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Eng. Proc., 2023, CSAC 2023

The 2nd International Electronic Conference on Chemical Sensors and Analytical Chemistry

Online | 16–30 September 2023

Volume Editors:
Nicole Jaffrezic-Renault, Institute of Analytical Sciences, UMR CNRS 5280, France
Marco Frasconi, University of Padova, Italy
Jose Vicente Ros-Lis, University of Valencia, Spain
Jin-Ming Lin, Tsinghua University, China
Camelia Bala, University of Bucharest, Romania

Number of Papers: 68
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Cover Story (view full-size image): This volume presents a collection of contributions at the 2nd International Electronic Conference on Chemical Sensors and Analytical Chemistry held on 16–30 September 2023. Chemical sensors are [...] Read more.
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1 pages, 145 KiB  
Editorial
Statement of Peer Review
by Nicole Jaffrezic-Renault
Eng. Proc. 2023, 48(1), 67; https://doi.org/10.3390/engproc2023048067 - 7 Mar 2024
Viewed by 362
Abstract
In submitting conference proceedings to Engineering Proceedings, the volume editors of the proceedings certify to the publisher that all papers published in this volume have been subjected to peer review administered by the volume editors [...] Full article
2 pages, 340 KiB  
Editorial
Preface: The 2nd International Electronic Conference on Chemical Sensors and Analytical Chemistry
by Nicole Jaffrezic-Renault
Eng. Proc. 2023, 48(1), 68; https://doi.org/10.3390/engproc2023048068 - 7 Mar 2024
Viewed by 496
Abstract
This conference volume presents the proceedings of the 2nd International Electronic Conference on Chemical Sensors and Analytical Chemistry held on 16–30 September 2023 [...] Full article
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27946 KiB  
Proceeding Paper
Characteristics of Thermoresponsive Biohydrogels
by Bożena Tyliszczak, Magdalena Bańkosz, Klaudyna Grzela, Korneliusz Rzepka, Monika Iglar, Jakub Piątkowski, Katarzyna Sala, Aniela Woźniak, Dominika Wanat and Magdalena Kędzierska
Eng. Proc. 2023, 48(1), 1; https://doi.org/10.3390/CSAC2023-14885 - 18 Sep 2023
Viewed by 583
Abstract
The aim of this work was the synthesis of functional hydrogel materials obtained via photopolymerization. The resulting systems were characterized in terms of chemical structure using Fourier transform infrared spectroscopy. Subsequently, their sorption capacity and surface morphology were determined along with roughness analysis. [...] Read more.
The aim of this work was the synthesis of functional hydrogel materials obtained via photopolymerization. The resulting systems were characterized in terms of chemical structure using Fourier transform infrared spectroscopy. Subsequently, their sorption capacity and surface morphology were determined along with roughness analysis. The resulting materials have been modified with fluorescein dye and can be used in many branches of industry and medicine, for example, in innovative diagnostic systems. Full article
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1848 KiB  
Proceeding Paper
Ultrasensitive Raman Spectroscopy-Based Virus Detection Using Glycan-Coated Plasmonic Substrates
by Ojodomo J. Achadu and Enoch Y. Park
Eng. Proc. 2023, 48(1), 2; https://doi.org/10.3390/CSAC2023-14922 - 7 Oct 2023
Viewed by 603
Abstract
Hepatitis viral infections are the most common cause of hepatitis liver disease, which eventually leads to cancer and fibrosis if not detected early. Therefore, early detection would allow for preventive and therapeutic actions. Here, a surface-enhanced Raman spectroscopy (SERS)-based biosensor was developed using [...] Read more.
Hepatitis viral infections are the most common cause of hepatitis liver disease, which eventually leads to cancer and fibrosis if not detected early. Therefore, early detection would allow for preventive and therapeutic actions. Here, a surface-enhanced Raman spectroscopy (SERS)-based biosensor was developed using plasmonic molybdenum trioxide quantum dots (MoO3-QDs) as the SERS substrates. The nanostructured substrate of MoO3-QDs was functionalized with a proteoglycan (syndecan-1) as a novel bioreceptor for the target hepatitis E virus (HEV). The innovative biodetection system achieved a detection limit of 1.05 fg/mL for the tested HEV target (ORF2), indicating superb clinically relevant sensitivity and performance. The designed biosensing system incorporating a glycan motif as a bioreceptor instead of the conventional antibodies or aptamers presents new insights for the ultrasensitive detection of HEV and other infectious viruses. Full article
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988 KiB  
Proceeding Paper
Ambient Chemiresistive Sensing of Hydrogen Peroxide Based on PEDOT:PSS/PEDOT Film
by Ling Zhu, Nan Gao, Xiaowen Xie and Shuai Chen
Eng. Proc. 2023, 48(1), 3; https://doi.org/10.3390/CSAC2023-14876 - 18 Sep 2023
Viewed by 353
Abstract
Compared with other gas-phase analytes, the coexistence and competing effect of the moisture component has long created great difficulty and technical challenges for the reliable detection of chemically oxidizing active H2O2 vapor (HPV). Recently, our group designed and prepared a [...] Read more.
Compared with other gas-phase analytes, the coexistence and competing effect of the moisture component has long created great difficulty and technical challenges for the reliable detection of chemically oxidizing active H2O2 vapor (HPV). Recently, our group designed and prepared a chemiresistive sensor based on conductive films of poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), and PEDOT:PSS/PEDOT to achieve direct detection of HPV at the ppm level. Specially, the hydrophobic PEDOT layer was polymerized on the surface of the PEDOT:PSS film using the electrochemical method to attenuate the adverse effect of moisture within HPV on the stability and detection performance of the PEDOT:PSS/PEDOT sensing film. Full article
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1876 KiB  
Proceeding Paper
Amperometric Ion-Selective Electrodes Based on Prussian Blue Nanoparticles
by Vera Shavokshina, Vita Nikitina and Arkady Karyakin
Eng. Proc. 2023, 48(1), 4; https://doi.org/10.3390/CSAC2023-14901 - 25 Sep 2023
Cited by 1 | Viewed by 520
Abstract
We report amperometric solid-contact potassium-selective electrodes based on catalytically synthesized Prussian Blue nanoparticles. Both the films and nanoparticles were able to generate an amperometric response in the flow-injection mode under a constant potential. However, the nanoparticles provided a higher sensitivity than the films. [...] Read more.
We report amperometric solid-contact potassium-selective electrodes based on catalytically synthesized Prussian Blue nanoparticles. Both the films and nanoparticles were able to generate an amperometric response in the flow-injection mode under a constant potential. However, the nanoparticles provided a higher sensitivity than the films. Moreover, the intrinsic permeability of Prussian Blue for potassium ions allowed for selective detection of potassium in comparison to sodium even without an ion-selective membrane. The results of electrochemical impedance spectroscopy were used to manage the sensitivity by controlling the charge transfer resistance for ion-selective membranes of different density. By performing measurements in Bis-Tris as a carrier buffer containing no interfering cations, an additional increase in selectivity was enabled. A record selectivity coefficient logK Na+/K+ of −2.7 for the amperometric flow-injection mode was achieved. The obtained results indicate the prospects for analysis of biological fluids as the Na+/K+ ratio is approximately 20–40. Full article
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1390 KiB  
Proceeding Paper
Chromium-Modified Lanthanum-Based Metal–Organic Framework: Novel Electrochemical Sensing Platform for Pb(II) Ions
by Shubham S. Patil, Vijaykiran N. Narwade, Tibor Hianik and Mahendra D. Shirsat
Eng. Proc. 2023, 48(1), 5; https://doi.org/10.3390/CSAC2023-14928 - 7 Oct 2023
Cited by 1 | Viewed by 580
Abstract
Heavy metal ions (HMIs) in drinking water result from industrialization and can cause a nuisance to the environment. Due to their toxicity and carcinogenic tendencies toward humans, determining HMIs remains challenging. This study focuses on creating a cutting-edge electrochemical sensor with unprecedented sensitivity [...] Read more.
Heavy metal ions (HMIs) in drinking water result from industrialization and can cause a nuisance to the environment. Due to their toxicity and carcinogenic tendencies toward humans, determining HMIs remains challenging. This study focuses on creating a cutting-edge electrochemical sensor with unprecedented sensitivity to lead (Pb(II)). In the present investigation, we have hydrothermally produced lanthanum porous coordination polymer (La-TMA), which was further modified with chromium (Cr) nanoparticles, characterized with structural, morphological, electrochemical, and spectroscopic techniques, and used as a sensing material. The differential pulse voltammogram pattern of the chromium-modified lanthanum porous coordination polymer (Cr@La-TMA) sensor indicates an affinity for Pb(II). Sensing parameters such as sensitivity, selectivity, and linearity have been investigated. The Cr@La-TMA sensor shows selectivity towards Pb(II), which is also validated by the interference study for various analytes such as Cd(II), Hg(II), Cu(II), Cr(II), and Fe(II). The sensor exhibited excellent linearity for the concentration range of 1 nM to 10 nM with a limit of detection of 1 nM, which is below the maximum contamination level (MCL) suggested by the United States Environmental Protection Agency (US-EPA) and World Health Organization (WHO). The proposed sensor would be incredibly useful for the real-time monitoring of heavy metal ions. Full article
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706 KiB  
Proceeding Paper
Development of a “Green” Paper-Based Voltammetric Platform for the On-Site Assay of Tl(I)
by Katerina Kouseri, Irini Panagiotopoulou, Dionysios Soulis, Anastasios Economou, Mamas Prodromidis and Christos Kokkinos
Eng. Proc. 2023, 48(1), 6; https://doi.org/10.3390/CSAC2023-14904 - 26 Sep 2023
Viewed by 406
Abstract
In this work, a “green” electrochemical paper-based device (ePAD) for the voltammetric determination of Tl(I) is described. A mini voltammetric cell was patterned on chromatographic paper by using screen printing to deposit three carbon electrodes and plotting with hydrophobic ink to form a [...] Read more.
In this work, a “green” electrochemical paper-based device (ePAD) for the voltammetric determination of Tl(I) is described. A mini voltammetric cell was patterned on chromatographic paper by using screen printing to deposit three carbon electrodes and plotting with hydrophobic ink to form a circular assay zone. The sample was added to the assay zone (which was pre-loaded with Bi(III)) and Tl(I) was quantified using anodic stripping voltammetry (ASV). The experimental conditions and potential interferences were studied. The limit of detection was at the low μg L−1 level, indicating that these devices can serve successfully as fit-for-purpose disposable voltammetric sensors for Tl(I). Full article
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933 KiB  
Proceeding Paper
A Sensitive Voltammetric Approach Employing a Bare Boron-Doped Diamond Electrode as a Sensor for the Determination of Hydroxocobalamin
by Lenka Janíková, Renáta Šelešovská, Iveta Stýblová and Jaromíra Chýlková
Eng. Proc. 2023, 48(1), 7; https://doi.org/10.3390/CSAC2023-14894 - 25 Sep 2023
Viewed by 373
Abstract
The voltammetric behavior of hydroxocobalamin (OH-CBL) was firstly studied by employing a bare boron-doped diamond electrode as a working electrode. It was found that OH-CBL provided four anodic signals on BDDE in acidic supporting electrolytes and one cathodic signal. The anodic peak situated [...] Read more.
The voltammetric behavior of hydroxocobalamin (OH-CBL) was firstly studied by employing a bare boron-doped diamond electrode as a working electrode. It was found that OH-CBL provided four anodic signals on BDDE in acidic supporting electrolytes and one cathodic signal. The anodic peak situated at +412 mV (vs. Ag|AgCl|KCl (sat.) recorded in 0.1 mol/L H2SO4) was found to be suitable for analytical purposes due to its position and shape. A novel voltammetric approach based on differential pulse voltammetry was developed and it was found as a sensitive analytical tool, with low limit of detection (LD = 13.2 nmol/L), applicable in analysis of vitamin preparations. Full article
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1546 KiB  
Proceeding Paper
Development of Low-Cost Arduino-Based Equipment for Analytical and Educational Applications
by Sergey Gubsky
Eng. Proc. 2023, 48(1), 8; https://doi.org/10.3390/CSAC2023-14893 - 22 Sep 2023
Viewed by 1520
Abstract
A modern microcontroller Arduino platform is often used to create electronic devices with the ability to receive signals from various digital and analog sensors, to perform further primary processing of information to be transferred to a computer, as well as to control various [...] Read more.
A modern microcontroller Arduino platform is often used to create electronic devices with the ability to receive signals from various digital and analog sensors, to perform further primary processing of information to be transferred to a computer, as well as to control various devices. This versatility makes it possible to create low-cost equipment for analytical and educational applications on these platforms. As an example, this white paper describes the benefits of using Arduino microcontroller boards to create two powerful and inexpensive interfaces for computers and laboratory equipment for automating analytical chemistry laboratories. The first one is a device for carrying out coulometric titration in galvanostatic mode with potentiometric or amperometric indication of the titration end point. The instrument is used to determine the concentration of individual substances and the total antioxidant capacity of food systems. Another development is a device for determining the water activity of food systems with a capacitive sensor for determining relative humidity. Both types of measurement equipment use Arduino One or Nano microcontrollers in combination with various controls for analog signal measurement, A/D conversion, and indication. The measured values are monitored in real time by transferring information to a personal computer via a USB port under the control of the developed software. The effective use of the developed devices is presented on the example of measurements of foodstuff samples when obtaining validated data. Full article
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1845 KiB  
Proceeding Paper
Comparison of Different Formats for Immunochromatographic Detection of Surfactant Nonylphenol
by Anna N. Berlina, Nadezhda S. Komova, Kseniya V. Serebrennikova, Anatoly V. Zherdev and Boris B. Dzantiev
Eng. Proc. 2023, 48(1), 9; https://doi.org/10.3390/CSAC2023-14919 - 27 Sep 2023
Cited by 2 | Viewed by 393
Abstract
Immunochromatographic tests are of particular interest as tools for monitoring toxic environmental pollutants. In this regard, the aim of this study was to develop an immunochromatographic test system for the detection of surfactant nonylphenol in water. Two schemes of the assay were compared; [...] Read more.
Immunochromatographic tests are of particular interest as tools for monitoring toxic environmental pollutants. In this regard, the aim of this study was to develop an immunochromatographic test system for the detection of surfactant nonylphenol in water. Two schemes of the assay were compared; they are characterized by detection limits of 1.1 and 0.4 μg/mL and recoveries of nonylphenol from spring water in the range of 78–113.7%. Full article
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471 KiB  
Proceeding Paper
Ion-Selective Electrode (ISE) Based on Polyvinyl Chloride Membrane Formed from Heterocyclic Quinazoline Compounds as Ionophore material
by Chandra Mohan, Jenifer Robinson and Arvind Negi
Eng. Proc. 2023, 48(1), 10; https://doi.org/10.3390/CSAC2023-14914 - 26 Sep 2023
Cited by 4 | Viewed by 775
Abstract
A heterocyclic compound of S and N with cyclic structures, like Furans, thiophenes and related azole analogs, is important as a ligand because of it is readily available, stable and easily functionalized. Various types of heterocyclic molecules quinazolines and their derivatives contain important [...] Read more.
A heterocyclic compound of S and N with cyclic structures, like Furans, thiophenes and related azole analogs, is important as a ligand because of it is readily available, stable and easily functionalized. Various types of heterocyclic molecules quinazolines and their derivatives contain important chromophores with desirable electrochemical properties to be applied in the sensor field. Metal complexes of these compounds have demonstrated significant electrochemical properties as ionophore or electroactive materials for the fabrication of ISEs with different polymeric membranes. R. Selva Kumar et al. 2019 reported the use of dibutyl(8-hydroxyquinolin-2-yl)methylphosphonate as ionophore in a PVC matrix for the fabrication of a potentiometric thorium(IV) ion-selective electrode These quinazoline-based membranes with other additives and plasticizers are very useful for the development of a potential difference across the membrane at membrane-solution interface in the required proportions . Analytes, such as Butralin, Hydroxylamine, and Nitrite, and heavy metal ions, like Fe3+ and Th4+, have also been determined using quinazoline-based membrane sensors. ISE-based electrochemical sensors are very useful in the analysis of food products, drinking water, beverages, fertilizers, soil industrial effluents, etc. They also are applied in potentiometric titration as indicator electrodes. Full article
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992 KiB  
Proceeding Paper
PEDOT-Based Chemiresistive and Colorimetric Dual-Mode Sensors for the Detection of Hydrogen Peroxide Vapor
by Siying An, Xiaowen Xie, Nan Gao and Shuai Chen
Eng. Proc. 2023, 48(1), 11; https://doi.org/10.3390/CSAC2023-14924 - 7 Oct 2023
Viewed by 559
Abstract
Hydrogen peroxide (H2O2) is an aqueous solution that is widely used for oxidation, disinfection and sterilization, and its detection is very important in the fields of biological health and environment. The main detection methods of H2O2 [...] Read more.
Hydrogen peroxide (H2O2) is an aqueous solution that is widely used for oxidation, disinfection and sterilization, and its detection is very important in the fields of biological health and environment. The main detection methods of H2O2 include colorimetric, electrochemical, enzymatic and fluorescence analysis. However, due to the influence of moisture and oxidation, it is very difficult to realize simple, convenient, real-time and efficient detection technology for hydrogen peroxide vapor (HPV). Recently, our group proposed adding ammonium titanyl oxalate (ATO) to the sensing film composite system to prepare a chemosensor based on PEDOT:PSS-ATO/PEDOT composite film. The limit of detection (LOD) of the film was 1.0 ppm, and the linear trend was in the range of 1.0 ppm to 10.5 ppm. We then explored the influence of various material systems on its HPV sensing performance, which exhibited both electrical and colorimetric responses. This study was expected to realize a practical HPV sensor as well as promote the further application of PEDOT-based composites in the field of chemosensors. Full article
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572 KiB  
Proceeding Paper
Flexible Perylene Tetracarboxylic Diimide–Poly(3,4−Ethylenedioxythiophene) (PTCDIs@PEDOT) Films with Interpenetrating P−N Heterojunction and Their Gas Sensing Use
by Meng Zhou, Nan Gao, Zexu Xue, Xiaowen Xie and Shuai Chen
Eng. Proc. 2023, 48(1), 12; https://doi.org/10.3390/CSAC2023-14877 - 18 Sep 2023
Viewed by 348
Abstract
Through the selection of N-type organic semiconductor molecules and the method of supramolecular self-assembly at the solvent phase interface, a perylene tetracarboxylic diimide (PTCDIs) nanofiber film with loose and porous morphology was constructed via in situ deposition on the surface of ITO conductive [...] Read more.
Through the selection of N-type organic semiconductor molecules and the method of supramolecular self-assembly at the solvent phase interface, a perylene tetracarboxylic diimide (PTCDIs) nanofiber film with loose and porous morphology was constructed via in situ deposition on the surface of ITO conductive glass. Then, the P-type organic semiconducting polymer poly(3,4−ethylenedioxythiophene) (PEDOT) was grown in the fiber interweaving network of this film via quantitative electrochemical polymerization, thus preparing a PTCDIs@PEDOT composite film with N−P heterojunction architecture. The composite film has a nanometer-sized N−P heterojunction interpenetrating network structure, which is beneficial for full exposure to and contact of hydrogen peroxide vapor (HPV). The response time is 5.76 min, the recovery time is 5.53 min, and the response to 1.0 ppm concentration of HPV is 1.76. The PTCDIs@PEDOT film has good moisture resistance and improved sensitivity and signal response for gas-phase H2O2 detection. Full article
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883 KiB  
Proceeding Paper
The Analytical Capabilities of Electrochemical Sensors Based on Transition Metal Oxide Nanomaterials
by Guzel Ziyatdinova, Liliya Gimadutdinova, Tatyana Antonova, Irina Grigoreva and Elvira Yakupova
Eng. Proc. 2023, 48(1), 13; https://doi.org/10.3390/CSAC2023-14916 - 27 Sep 2023
Cited by 1 | Viewed by 434
Abstract
Voltammetric sensors based on CeO2, SnO2, CeO2·Fe2O3 nanoparticles (NPs) and MnO2 nanorods (NRs) were developed for the quantification of various organic substances. Surfactant media were applied as dispersive agents for metal oxide nanomaterials, providing [...] Read more.
Voltammetric sensors based on CeO2, SnO2, CeO2·Fe2O3 nanoparticles (NPs) and MnO2 nanorods (NRs) were developed for the quantification of various organic substances. Surfactant media were applied as dispersive agents for metal oxide nanomaterials, providing a high stability of the dispersions after sonication and a decrease in the NPs’ size, as well as the preconcentration of the target analytes at the sensor surface due to the hydrophobic interactions between the surfactant and the analyte molecules. Natural phenolics (quercetin, rutin, gallic acid, taxifolin, eugenol, vanillin, and hesperidin), propyl gallate, α-lipoic acid, and synthetic food colorants (tartrazine, brilliant blue FCF, and sudan I) were studied as analytes. The effect of the nature and concentration of the surfactant on the target analyte response was evaluated. Cationic surfactants (cetylpyridinium (CPB) or cetyltriphenylphosphonium bromides (CTPPB)) showed the best effect for the majority of the analytes. Wide linear dynamic ranges and low detection limits were obtained and were improved vs. reported to date. The simultaneous quantification of tartrazine and brilliant blue FCF was achieved with a high selectivity. The practical applicability of the sensors was shown on the real samples and was validated by comparison to independent methods. Full article
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808 KiB  
Proceeding Paper
Advances in Electronic Nose Sensors for Plant Disease and Pest Detection
by Ana Fundurulic, Jorge M. S. Faria and Maria L. Inácio
Eng. Proc. 2023, 48(1), 14; https://doi.org/10.3390/CSAC2023-14890 - 20 Sep 2023
Cited by 1 | Viewed by 1502
Abstract
The spread of invasive pests is accelerated by globalization and changes in climate conditions, posing a significant threat to agricultural and forest ecosystems. Advances in electronic nose sensors (e-noses) have opened new avenues for monitoring and detecting plant diseases and pests through the [...] Read more.
The spread of invasive pests is accelerated by globalization and changes in climate conditions, posing a significant threat to agricultural and forest ecosystems. Advances in electronic nose sensors (e-noses) have opened new avenues for monitoring and detecting plant diseases and pests through the analysis of emitted volatile organic compounds (VOCs). The current work reviews the most recent developments in e-nose sensors and their application in plant disease and pest detection over the past five years. It also explores the challenges associated with VOC detection in agricultural settings where field sampling has a focal role in monitoring and management. Full article
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1124 KiB  
Proceeding Paper
Design and Modelling of MEMS Resonators for an Artificial Basilar Membrane
by Basit Abdul, Mohammad Abul Hasan Shibly, Abdul Rab Asary and Nusrat Jahan Ruma
Eng. Proc. 2023, 48(1), 15; https://doi.org/10.3390/CSAC2023-14896 - 25 Sep 2023
Viewed by 645
Abstract
The human cochlea is undeniably one of the most amazing organs in the body. One of its most intriguing features is its unique capability to convert sound waves into electrical nerve impulses. Humans can generally perceive frequencies between 20 Hz and 20 kHz [...] Read more.
The human cochlea is undeniably one of the most amazing organs in the body. One of its most intriguing features is its unique capability to convert sound waves into electrical nerve impulses. Humans can generally perceive frequencies between 20 Hz and 20 kHz with their auditory systems. Several studies have been conducted on building an artificial basilar membrane for the human cochlea (cochlear biomodel). It is possible to mimic the active behavior of the basilar membrane using micro-electromechanical systems (MEMSs). This paper proposes an array of MEMS bridge beams that are mechanically sensitive to the perceived audible frequency. They were designed to operate within the audible frequency range of bridge beams with 450 µm thickness and varying lengths between 200 µm and 2000 µm. As for the materials for the bridge beam structures, molybdenum (Mo), platinum (Pt), chromium (Cr) and gold (Au) have been considered. For the cochlear biomodel, gold has proven to be the best material, closely mimicking the basilar membrane, based on finite-element (FE) and lumped-element (LE) models. Full article
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5 pages, 851 KiB  
Proceeding Paper
Optical Colorimetric Sensing Label for Monitoring Food Freshness
by Nedal Abu-Thabit
Eng. Proc. 2023, 48(1), 16; https://doi.org/10.3390/CSAC2023-14932 - 12 Oct 2023
Viewed by 652
Abstract
The development of optical sensors to monitor food freshness during storage and transportation helps to increase food security and customer satisfaction by preventing the misinterpretation of food date labeling. In this study, a simple, rapid, and low-cost paper-based optical sensing label was fabricated [...] Read more.
The development of optical sensors to monitor food freshness during storage and transportation helps to increase food security and customer satisfaction by preventing the misinterpretation of food date labeling. In this study, a simple, rapid, and low-cost paper-based optical sensing label was fabricated for the visual detection of food spoilage by the naked eye. The filter paper was coated with electrically conductive polyaniline ink. The pH-responsiveness of the coated polyaniline nanofibers allowed for the colorimetric detection of shrimp spoilage through the transition from the doped green emeraldine acid state to the dedoped blue emeraldine base state. The combination of the flexible filter paper as a substrate and the polyaniline ink as an indicator represents a facile approach for the fabrication of a colorimetric optical sensing label for food freshness monitoring applications. Full article
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840 KiB  
Proceeding Paper
RGB LED Sensor for Fat Quantification in Milk
by Marina Salukova, Anastasiia Surkova, Yana Shmakova, Natalya Samokhina, Julia Kostyuchenko, Alina Parshina, Ildar Ibatullin and Andrey Bogomolov
Eng. Proc. 2023, 48(1), 17; https://doi.org/10.3390/CSAC2023-14927 - 7 Oct 2023
Viewed by 609
Abstract
In this study, a portable desktop analyzer for the determination of fat content in milk is introduced. The prototype of the sensor consists of three light-emitting diodes (red, green, and blue) as a light source. The transmitted light is detected by a photoresistor [...] Read more.
In this study, a portable desktop analyzer for the determination of fat content in milk is introduced. The prototype of the sensor consists of three light-emitting diodes (red, green, and blue) as a light source. The transmitted light is detected by a photoresistor and continuous voltage measurements provided by the microcontroller, and is recorded by a computer. The resulting univariate and multivariate models show that the developed analytical device is capable of determining fat content in raw and homogenized milk with sufficient accuracy. Full article
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210 KiB  
Proceeding Paper
Nanostructured Platinum and Platinum Alloy-Based Resistive Hydrogen Sensors: A Review
by Necmettin Kilinc and Mustafa Erkovan
Eng. Proc. 2023, 48(1), 18; https://doi.org/10.3390/CSAC2023-14912 - 26 Sep 2023
Viewed by 528
Abstract
As a future energy source, hydrogen is used in many industrial applications, such as chemicals, semiconductors, transportation, etc. Hydrogen gas, which has many unusual properties compared to other gases, has the risk of being flammable and explosive when it is present in the [...] Read more.
As a future energy source, hydrogen is used in many industrial applications, such as chemicals, semiconductors, transportation, etc. Hydrogen gas, which has many unusual properties compared to other gases, has the risk of being flammable and explosive when it is present in the atmosphere at concentrations of 4% and higher. We need hydrogen sensors both to determine the risks in advance and because we do not want hydrogen gas, which is a source of energy, to be lost due to leakage. Hydrogen sensors are used in hydrogen production plants to determine hydrogen purity, for leakage and safety in all areas where hydrogen gas is used, and also in the medical field, as hydrogen gas is a marker in disease diagnosis. In the context of classifying hydrogen sensors according to their physicochemical sensing mechanisms, resistive metallic hydrogen sensors stand out as a prevalent choice, with Pd, Pt, and their alloy counterparts being commonly employed as designated sensing materials. In this study, nanostructured platinum (Pt) and Pt alloy-based resistive hydrogen sensors are reviewed and discussed in detail. The sensing mechanism of Pt-based resistive hydrogen sensors has been explained by the scattering of charge carriers at the surface, coupled with its defects and grain boundaries, and by the formation of hydride (PtHx) phenomena, depending on the increase or decrease in resistance in the hydrogen environment. Full article
1392 KiB  
Proceeding Paper
Synthesis of Ti3C2Tx/TiO2 Nanowires for Ascorbic Acid, Dopamine, and Uric Acid Simultaneous Sensing
by Tao Yang, Dengzhou Jia and Xinmei Hou
Eng. Proc. 2023, 48(1), 19; https://doi.org/10.3390/CSAC2023-14905 - 26 Sep 2023
Viewed by 467
Abstract
The development of electrochemical sensors with high sensitivity for the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) is urgently desirable in clinical medicine. However, the challenge lies in achieving simultaneous detection due to their close oxidation potentials. In [...] Read more.
The development of electrochemical sensors with high sensitivity for the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) is urgently desirable in clinical medicine. However, the challenge lies in achieving simultaneous detection due to their close oxidation potentials. In this work, we present the synthesis of a composite material comprised of in situ-grown TiO2 nanowires (NWs) on a Ti3C2Tx substrate (Ti3C2Tx/TiO2 NWs) through a facile alkali process. By modifying a glassy carbon electrode (GCE) with Ti3C2Tx/TiO2 NWs (Ti3C2Tx/TiO2 NWs/GCE), it showed excellent electrocatalytic activity for the simultaneous detection of AA/DA/UA by regulating the surface functional groups of Ti3C2Tx. Remarkably, the Ti3C2Tx/TiO2 NWs/GCE enabled simultaneous detection of AA in the range of 300–1800 μM, DA in the range of 2–33 μM, and UA in the range of 2–33 μM. The limits of detection (LODs) for AA, DA, and UA were estimated as 66.07 μM, 0.023 μM, and 0.011 μM, respectively. The proposed Ti3C2Tx/TiO2 NWs/GCE demonstrated good stability, high selectivity, and reliable reproducibility, making it a promising electrochemical sensor for the detection of AA, DA, and UA. This work offers a new perspective for human health monitoring, paving the way for advancements in this field. Full article
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898 KiB  
Proceeding Paper
Classification of Teas Using Different Feature Extraction Methods from Signals of a Lab-Made Electronic Nose
by Irari Jiménez-López, Jeniffer Molina-Quiroga and Juan Manuel Gutiérrez
Eng. Proc. 2023, 48(1), 20; https://doi.org/10.3390/CSAC2023-14933 - 12 Oct 2023
Viewed by 637
Abstract
Tea and herbal infusions are the most consumed non-alcoholic beverages worldwide and possess bioactive components with multiple health benefits. They are categorized into different classes that depend on their elaboration process, origin, and components. Commonly, analytical methods are employed to classify tea according [...] Read more.
Tea and herbal infusions are the most consumed non-alcoholic beverages worldwide and possess bioactive components with multiple health benefits. They are categorized into different classes that depend on their elaboration process, origin, and components. Commonly, analytical methods are employed to classify tea according to its chemical composition using liquid and gas chromatography–mass spectrometry, among others. Novel methods, such as electronic noses (e-noses), effectively provide real-time and objective monitoring of odors for extended periods of time. This work aimed to classify eight different types of tea (green, white, black, spearmint, mint, hibiscus, lemongrass, and chamomile) using two feature extraction methods and two pattern recognition analyses that were compared. A total of 34 tea samples were analyzed using an e-nose consisting of an olfactometer as a sample-handling system, seven chemo-resistive gas sensors, and a 12-bit analog-to-digital converter. Tea samples were measured 10 times to ensure repeatability, resulting in a database of 340 tea measures with 2499 samples each per sensor. Data were preprocessed using Principal Component Analysis (PCA) and Parallel Factor Analysis (PARAFAC). The information extracted was classified using an Artificial Neural Network (ANN) and k-nearest neighbor (k–NN). The best architecture in ANN and distance in k-NN were demonstrated through 10 k-fold cross-validation. The classification rate was 93% in ANN and PCA, 73% in ANN and PARAFAC, 94% in k-NN and PCA, and 84% in k-NN and PARAFAC. This demonstrates that conventional PCA is better than complex PARAFAC. Our findings not only contribute to the field of tea and herbal infusion classification but also underscore the potential of e-nose systems for discriminating between diverse tea types and herbal infusions based on their odor profiles. Full article
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249 KiB  
Proceeding Paper
Application of Piezoelectric Sensors with Polycomposite Coatings for Assessing Milk Quality Indicators
by Anastasiia Shuba, Ekaterina Anokhina, Ruslan Umarkhanov, Ekaterina Bogdanova and Inna Burakova
Eng. Proc. 2023, 48(1), 21; https://doi.org/10.3390/CSAC2023-14874 - 18 Sep 2023
Cited by 1 | Viewed by 452
Abstract
Milk is an important and necessary food product for reducing morbidity in the human body. There are numerous misconceptions around milk and dairy products in this regard. At the same time, one of the most time-consuming indicators of raw milk comprises its microbiological [...] Read more.
Milk is an important and necessary food product for reducing morbidity in the human body. There are numerous misconceptions around milk and dairy products in this regard. At the same time, one of the most time-consuming indicators of raw milk comprises its microbiological parameters. The purpose of this research is to study the gas phase of raw milk samples, using piezoelectric sensors with polycomposite coatings, to predict its physicochemical or microbiological properties. The sorption of volatile compounds onto the coatings based on chitosan–micellar-casein concentrate with polymeric sorbents was studied. This array was employed to analyze the gas phase over raw milk samples. It evaluated the physicochemical indicators of milk (the contents of fat, protein, and solid substances; the acidity) and the microbiological indicators (the total microbial count; the presence of mold, yeasts, or pathogenic microorganisms). The influence of several factors on the composition of volatile compounds in milk was evaluated using the output data of the sensors. These are the injector or frontal mode of inputting the gas phase into the detection cell, the processing of milk samples via ultrasound and microwave radiation, and the introduction of glucose and hydrogen peroxide additives into samples. Statistically significant correlations have been established between the sensor output data and the physicochemical or microbiological indicators of raw milk samples. The regression model was constructed using partial least squares regression to predict the total microbial count of milk based on the output data of piezoelectric sensors with composite coatings, with an appropriate error. Full article
311 KiB  
Proceeding Paper
Enhancing Kiwi Bacterial Canker Leaf Assessment: Integrating Hyperspectral-Based Vegetation Indexes in Predictive Modeling
by Mafalda Reis-Pereira, Renan Tosin, Rui C. Martins, Filipe Neves Dos Santos, Fernando Tavares and Mário Cunha
Eng. Proc. 2023, 48(1), 22; https://doi.org/10.3390/CSAC2023-14920 - 5 Oct 2023
Cited by 2 | Viewed by 581
Abstract
The potential of hyperspectral UV–VIS–NIR reflectance for the in-field, non-destructive discrimination of bacterial canker on kiwi leaves caused by Pseudomonas syringae pv. actinidiae (Psa) was analyzed. Spectral data (325–1075 nm) of twenty kiwi plants were obtained in vivo and in situ with a [...] Read more.
The potential of hyperspectral UV–VIS–NIR reflectance for the in-field, non-destructive discrimination of bacterial canker on kiwi leaves caused by Pseudomonas syringae pv. actinidiae (Psa) was analyzed. Spectral data (325–1075 nm) of twenty kiwi plants were obtained in vivo and in situ with a handheld spectroradiometer in two commercial kiwi orchards in northern Portugal over 15 weeks, resulting in 504 spectral measurements. The suitability of different vegetation indexes (VIs) and applied predictive models (based on supervised machine learning algorithms) for classifying non-symptomatic and symptomatic kiwi leaves was evaluated. Eight distinct types of VIs were identified as relevant for disease diagnosis, highlighting the relevance of the Green, Red, Red-Edge, and NIR spectral features. The class prediction was achieved with good model metrics, achieving an accuracy of 0.71, kappa of 0.42, sensitivity of 0.67, specificity of 0.75, and F1 of 0.67. Thus, the present findings demonstrated the potential of hyperspectral UV–VIS–NIR reflectance for the non-destructive discrimination of bacterial canker on kiwi leaves. Full article
713 KiB  
Proceeding Paper
A Flow Photometric Cell for In-Line Analysis of the Biomass Content of the Microalgae Nannochloropsis sp.
by Evgenii Bazarnov and Andrey Bogomolov
Eng. Proc. 2023, 48(1), 23; https://doi.org/10.3390/CSAC2023-14892 - 22 Sep 2023
Viewed by 395
Abstract
A photometric flow cell for the in-line determination of the biomass content in a microalgae Nannochloropsis sp. cultivation has been constructed, integrated into the photobioreactor and tested. This process is used for the development of third-generation biofuel technology. The results obtained have shown [...] Read more.
A photometric flow cell for the in-line determination of the biomass content in a microalgae Nannochloropsis sp. cultivation has been constructed, integrated into the photobioreactor and tested. This process is used for the development of third-generation biofuel technology. The results obtained have shown the linear dependence of the detected optical density on the biomass content. Therefore, the concept of the in-line determination of the biomass content in similar cultivation processes using a photometric sensor based on a single laser light source has been proved. Full article
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1846 KiB  
Proceeding Paper
A Novel Approach to Fabricating a Screen-Printed Electrode Based on a Gold Nanorod–Graphene Oxide Composite for the Detection of Uric Acid
by Wulan Tri Wahyuni, Hana Safitri, Eti Rohaeti, Munawar Khalil and Budi Riza Putra
Eng. Proc. 2023, 48(1), 24; https://doi.org/10.3390/CSAC2023-14908 - 28 Sep 2023
Viewed by 1047
Abstract
In this study, we report the development of a technique to fabricate a screen-printed electrode (SPE) and apply it in uric acid sensing. The SPE was fabricated by printing it on a photo paper substrate using a printing technique on an office printer. [...] Read more.
In this study, we report the development of a technique to fabricate a screen-printed electrode (SPE) and apply it in uric acid sensing. The SPE was fabricated by printing it on a photo paper substrate using a printing technique on an office printer. In particular, the conductive ink used to print the working electrode (WE) and counter electrode (CE) consisted of graphene oxide (GO) and a gold nanorod (AuNR) material. While the reference electrode (RE) was made by applying a conductive silver paste to the fabricated SPE, the electrochemical measurement of uric acid solution using fabricated SPE GO/AuNR provided a higher signal than commercially available SPE. The electroanalytical performance of the fabricated SPE based on GO/AuNR, which was used to measure the uric acid solution, exhibited a linear range of 0.8−200 μM, a detection limit of 0.5 μM, a quantitation limit of 1.0 μM, an outstanding repeatability (% relative standard deviation) of 4.885%, and good selectivity with ascorbic acid, dopamine, glucose, urea, and sodium as interference. Furthermore, an SPE, fabricated based on GO/AuNR, was successfully employed for the determination of uric acid concentration in human urine samples using the standard addition approach. Full article
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1506 KiB  
Proceeding Paper
Bridging Virtual and Reality: Testing Design of Experiment Procedures with Simulated and Experimental Data
by Agnieszka Królicka and Anna Szczurkowska
Eng. Proc. 2023, 48(1), 25; https://doi.org/10.3390/CSAC2023-14888 - 20 Sep 2023
Viewed by 294
Abstract
A virtual experiment conducted using the ICP-MS TuneSim software served as the basis for studies that compared the applicability of the central composite design with the Box–Behnken design in analytical chemistry applications. The insights gathered from these virtual experiments were used in real-life [...] Read more.
A virtual experiment conducted using the ICP-MS TuneSim software served as the basis for studies that compared the applicability of the central composite design with the Box–Behnken design in analytical chemistry applications. The insights gathered from these virtual experiments were used in real-life electroanalytical tests, including the determination of germanium and the studies of the antioxidant properties of herbal infusions. The experimental design and interpretation of the results were performed using Statistica software. Full article
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1875 KiB  
Proceeding Paper
Air Quality Monitoring in a Near-City Industrial Zone by Low-Cost Sensor Technologies: A Case Study
by Domenico Suriano, Mario Prato and Michele Penza
Eng. Proc. 2023, 48(1), 26; https://doi.org/10.3390/CSAC2023-14910 - 26 Sep 2023
Cited by 1 | Viewed by 579
Abstract
Urban industrial areas are often a matter of concern due to the emission of air pollutants that may affect the air quality of adjacent cities. Aerosol pollutants are monitored by governmental agencies that employ regulatory monitoring stations which are very accurate, but also [...] Read more.
Urban industrial areas are often a matter of concern due to the emission of air pollutants that may affect the air quality of adjacent cities. Aerosol pollutants are monitored by governmental agencies that employ regulatory monitoring stations which are very accurate, but also very expensive, bulky, and demanding in terms of maintenance. For this reason, it often happens that the monitoring of the air quality in large areas is covered by few stations. This situation can lead to the building of air pollutant maps with low spatio-temporal resolution. An appealing way to address this issue is represented by low-cost miniaturized gas sensors (LCSs) employed in low-cost air quality monitors (LCMs). Despite the various and unquestionable points of strength characterizing these devices, the scientific community has raised several warnings about the accuracy of their measurements and issued many caveats regarding their use. In this study, a new LCM model designed and implemented in our laboratories was used to measure the NO2 and PM concentrations in the industrial area of Brindisi (Italy). Data gathered by the LCM were compared with reference instrumentations for a rigorous analysis of the performance achievable through these low-cost technologies in this particular case. Full article
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950 KiB  
Proceeding Paper
Field Performance Evaluation of Air Quality Low-Cost Sensors Deployed in a Near-City Space-Airport
by Valerio Pfister, Mario Prato and Michele Penza
Eng. Proc. 2023, 48(1), 27; https://doi.org/10.3390/CSAC2023-14911 - 26 Sep 2023
Cited by 1 | Viewed by 414
Abstract
Air pollution is a current problem for the environment and public health. Its impact needs to be monitored in urban agglomerates and critical hot spots such as airports. Green aviation with low air emissions is a sustainable goal for the future. The air [...] Read more.
Air pollution is a current problem for the environment and public health. Its impact needs to be monitored in urban agglomerates and critical hot spots such as airports. Green aviation with low air emissions is a sustainable goal for the future. The air pollutants are monitored by governmental agencies that employ regulatory monitoring stations, which are very accurate but also very expensive, bulky, and maintenance demands. On the contrary, low-cost sensor systems can offer a proper solution to cover large areas at high spatial-temporal resolution. However, the low-cost air quality sensors are less accurate than reference analyzers operating in the regulatory stations. To enhance the sensor accuracy, field calibration, and data correction with reference instrumentation is a valid strategy to improve sensor data quality. In this study, a sensor system with a selected set of air quality gas sensors (NO2, O3) and particulate matter (PM10, PM2.5) has been developed and deployed in a near-city space-airport at Grottaglie (Southern Italy) to perform measurements in a period of 4 months, from October 2021 to February 2022. The sensor units installed in the Airbox system used for this measurements campaign are the GS+4NO2 (DD Scientific) for NO2 measurements, the O3-3E1F (City Technology, Sensoric) for O3 measurements, and the NextPM (Tera Sensor) for PM10 and PM2.5 measurements. Data gathered by the low-cost air quality sensors have been compared to reference instrumentations both co-located (ca. 1 m distance) together with low-cost sensors (PM10, R2 > 0.87; PM2.5, R2 > 0.50) and a distributed regulatory network of 14 environmental stations operating in the local area around space-airport at a distance ranging from 3 to 26 km. Full article
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633 KiB  
Proceeding Paper
Milk Analysis using a New Optical Multisensor System Based on Lanthanide(III) Complexes
by Anastasiia Surkova, Andrey Bogomolov, Aleksandra Paderina, Viktoria Khistiaeva, Ekaterina Boichenko, Elena Grachova and Dmitry Kirsanov
Eng. Proc. 2023, 48(1), 28; https://doi.org/10.3390/CSAC2023-14923 - 7 Oct 2023
Viewed by 362
Abstract
This study discusses the design, development, and construction of a low-cost optical multisensor system. The light sources in the proposed system are lanthanide(III) complexes emitting light in the near-infrared spectral region. Through the ability to adjust the source wavelength, this measuring platform can [...] Read more.
This study discusses the design, development, and construction of a low-cost optical multisensor system. The light sources in the proposed system are lanthanide(III) complexes emitting light in the near-infrared spectral region. Through the ability to adjust the source wavelength, this measuring platform can be used for a variety of practical tasks. The feasibility of the developed devices is demonstrated for the analysis of milk samples. Full article
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814 KiB  
Proceeding Paper
The Emergence of Microneedle-Based Smart Sensor/Drug-Delivery Patches: A Scaling Theory Defines the Tradeoff between the Response Time and the Limits of Detection
by Marco Fratus and Muhammad A. Alam
Eng. Proc. 2023, 48(1), 29; https://doi.org/10.3390/CSAC2023-14906 - 26 Sep 2023
Viewed by 586
Abstract
Smart, ultra-scaled, always-on wearable, and implantable (WI) sensors are an exciting frontier in personalized medicine. These sensors integrate sensing and actuation capabilities, enabling real-time analyte detection for on-demand drug delivery, akin to a biological organ. The microneedle (MN)-based patch serves as a critical [...] Read more.
Smart, ultra-scaled, always-on wearable, and implantable (WI) sensors are an exciting frontier in personalized medicine. These sensors integrate sensing and actuation capabilities, enabling real-time analyte detection for on-demand drug delivery, akin to a biological organ. The microneedle (MN)-based patch serves as a critical novel interface element in this system. It is inexpensive, minimally invasive, and safe, showing promise in glycemic management and insulin therapy in laboratory and animal studies. However, the current design of MNs relies primarily on empirical approaches, with significant challenges. These challenges include potential diffusion delays that may impede time-critical drug intervention and an iterative design process lacking a clear understanding of the tradeoff between the response time and the limits of detection. In this paper, we introduce the first predictive framework for MN sensors, based on physical scaling laws and biomimetic concepts. Our framework is supported by experimental and numerical validations, establishing analytical scaling relationships that capture the fundamental workings of hollow and porous-swellable MN sensors. It quantifies essential performance metrics like the ’response time (RT)’ and the ’limit of detection (LOD)’ while assessing the tradeoffs associated with various geometrical and physical parameters of the MN technology. As a result, our model provides a universal framework for interpreting/integrating the experimental findings reported by laboratories worldwide. By leveraging this predictive framework, researchers can advance the development and optimization of MN sensors, leading to improved performance and expanded applications in the field of wearable and implantable technologies. Full article
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793 KiB  
Proceeding Paper
Mathematical Separation of the Main Components of Milk from Kinetic Data Obtained Using Attenuated Total Reflection Infrared Spectroscopy
by Julia Kostyuchenko and Andrey Bogomolov
Eng. Proc. 2023, 48(1), 30; https://doi.org/10.3390/CSAC2023-14926 - 7 Oct 2023
Viewed by 348
Abstract
The possibility of using mid-infrared (IR) spectroscopy in combination with the method of attenuated total reflection (ATR) to analyze the quality of dairy products is shown. The application of chemometrics, in particular the multivariate curve resolution (MCR) algorithm, to the spectral data of [...] Read more.
The possibility of using mid-infrared (IR) spectroscopy in combination with the method of attenuated total reflection (ATR) to analyze the quality of dairy products is shown. The application of chemometrics, in particular the multivariate curve resolution (MCR) algorithm, to the spectral data of the milk drop-drying process allows us to obtain spectra of its individual components, which is potentially useful to make quantitative estimates of the sample composition. Full article
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1082 KiB  
Proceeding Paper
Indoor Air Measurements with a Low-Cost Air Quality Sensor: A Preliminary Report
by Francis Olawale Abulude, Arinola Oluwatoyin Gbotoso and Susan Omolade Ademilua
Eng. Proc. 2023, 48(1), 31; https://doi.org/10.3390/CSAC2023-14898 - 25 Sep 2023
Viewed by 377
Abstract
The goal of the project was to monitor PM0.1 to PM10 levels in one of the four rooms in a four-bed building for a period of one month using a low cost in accordance with the manufacturer’s instructions. The data collected [...] Read more.
The goal of the project was to monitor PM0.1 to PM10 levels in one of the four rooms in a four-bed building for a period of one month using a low cost in accordance with the manufacturer’s instructions. The data collected during this period were statistically analyzed using Minitab software. The mean PM (µg/m3) values obtained when compared with the available World Health Organisation (WHO) standards, PM2.5 and PM10, were found to be above the 24 h limits, indicating a potential danger to the environment and individuals. Full article
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2139 KiB  
Proceeding Paper
Chemiresistive Sensor Based on Metal Organic Framework-Reduced Graphene Oxide (Cu-BTC@rGO) Nanocomposite for the Detection of Ammonia
by Mayuri S. More, Gajanan A. Bodkhe, Fouran Singh, Babasaheb. N. Dole, Tibor Hianik and Mahendra D. Shirsat
Eng. Proc. 2023, 48(1), 32; https://doi.org/10.3390/CSAC2023-14882 - 18 Sep 2023
Cited by 1 | Viewed by 599
Abstract
The detection of ammonia is very crucial for the welfare of modern society because of its hazardous effect on the environment and human beings. High response time is one of the serious concerns of most of the ammonia detectors reported so far in [...] Read more.
The detection of ammonia is very crucial for the welfare of modern society because of its hazardous effect on the environment and human beings. High response time is one of the serious concerns of most of the ammonia detectors reported so far in the literature. This issue has been comprehensively addressed in the present investigation. Herein, the solvothermally synthesized Cu-BTC was combined with the 5 wt%, 10 wt% and 20 wt% of partially reduced graphene oxide (rGO). The structural, spectroscopic, morphological and electrical studies of as-synthesized CuBTC@rGO-5wt%, CuBTC@rGO-10wt% and CuBTC@rGO-20wt% were done by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic force microscopy, and current-voltage (I-V) characterization. The chemiresistive sensor based on Cu-BTC@rGO was developed on a copper-coated glass electrode via the shadow mask technique. It shows excellent sensing properties for CuBTC@rGO-10wt% in a range of 10 ppm to 80 ppm with a high stability of up to 30 days, good linearity, and excellent response/recovery time, i.e., 84 s and 125 s, respectively. The limit of detection has been established as 10 ppm, which is below the maximum residue limit established by the OSHA (Occupational Safety and Health Administration). Full article
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7 pages, 1611 KiB  
Proceeding Paper
Simple Modifications of Sonogel-Carbon Electrodes to Obtain New pH and T Sensors—Target: Reducing Costs, Not Value
by Juan José García-Guzmán, Álvaro Jesús Sainz-Calvo, Ana Pérez-Fernández, Alfonso Sierra-Padilla, Dolores Bellido-Milla, Laura Cubillana-Aguilera and José María Palacios-Santander
Eng. Proc. 2023, 48(1), 33; https://doi.org/10.3390/CSAC2023-14891 - 27 Oct 2023
Viewed by 614
Abstract
In this work two new different sensors are developed: a pH sensor and a temperature probe. The former is based on an electrodeposited polyaniline (PANI) layer employing sinusoidal voltages and optimizing the deposition time (10–20 min). On the other hand, the temperature probe [...] Read more.
In this work two new different sensors are developed: a pH sensor and a temperature probe. The former is based on an electrodeposited polyaniline (PANI) layer employing sinusoidal voltages and optimizing the deposition time (10–20 min). On the other hand, the temperature probe was designed by taking advantage of the carbon nanotubes’ temperature properties. Both sensors were built on sonogel-carbon electrodes, seeking cost effective devices. In both scenarios, the results were satisfactory; the repeatability and reproducibility had values below 5%. Additionally, an excellent pH sensor selectivity was evaluated with the challenging interstitial matrix, prospecting an adequate future employment in real clinical samples. Full article
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656 KiB  
Proceeding Paper
Development of a Chemical Sensor Based on Deep Eutectic Solvents and Its Application for Milk Analysis
by Anastasiia Shuba, Ekaterina Anokhina, Ruslan Umarkhanov and Ekaterina Bogdanova
Eng. Proc. 2023, 48(1), 34; https://doi.org/10.3390/CSAC2023-14889 - 20 Sep 2023
Cited by 2 | Viewed by 410
Abstract
Deep eutectic solvents (DESs) have unique physical and chemical properties, such as low vapor pressure, ease of synthesis, stability, and non-toxicity. Although they have found application in areas of research such as organic synthesis, electrochemistry, biocatalysis, and the development of biosensors, their use [...] Read more.
Deep eutectic solvents (DESs) have unique physical and chemical properties, such as low vapor pressure, ease of synthesis, stability, and non-toxicity. Although they have found application in areas of research such as organic synthesis, electrochemistry, biocatalysis, and the development of biosensors, their use as sensitive coatings for chemical sensors has not been previously considered. This study examines the fundamental principles of generating sensitive coatings for piezoelectric quartz sensors utilizing hydrophilic deep eutectic solvents (choline + polyalcohols). Thin films from DESs with a melting point above 50 °C, including those in the composite coatings with amorphous silicon oxide, have been studied. The sorption characteristics of the coatings were thoroughly examined via piezoelectric quartz microbalance. It has been demonstrated that the limits of detection and determination of volatile organic compounds in aqueous solutions by films based on DESs exhibit lower limits than other polymer coatings. A novel approach is proposed for processing the kinetic curve of the sorption of volatile substances by films based on DES to improve the reliability and detection of volatile compounds in the gas phase above aqueous solutions. The use of DES-based piezoelectric quarts sensors has been demonstrated for assessing microbiological indicators of milk. Full article
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1663 KiB  
Proceeding Paper
Electrical Characterization of Hydrothermally Synthesized Manganese Dioxide Nanowires with Regard to NO2 Adsorption/Desorption Thermodynamics
by Petr Smisitel, Helena Simunkova, Ondrej Chmela, Martha Claros, Stella Vallejos and Jaromir Hubalek
Eng. Proc. 2023, 48(1), 35; https://doi.org/10.3390/CSAC2023-14883 - 18 Sep 2023
Viewed by 387
Abstract
Self-assembled MnO2 nanowires were hydrothermally synthesized and electrically characterized under different conditions. The nanowires were approximately 3–10 µm long and about 20–100 nm in diameter. Single nanowires were aligned perpendicularly across two parallel gold electrode transducers by means of the dielectrophoresis (DEP) [...] Read more.
Self-assembled MnO2 nanowires were hydrothermally synthesized and electrically characterized under different conditions. The nanowires were approximately 3–10 µm long and about 20–100 nm in diameter. Single nanowires were aligned perpendicularly across two parallel gold electrode transducers by means of the dielectrophoresis (DEP) technique. Resistivity changes in synthetic air, nitrogen, and NO2 were tested in a range from 100 °C up to 300 °C. The resistivity changes were observed to account for the oxygen reduction on the NWs’ surface as the electrons were moving from the NWs to the oxygen. The resistivity was explored through a constant current arrangement test. Based on the resistivity changes, electrical properties, such as activation energy and type of semiconductor, were estimated. Full article
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1294 KiB  
Proceeding Paper
Exploring the Impact of Water Stress on Grapevine Gene Expression and Polyphenol Production: Insights for Developing a Systems Biology Model
by Igor Portis, Renan Tosin, Paulo R. Oliveira-Pinto, Leandro Pereira-Dias, Conceição Santos, Rui Martins and Mário Cunha
Eng. Proc. 2023, 48(1), 36; https://doi.org/10.3390/CSAC2023-14917 - 27 Sep 2023
Viewed by 571
Abstract
This scientific paper delves into the effects of water stress on grapevines, specifically focusing on gene expression and polyphenol production. We conducted a controlled greenhouse experiment with three hydric conditions and analyzed the expression of genes related to polyphenol biosynthesis. Our results revealed [...] Read more.
This scientific paper delves into the effects of water stress on grapevines, specifically focusing on gene expression and polyphenol production. We conducted a controlled greenhouse experiment with three hydric conditions and analyzed the expression of genes related to polyphenol biosynthesis. Our results revealed significant differences in the expression of ABCC1, a gene linked to anthocyanin metabolism, under different irrigation treatments. These findings highlight the importance of anthocyanins in grapevine responses to abiotic stresses. By integrating genomics, metabolomics, and systems biology, this study contributes to our understanding of grapevine physiology under water stress conditions and offers insights into developing sensor technologies for real-world applications in viticulture. Full article
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678 KiB  
Proceeding Paper
Profiling of Phenolic Compounds in Citrus Flowers and Their Biological Activities
by Sepidar Seyyedi-Mansour, Maria Carpena, Pauline Donn, Paula Garcia-Oliveira, Javier Echave, Paula Barciela, Maria Fraga-Corral, Lucia Cassani, Jesus Simal-Gandara and Miguel A. Prieto
Eng. Proc. 2023, 48(1), 37; https://doi.org/10.3390/CSAC2023-14895 - 25 Sep 2023
Viewed by 435
Abstract
Citrus, a genus of flowering plants in the Rutaceae family, holds substantial market importance as a crop worldwide. After prolonged periods of breeding and extensive hybridization, numerous species have emerged, each possessing a unique metabolism that produces a diverse array of secondary [...] Read more.
Citrus, a genus of flowering plants in the Rutaceae family, holds substantial market importance as a crop worldwide. After prolonged periods of breeding and extensive hybridization, numerous species have emerged, each possessing a unique metabolism that produces a diverse array of secondary metabolites. It is important to note that phenolic compounds, in particular phenols and flavonoids, are among the most important secondary metabolites in Citrus flowers. These chemical compositions of Citrus flowers differ depending on various factors, such as variety, fruit maturity, environmental conditions, storage conditions, and extraction methods. Nevertheless, phenolic compounds extracted from Citrus flowers are well-recognized for their bioavailability characteristics and exhibit numerous health-promoting effects, including antioxidant, anti-inflammatory, anti-cancer, and antibacterial activities in humans. The information contained in this document provides a comprehensive summary of the latest investigations conducted on the subject matter. The aim is to thoroughly comprehend the biological functions of the bioactive compounds in the Citrus flowers and their potential impacts on various biological systems, shedding light on their potential therapeutic applications. Full article
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1131 KiB  
Proceeding Paper
Multivariate Method to Analyze Archaeol in Cattle Feces
by Coral Salvo-Comino, Clara Perez-Gonzalez, Cristina Garcia-Cabezon and Maria Luz Rodriguez-Mendez
Eng. Proc. 2023, 48(1), 38; https://doi.org/10.3390/CSAC2023-14899 - 25 Sep 2023
Viewed by 392
Abstract
The analysis of archaeol is necessary in order to obtain greater knowledge about their presence in feces. This study was conducted to explore the capability of using data obtained from two spectroscopic methods, UV-Vis and FTIR, and from electrochemical sensors to determine the [...] Read more.
The analysis of archaeol is necessary in order to obtain greater knowledge about their presence in feces. This study was conducted to explore the capability of using data obtained from two spectroscopic methods, UV-Vis and FTIR, and from electrochemical sensors to determine the composition of cattle feces. Principal component analysis and correlation analysis using spectral data were used. By combining spectral and compositional data, useful calibrations were developed. These calibrations can be used to rapidly predict the constituents of new samples. On the basis of the results obtained here, electrochemical sensors were found to be successful in the rapid determination of archaeol and several other parameters in feces. Full article
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773 KiB  
Proceeding Paper
Design of an Electrochemical Genosensor for BDNF Gene Polymorphism Sequence Detection Using an Enzymatically Labeled DNA Probe
by Renato Caldevilla, Stephanie Morais, Serafim Carvalho, Rui Medeiros, Cristina Delerue-Matos, Agostinho Cruz, Marlene Santos and Maria Fátima Barroso
Eng. Proc. 2023, 48(1), 39; https://doi.org/10.3390/CSAC2023-14913 - 26 Sep 2023
Viewed by 569
Abstract
The BDNF gene is associated with high degrees of variability in antidepressant treatments. The Val66Met polymorphism is widely known as a source of this variability, warranting growing interest in genotyping patients that undergo antidepressant treatment to better suit their needs. This paper reports [...] Read more.
The BDNF gene is associated with high degrees of variability in antidepressant treatments. The Val66Met polymorphism is widely known as a source of this variability, warranting growing interest in genotyping patients that undergo antidepressant treatment to better suit their needs. This paper reports on an electrochemical genosensing platform, based on gold electrodes, capable of detecting this polymorphism, through the use of synthetic enzymatically labeled DNA probes for two different BDNF alleles. The sensor showed promising results, and its applicability to real samples is currently being tested. Full article
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1224 KiB  
Proceeding Paper
Smartphone-Addressable Paper-Based Devices for the Colorimetric Detection of Ampicillin Based on Salt-Induced Aggregation of Gold Nanoparticles
by Dionysios Soulis, Anastasios Economou and Christos Kokkinos
Eng. Proc. 2023, 48(1), 40; https://doi.org/10.3390/CSAC2023-14875 - 18 Sep 2023
Viewed by 344
Abstract
In this work, we describe the fabrication of paper-based aptasensing devices for ampicillin determination that rely on the salt-induced aggregation of gold nanoparticles (AuNPs) in the presence of the target. Circular paper-based devices were created on paper via pen-plotting (using water-repellent ink to [...] Read more.
In this work, we describe the fabrication of paper-based aptasensing devices for ampicillin determination that rely on the salt-induced aggregation of gold nanoparticles (AuNPs) in the presence of the target. Circular paper-based devices were created on paper via pen-plotting (using water-repellent ink to create hydrophobic barriers) and modified with NaCl. The sample was incubated with an ampicillin aptamer and AuNPs and was added to the assay zones of the paper-based devices. In the absence of ampicillin, the aptamer prevented the aggregation of the AuNPs, and the assay zones remained red. When ampicillin was present, it selectively bound with the aptamer and the AuNP aggregate, producing a purple color. The color of the assay zones was monitored via a smartphone, and the color graduation was related to the ampicillin concentration in the sample. Different experimental parameters (type of paper, concentration of reagents) were investigated, and the analytical features of the method for the determination of ampicillin were established. Full article
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761 KiB  
Proceeding Paper
Development of the Hydrogel-Based Biosensors: An Overview of Patented Technologies
by Ahmed Fatimi
Eng. Proc. 2023, 48(1), 41; https://doi.org/10.3390/CSAC2023-14879 - 18 Sep 2023
Viewed by 442
Abstract
This overview concerns recent patents and patented technologies in relation to the development of hydrogel-based biosensors, published until 2022. As a result, 257 patent documents and 145 simple patent families have been searched through different specialized patent databases. Furthermore, the patent classification confirmed [...] Read more.
This overview concerns recent patents and patented technologies in relation to the development of hydrogel-based biosensors, published until 2022. As a result, 257 patent documents and 145 simple patent families have been searched through different specialized patent databases. Furthermore, the patent classification confirmed that the most claimed inventions concern chemical analysis of biological material and biospecific binding assay materials with an insoluble carrier for immobilizing immunochemicals. Overall, the research, development, and innovation concerning hydrogel-based biosensors are based on improvements in the synthesis of hydrogels, biomolecule immobilization and detection, as well as microelectronic device integration and microfabrication techniques. A collection of recent patented technologies is proposed at the end. In this respect, it aimed to demonstrate the potential trends and challenges in relation to the development of hydrogel-based biosensors. Full article
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1157 KiB  
Proceeding Paper
Sensor Device for Contactless Chemical Analysis Based on High-Frequency Inductance Coil
by Ekaterina Yuskina, Nikodim Makarov, Maria Khaydukova, Valentin Semenov, Vitaly Panchuk and Dmitry Kirsanov
Eng. Proc. 2023, 48(1), 42; https://doi.org/10.3390/CSAC2023-14886 - 18 Sep 2023
Viewed by 549
Abstract
In this work, we explore the analytical potential of a simple inexpensive sensor device based on the evolution of the high-frequency contactless conductometry method. This method was developed in the middle of the 20th century as one of the options to assess the [...] Read more.
In this work, we explore the analytical potential of a simple inexpensive sensor device based on the evolution of the high-frequency contactless conductometry method. This method was developed in the middle of the 20th century as one of the options to assess the electrical conductivity of samples, and it employed electrical signals registered at a specific, single AC frequency. The method did not find a wide application since the analytical signal in the developed systems was a complex function of many factors (sample conductivity, capacitive characteristics, dielectric permittivity, and magnetic properties), which was difficult to be mathematically processed. We came back to this technology with the following in mind: (1) modern electronic components enable the design of such measuring devices in a very-low-cost manner and allow registering the response signal in a whole range of AC frequencies; (2) the application of modern machine learning tools to process these signals allows for the extraction of qualitative and quantitative information about the samples. It was found that the detector has numerous capabilities such as the quantification of inorganic salts in individual aqueous solutions and in complex mixtures, the quantification of dielectric constants of organic solvents, and distinguishing the cultures of various bacteria and cancer cells. Full article
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7 pages, 613 KiB  
Proceeding Paper
LIBS-Based Analysis of Elemental Composition in Skin, Pulp, and Seeds of White and Red Grape Cultivars
by Renan Tosin, Filipe Monteiro-Silva, Rui Martins and Mario Cunha
Eng. Proc. 2023, 48(1), 43; https://doi.org/10.3390/CSAC2023-14918 - 26 Oct 2023
Cited by 1 | Viewed by 646
Abstract
Laser-induced breakdown spectroscopy (LIBS) was explored to assess the element constituents (Ca, Mg and N) in the skin, pulp, and seed of two Vitis vinifera cultivars—a white (Loureiro) and a red (Vinhão) cultivar. This study compares the two grape cultivars chosen and the [...] Read more.
Laser-induced breakdown spectroscopy (LIBS) was explored to assess the element constituents (Ca, Mg and N) in the skin, pulp, and seed of two Vitis vinifera cultivars—a white (Loureiro) and a red (Vinhão) cultivar. This study compares the two grape cultivars chosen and the characterisation of Ca, Mg and N in the skin, pulp and seed on three dates after veraison. Significant differences (p < 0.05) were found in the Ca, Mg and N in the skin, pulp and seed of both grape cultivars during the three assessment dates considered. The results of this study could provide insights into the element composition of grapes, offering a fast, accurate, and cost-effective alternative to traditional element quantification methods. Full article
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1645 KiB  
Proceeding Paper
A Graphene Oxide Flexible Sensor for Humidity Detection
by Anna Maria Laera, Gennaro Cassano, Emiliano Burresi, Maria Lucia Protopapa and Michele Penza
Eng. Proc. 2023, 48(1), 44; https://doi.org/10.3390/CSAC2023-14884 - 18 Sep 2023
Viewed by 372
Abstract
A flexible humidity sensor operating at room temperature was produced by direct drop casting of a graphene oxide (GO) water solution on a substrate of bimatted polyester, previously coated with inkjet-printed interdigitated electrodes in silver. The GO was synthesized by using a modified [...] Read more.
A flexible humidity sensor operating at room temperature was produced by direct drop casting of a graphene oxide (GO) water solution on a substrate of bimatted polyester, previously coated with inkjet-printed interdigitated electrodes in silver. The GO was synthesized by using a modified Hummers’ method, followed by an alkaline treatment with a water solution of KOH. Changes in the device resistance were measured for varying levels of relative humidity in the range from 15% to 70% in a sealed stainless cell. The device showed high sensitivity, good repeatability, and fast recovery time. Being flexible and robust, the proposed sensors could be easily integrated into wearable equipment. Full article
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1509 KiB  
Proceeding Paper
Functionalized 2D Germanene and Its Derivatives for Electrochemical Detection of Gut-Derived Metabolites in Human Serum
by Rachel Rui Xia Lim, Zdeněk Sofer and Alessandra Bonanni
Eng. Proc. 2023, 48(1), 45; https://doi.org/10.3390/CSAC2023-14903 - 26 Sep 2023
Viewed by 443
Abstract
In this work, germanene and its derivatives (Ge-H, Ge-CH3, Ge-C3-CN) were explored as electrochemical impedimetric platforms to develop a competitive immunoassay for the direct detection of gut-derived metabolites, kynurenic acid (KA) and quinolinic acid (QA). The competition occurs between [...] Read more.
In this work, germanene and its derivatives (Ge-H, Ge-CH3, Ge-C3-CN) were explored as electrochemical impedimetric platforms to develop a competitive immunoassay for the direct detection of gut-derived metabolites, kynurenic acid (KA) and quinolinic acid (QA). The competition occurs between the free KA/QA standards and BSA-conjugated antigens for a fixed amount of primary antibody binding sites. This affects the electron transfer rate of the [Fe(CN)6]3−/4− redox couple and changes the charge transfer resistance (Rct) on the electrode surface. The impedimetric signal measured due to the change in Rct is then correlated to the KA and QA concentration. Full article
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580 KiB  
Proceeding Paper
Precision Meets Affordability: A Highly Sensitive HPLC-FLD Technique for Accurate Pitavastatin Quantification in Human Plasma
by João Basso, Ana Fortuna, Rui Vitorino and Carla Vitorino
Eng. Proc. 2023, 48(1), 46; https://doi.org/10.3390/CSAC2023-14931 - 12 Oct 2023
Viewed by 460
Abstract
High-Performance Liquid Chromatography (HPLC) combined with ultraviolet/visible (UV/Vis) or diode array detection (DAD) is routinely used for drug quantification in R&D around the world. However, it may lack the sensitivity required for bioanalytical studies. On the other hand, HPLC with fluorescence detection (FLD) [...] Read more.
High-Performance Liquid Chromatography (HPLC) combined with ultraviolet/visible (UV/Vis) or diode array detection (DAD) is routinely used for drug quantification in R&D around the world. However, it may lack the sensitivity required for bioanalytical studies. On the other hand, HPLC with fluorescence detection (FLD) is a cost-effective alternative that significantly increases drug signals, enabling the detection of compounds at very low concentrations. Pitavastatin is a lipid-lowering drug that contains the structure of quinoline, a highly fluorescent molecule. Recently, it has gained interest due to its pleiotropic effects on different conditions. Bearing this in mind, an HPLC-FLD method was developed and validated for the quantification of pitavastatin in human plasma. Overall, a signal gain of 54–70 times compared to that of UV detection was achieved when using fluorescence. Sample preparation included one-step protein precipitation with acetonitrile, followed by centrifugation and filtration prior to injection. Pitavastatin was separated from endogenous matrix interferents using a C18 column and by applying gradient elution. Atorvastatin was used as an internal standard. Accordingly, the method was shown to be selective, specific, and sensitive, with a lower limit of quantification of 3 ng/mL and complete absolute and relative recoveries higher than 94%. The method was linear over the wide concentration range of 3–900 ng/mL (R2 = 0.998), accurate (bias < 7.15%), and precise (RSD < 9.63%). This method allows for the therapeutic monitoring of patients treated with pitavastatin but can also support novel clinical studies of this drug in human plasma. Full article
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1208 KiB  
Proceeding Paper
Binary and Ternary Oxide Nanostructured Multisystems for Gas Sensors
by Svetlana Nalimova, Zamir Shomakhov and Vyacheslav Moshnikov
Eng. Proc. 2023, 48(1), 47; https://doi.org/10.3390/CSAC2023-14880 - 18 Sep 2023
Viewed by 366
Abstract
Currently, semiconductor gas sensors are among the most common types of sensing devices for detecting dangerous and toxic gases in the atmosphere. However, their characteristics should be improved in order to use them in practical applications. In this study, techniques have been developed [...] Read more.
Currently, semiconductor gas sensors are among the most common types of sensing devices for detecting dangerous and toxic gases in the atmosphere. However, their characteristics should be improved in order to use them in practical applications. In this study, techniques have been developed to improve the response of sensors based on zinc oxide nanowires. The first technique is to modify the chemical composition of the nanowires by forming a shell of ternary Zn-Sn-O and Zn-Fe-O systems on their surfaces. Another approach is to control the surface concentration of oxygen vacancies by adding sodium bromide during the synthesis of zinc oxide nanowires. The surface chemical composition and the sensor properties of the samples were studied. It was found that the sensor responses of samples of ternary oxide systems and zinc oxide samples with a high content of oxygen vacancies exceeded the sensor responses of the samplewithinitial zinc oxide nanowires. The results are analyzed in terms of the interaction involving reducing gases with metal oxides. Full article
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1644 KiB  
Proceeding Paper
Innovative Multipolymer-Based Electrochemical Biosensor Built on a Sonogel–Carbon Electrode Aiming for Continuous and Real-Time Lactate Determination in Physiological Samples: A New Scenario to Exploit Additive Printing
by Alfonso Sierra-Padilla, Juan José García-Guzmán, Lorena Blanco-Díaz, Dolores Bellido-Milla, José María Palacios-Santander and Laura Cubillana-Aguilera
Eng. Proc. 2023, 48(1), 48; https://doi.org/10.3390/CSAC2023-14902 - 26 Sep 2023
Viewed by 422
Abstract
In this work, an amperometric biosensor for lactate determination based on a sonogel–carbon transducer has been developed and evaluated using the lactate oxidase enzyme coated with a multipolymer layer as a bioreceptor. The biosensor obtained had adequate sensitivity (4.16 × 10−8 A [...] Read more.
In this work, an amperometric biosensor for lactate determination based on a sonogel–carbon transducer has been developed and evaluated using the lactate oxidase enzyme coated with a multipolymer layer as a bioreceptor. The biosensor obtained had adequate sensitivity (4.16 × 10−8 A mM−1) and a wide linear working range (0.2–20 mM) that allowed for the determination of lactate at high concentrations without showing enzyme saturation phenomena. The selectivity of the biosensor was also verified using interferents commonly observed in physiological samples. Moreover, a microfluidic cell was designed and fabricated to allow the determination of lactate with the proposed biosensor in a continuous regime. In the end, the viability of the biosensor was tested with the proposed flow system using synthetic samples, obtaining excellent results. Full article
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1779 KiB  
Proceeding Paper
The Photometric Determination of Iron(III) with 2-Napthylcarboxymethylene Citrate
by Ruzimurod Sattorovich Jurayev, Azimjon Uralovich Choriev and Navruz Toyirovich Qaxxorov
Eng. Proc. 2023, 48(1), 49; https://doi.org/10.3390/CSAC2023-14878 - 18 Sep 2023
Cited by 1 | Viewed by 713
Abstract
The most prevalent element in nature is iron, which is also one of the essential, active macroelements. Today, photometric techniques are frequently employed to identify harmful and extremely poisonous heavy metals. Due to its sensitivity, simplicity, and short analysis time, this approach is [...] Read more.
The most prevalent element in nature is iron, which is also one of the essential, active macroelements. Today, photometric techniques are frequently employed to identify harmful and extremely poisonous heavy metals. Due to its sensitivity, simplicity, and short analysis time, this approach is extremely important. The technique of photometrically determining Fe(III) was devised, and the ideal conditions for the formation of a complex of Fe(III) with 2-napthylcarboxymethylne citrate reagent were explored. The following steps were taken during the photometric determination of Fe (III) using 2-napthylcarboxymethylcitrate: the selection of a light filter, the dependence of complex formation on environmental acidity, dependence on the composition of the buffer solution, dependence on the composition of the reagent, the field of obedience to Ber’s law, the ratio of the component moles of the complex, the Sendal sensitivity, the lowest detection limit of Fe(III), the molar extinction coefficient, and the technique of photometrically determining Fe(III). Full article
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8 pages, 4144 KiB  
Proceeding Paper
Development of a Portable Electrochemical Platform with Chip-Integrated Gold Electrodes for Detection of Pharmaceutical Pollutants
by Miguel Tavares, Álvaro Torrinha, Raquel Queirós, João Piteira, Cristina Delerue-Matos and Simone Morais
Eng. Proc. 2023, 48(1), 50; https://doi.org/10.3390/CSAC2023-14900 - 31 Oct 2023
Viewed by 595
Abstract
Electrochemical portable sensing systems can offer viable support in the analysis of environmental contaminants due to the compactness of their electronic components and overall simplicity of their detection principles. In the present work, a new electrochemical portable platform (EPP) with miniaturized chip-integrated gold [...] Read more.
Electrochemical portable sensing systems can offer viable support in the analysis of environmental contaminants due to the compactness of their electronic components and overall simplicity of their detection principles. In the present work, a new electrochemical portable platform (EPP) with miniaturized chip-integrated gold electrodes was developed and applied in the detection of the drug acetaminophen (APAP) as a model analyte. The produced miniaturized chip-integrated gold electrodes were first characterized via atomic force and scanning electron microscopy and integrated into the EPP, and subsequently the complete set-up was tested for electrochemical detection of APAP. The results showed adequate performance of the developed EPP when compared to a traditional electrochemical system under optimal conditions (pH 8, deposition potential 0.1 V, deposition time 240 s and scan rate of 50 mV.s−1), with a sensitivity of 1.6 μA.mM−1 and limit of detection of 67 µM. The EPP was validated in river and wastewater samples, achieving recoveries ranging from 93.0 to 96.6%. Full article
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778 KiB  
Proceeding Paper
Elaboration of Undoped ZnO Nanowires for Use as Acetone Gas Sensors
by Asmaa Zeboudj, Saad Hamzaoui, Mokhter Zardali and Asmaa Tadji
Eng. Proc. 2023, 48(1), 51; https://doi.org/10.3390/CSAC2023-14925 - 7 Oct 2023
Viewed by 345
Abstract
The objective of our work is to provide an advantage for designing new, more efficient sensors using undoped ZnO nanowires. Nanostructures based on ZnO have demonstrated improved sensor performance, thanks to their excellent chemical and thermal stability, as evidenced by their high melting [...] Read more.
The objective of our work is to provide an advantage for designing new, more efficient sensors using undoped ZnO nanowires. Nanostructures based on ZnO have demonstrated improved sensor performance, thanks to their excellent chemical and thermal stability, as evidenced by their high melting temperature. We have utilized the Schottky defect model to simulate the behavior of free carriers in ZnO semiconductors. Additionally, we have investigated the theoretical model of oxygen molecule adsorption and desorption. Furthermore, we have examined the adsorption of reducing gases, with acetone gas being used as an example. By employing the Comsol software, we have discovered that the solid–gas interaction is significantly reduced at a temperature of 295 °C for ZnO nanowires compared to bulk ZnO, which typically requires a temperature of 500 °C. This reduction can be attributed to the predominant behavior of the side surfaces (101 0) in ZnO nanostructures, as well as the lower activation energy of these surfaces compared to the (0002) surfaces. These ZnO nanowire nanostructures provide numerous active and thermodynamically favorable surfaces for the adsorption of reducing gases. The simulation method using Comsol is one of the means to achieve improved design and offer optimal device operation. Full article
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3003 KiB  
Proceeding Paper
Amino Acid-Functionalized Polyfluorenes: A Class of Ultra-Sensitive Fluorescent Sensors Favoring Cr2O72− 
by Wanyi Zhang, Hui Li, Yu Li, Lei Cao, Li Sheng, Ge Zhang and Shuai Chen
Eng. Proc. 2023, 48(1), 52; https://doi.org/10.3390/CSAC2023-14909 - 26 Sep 2023
Viewed by 321
Abstract
Conjugated polymers (CPs) are an intriguing material with which to build fluorescent Cr2O72− sensors with excellent sensitivity, but they often lack specific recognition groups. In this study, several typical amino acids with N and O atom-identifying groups were incorporated [...] Read more.
Conjugated polymers (CPs) are an intriguing material with which to build fluorescent Cr2O72− sensors with excellent sensitivity, but they often lack specific recognition groups. In this study, several typical amino acids with N and O atom-identifying groups were incorporated into fluorene, and then six polyfluorene derivatives were synthesized using electrochemical polymerization. Compared to other cations and anions, all of these amino acid-functionalized polyfluorenes have good selectivity towards Cr2O72− and enable ultra-trace responses with detection thresholds at pM or even fM level. Full article
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1505 KiB  
Proceeding Paper
Voltammetric Determination of Tannic Acid in Medicinal Plants Using Multi-Walled Carbon Nanotube-Modified Electrode
by Guzel Ziyatdinova and Maria Ivanova
Eng. Proc. 2023, 48(1), 53; https://doi.org/10.3390/CSAC2023-15165 - 20 Oct 2023
Viewed by 407
Abstract
Tannins are a class of natural phenolic antioxidants represented by oligomers and polymers. Tannic acid (gallotannin) (TA) is one of the most typical compounds widely distributed in plants. It has a wide application area in food technology and as a part of traditional [...] Read more.
Tannins are a class of natural phenolic antioxidants represented by oligomers and polymers. Tannic acid (gallotannin) (TA) is one of the most typical compounds widely distributed in plants. It has a wide application area in food technology and as a part of traditional herbal medicine in the treatment of various diseases. TA is one of the standards used in medicinal plant quality control for plants rich in tannins. Therefore, the development of sensitive and simple methods for TA quantification is of practical interest. Glassy carbon electrode modified with multi-walled carbon nanotubes (GCE/MWCNTs) has been developed for the determination of TA in medicinal plants. An improvement in TA voltammetric response has been achieved using modified electrode due to the high electroactive surface area and electron transfer rate vs. bare electrode. TA electrooxidation at the GCE/MWCNTs is an irreversible surface-controlled process involving the transfer of two electrons and two protons in the first step. In differential pulse mode using Britton–Robinson buffer pH 2.0 as the supporting electrolyte, a linear dynamic range of 0.10–7.5 μM with a detection limit of 0.038 μM has been obtained. The method has been applied for the analysis of infusions and decoctions of tannin-containing medicinal plants and compared to the spectrophotometric method. A positive correlation has been observed with ferric reducing power reflecting the total content of phenolic compounds in the sample. Full article
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737 KiB  
Proceeding Paper
Development of a Novel Silicon Membrane MEMS Capacitive Pressure Sensor for Biological Applications
by Basit Abdul
Eng. Proc. 2023, 48(1), 54; https://doi.org/10.3390/CSAC2023-15170 - 20 Oct 2023
Viewed by 809
Abstract
MEMS capacitive pressure sensors have proven to be more reliable in terms of temperature drift and long-term stability when compared to MEMS piezoresistive pressure sensors. In this study, a MEMS capacitive pressure sensor using micromachined technology has been designed and fabricated. As the [...] Read more.
MEMS capacitive pressure sensors have proven to be more reliable in terms of temperature drift and long-term stability when compared to MEMS piezoresistive pressure sensors. In this study, a MEMS capacitive pressure sensor using micromachined technology has been designed and fabricated. As the movable electrode, a silicon membrane is used, while the fixed electrode is a gold metal film on a glass substrate. There is no deformation of the silicon membrane when the pressure is equal on both sides. As a result of the pressure of 0 kPa applied to the silicon membrane, a capacitance exists between it and the metal electrode. Differences in pressure on both sides of the silicon membrane will cause the membrane to deform. Silicon membranes deform due to pressure differences, which affect the capacitance between metal electrodes and silicon membranes. MEMS capacitive pressure sensors benefit from the superior mechanical properties of silicon material compared to metal-based sensors. Capacitive MEMS sensors are more desirable for applications requiring high performance and stability as compared to metal pressure sensors. This device is suited to measuring blood pressure with a measurement range of 0–45 kPa. When applied pressure was 0 kPa, the measurement capacitance was 3.61 pF, and when 45 kPa was applied, it was 7.19 pF. Full article
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1149 KiB  
Proceeding Paper
Humic Acid Functionalized-Silver Nanoparticles as a Colorimetric Nanosensor for the Rapid Detection of Divalent Nickel Ions in Aqueous Solutions
by Edgar Clyde R. Lopez
Eng. Proc. 2023, 48(1), 55; https://doi.org/10.3390/CSAC2023-15168 - 20 Oct 2023
Cited by 1 | Viewed by 447
Abstract
Heavy metal contamination in groundwater has become more prevalent due to the leaching of toxic wastes from various anthropogenic sources. When ingested, this can cause serious ill effects detrimental to human health. Hence, there is a need to monitor the levels of heavy [...] Read more.
Heavy metal contamination in groundwater has become more prevalent due to the leaching of toxic wastes from various anthropogenic sources. When ingested, this can cause serious ill effects detrimental to human health. Hence, there is a need to monitor the levels of heavy metals in various water sources to ensure that they are fit for human consumption. Standard detection methods such as AAS and ICP-MS are typically used for quantifying the concentration of heavy metals. However, these require expensive equipment, not to mention the need for a trained and highly-skilled technician to operate the equipment. Nanosensors offer a low-cost alternative to these methods. By utilizing the localized surface plasmon resonance (LSPR) and the properties of noble metal nanoparticles such as AgNPs, the colorimetric detection of heavy metals is made possible. Herein, we report the synthesis of humic-acid-functionalized silver nanoparticles (HA-AgNPs) using a borohydride reduction approach as a colorimetric nanosensor for Ni (II) detection in aqueous solutions. Humic acid acts as a capping agent that stabilizes the AgNPs in the colloidal mixture while providing functional groups for the detection of heavy metals. The synthesized HA-AgNPs had an average hydrodynamic diameter of 42.9 nm, a polydispersity index of 0.438, and an LSPR peak of 400.6 nm. The nanosensor could be used for the colorimetric detection of Ni (II) ions within the linear range of 0.15–0.40 mM Ni (II) with a limit of detection (LoD) of 2.35 mg L−1. The HA-AgNPs were shown to be selective when detecting Ni (II) ions; common metals in water such as Ca (II), Mg (II), Al (III), Zn (II), Na (I), and K (I) did not interfere with Ni (II) detection. As such, HA-AgNPs can be used as reliable and environmentally friendly colorimetric nanosensors for the rapid and point-of-need detection of Ni (II) ions in aqueous solutions. Full article
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3637 KiB  
Proceeding Paper
Synthesis and Characterization of Three-Dimensional Nanoporous Copper Oxide Materials via Dealloying and Thermal Oxidation of Amorphous Ribbons
by Mircea Nicolaescu, Cosmin Codrean, Corina Orha and Cornelia Bandas
Eng. Proc. 2023, 48(1), 56; https://doi.org/10.3390/CSAC2023-15171 - 20 Oct 2023
Cited by 1 | Viewed by 450
Abstract
The synthesis of nanoporous copper oxide (NP-CuO) materials via the dealloying and thermal oxidation of amorphous CuZrAl ribbons, representing the novelty of this research and previously achieved via a melt-spinning process, was carried out in an aqueous hydrofluoric acid (HF) solution by varying [...] Read more.
The synthesis of nanoporous copper oxide (NP-CuO) materials via the dealloying and thermal oxidation of amorphous CuZrAl ribbons, representing the novelty of this research and previously achieved via a melt-spinning process, was carried out in an aqueous hydrofluoric acid (HF) solution by varying the holding time. These nanoporous copper (NPC) structures were used as a template to achieve a 3D-NP-CuO materials with different surface morphologies. To investigate the structural and morphological properties of the obtained sandwich-type materials, X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy (SEM/EDX), and ultraviolet–visible spectroscopy (UV-VIS) techniques were used. In summary, the dealloying and thermal oxidation of amorphous ribbons is an interesting approach to achieving a three-dimensional (3D) network of NP-CuO with different morphologies and with a low production cost. These sandwich-type structures, consisting of NPC and copper oxide nanowires (CuO/Cu2O), combine the good electrical properties of NPC with the catalytic properties of copper oxide semiconductors, making them suitable materials for photocatalysis, photoelectrodes in solar cells, battery applications, and electrochemical sensors. Full article
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883 KiB  
Proceeding Paper
Microplate Methods for Measuring Phenolic Content and Antioxidant Capacity in Chickpea: Impact of Shaking
by Joel B. Johnson, Janice S. Mani and Mani Naiker
Eng. Proc. 2023, 48(1), 57; https://doi.org/10.3390/CSAC2023-15167 - 20 Oct 2023
Cited by 1 | Viewed by 1427
Abstract
Microplate-based methods are commonly used to conduct spectrophotometric-based assays on large batches of sample extracts as they allow much greater throughput compared to traditional benchtop methods. However, many reported methods have not undergone a thorough method development/optimisation process; thus, the significance of maintaining [...] Read more.
Microplate-based methods are commonly used to conduct spectrophotometric-based assays on large batches of sample extracts as they allow much greater throughput compared to traditional benchtop methods. However, many reported methods have not undergone a thorough method development/optimisation process; thus, the significance of maintaining certain parameters and procedures is often unknown. This study investigated the importance of plate shaking prior to the absorbance measurement step in two common assays: total phenolic content (TPC) measured using the Folin–Ciocalteu method, and total antioxidant activity measured using the Ferric Reducing Antioxidant Power (FRAP) method. A comparison was conducted on 36 methanol extracts of chickpea (Cicer arietinum) kernel, which had TPCs ranging from 43 to 111 mg GAEs (gallic acid equivalents)/L and FRAP values ranging from 25 to 67 mg TE (Trolox equivalents)/L. The absorbance of the samples was measured before and after the plate was shaken (300 s); each sample was analysed in duplicate. For the TPC, the unshaken and shaken absorbance values showed a high correlation with one another (R2 = 0.990); however, a paired samples t-test demonstrated a significant increase in absorbance after shaking (p < 0.001; mean increase of 10.6%). Similarly, the unshaken and shaken absorbance values for FRAP showed a strong correlation (R2 = 0.973), but again the shaken absorbance values were significantly higher (p < 0.001, mean increase of 12.1%). This demonstrates the importance of plate shaking for ensuring the complete reaction of the well contents prior to measuring their absorbance values. Furthermore, it highlights the need to closely follow the specified procedure when attempting to replicate or set up a microplate-based spectrophotometric method from the literature. Full article
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4373 KiB  
Proceeding Paper
Physicochemical Properties of Temperature-/pH-Sensitive Hydrogel Materials
by Magdalena Bańkosz, Katarzyna Sala, Klaudyna Grzela, Dominika Wanat, Korneliusz Rzepka, Monika Iglar, Jakub Piątkowski, Aniela Woźniak, Magdalena Kędzierska and Bożena Tyliszczak
Eng. Proc. 2023, 48(1), 58; https://doi.org/10.3390/CSAC2023-15166 - 20 Oct 2023
Viewed by 509
Abstract
This paper presents the synthesis of fluorescein-modified hydrogel materials. The obtained materials were characterized using FT-IR spectroscopy. Then, their sorption capacity in distilled water and Ringer’s liquid was determined. Using digital microscopy, the morphology of the obtained systems was characterized. Full article
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261 KiB  
Proceeding Paper
Inclusion of Natural Anthocyanins as Food Spoilage Sensors
by Maria Carpena, Aurora Silva, Paula Barciela, Ana Perez-Vazquez, Franklin Chamorro, Lucía Cassani, Maria Fátima Barroso, Jianbo Xiao, Miguel A. Prieto and Jesus Simal-Gandara
Eng. Proc. 2023, 48(1), 59; https://doi.org/10.3390/CSAC2023-15163 - 7 Oct 2023
Viewed by 534
Abstract
Food safety is one of the most contemporary subjects under the scope of the scientific community since it is a fundamental issue for the general population. The desire to use a simple, inexpensive, easy-to-read package freshness-indicator led to a multitude of proposals for [...] Read more.
Food safety is one of the most contemporary subjects under the scope of the scientific community since it is a fundamental issue for the general population. The desire to use a simple, inexpensive, easy-to-read package freshness-indicator led to a multitude of proposals for package real-time sensors for food freshness indicators. The sensors’ design strategy is to target a physical or chemical modification that occurs by the spoiling process, such as changes in temperature, moisture, or the detection of foodborne pathogens. One of the most common approaches is evaluating changes in pH, since a significant amount of food spoilage occurs with significant alterations (e.g., acidity increases on dairy products). However, some safety concerns emerge from the use of complex artificial chemical molecules such as pH indicators in active labels/packages for food. Naturally occurring anthocyanins are a safe alternative to classic pH indicators and have been applied as sensitive molecules for pH changes aimed at the development of active labels and active packing for food. This proposal briefly reviews the latest scientific contributions on the application of anthocyanins in food spoilage sensors. Full article
1099 KiB  
Proceeding Paper
Pectin Recovery Based on the Exploitation of Kiwi By-Products and the Application of Green Extraction Techniques
by Franklin Chamorro, Paula Garcia-Oliveira, Sepidar Seyyedi-Mansour, Javier Echave, Antia G. Pereira, Paz Otero, Jesus Simal-Gandara, Miguel A. Prieto, Lucía Cassani and Maria Fraga-Corral
Eng. Proc. 2023, 48(1), 60; https://doi.org/10.3390/CSAC2023-14930 - 11 Oct 2023
Cited by 1 | Viewed by 581
Abstract
The Actinidia genus comprises 54 species and 21 varieties of which A. chinensis var. chinensis and A. chinensis var. deliciosa are the most commercialized ones. The nutritional properties of kiwifruit have prompted their global production to nearly reach the value of 4.5 million [...] Read more.
The Actinidia genus comprises 54 species and 21 varieties of which A. chinensis var. chinensis and A. chinensis var. deliciosa are the most commercialized ones. The nutritional properties of kiwifruit have prompted their global production to nearly reach the value of 4.5 million tons per year, with Asia being one of the top producers. This increment in their production has raised a parallel augment of associated organic wastes, especially when kiwifruits are used for processed products. The most abundant by-products obtained include skins, seeds and discarded fruits. This biomass has a huge potential for its high content of bioactive compounds, such as dietary fiber or polyphenols. Therefore, it has been targeted by the food industry as a sustainable and cost-effective source of natural ingredients, highly demanded by consumers. Indeed, kiwi skins and seeds have been pointed out as a relevant source of pectin followed by the kiwi pulp. Pectin is a recognized ingredient due to the organoleptic properties it may confer but also for its prebiotic capacities. The recovery of pectin has been mainly performed via the application of extraction techniques that implied the use of chemical reagents such as acids. Nowadays, the use of chemicals is negatively regarded for their associated side effects. Indeed, customers’ claims for chemical-free food ingredients have triggered the development and application of green extraction techniques: ultrasonic, microwave, enzyme, supercritical fluid or electrical pulse. Pectin has been successfully extracted with these green techniques both in terms of yield and quality, improving results obtained with traditional extraction techniques. Therefore, the main objective of this work is to review the wide variability of green techniques applied to extract pectin along with the comparison of the optimal parameters as a basis for the future development of an optimized extraction method. In addition, this work also aims to disclose the potential of kiwifruit by-products as a source of pectin and their industrial applications for the development of functional foods, nutraceuticals, food additives or cosmetics. Full article
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810 KiB  
Proceeding Paper
Characterization of Phenolic Compounds of Arnica montana Conventional Extracts
by Paula Garcia-Oliveira, Franklin Chamorro, Pauline Donn, Pascual Garcia-Perez, Sepidar Seyyedi-Mansour, Aurora Silva, Javier Echave, Jesus Simal-Gandara, Lucia Cassani and Miguel A. Prieto
Eng. Proc. 2023, 48(1), 61; https://doi.org/10.3390/CSAC2023-15164 - 20 Oct 2023
Viewed by 566
Abstract
Arnica montana L. (Asteraceae family) is a plant commonly used in traditional medicine, and several reports have characterized this plant’s bioactivities, especially its phenolic compounds. These compounds are well known for their numerous beneficial biological properties. Consequently, industry stakeholders from the feed, food, [...] Read more.
Arnica montana L. (Asteraceae family) is a plant commonly used in traditional medicine, and several reports have characterized this plant’s bioactivities, especially its phenolic compounds. These compounds are well known for their numerous beneficial biological properties. Consequently, industry stakeholders from the feed, food, cosmetic, and pharmaceutical sectors are seeking extracts rich in phenolic compounds, which could be interesting for the development of bio-based applications. The objective of the present study was to characterize the phenolic profile of this species to lay the groundwork for further optimization studies to obtain the highest amount of phenolic compounds. Therefore, A. montana was extracted with an ethanol/water ratio of 80:20 (v/v) at room temperature for 1 h, and phenolic compounds were identified and quantified through UPLC (HPLC Dionex Ultimate 3000) with a mass detector (TSQ Quantis). In the extract, phenolics belonging to different groups were identified, namely eriodictyol-O-glucuronide (flavanone), hispidulin and luteolin (flavones), kaempferol and 6-methoxykaempferol, (flavonols), p-coumaric, feruloylquinic, caffeoylquinic, and dicaffeoylquinic isomers (hydroxycinnamic acids). However, only four of them could be quantified: kaempferol and the three hydroxycinnamic acids. The total phenolic content (mg/g of dry sample) was estimated to be 27.34 mg/g, with the most prevalent compounds being the dicaffeoylquinic acids (accounting for 79.5% of the total phenolics). It has been demonstrated that dicaffeoylquinic acids present anti-inflammatory and antioxidant activities, which have been linked to several beneficial effects. Thus, obtaining phenolic-rich extracts of A. montana may allow us to exploit this plant’s significant biological properties, and it could be a new ingredient for developing new applications in the nutraceutical, cosmetic, and/or pharmaceutical industries. Full article
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1955 KiB  
Proceeding Paper
Application of Low-Cost Sensors in Stationary and Mobile Nodes for Urban Air Quality Index Monitoring
by Michele Penza, Valerio Pfister, Domenico Suriano, Sebastiano Dipinto, Mario Prato and Gennaro Cassano
Eng. Proc. 2023, 48(1), 62; https://doi.org/10.3390/CSAC2023-14881 - 18 Sep 2023
Cited by 2 | Viewed by 613
Abstract
The air quality in modern cities and urban areas is strongly affected by chemical pollutants such as toxic gases, volatile organic compounds, and particulate matter. They are monitored by governmental agencies using regulatory monitoring stations, which are highly accurate, but also very expensive, [...] Read more.
The air quality in modern cities and urban areas is strongly affected by chemical pollutants such as toxic gases, volatile organic compounds, and particulate matter. They are monitored by governmental agencies using regulatory monitoring stations, which are highly accurate, but also very expensive, bulky, and maintenance demanding. There is a compulsory need to monitor air quality at high spatial–temporal resolution in smart cities for public health protection and environmental sustainability. Properly calibrated low-cost and low-accuracy sensors are usually deployed in stationary and mobile nodes for urban air quality monitoring. A simple indicator of the current status of urban air pollution is the Air Quality Index (AQI) used to communicate the pollution level under the time-changing trend of a specific pollutant. In this study, continuous measurements have been performed in the city of Bari (southern Italy) by electrochemical gas sensors (NO2, O3, CO), optical particle counters (OPC) for particulate matter (PM10), and NDIR infrared sensors (CO2), including microsensors for temperature and relative humidity. The sensors have been installed in stationary nodes located in urban sites and in a mobile node mounted on a public bus moving on urban routes. AQI data gathered by the low-cost sensors have been compared with reference instrumentations as a case study of citizen science. Full article
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9 pages, 2021 KiB  
Proceeding Paper
Indicator Carbon-Paste Electrode for Voltammetric Analysis
by Dmitry Aronbaev, Sergey Aronbaev and Dilnoza Isakova
Eng. Proc. 2023, 48(1), 63; https://doi.org/10.3390/CSAC2023-15939 - 9 Nov 2023
Viewed by 506
Abstract
The design of an indicator electrode made of carbon paste of ergonomic design for the voltammetric determination of a number of substances of inorganic and organic origin is described. The electrode is made of a graphite rod with a diameter of 6 mm [...] Read more.
The design of an indicator electrode made of carbon paste of ergonomic design for the voltammetric determination of a number of substances of inorganic and organic origin is described. The electrode is made of a graphite rod with a diameter of 6 mm and a length of 70 mm, covered with insulation, and having a cavity filled with an electroactive carbon-containing material at the end of the rod. The characteristic features of the proposed electrode—the insulating shell of the housing made of shrink tubing and the electrolytic coating of the cavity surface with a conductive metal film—make it possible to simplify the design of the electrode and increase mechanical strength, extend the service life of the electrode, and also provide the possibility of volumetric and surface modifications with an economical consumption of modifying reagents. Examples of the use of an indicator electrode modified with mercury and bismuth films and volumetrically modified with manganese dioxide nanoparticles in the analysis of food, beverages, natural objects for the content of heavy metal ions, pharmaceuticals for the content of hydrogen peroxide, and vitamins of groups B and C are given. The simplicity of making the developed indicator electrode from carbon paste and its mechanical strength and cost-effectiveness when using expensive and scarce modifiers allow us to recommend it for use in voltammetric analysis and the creation of various biosensor systems. Full article
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2953 KiB  
Proceeding Paper
Pilot Study on the Qualitative Analysis of Urinary Stones Using Near-Infrared Spectroscopy and Chemometrics
by Ekaterina Boichenko, Mikhail Paronnikov and Dmitry Kirsanov
Eng. Proc. 2023, 48(1), 64; https://doi.org/10.3390/CSAC2023-15162 - 20 Oct 2023
Viewed by 418
Abstract
Urolithiasis is one of most common urogenital diseases. Its diagnosis and treatment require an efficient analytical method to determine the chemical composition of a urinary stone, ideally during surgery. Near-infrared spectroscopy seems to be a promising method for conducting intraoperative qualitative analysis on [...] Read more.
Urolithiasis is one of most common urogenital diseases. Its diagnosis and treatment require an efficient analytical method to determine the chemical composition of a urinary stone, ideally during surgery. Near-infrared spectroscopy seems to be a promising method for conducting intraoperative qualitative analysis on urinary stones (calcium oxalates, uric acid, etc.), providing fast measurements and portable equipment. In this study, the pilot study results based on analyzing several urinary stones with different chemical compositions (dry and soaked in saline) within the 939–1799 nm range are presented. Principal component analysis results confirm the potential of this technique in qualitatively analyzing urinary stones before their surgical removal. Full article
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6 pages, 1355 KiB  
Proceeding Paper
Oxidative Grafting of Adrenaline onto Carbon Electrode Surface: Preliminary Studies
by Gabriela Machura, Jagoda Seroka, Sylwia Smarzewska and Kamila Koszelska
Eng. Proc. 2023, 48(1), 65; https://doi.org/10.3390/CSAC2023-16285 - 16 Nov 2023
Viewed by 414
Abstract
In the present work, we performed the optimization of electrografting of adrenaline onto a glassy carbon electrode surface. The cyclic voltammetry technique was used to immobilize the compound on the electrode surface by immersing it in an acidic adrenaline solution. This grafting was [...] Read more.
In the present work, we performed the optimization of electrografting of adrenaline onto a glassy carbon electrode surface. The cyclic voltammetry technique was used to immobilize the compound on the electrode surface by immersing it in an acidic adrenaline solution. This grafting was achieved by conducting 20 successive CV scans over a wide potential range. The stability of the obtained layer was analyzed using the SWV technique. The conducted research shows that it is possible to create a stable adrenaline layer on the GCE surface using voltammetric techniques. Additionally, once a stable layer was immobilized, its sensitivity to certain metal cations—which cannot be directly detected electrochemically—was verified. After exposing the sensor to designated cationic solutions, there was a significant decrease in the adrenaline signal. This suggests potential future applications in cation determination. Full article
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1639 KiB  
Proceeding Paper
Synthesis of Carboxylated Magnetite Nanoparticles Covalent Conjugates with Folic Acid Antibody FA-1 for Lateral Flow Immunoassay
by Maria O. Zolotova, Sergey L. Znoyko, Alexey V. Orlov, Petr I. Nikitin and Artem V. Sinolits
Eng. Proc. 2023, 48(1), 66; https://doi.org/10.3390/CSAC2023-15169 - 20 Oct 2023
Viewed by 347
Abstract
Magnetite nanoparticles (MNPs) are a preferable material for different bioassays because of their quite low toxicity both for cells and for mammals, and they have a big variety of surface functionalization approaches. We have synthesized MNPs via a simple and convenient co-precipitation method [...] Read more.
Magnetite nanoparticles (MNPs) are a preferable material for different bioassays because of their quite low toxicity both for cells and for mammals, and they have a big variety of surface functionalization approaches. We have synthesized MNPs via a simple and convenient co-precipitation method with preliminary filtration of FeCl2 and FeCl3 solution, under argon atmosphere and non-magnetic stirring. MNPs were citrate-stabilized and then modified stage by stage with tetraethoxysilane (TEOS), (3-Aminopropyl)triethoxysilane (APTES) and acylated with succinic anhydride, resulting in carboxylated MNPs. Carboxylated MNPs were covalently bounded with folic acid antibody (FA-1) via 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). MNP-EDC-FA-1 were passed through a test-stripe with the line consisting of folic acid–gelatin conjugate. The conjugation of MNP-EDC-FA-1 with folic acid was observed visually, and the magnetic signal distribution was scanned through the test-stripe with the magnetic particle quantification technique (MPQ) developed earlier. Visually, the line with folic acid–gelatin conjugate on the test-stripe turned dark, with color intensity strongly depending on the MNP-EDC-FA-1 concentration. MPQ has shown that the great majority of MNP-EDC-FA-1 was bound with the acid–gelatin conjugate. The MPQ technique allowed quantification down to 5 ng of MNP-EDC-FA-1 in this experiment with MNPs synthesized, with a strong peak at the acid–conjugate line. Full article
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