Editor's Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to authors, or important in this field. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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Research

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Article
Graphene Oxide as a Sensing Material for Gas Detection Based on Nanomechanical Sensors in the Static Mode
Chemosensors 2020, 8(3), 82; https://doi.org/10.3390/chemosensors8030082 - 02 Sep 2020
Cited by 4
Abstract
Graphene is a key material for gas sensing applications owing to its high specific surface area and vast chemical modification potential. To fully utilize the potential of graphene, a sensing platform independent of conductive properties is required. In this study, we employed membrane-type [...] Read more.
Graphene is a key material for gas sensing applications owing to its high specific surface area and vast chemical modification potential. To fully utilize the potential of graphene, a sensing platform independent of conductive properties is required. In this study, we employed membrane-type surface stress sensors (MSS)—A kind of nanomechanical sensor operated in the static mode—As a sensing platform and utilized graphene oxide (GO) as a gas sensing material. MSS detect surface stress caused by gas sorption; therefore, chemically modified graphene with low conductivity can be utilized as a gas sensing material. We evaluated the sensing performance of a GO-coated MSS by measuring its responses to five gases. We demonstrated with the GO-coated MSS the feasibility of GO as a gas sensing material for static mode nanomechanical sensors and revealed its high selectivity to water vapor. Moreover, we investigated the sensing mechanism of the GO-coated MSS by comparing it with the sensing performance of MSS coated with reduced graphene oxide and graphite powder and deduced key factors for sensitivity and selectivity. Considering the high sensitivity of the GO-coated MSS and the compact measurement system that MSS can realize, the present study provides a new perspective on the sensing applications of graphene. Full article
(This article belongs to the Section Materials for Chemical Sensing)
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Article
Molecular Imprinted Based Quartz Crystal Microbalance Sensors for Bacteria and Spores
Chemosensors 2020, 8(3), 64; https://doi.org/10.3390/chemosensors8030064 - 04 Aug 2020
Cited by 2
Abstract
A molecular imprinting strategy was combined with mass-sensitive transducers to generate robust and reliable biomimetic sensor systems for the detection of bioparticles. The patterning of polymers with bioanalytes enabled us to detect Escherichia coli (E. coli) bacteria with quartz crystal microbalance [...] Read more.
A molecular imprinting strategy was combined with mass-sensitive transducers to generate robust and reliable biomimetic sensor systems for the detection of bioparticles. The patterning of polymers with bioanalytes enabled us to detect Escherichia coli (E. coli) bacteria with quartz crystal microbalance (QCM). The QCM sensor results were compared with direct Atomic Force Microscopy (AFM) measurements—bacteria cells adhering to the sensor coatings were counted. The recognition sites generated by Bacillus subtilis (B. subtilis) spores could successfully and reversibly recognize the template analyte and ensured rapid sensing. Cross sensitive measurements clearly showed the advantage of the molecular imprinting strategy, by which spores of Bacillus species (subtilis and thuringiensis) could easily be differentiated and selectively detected. The growth of B. subtilis from its spores was observed at 42 °C in appropriate nutrient solution of glucose and ammonium sulfate over a period of 15 h. Moreover, the growth of B. subtilis bacteria from its respective spores was studied by increasing the glucose concentration until saturation effect of the sensor. The polymeric sensor coatings were patterned to fix the B. subtilis in order to investigate osmotic effects according to a frequency response of 400 Hz by altering the ionic strength of 0.1 M. Full article
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Article
Chemical and Temperature Sensors Based on Functionalized Reduced Graphene Oxide
Chemosensors 2020, 8(2), 43; https://doi.org/10.3390/chemosensors8020043 - 21 Jun 2020
Cited by 2
Abstract
In this work, we investigated the functionalization of reduced graphene oxide (rGO) with 2-(dodecen-1-yl) succinic anhydride (TPSA) to increase the rGO effective interactions with organic solvents both in liquid and vapor phases. Thermogravimetric analysis, STEM, XPS, FTIR-ATR, and Raman spectroscopy confirmed the effective [...] Read more.
In this work, we investigated the functionalization of reduced graphene oxide (rGO) with 2-(dodecen-1-yl) succinic anhydride (TPSA) to increase the rGO effective interactions with organic solvents both in liquid and vapor phases. Thermogravimetric analysis, STEM, XPS, FTIR-ATR, and Raman spectroscopy confirmed the effective functionalization of rGO with about the 30 wt% of grafted TPSA without affecting the structural characteristics of graphene but successfully enhancing its dispersibility in the selected solvent except for the apolar hexane. Solid TPSA-rGO dispersions displayed a reproducible semiconducting (activated) electrical transport with decreased resistance when heated from 20 °C to 60 °C and with a negative temperature coefficient of 10−3 K−1, i.e., comparable in absolute value with temperature coefficient in metals. It is worth noting that the same solid dispersions showed electrical resistance variation upon exposure to vapors with a detection limit in the order of 10 ppm and sensitivity α of about 10−4 ppm−1. Full article
(This article belongs to the Section Materials for Chemical Sensing)
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Article
Electrochemical Aptasensor for Detection of Dopamine
Chemosensors 2020, 8(2), 28; https://doi.org/10.3390/chemosensors8020028 - 15 Apr 2020
Cited by 4
Abstract
This work presents a proof of concept of a novel, simple, and sensitive method of detection of dopamine, a neurotransmitter within the human brain. We propose a simple electrochemical method for the detection of dopamine using a dopamine-specific aptamer labeled with an electrochemically [...] Read more.
This work presents a proof of concept of a novel, simple, and sensitive method of detection of dopamine, a neurotransmitter within the human brain. We propose a simple electrochemical method for the detection of dopamine using a dopamine-specific aptamer labeled with an electrochemically active ferrocene tag. Aptamers immobilized on the surface of gold screen-printed gold electrodes via thiol groups can change their secondary structure by wrapping around the target molecule. As a result, the ferrocene labels move closer to the electrode surface and subsequently increase the electron transfer. The cyclic voltammograms and impedance spectra recorded on electrodes in buffer solutions containing different concentration of dopamine showed, respectively, the increase in both the anodic and cathodic currents and decrease in the double layer resistance upon increasing the concentration of dopamine from 0.1 to 10 nM L−1. The high affinity of aptamer-dopamine binding (KD ≈ 5 nM) was found by the analysis of the binding kinetics. The occurrence of aptamer-dopamine binding was directly confirmed with spectroscopic ellipsometry measurements. Full article
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Article
Development of Novel and Highly Specific ssDNA-Aptamer-Based Electrochemical Biosensor for Rapid Detection of Mercury (II) and Lead (II) Ions in Water
Chemosensors 2019, 7(2), 27; https://doi.org/10.3390/chemosensors7020027 - 04 Jun 2019
Cited by 19
Abstract
In this work, we report on the development of an electrochemical biosensor for high selectivity and rapid detection of Hg2+ and Pb2+ ions using DNA-based specific aptamer probes labeled with ferrocene (or methylene blue) and thiol groups at their 5′ and [...] Read more.
In this work, we report on the development of an electrochemical biosensor for high selectivity and rapid detection of Hg2+ and Pb2+ ions using DNA-based specific aptamer probes labeled with ferrocene (or methylene blue) and thiol groups at their 5′ and 3′ termini, respectively. Aptamers were immobilized onto the surface of screen-printed gold electrodes via the SH (thiol) groups, and then cyclic voltammetry and impedance spectra measurements were performed in buffer solutions with the addition of HgCl2 and PbCl2 salts at different concentrations. Changes in 3D conformation of aptamers, caused by binding their respective targets, e.g., Hg2+ and Pb2+ ions, were accompanied by an increase in the electron transfer between the redox label and the electrode. Accordingly, the presence of the above ions can be detected electrochemically. The detection of Hg2+ and Pb2+ ions in a wide range of concentrations as low as 0.1 ng/mL (or 0.1 ppb) was achieved. The study of the kinetics of aptamer/heavy metal ions binding gave the values of the affinity constants of approximately 9.10−7 mol, which proved the high specificity of the aptamers used. Full article
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Article
Smartphone Coupled with a Paper-Based Colorimetric Device for Sensitive and Portable Mercury Ion Sensing
Chemosensors 2019, 7(2), 25; https://doi.org/10.3390/chemosensors7020025 - 17 May 2019
Cited by 45
Abstract
The rapid development of information and communication technology provides an opportunity for scientists to develop a quantitative analytical method that is built on a mobile gadget as a detector. In this paper, we report a low-cost, simple and portable analytical method for mercury [...] Read more.
The rapid development of information and communication technology provides an opportunity for scientists to develop a quantitative analytical method that is built on a mobile gadget as a detector. In this paper, we report a low-cost, simple and portable analytical method for mercury ion quantification based on digital image colorimetry coupled with a smartphone application. A small amount of silver nanoparticles (AgNPs) was used as a colorimetric agent that is selective only to mercury ions. The yellowish brown color of AgNPs instantly changed to colorless after the addition of mercury ions due to a redox reaction. To increase the portability, we attached the AgNPs onto a medium to create a paper-based analytical device. The final data processing of the colorimetric analysis was conducted using an android application available on the Google Play Store, called “Mercury Detector”. The proposed method has good sensitivity, with a detection limit of 0.86 ppb, which is comparable to those of bulk and more expensive instruments. This allows for the detection of mercury ions as low as 2 ppb (10 nM), which is also the maximum contaminant level permitted in drinking water by the US Environmental Protection Agency. The proposed method was applied to real samples that provide satisfactory results on accuracy (2.4%) and precision (2.5%). Full article
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Article
Handheld Enzymatic Luminescent Biosensor for Rapid Detection of Heavy Metals in Water Samples
Chemosensors 2019, 7(1), 16; https://doi.org/10.3390/chemosensors7010016 - 26 Mar 2019
Cited by 12
Abstract
Enzymatic luminescent systems are a promising tool for rapid detection of heavy metals ions for water quality assessment. Nevertheless, their widespread use is limited by the lack of test procedure automation and available sensitive handheld luminometers. Herein we describe integration of disposable microfluidic [...] Read more.
Enzymatic luminescent systems are a promising tool for rapid detection of heavy metals ions for water quality assessment. Nevertheless, their widespread use is limited by the lack of test procedure automation and available sensitive handheld luminometers. Herein we describe integration of disposable microfluidic chips for bioluminescent enzyme-inhibition based assay with a handheld luminometer, which detection system is based on a thermally stabilized silicon photomultiplier (SiPM). Microfluidic chips were made of poly(methyl methacrylate) by micro-milling method and sealed using a solvent bonding technique. The composition of the bioluminescent system in microfluidic chip was optimized to achieve higher luminescence intensity and storage time. Results indicate that developed device provided comparable sensitivity with bench-scale PMT-based commercial luminometers. Limit of detection for copper (II) sulfate reached 2.5 mg/L for developed biosensor. Hereby we proved the concept of handheld enzymatic optical biosensors with disposable chips for bioassay. The proposed biosensor can be used as an early warning field-deployable system for rapid detection of heavy metals salts and other toxic chemicals, which affect bioluminescent signal of enzymatic reaction. Full article
(This article belongs to the Special Issue Chemical Sensors for Heavy Metals/Toxin Detection)
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Article
Real-Time Frequency Tracking of an Electro-Thermal Piezoresistive Cantilever Resonator with ZnO Nanorods for Chemical Sensing
Chemosensors 2019, 7(1), 2; https://doi.org/10.3390/chemosensors7010002 - 03 Jan 2019
Cited by 14
Abstract
The asymmetric resonance response in electro-thermal piezoresistive cantilever resonators causes a need of an optimization treatment for taking parasitic actuation-sensing effects into account. An electronic reference circuit for signal subtraction, integrated with the cantilever resonator has the capability to reduce the effect of [...] Read more.
The asymmetric resonance response in electro-thermal piezoresistive cantilever resonators causes a need of an optimization treatment for taking parasitic actuation-sensing effects into account. An electronic reference circuit for signal subtraction, integrated with the cantilever resonator has the capability to reduce the effect of parasitic coupling. Measurement results demonstrated that a symmetric amplitude shape (Lorentzian) and an optimized phase characteristic (i.e., monotonically decreasing) were successfully extracted from an asymmetric resonance response. With the monotonic phase response, real-time frequency tracking can be easier to implement using a phase-locked loop (PLL) system. In this work, an electro-thermal piezoresistive cantilever resonator functionalized with self-assembled monolayers of chitosan-covered ZnO nanorod arrays as sensitive layers has been investigated under different relative humidity (rH) levels. Enhancement of resonance phase response has been demonstrated by implementing the reference signal subtraction. Subsequently, a lock-in amplifier integrated with PLL system (MFLI, Zurich Instruments, Zurich, Switzerland) was then employed for continuously tracking the resonant frequency. As a result, we find a good correlation of frequency shift (∆f0) with change in rH monitored using a commercial reference sensor. Full article
(This article belongs to the Special Issue Nanotechnology Efforts for Chemical Sensors)
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Article
Nanostructured Nickel on Porous Carbon-Silica Matrix as an Efficient Electrocatalytic Material for a Non-Enzymatic Glucose Sensor
Chemosensors 2018, 6(4), 54; https://doi.org/10.3390/chemosensors6040054 - 16 Nov 2018
Cited by 10
Abstract
Nanostructured nickel on porous carbon-silica matrix (N-CS) has been synthesized using a sol gel process and subsequent pyrolysis treatment at a temperature of 650 °C. The morphology and microstructure of the N-CS sample has been investigated using XRD (X-ray Diffraction), SEM-EDS (Scanning Electron [...] Read more.
Nanostructured nickel on porous carbon-silica matrix (N-CS) has been synthesized using a sol gel process and subsequent pyrolysis treatment at a temperature of 650 °C. The morphology and microstructure of the N-CS sample has been investigated using XRD (X-ray Diffraction), SEM-EDS (Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy), and BET (Brunauer-Emmett-Teller) analysis. The synthesized nanocomposite has been used for developing NCS-modified screen-printed electrodes (NCS-SPCEs) and was applied in the electrochemical monitoring of glucose. After electrochemical activation, via cycling the modified electrode in a potential window from 0 to 0.8 V in 0.1 M KOH solution, the fabricated NCS-SPCEs electrodes were evaluated for the voltammetric and amperometric determination of glucose. The developed sensors showed good sensing performance towards glucose, displaying a sensitivity of 585 µA/mM cm−1 in the linear range from 0.05 to 1.5 mM, a detection limit lower than 30 µM with excellent selectivity. Full article
(This article belongs to the Special Issue Nanotechnology Efforts for Chemical Sensors)
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Review

Jump to: Research

Review
Electrochemical Impedance Spectroscopy on 2D Nanomaterial MXene Modified Interfaces: Application as a Characterization and Transducing Tool
Chemosensors 2020, 8(4), 127; https://doi.org/10.3390/chemosensors8040127 - 07 Dec 2020
Cited by 5
Abstract
This review presents the basic characteristics of MXene, a novel 2D nanomaterial with many outstanding properties applicable to electrochemical sensing and biosensing. The second part deals with electrochemical impedance spectroscopy (EIS) and its beneficial features applicable to ultrasensitive electrochemical sensing and label-free biosensing. [...] Read more.
This review presents the basic characteristics of MXene, a novel 2D nanomaterial with many outstanding properties applicable to electrochemical sensing and biosensing. The second part deals with electrochemical impedance spectroscopy (EIS) and its beneficial features applicable to ultrasensitive electrochemical sensing and label-free biosensing. The main part of the review presents recent advances in the integration of MXene to design electrochemical interfaces. EIS was used to evaluate the effect of anodic potential on MXene and the effect of the MXene preparation route and for characterization of MXene grafted with polymers. It also included the application of EIS as the main transducing tool for antibody- and aptamer-based biosensors or biosensors integrating molecularly imprinted polymers. Full article
(This article belongs to the Special Issue Analytical (Chem and Bio)sensors Based on EIS Measurements)
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Review
Biomarkers Determination Based on Surface-Enhanced Raman Scattering
Chemosensors 2020, 8(4), 118; https://doi.org/10.3390/chemosensors8040118 - 22 Nov 2020
Cited by 4
Abstract
An overview of noteworthy new methods of biomarker determination based on surface-enhanced Raman scattering (SERS) is presented. Biomarkers can be used to identify the occurrence and development of diseases, which furthers the understanding of biological processes in the body. Accurate detection of a [...] Read more.
An overview of noteworthy new methods of biomarker determination based on surface-enhanced Raman scattering (SERS) is presented. Biomarkers can be used to identify the occurrence and development of diseases, which furthers the understanding of biological processes in the body. Accurate detection of a disease-specific biomarker is helpful for the identification, early diagnosis and prevention of a disease and for monitoring during treatment. The search for and discovery of valuable biomarkers have become important research hotspots. Different diseases have different biomarkers, some of which are involved in metabolic processes. Therefore, the fingerprint characteristics and band intensities in SERS spectra have been used to identify metabolites and analyze markers. As a promising technique, SERS has been widely used for the quantitative and qualitative determination of different types of biomarkers for different diseases. SERS techniques provide new technologies for the diagnosis of disease-related markers and determining the basis for clinical treatment. Herein, several SERS-based methods with excellent sensitivity and selectivity for the determination of biomarkers for tumors, viruses, Alzheimer’s disease, cardiac muscle tissue injury, and cell activity are highlighted. Full article
(This article belongs to the Section Optical Chemical Sensors)
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Review
Nanomaterials for Diagnosis and Treatment of Brain Cancer: Recent Updates
Chemosensors 2020, 8(4), 117; https://doi.org/10.3390/chemosensors8040117 - 20 Nov 2020
Cited by 20
Abstract
Brain tumors, especially glioblastoma, remain the most aggressive form of all the cancers because of inefficient diagnosis and profiling. Nanostructures, such as metallic nanostructures, silica nano-vehicles, quantum dots, lipid nanoparticles (NPs) and polymeric NPs, with high specificity have made it possible to permeate [...] Read more.
Brain tumors, especially glioblastoma, remain the most aggressive form of all the cancers because of inefficient diagnosis and profiling. Nanostructures, such as metallic nanostructures, silica nano-vehicles, quantum dots, lipid nanoparticles (NPs) and polymeric NPs, with high specificity have made it possible to permeate the blood–brain barrier (BBB). NPs possess optical, magnetic and photodynamic properties that can be exploited by surface modification, bio composition, contrast agents’ encapsulation and coating by tumor-derived cells. Hence, nanotechnology has brought on a revolution in the field of diagnosis and imaging of brain tumors and cancers. Recently, nanomaterials with biomimetic functions have been introduced to efficiently cross the BBB to be engulfed by deep skin tumors and cancer malignancies for imaging. The review focuses on nanotechnology-based diagnostic and imaging approaches for exploration in brain tumors and cancers. Moreover, the review also summarizes a few strategies to image glioblastoma and cancers by multimodal functional nanocomposites for more precise and accurate clinical diagnosis. Their unique physicochemical attributes, including nanoscale sizes, larger surface area, explicit structural features and ability to encapsulate diverse molecules on their surface, render nanostructured materials as excellent nano-vehicles to cross the blood–brain barrier and convey drug molecules to their target region. This review sheds light on the current progress of various kinds of nanomaterials, such as liposomes, nano-micelles, dendrimers, carbon nanotubes, carbon dots and NPs (gold, silver and zinc oxide NPs), for efficient drug delivery in the treatment and diagnosis of brain cancer. Full article
(This article belongs to the Special Issue The Application of Nanocarriers in Therapeutic Agents)
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Review
Macrocyclic Arenes Functionalized with BODIPY: Rising Stars among Chemosensors and Smart Materials
Chemosensors 2020, 8(3), 51; https://doi.org/10.3390/chemosensors8030051 - 06 Jul 2020
Cited by 3
Abstract
Macrocycles play a crucial role in supramolecular chemistry and the family of macrocyclic arenes represents one of the most important types of hosts. Among them, calixarenes, resorcinarenes and pillararenes are the most commonly encountered macrocyclic arenes, and they have received considerable attention. Boron-dipyrromethene [...] Read more.
Macrocycles play a crucial role in supramolecular chemistry and the family of macrocyclic arenes represents one of the most important types of hosts. Among them, calixarenes, resorcinarenes and pillararenes are the most commonly encountered macrocyclic arenes, and they have received considerable attention. Boron-dipyrromethene (BODIPY) dyes are fascinating compounds with multiple functionalization sites and outstanding luminescence properties including high fluorescence quantum yields, large molar absorption coefficients and remarkable photo- and chemical stability. The combination of macrocyclic arenes and BODIPY dyes has been demonstrated to be an effective strategy to construct chemosensors for various guests and smart materials with tailored properties. Herein, we firstly summarize the recent advances made so far in macrocyclic arenes substituted with BODIPY. This review only focuses on the three macrocyclic arenes of calixarenes, resorcinarenes and pillararenes, as there are no other macrocyclic arenes substituted BODIPY units at the present time. Hopefully, this review will not only afford a guide and useful information for those who are interested in developing novel chemosensors and smart materials, but also inspire new opportunities in this field. Full article
(This article belongs to the Special Issue Organic Fluorescent Materials as Chemical Sensors)
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Review
Silver Nanoparticles as Colorimetric Sensors for Water Pollutants
Chemosensors 2020, 8(2), 26; https://doi.org/10.3390/chemosensors8020026 - 31 Mar 2020
Cited by 35
Abstract
This review provides an up-to-date overview on silver nanoparticles-based materials suitable as optical sensors for water pollutants. The topic is really hot considering the implications for human health and environment due to water pollutants. In fact, the pollutants present in the water disturb [...] Read more.
This review provides an up-to-date overview on silver nanoparticles-based materials suitable as optical sensors for water pollutants. The topic is really hot considering the implications for human health and environment due to water pollutants. In fact, the pollutants present in the water disturb the spontaneity of life-related mechanisms, such as the synthesis of cellular constituents and the transport of nutrients into cells, and this causes long / short-term diseases. For this reason, research continuously tends to develop always innovative, selective and efficient processes / technologies to remove pollutants from water. In this paper we will report on the silver nanoparticles synthesis, paying attention to the stabilizers and mostly used ligands, to the characterizations, to the properties and applications as colorimetric sensors for water pollutants. As water pollutants our attention will be focused on several heavy metals ions, such as Hg(II), Ni(II),Cu(II), Fe(III), Mn(II), Cr(III/V) Co(II) Cd(II), Pb(II), due to their dangerous effects on human health. In addition, several systems based on silver nanoparticles employed as pesticides colorimetric sensors in water will be also discussed. All of this with the aim to provide to readers a guide about recent advanced silver nanomaterials, used as colorimetric sensors in water. Full article
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Review
Heavy Metal/Toxins Detection Using Electronic Tongues
Chemosensors 2019, 7(3), 36; https://doi.org/10.3390/chemosensors7030036 - 02 Aug 2019
Cited by 10
Abstract
The growing concern for sustainability and environmental preservation has increased the demand for reliable, fast response, and low-cost devices to monitor the existence of heavy metals and toxins in water resources. An electronic tongue (e-tongue) is a multisensory array mostly based on electroanalytical [...] Read more.
The growing concern for sustainability and environmental preservation has increased the demand for reliable, fast response, and low-cost devices to monitor the existence of heavy metals and toxins in water resources. An electronic tongue (e-tongue) is a multisensory array mostly based on electroanalytical methods and multivariate statistical techniques to facilitate information visualization in a qualitative and/or quantitative way. E-tongues are promising analytical devices having simple operation, fast response, low cost, easy integration with other systems (microfluidic, optical, etc) to enable miniaturization and provide a high sensitivity for measurements in complex liquid media, providing an interesting alternative to address many of the existing environmental monitoring challenges, specifically relevant emerging pollutants such as heavy metals and toxins. Full article
(This article belongs to the Special Issue Chemical Sensors for Heavy Metals/Toxin Detection)
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Review
Electrochemical Immuno- and Aptasensors for Mycotoxin Determination
Chemosensors 2019, 7(1), 10; https://doi.org/10.3390/chemosensors7010010 - 04 Mar 2019
Cited by 23
Abstract
Modern analysis of food and feed is mostly focused on development of fast and reliable portable devices intended for field applications. In this review, electrochemical biosensors based on immunological reactions and aptamers are considered in the determination of mycotoxins as one of most [...] Read more.
Modern analysis of food and feed is mostly focused on development of fast and reliable portable devices intended for field applications. In this review, electrochemical biosensors based on immunological reactions and aptamers are considered in the determination of mycotoxins as one of most common contaminants able to negatively affect human health. The characteristics of biosensors are considered from the point of view of general principles of bioreceptor implementation and signal transduction providing sub-nanomolar detection limits of mycotoxins. Moreover, the modern trends of bioreceptor selection and modification are discussed as well as future trends of biosensor development for mycotoxin determination are considered. Full article
(This article belongs to the Special Issue Chemical Sensors for Heavy Metals/Toxin Detection)
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Review
Thin Films Sensor Devices for Mycotoxins Detection in Foods: Applications and Challenges
Chemosensors 2019, 7(1), 3; https://doi.org/10.3390/chemosensors7010003 - 04 Jan 2019
Cited by 10
Abstract
Mycotoxins are a group of secondary metabolites produced by different species of filamentous fungi and pose serious threats to food safety due to their serious human and animal health impacts such as carcinogenic, teratogenic and hepatotoxic effects. Conventional methods for the detection of [...] Read more.
Mycotoxins are a group of secondary metabolites produced by different species of filamentous fungi and pose serious threats to food safety due to their serious human and animal health impacts such as carcinogenic, teratogenic and hepatotoxic effects. Conventional methods for the detection of mycotoxins include gas chromatography and high-performance liquid chromatography coupled with mass spectrometry or other detectors (fluorescence or UV detection), thin layer chromatography and enzyme-linked immunosorbent assay. These techniques are generally straightforward and yield reliable results; however, they are time-consuming, require extensive preparation steps, use large-scale instruments, and consume large amounts of hazardous chemical reagents. Rapid detection of mycotoxins is becoming an increasingly important challenge for the food industry in order to effectively enforce regulations and ensure the safety of food and feed. In this sense, several studies have been done with the aim of developing strategies to detect mycotoxins using sensing devices that have high sensitivity and specificity, fast analysis, low cost and portability. The latter include the use of microarray chips, multiplex lateral flow, Surface Plasmon Resonance, Surface Enhanced Raman Scattering and biosensors using nanoparticles. In this perspective, thin film sensors have recently emerged as a good candidate technique to meet such requirements. This review summarizes the application and challenges of thin film sensor devices for detection of mycotoxins in food matrices. Full article
(This article belongs to the Special Issue Thin Film Based Sensors)
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Review
Advances on Sensors Based on Carbon Nanotubes
Chemosensors 2018, 6(4), 62; https://doi.org/10.3390/chemosensors6040062 - 06 Dec 2018
Cited by 55
Abstract
Carbon nanotubes have been attracting considerable interest among material scientists, physicists, chemists, and engineers for almost 30 years. Owing to their high aspect ratio, coupled with remarkable mechanical, electronic, and thermal properties, carbon nanotubes have found application in diverse fields. In this review, [...] Read more.
Carbon nanotubes have been attracting considerable interest among material scientists, physicists, chemists, and engineers for almost 30 years. Owing to their high aspect ratio, coupled with remarkable mechanical, electronic, and thermal properties, carbon nanotubes have found application in diverse fields. In this review, we will cover the work on carbon nanotubes used for sensing applications. In particular, we will see examples where carbon nanotubes act as main players in devices sensing biomolecules, gas, light or pressure changes. Furthermore, we will discuss how to improve the performance of carbon nanotube-based sensors after proper modification. Full article
(This article belongs to the Special Issue Carbon Nanotube Sensors)
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Review
From Gas Sensors to Biomimetic Artificial Noses
Chemosensors 2018, 6(3), 32; https://doi.org/10.3390/chemosensors6030032 - 07 Aug 2018
Cited by 22
Abstract
Since the first attempts to mimic the human nose with artificial devices, a variety of sensors have been developed, ranging from simple inorganic and organic gas detectors to biosensing elements incorporating proteins of the biological olfactory system. In order to design a device [...] Read more.
Since the first attempts to mimic the human nose with artificial devices, a variety of sensors have been developed, ranging from simple inorganic and organic gas detectors to biosensing elements incorporating proteins of the biological olfactory system. In order to design a device able to mimic the human nose, two major issues still need to be addressed regarding the complexity of olfactory coding and the extreme sensitivity of the biological system. So far, only 50 of the approximately 300–400 functioning olfactory receptors have been de-orphanized, still a long way from breaking the human olfactory code. On the other hand, the exceptional sensitivity of the human nose is based on amplification mechanisms difficult to reproduce with electronic circuits, and perhaps novel approaches are required to address this issue. Here, we review the recent literature on chemical sensing both in biological systems and artificial devices, and try to establish the state-of-the-art towards the design of an electronic nose. Full article
(This article belongs to the Special Issue Electronic nose’s, Machine Olfaction and Electronic Tongue’s)
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Review
Label-Free Sensing in Microdroplet-Based Microfluidic Systems
Chemosensors 2018, 6(2), 23; https://doi.org/10.3390/chemosensors6020023 - 24 May 2018
Cited by 13
Abstract
Droplet microfluidic systems have evolved as fluidic platforms that use much less sample volume and provide high throughput for biochemical analysis compared to conventional microfluidic devices. The variety of droplet fluidic applications triggered several detection techniques to be applied for analysis of droplets. [...] Read more.
Droplet microfluidic systems have evolved as fluidic platforms that use much less sample volume and provide high throughput for biochemical analysis compared to conventional microfluidic devices. The variety of droplet fluidic applications triggered several detection techniques to be applied for analysis of droplets. In this review, we focus on label-free droplet detection techniques that were adapted to various droplet microfluidic platforms. We provide a classification of most commonly used droplet platform technologies. Then we discuss the examples of various label-free droplet detection schemes implemented for these platforms. While providing the research landscape for label-free droplet detection methods, we aim to highlight the strengths and shortcomings of each droplet platform so that a more targeted approach can be taken by researchers when selecting a droplet platform and a detection scheme for any given application. Full article
(This article belongs to the Special Issue Label-Free Biosensors and Chemical Sensors)
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Review
Metal Oxide Nanostructures in Food Applications: Quality Control and Packaging
Chemosensors 2018, 6(2), 16; https://doi.org/10.3390/chemosensors6020016 - 14 Apr 2018
Cited by 37
Abstract
Metal oxide materials have been applied in different fields due to their excellent functional properties. Metal oxides nanostructuration, preparation with the various morphologies, and their coupling with other structures enhance the unique properties of the materials and open new perspectives for their application [...] Read more.
Metal oxide materials have been applied in different fields due to their excellent functional properties. Metal oxides nanostructuration, preparation with the various morphologies, and their coupling with other structures enhance the unique properties of the materials and open new perspectives for their application in the food industry. Chemical gas sensors that are based on semiconducting metal oxide materials can detect the presence of toxins and volatile organic compounds that are produced in food products due to their spoilage and hazardous processes that may take place during the food aging and transportation. Metal oxide nanomaterials can be used in food processing, packaging, and the preservation industry as well. Moreover, the metal oxide-based nanocomposite structures can provide many advantageous features to the final food packaging material, such as antimicrobial activity, enzyme immobilization, oxygen scavenging, mechanical strength, increasing the stability and the shelf life of food, and securing the food against humidity, temperature, and other physiological factors. In this paper, we review the most recent achievements on the synthesis of metal oxide-based nanostructures and their applications in food quality monitoring and active and intelligent packaging. Full article
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Review
Spectroscopic Chemical Sensing and Imaging: From Plants to Animals and Humans
Chemosensors 2018, 6(1), 11; https://doi.org/10.3390/chemosensors6010011 - 26 Feb 2018
Cited by 16
Abstract
Chemical sensing and imaging technologies are of great importance in medical diagnostics and environmental sensing due to their ability to detect and localize chemical targets and provide valuable information in real-time. Biophotonic techniques are the most promising for in vivo applications due to [...] Read more.
Chemical sensing and imaging technologies are of great importance in medical diagnostics and environmental sensing due to their ability to detect and localize chemical targets and provide valuable information in real-time. Biophotonic techniques are the most promising for in vivo applications due to their minimal invasivity. Our laboratory has introduced various biophotonics-based technologies for chemical sensing and imaging for biochemical sensing, medical diagnostics, and fundamental research. Over the years, we have developed a wide variety of fluorescence and surface-enhanced Raman scattering (SERS)-based technologies for the detection of biomarkers for cancer and other diseases. This paper provides an overview of the research on chemical and biological sensors developed in our laboratory, highlighting our work on in vivo imaging and sensing, including minimally invasive detection of endogenous fluorophores associated with malignant tissue, SERS-tag localization of cancer cells and tissues, and SERS-based detection of nucleic acid biotargets and its feasibility for in vivo applications. This manuscript also presents new development on the use of Raman imaging of SERS-labeled nanoprobes incubated in leaves for use in biofuel research, laying the foundation for studies on functional imaging of nucleic acid biomarkers in plants. Full article
(This article belongs to the Special Issue Advances in Chemical Imaging and its Applications)
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Review
Recent Advances in the Detection of Neurotransmitters
Chemosensors 2018, 6(1), 1; https://doi.org/10.3390/chemosensors6010001 - 04 Jan 2018
Cited by 75
Abstract
Neurotransmitters are chemicals that act as messengers in the synaptic transmission process. They are essential for human health and any imbalance in their activities can cause serious mental disorders such as Parkinson’s disease, schizophrenia, and Alzheimer’s disease. Hence, monitoring the concentrations of various [...] Read more.
Neurotransmitters are chemicals that act as messengers in the synaptic transmission process. They are essential for human health and any imbalance in their activities can cause serious mental disorders such as Parkinson’s disease, schizophrenia, and Alzheimer’s disease. Hence, monitoring the concentrations of various neurotransmitters is of great importance in studying and diagnosing such mental illnesses. Recently, many researchers have explored the use of unique materials for developing biosensors for both in vivo and ex vivo neurotransmitter detection. A combination of nanomaterials, polymers, and biomolecules were incorporated to implement such sensor devices. For in vivo detection, electrochemical sensing has been commonly applied, with fast-scan cyclic voltammetry being the most promising technique to date, due to the advantages such as easy miniaturization, simple device architecture, and high sensitivity. However, the main challenges for in vivo electrochemical neurotransmitter sensors are limited target selectivity, large background signal and noise, and device fouling and degradation over time. Therefore, achieving simultaneous detection of multiple neurotransmitters in real time with long-term stability remains the focus of research. The purpose of this review paper is to summarize the recently developed sensing techniques with the focus on neurotransmitters as the target analyte, and to discuss the outlook of simultaneous detection of multiple neurotransmitter species. This paper is organized as follows: firstly, the common materials used for developing neurotransmitter sensors are discussed. Secondly, several sensor surface modification approaches to enhance sensing performance are reviewed. Finally, we discuss recent developments in the simultaneous detection capability of multiple neurotransmitters. Full article
(This article belongs to the Special Issue Polymers Based Chemical Sensors)
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