of [Fe(CN)₆]^3−/4−. In the future, we will continue to develop this biosensor in hope that it will be commercialized and be common in medical procedures during flu seasons and future influenza pandemics. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

New Half Metal Perovskite NbScO₃ for Spintronic Sensing Applications

by Amall Ahmed Ramanathan

Chem. Proc. 2021, 5(1), 82; https://doi.org/10.3390/CSAC2021-10628 - 7 Jul 2021

Viewed by 1299

Abstract

Half-metallic ferromagnetic (HMF) materials demonstrate 100% spin polarization at the Fermi level, making them promising candidates for spintronic sensing applications. In this work, the full potential linearized augmented plane wave (FP-LAPW) density functional theory (DFT) method is used to calculate the electro-magnetic properties [...] Read more.

Half-metallic ferromagnetic (HMF) materials demonstrate 100% spin polarization at the Fermi level, making them promising candidates for spintronic sensing applications. In this work, the full potential linearized augmented plane wave (FP-LAPW) density functional theory (DFT) method is used to calculate the electro-magnetic properties of the transition metal perovskite NbScO₃ using the generalized gradient approximation (GGA) and the modified Becke-Johnson (mBJ) approximation for the exchange correlations. The electronic band structures for the two spin orientations using GGA, predict NbScO₃ to be an HMF with an integer magnetic moment of 2.0 μB and hence a promising candidate for spintronics. The new half metal perovskite shows metallic behavior in the majority spin and semiconducting in the minority spin channel with a direct Γ−Γ band gap of 1.870 eV. The integer magnetic moment of 2.0 μB is also preserved with mBJ exchange potential. The band structure, however, shows indirect gaps R−Γ and X−Γ of 2.023 eV and 0.780 eV in the minority and majority channels, respectively indicating NbScO₃ to be a magnetic semiconductor. The results indicate the suitability of NbScO₃ for spintronics as the necessary conditions are satisfied. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

Group 14 Metallafluorenes for Lipid Structure Detection and Cellular Imaging

by Helena J. Spikes, Shelby J. Jarrett-Noland, Stephan M. Germann, Wendy Olivas, Janet Braddock-Wilking and Cynthia M. Dupureur

Chem. Proc. 2021, 5(1), 83; https://doi.org/10.3390/CSAC2021-10455 - 30 Jun 2021

Viewed by 1211

Abstract

Fluorescent compounds have been shown to be useful in probing lipid dynamics, and there is ongoing interest in nontoxic, photostable, and sensitive dyes. Recently, we evaluated a number of 2,7-disubstituted-alkynyl(aryl)-3,6-dimethoxy-9,9-diphenyl sila- and germafluorenes for their potential as cellular fluorescent probes. These compounds exhibit [...] Read more.

Fluorescent compounds have been shown to be useful in probing lipid dynamics, and there is ongoing interest in nontoxic, photostable, and sensitive dyes. Recently, we evaluated a number of 2,7-disubstituted-alkynyl(aryl)-3,6-dimethoxy-9,9-diphenyl sila- and germafluorenes for their potential as cellular fluorescent probes. These compounds exhibit remarkable quantum yields in hydrophobic environments and dramatic increases in emission intensity in the presence of surfactants. Here, we show that they exhibit significant emission enhancements in the presence of small unilamellar vesicles and are nontoxic to E. coli, S. aureus, and S. cerevisiae. Furthermore, they luminesce in S. cerevisiae cells with strong photostability and colocalize with the lipid droplet stain Nile Red, demonstrating their promise as lipid probes. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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Open AccessProceeding Paper

QSPR Modelling of Potentiometric HCO₃⁻/Cl⁻ Selectivity for Polymeric Membrane Sensors

by Nadezhda Vladimirova, Julia Ashina and Dmitry Kirsanov

Chem. Proc. 2021, 5(1), 84; https://doi.org/10.3390/CSAC2021-10621 - 6 Jul 2021

Viewed by 1017

Abstract

Since the development process of new sensors is long and tedious, it would be very helpful to develop a model that could predict sensor properties based on active compound structure without the actual synthesis and characterization of the corresponding sensors. In this work, [...] Read more.

Since the development process of new sensors is long and tedious, it would be very helpful to develop a model that could predict sensor properties based on active compound structure without the actual synthesis and characterization of the corresponding sensors. In this work, the model for the prediction of logK (HCO₃⁻/Cl⁻) was constructed based on 40 ligand structures suggested in the literature for carbonate sensing. Substructural molecular fragments (SMF) were used to describe the structure of compounds, where fragments were considered as sequences of bonds and atoms. The projection on latent structures (PLS) method was used to calculate the regression model. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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5980 KiB

Open AccessProceeding Paper

Room Temperature Hydrogen Sensing Based on Tapered Optical Fiber Coated with Polyaniline (PANI)

by Mohammed Majeed Alkhabet, Saad Hayatu Girei, Abdul Hadi Ismail, Suriati Paiman, Norhana Arsad, Mohd Adzir Mahdi and Mohd Hanif Yaacob

Chem. Proc. 2021, 5(1), 85; https://doi.org/10.3390/CSAC2021-10415 - 30 Jun 2021

Cited by 2 | Viewed by 1071

Abstract

This work demonstrates a hydrogen (H₂) sensor at room temperature made of tapered optical fibers coated with a polyaniline (PANI) nanofiber. A transducing platform was constructed using a multimode optical fiber (MMF) with a 125 µm cladding and a 62.5 µm [...] Read more.

This work demonstrates a hydrogen (H₂) sensor at room temperature made of tapered optical fibers coated with a polyaniline (PANI) nanofiber. A transducing platform was constructed using a multimode optical fiber (MMF) with a 125 µm cladding and a 62.5 µm core diameter. In order to enhance the light evanescent field surrounding the fiber, the fibers were tapered from 125 µm in diameter to 20 µm in diameter with 10 mm waist and coated PANI using the drop casting technique. Various characterization techniques, such as field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), differential X-ray (XRD), and atomic force microscopy, have been used to establish the PANI’s properties. When H₂ is subtracted, the optical properties of the PANI layer change, resulting in a change in light absorption. The fabricated sensor was tested by exposing it to H₂ at different concentration from 0.125% to 1%. In this case, the sensitivity, response, and recovery times were 15.928/vol%, 110 s, and 160 s, respectively. The improved hydrogen sensor holds great promise for environmental and industrial applications due to its ability to operate at room temperature. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1241 KiB

Open AccessProceeding Paper

Aqueous Medium Fluoride Anion Sensing by Fluorophore Encapsulated UiO-66 Type Zirconium Metal–Organic Framework

by Rana Dalapati and Ling Zang

Chem. Proc. 2021, 5(1), 86; https://doi.org/10.3390/CSAC2021-10551 - 1 Jul 2021

Cited by 1 | Viewed by 1144

Abstract

A well-known fluorophore molecule, pyrene was encapsulated into a stable metal organic framework by in situ encapsulation method. The existing metal-organic framework (MOF) called UiO-66 (UiO = University of Oslo) served as host material for pyrene fluorophore. The fluorescence of pyrene was quenched [...] Read more.

A well-known fluorophore molecule, pyrene was encapsulated into a stable metal organic framework by in situ encapsulation method. The existing metal-organic framework (MOF) called UiO-66 (UiO = University of Oslo) served as host material for pyrene fluorophore. The fluorescence of pyrene was quenched after encapsulation inside the porous host. Recovery of quenched fluorescence was accomplished by anion induced host dissolution, followed by the release of the fluorophore molecule. Using this anion induced dissolution, a selective sensing of fluoride anion in pure aqueous was achieved. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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1649 KiB

Open AccessProceeding Paper

Customized Screen-Printed Electrodes Based on Ag-Nanoseeds for Enhanced Electroanalytical Response towards Cd(II), Pb(II) and As(V) in Aqueous Samples

by Karina Torres-Rivero, Clara Pérez-Ràfols, Julio Bastos-Arrieta, Núria Serrano, Vicenç Martí and Antonio Florido

Chem. Proc. 2021, 5(1), 87; https://doi.org/10.3390/CSAC2021-10469 - 30 Jun 2021

Viewed by 1142

Abstract

Electrochemical analysis based on screen-printed electrodes (SPEs) represents a great alternative to conventional analytical methods such as ICP-MS or LC-MS due to their portability, sensitivity, selectivity, and cost-effectiveness. In addition, the functionalization of SPEs with nanomaterials has been reported to provide an enhanced [...] Read more.

Electrochemical analysis based on screen-printed electrodes (SPEs) represents a great alternative to conventional analytical methods such as ICP-MS or LC-MS due to their portability, sensitivity, selectivity, and cost-effectiveness. In addition, the functionalization of SPEs with nanomaterials has been reported to provide an enhanced analytical performance. In this regard, silver nanoparticles (AgNPs) were synthesized and appropriately characterized, showing spherical silver nanoseeds (Ag-NS) with a diameter of 12.20 ± 0.04 nm. Using the drop-casting methodology, the synthesized AgNPs were used to modify screen-printed carbon nanofiber electrodes (SPCNFEs). Ag-NS deposition onto the electrode surface was confirmed by scanning electron microscopy (SEM). Furthermore, the analytical response of the modified electrodes (Ag-NS-SPCNFE) was evaluated for the determination of trace Pb(II), Cd(II), and As(V) using differential pulse anodic stripping voltammetry (DPASV), obtaining detection limits of 3.3, 3.7, and 2.6 µg L⁻¹, for Pb(II), Cd(II) and As(V), respectively. Finally, Ag-NS-SPCNFE was tested towards the determination of As(V) in a spiked tap water sample, showing a good agreement with concentrations determined by ICP-MS. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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2474 KiB

Open AccessProceeding Paper

Hydroponics Monitoring through UV-Vis Spectroscopy and Artificial Intelligence: Quantification of Nitrogen, Phosphorous and Potassium

by Aníbal Filipe Silva, Klara Löfkvist, Mikael Gilbertsson, Erik Van Os, Geert Franken, Jos Balendonck, Tatiana M. Pinho, José Boaventura-Cunha, Luís Coelho, Pedro Jorge and Rui Costa Martins

Chem. Proc. 2021, 5(1), 88; https://doi.org/10.3390/CSAC2021-10448 - 30 Jun 2021

Cited by 7 | Viewed by 2325

Abstract

In hydroponic cultivation, monitoring and quantification of nutrients is of paramount importance. Precision agriculture has an urgent need for measuring fertilization and plant nutrient uptake. Reliable, robust and accurate sensors for measuring nitrogen (N), phosphorus (P) and potassium (K) are regarded as critical [...] Read more.

In hydroponic cultivation, monitoring and quantification of nutrients is of paramount importance. Precision agriculture has an urgent need for measuring fertilization and plant nutrient uptake. Reliable, robust and accurate sensors for measuring nitrogen (N), phosphorus (P) and potassium (K) are regarded as critical in this process. It is vital to understand nutrients’ interference; thusly, a Hoagland fertilizer solution-based orthogonal experimental design was deployed. Concentration ranges were varied in a target analyte-independent style, as follows: [N] = [103.17–554.85] ppm; [P] = [15.06–515.35] ppm; [K] = [113.78–516.45] ppm, by dilution from individual stock solutions. Quantitative results for N and K, and qualitative results for P were obtained. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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5331 KiB

Open AccessProceeding Paper

Influence of the Type and Amount of Plasticizer on the Sensory Properties of Microspheres Sensitive to Lipophilic Ions

by Aleksandra Kalinowska, Patrycja Matusiak, Sandra Skorupska, Ilona Grabowska-Jadach and Patrycja Ciosek-Skibińska

Chem. Proc. 2021, 5(1), 90; https://doi.org/10.3390/CSAC2021-10487 - 30 Jun 2021

Cited by 3 | Viewed by 1106

Abstract

Working parameters of chemical sensors, such as selectivity and sensitivity, can be adjusted by optimizing components of chemosensitive layers, including type and amount of plasticizer in the case of PVC membranes in optodes. Plasticizers are also used in the process of creating micro/nanospheres [...] Read more.

Working parameters of chemical sensors, such as selectivity and sensitivity, can be adjusted by optimizing components of chemosensitive layers, including type and amount of plasticizer in the case of PVC membranes in optodes. Plasticizers are also used in the process of creating micro/nanospheres that are incorporated with chemical indicators to form micro/nano-scale optodes. This study investigated the influence of the type of plasticizer (polar o-NPOE and non-polar DOS) on the optical response of microspheres that are sensitive to lipophilic ions. Moreover, the amount of plasticizer was also adjusted in order to obtain satisfactory sensitivity in the widest linear range. The chemosensory response of the developed microspheres was studied with the use of spectrophotometry and spectrofluorimetry, while size of the optodes was estimated by confocal microscopy. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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141 KiB

Open AccessCorrection

Correction: Kumar et al. Numerical and Experimental Modeling of Paper-Based Actuators. Chem. Proc. 2021, 5, 15

by Ashutosh Kumar, Hojat Heidari-Bafroui, Amer Charbaji, Nasim Rahmani, Constantine Anagnostopoulos and Mohammad Faghri

Chem. Proc. 2021, 5(1), 92; https://doi.org/10.3390/chemproc2021005092 - 19 Mar 2024

Viewed by 1045

Abstract

Text Correction [...] Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry)

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