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Chemosensors
Volume 11
Issue 6
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Chemosensors, Volume 11, Issue 6 (June 2023) – 40 articles

Cover Story (view full-size image): The presence of emerging contaminants, such as pharmaceuticals, pesticides, and personal care products, in environmental waters hasve challenged existing analytical methods and water treatment technologies. Driven by the need for simple, accurate, and cost-effective analysis tools, molecularly imprinted polymer (MIP)-based plasmonic sensors have been proposed as a powerful alternative to detect and monitor a wide range of these contaminants. The selective recognition ability of MIPs ensures specific analyte detection, while plasmonic detection approaches offer highly sensitive and real-time responses. This work issue presents a comprehensive overview of plasmonic MIP sensors for the analysis of contaminants in water samples using surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS) techniques. View this paper
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17 pages, 3047 KiB  
Article
Self-Adaptation of Oxygen Adsorption and Sub-Surface Junction Formation in Thin Nanometric Sheets of Metal Oxides
by Gerhard Müller and Giorgio Sberveglieri
Chemosensors 2023, 11(6), 352; https://doi.org/10.3390/chemosensors11060352 - 20 Jun 2023
Viewed by 1242
Abstract
Oxygen adsorption at metal oxide (MOX) surfaces and the formation of sub-surface depletion zones in thin nanometric sheets of MOX materials are theoretically investigated. It is shown that—under conditions of sufficient oxygen mobility—the bulk thermal generation of oxygen vacancy donors and the adsorption [...] Read more.
Oxygen adsorption at metal oxide (MOX) surfaces and the formation of sub-surface depletion zones in thin nanometric sheets of MOX materials are theoretically investigated. It is shown that—under conditions of sufficient oxygen mobility—the bulk thermal generation of oxygen vacancy donors and the adsorption of surface oxygen ions cooperate in a self-organizing manner to form narrow sub-surface depletion zones which optimally fit into the limited spaces of MOX layers with nanometric cross sections. With this self-organization process in place, both the oxygen adsorption at free surfaces and the bulk generation of oxygen vacancy donors continuously increases as the MOX sheet thickness L is reduced, maintaining at the same time overall electro-neutrality and a state of perfect volume depletion of free carriers in bulk. This process comes to an end when MOX sheet thicknesses of L ≈ 1 nm are approached and when 3d-volumes of about 1 nm3 contain only one single double-donor and two surface oxygen ions on average. It is argued that at this limit of miniaturization, different interpretations of MOX gas sensing phenomena might be required than on larger length scales. Full article
(This article belongs to the Collection Sensing Materials: Advances in Synthesis, Functionalities, and Applications)
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11 pages, 2251 KiB  
Article
Rapid Matching Antibodies Pair and Fast Detecting Melioidosis with Fluorescent Immunochromatographic Test Strips
by Yi-Zhi Lin, Ting-Ting Zhou, Jin Zhu and Shou-Nian Ding
Chemosensors 2023, 11(6), 351; https://doi.org/10.3390/chemosensors11060351 - 19 Jun 2023
Viewed by 1122
Abstract
The high infectivity, difficulty to diagnose, and high drug resistance of melioidosis limited the timeliness of treatment. Lateral flow assay (LFA) was operated in this research to provide an instant diagnosis method, and a fast antibody rapid matching test strategy based on LFA [...] Read more.
The high infectivity, difficulty to diagnose, and high drug resistance of melioidosis limited the timeliness of treatment. Lateral flow assay (LFA) was operated in this research to provide an instant diagnosis method, and a fast antibody rapid matching test strategy based on LFA was developed to select the most sensitive and specific pair of antibodies. Compared to the traditional ELISA method, the new matching strategy limits the pairing time to 3 h without any complex instruments. The rapid pairing test strategy is a universal strategy that is suitable for various sandwich immune antigen pairings. To fasten the test of the test strips, dry fluorescence immunoassay analyzer (DFIA) was designed and applied. The equipment also simplifies the process of data acquisition. Finally, the concentration gradient test was operated, and the detection lines and limits were presented. Full article
(This article belongs to the Special Issue Tenth Anniversary of Chemosensors—"Optical Chemical Sensors" Section)
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20 pages, 5892 KiB  
Article
Discrimination of Diabetes Mellitus Patients and Healthy Individuals Based on Volatile Organic Compounds (VOCs): Analysis of Exhaled Breath and Urine Samples by Using E-Nose and VE-Tongue
by Omar Zaim, Benachir Bouchikhi, Soukaina Motia, Sònia Abelló, Eduard Llobet and Nezha El Bari
Chemosensors 2023, 11(6), 350; https://doi.org/10.3390/chemosensors11060350 - 19 Jun 2023
Cited by 2 | Viewed by 1230
Abstract
Studies suggest that breath and urine analysis can be viable non-invasive methods for diabetes management, with the potential for disease diagnosis. In the present work, we employed two sensing strategies. The first strategy involved analyzing volatile organic compounds (VOCs) in biological matrices, such [...] Read more.
Studies suggest that breath and urine analysis can be viable non-invasive methods for diabetes management, with the potential for disease diagnosis. In the present work, we employed two sensing strategies. The first strategy involved analyzing volatile organic compounds (VOCs) in biological matrices, such as exhaled breath and urine samples collected from patients with diabetes mellitus (DM) and healthy controls (HC). The second strategy focused on discriminating between two types of DM, related to type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), by using a data fusion method. For this purpose, an electronic nose (e-nose) based on five tin oxide (SnO2) gas sensors was employed to characterize the overall composition of the collected breath samples. Furthermore, a voltametric electronic tongue (VE-tongue), composed of five working electrodes, was dedicated to the analysis of urinary VOCs using cyclic voltammetry as a measurement technique. To evaluate the diagnostic performance of the electronic sensing systems, algorithm tools including principal component analysis (PCA), discriminant function analysis (DFA) and receiver operating characteristics (ROC) were utilized. The results showed that the e-nose and VE-tongue could discriminate between breath and urine samples from patients with DM and HC with a success rate of 99.44% and 99.16%, respectively. However, discrimination between T1DM and T2DM samples using these systems alone was not perfect. Therefore, a data fusion method was proposed as a goal to overcome this shortcoming. The fusing of data from the two instruments resulted in an enhanced success rate of classification (i.e., 93.75% for the recognition of T1DM and T2DM). Full article
(This article belongs to the Special Issue The Application and Advance of Electronic Nose)
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14 pages, 1657 KiB  
Article
MoS2@Au as Label for Sensitive Sandwich-Type Immunoassay of Neuron-Specific Enolase
by Yingying Wang, Huixin Wang, Yaliang Bai, Guanhui Zhao, Nuo Zhang, Yong Zhang, Yaoguang Wang and Hong Chi
Chemosensors 2023, 11(6), 349; https://doi.org/10.3390/chemosensors11060349 - 19 Jun 2023
Cited by 5 | Viewed by 1040
Abstract
Neuron-specific enolase (NSE) has gained extensive attention as a reliable target for detecting small cell carcinoma of lungs. In this paper, an electrochemical immunoassay method based on molybdenum disulfide (MoS2) is proposed to detect NSE sensitively. By an in-situ growth method, [...] Read more.
Neuron-specific enolase (NSE) has gained extensive attention as a reliable target for detecting small cell carcinoma of lungs. In this paper, an electrochemical immunoassay method based on molybdenum disulfide (MoS2) is proposed to detect NSE sensitively. By an in-situ growth method, MoS2 and Au nanoclusters (Au NCs) were composited to form a MoS2@Au nanozyme, and then the secondary antibodies were modified. Primary antibodies were immobilized on amino-reduced graphene oxides to capture NSE. The flower-like MoS2 nanozyme provided abundant sites to load Au NCs and catalyze the decomposition of H2O2, which were beneficial to amplify an amperometric response as well as build up sensitivity. Under optimum conditions, the detection range of this strategy was 0.1 pg·mL−1–10 ng·mL−1 and the limit of detection was 0.05 pg·mL−1. This sensing strategy achieved the prospect of sensitively detecting NSE. Moreover, the prepared electrochemical immunosensor provides a theoretical basis and technical support for the detection of other disease markers. Full article
(This article belongs to the Special Issue Bionic Recognition and Biosensors: A Theme Issue in Honor of Professor Hong-Yuan Chen)
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18 pages, 3592 KiB  
Article
Ascorbic Acid Sensing by Molecularly Imprinted Electrosynthesized Polymer (e-MIP) on Screen-Printed Electrodes
by Giancarla Alberti, Camilla Zanoni, Lisa Rita Magnaghi and Raffaela Biesuz
Chemosensors 2023, 11(6), 348; https://doi.org/10.3390/chemosensors11060348 - 16 Jun 2023
Cited by 4 | Viewed by 1405
Abstract
This paper presents the development of a cheap and rapid electrochemical sensor for ascorbic acid detection. In particular, the graphite ink working electrode of screen-printed cells was covered by a film of elecrosynthesized molecularly imprinted polypyrrole (e-MIP); differential pulse voltammetry (DPV) was the [...] Read more.
This paper presents the development of a cheap and rapid electrochemical sensor for ascorbic acid detection. In particular, the graphite ink working electrode of screen-printed cells was covered by a film of elecrosynthesized molecularly imprinted polypyrrole (e-MIP); differential pulse voltammetry (DPV) was the selected method for the analyte detection. The ascorbic acid molecules were successfully entrapped in the polypyrrole film, creating the recognition sites. The best results were obtained after polypyrrole overoxidation and performing the measurements in phosphate buffer solution 0.05 M/KCl 0.1 M at pH 7.5. A comparison with the bare and the not-imprinted polypyrrole-modified electrodes showed that the e-MIP-based sensor had the highest selectivity and reproducibility. The developed method was applied to assess ascorbic acid in farmaceutical products, obtaining values not significantly different from the declared content. Full article
(This article belongs to the Special Issue 10th Anniversary of Chemosensors—Section ‘Electrochemical Devices and Sensors’)
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15 pages, 4455 KiB  
Article
Recyclable Multifunctional Magnetic Fe3O4@SiO2@Au Core/Shell Nanoparticles for SERS Detection of Hg (II)
by Chao Liu, Hui Wang, Shengmin Xu, Hongbao Li, Yilin Lu and Chuhong Zhu
Chemosensors 2023, 11(6), 347; https://doi.org/10.3390/chemosensors11060347 - 15 Jun 2023
Cited by 2 | Viewed by 1336
Abstract
Mercury ions can be enriched along the food chain and even low concentrations of mercury ions can seriously affect human health and the environment. Therefore, rapid, sensitive, and highly selective detection of mercury ions is of great significance. In this work, we synthesized [...] Read more.
Mercury ions can be enriched along the food chain and even low concentrations of mercury ions can seriously affect human health and the environment. Therefore, rapid, sensitive, and highly selective detection of mercury ions is of great significance. In this work, we synthesized Fe3O4@SiO2@Au three-layer core/shell nanoparticles, and then modified 4-MPy (4-mercaptopyridine) to form a SERS sensor. Mercury ions in water can be easily captured by 4-MPy which were used as the reporter molecules, and the concentration of mercury ions can be evaluated based on the spectral changes (intensification and reduction of peaks) from 4-MPy. After the mercury ion was combined with the pyridine ring, the peak intensity at 1093 cm−1 increased with the concentration of mercury ion in the range of 10 ppm–1 ppb, while the Raman intensity ratio I (416 cm−1)/I (436 cm−1) decreased with the increase of mercury ion concentration. This magnetically separatable and recyclable SERS sensor demonstrates good stability, accuracy, and anti-interference ability and shows the potential to detect actual samples. Furthermore, we demonstrate that the probe is applicable for Hg2+ imaging in macrophage cells. Full article
(This article belongs to the Special Issue The Application of Surface-Enhanced Raman Spectroscopy (SERS) Platform)
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13 pages, 2661 KiB  
Article
Layer-by-Layer Films of Silsesquioxane and Nickel(II) Tetrasulphophthalocyanine as Glucose Oxidase Platform Immobilization: Amperometric Determination of Glucose in Kombucha Beverages
by João Paulo Winiarski, Douglas José de Melo, Edson Roberto Santana, Cleverson Siqueira Santos, Cliciane Guadalupe de Jesus, Sérgio Toshio Fujiwara, Karen Wohnrath and Christiana Andrade Pessôa
Chemosensors 2023, 11(6), 346; https://doi.org/10.3390/chemosensors11060346 - 14 Jun 2023
Cited by 5 | Viewed by 947
Abstract
This paper describes the development of a novel glucose biosensor through the layer-by-layer technique (LbL). The self-assembled architectures were composed of a positive-charged silsesquioxane polyelectrolyte, 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl−), nickel (II) tetrassulphophthalocyanine (NiTsPc), and a conductive surface [...] Read more.
This paper describes the development of a novel glucose biosensor through the layer-by-layer technique (LbL). The self-assembled architectures were composed of a positive-charged silsesquioxane polyelectrolyte, 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl−), nickel (II) tetrassulphophthalocyanine (NiTsPc), and a conductive surface of FTO (fluor tin oxide). The construction of the biosensor was influenced by the isoelectric point (pI) of the glucose oxidase enzyme (GOx), which allowed electrostatic interaction between the outer layer of the silsesquioxane film and the enzyme. The architecture of modified electrode GOx/(SiPy+Cl−/NiTsPc)5.5/FTO was confirmed by UV-Vis, FTIR, and chronoamperometry techniques using different immobilization methods of GOx. Among the studied methods, a higher variation of current was observed for the modified electrode formed by mixed LbL films of SiPy+Cl− and NiTsPc and the enzyme immobilized by drop coating. The stability and reproducibility of the biosensor were verified when the last layer containing the enzyme was coated with 0.2% Nafion® polymer. Under these conditions, a linear response for glucose was obtained in the concentration range of 0.2 to 1.6 mmol L−1 (R2 = 0.991) with a limit of detection of 0.022 mmol L−1. The proposed biosensor was applied to quantify glucose in two different samples of kombucha juices with accuracy, allowing the glucose content of the healthy beverages to be estimated. Full article
(This article belongs to the Special Issue Advanced Nanomaterials-Based (Bio)sensors for Electrochemical Detection and Analysis)
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13 pages, 5348 KiB  
Article
Glucose Oxidase Captured into Electropolymerized p-Coumaric Acid towards the Development of a Glucose Biosensor
by Gabriela Valdés-Ramírez and Laura Galicia
Chemosensors 2023, 11(6), 345; https://doi.org/10.3390/chemosensors11060345 - 14 Jun 2023
Cited by 2 | Viewed by 1406
Abstract
An electrochemical biosensor based on the immobilization of glucose oxidase into an electropolymerized p-coumaric acid membrane on a Pt electrode has been developed and evaluated for glucose detection in the range of 1 to 30 mM. The glucose biosensor exhibits a sensitivity [...] Read more.
An electrochemical biosensor based on the immobilization of glucose oxidase into an electropolymerized p-coumaric acid membrane on a Pt electrode has been developed and evaluated for glucose detection in the range of 1 to 30 mM. The glucose biosensor exhibits a sensitivity of 36.96 mA/mMcm2, a LOD of 0.66 mM, and a LOQ of 2.18 mM. The biosensing membrane was electropolymerized by cyclic voltammetry in 100 mM phosphates pH 7.00 and 3% ethanol containing glucose oxidase and p-coumaric acid. The glucose biosensors’ stability, repeatability, reproducibility, and selectivity were estimated. The biosensing membrane shows permselective properties and antifouling effects. The applicability of the developed glucose biosensor was evaluated in the presence of 20 mg/mL proteins, and any signal associated with biofouling was observed. The glucose biosensors were employed for the determination of the glucose concentration in three commercial beverages. Full article
(This article belongs to the Special Issue Advanced Glucose Biosensors)
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22 pages, 8380 KiB  
Review
Room Temperature Resistive Hydrogen Sensor for Early Safety Warning of Li-Ion Batteries
by Sixun Li, Shiyu Zhou, Shuaiyin Zhao, Tengfei Jin, Maohua Zhong, Zhuhao Cen, Peirong Gao, Wenjun Yan and Min Ling
Chemosensors 2023, 11(6), 344; https://doi.org/10.3390/chemosensors11060344 - 12 Jun 2023
Cited by 1 | Viewed by 1884
Abstract
Lithium-ion batteries (LIBs) have become one of the most competitive energy storage technologies. However, the “thermal runaway” of LIBs leads to serious safety issues. Early safety warning of LIBs is a prerequisite for the widely applications of power battery and large-scale energy storage [...] Read more.
Lithium-ion batteries (LIBs) have become one of the most competitive energy storage technologies. However, the “thermal runaway” of LIBs leads to serious safety issues. Early safety warning of LIBs is a prerequisite for the widely applications of power battery and large-scale energy storage systems. As reported, hydrogen (H2) could be generated due to the reaction of lithium metal and polymers inside the battery. The generation of H2 is some time earlier than the “thermal runaway”. Therefore, the rapid detection of trace hydrogen is the most effective method for early safety warning of LIBs. Resistive hydrogen sensors have attracted attention in recent years. In addition, they could be placed inside the LIB package for the initial hydrogen detection. Here, we overview the recent key advances of resistive room temperature (RT) H2 sensors, and explore possible applications inside LIB. We explored the underlying sensing mechanisms for each type of H2 sensor. Additionally, we highlight the approaches to develop the H2 sensors in large scale. Finally, the present review presents a brief conclusion and perspectives about the resistive RT H2 sensors for early safety warning of LIBs. Full article
(This article belongs to the Special Issue Gas Sensors and Electronic Noses for the Real Condition Sensing)
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19 pages, 4671 KiB  
Article
Redoxless Electrochemical Capacitance Spectroscopy for Investigating Surfactant Adsorption on Screen-Printed Carbon Electrodes
by Tzong-Jih Cheng, Hsien-Yi Hsiao, Pei-Chia Tsai and Richie L. C. Chen
Chemosensors 2023, 11(6), 343; https://doi.org/10.3390/chemosensors11060343 - 11 Jun 2023
Cited by 1 | Viewed by 1283
Abstract
Electrochemical impedance spectroscopy (EIS) is a sensitive analytical method for surface and bulk properties. Classical EIS and derived electrochemical capacitance spectroscopy (ECS) with a redox couple are label-free approaches for biosensor development, but doubts arise regarding interpretability when a redox couple is employed [...] Read more.
Electrochemical impedance spectroscopy (EIS) is a sensitive analytical method for surface and bulk properties. Classical EIS and derived electrochemical capacitance spectroscopy (ECS) with a redox couple are label-free approaches for biosensor development, but doubts arise regarding interpretability when a redox couple is employed (redox EIS) due to interactions between electroactive probes and interfacial charges or forced potential. Here, we demonstrated redoxless ECS for directly determining surfactant adsorption on screen-printed carbon electrodes (SPCEs), validated through a simulation of equivalent circuits and the electrochemistry of electronic dummy cells. Redoxless ECS provides excellent capacitance plot loci for quantifying the interfacial permittivity of di-electric layers on electrode surfaces. Redoxless ECS was compared with redox EIS/ECS, revealing a favorable discrimination of interfacial capacitances under both low and high SDS coverage on SPCEs and demonstrating potential for probeless (reagentless) sensing. Furthermore, the proposed method was applied in an electrolyte without a redox couple and bare electrodes, obtaining a high performance for the adsorption of surfactants Tween-20, Triton-X100, sodium dodecyl sulfate, and tetrapropylammonium bromide. This approach offers a simple and straightforward means for a semi-quantitative evaluation of small molecule interactions with electrode surfaces. Our proposed approach may serve as a starting point for future probeless (reagentless) and label-free biosensors based on electrochemistry, eliminating disturbance with surface charge properties and minimizing forced potential bias by avoiding redox couples. An unambiguous and quantitative determination of physicochemical properties of biochemically recognizable layers will be relevant for biosensor development. Full article
(This article belongs to the Special Issue 10th Anniversary of Chemosensors—Section ‘Electrochemical Devices and Sensors’)
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11 pages, 737 KiB  
Article
Detection of Aroma Profile in Spanish Rice Paella during Socarrat Formation by Electronic Nose and Sensory Panel
by Juan Diego Barea-Ramos, José Pedro Santos, Jesús Lozano, María José Rodríguez, Ismael Montero-Fernández and Daniel Martín-Vertedor
Chemosensors 2023, 11(6), 342; https://doi.org/10.3390/chemosensors11060342 - 11 Jun 2023
Cited by 2 | Viewed by 1594
Abstract
Valencian paella is a world-famous dish that is originally from the Valencia Spanish region, in which rice is the basic ingredient along with others such as extra virgin olive oil, vegetables, seafood and/or meat. During the cooking process, the paella rice suffers a [...] Read more.
Valencian paella is a world-famous dish that is originally from the Valencia Spanish region, in which rice is the basic ingredient along with others such as extra virgin olive oil, vegetables, seafood and/or meat. During the cooking process, the paella rice suffers a loss of moisture and the socarrat is formed, being crunchy and brown in color. The objective of this work was to evaluate the aromas generated during the formation of socarrat in paella rice (P) by an electronic nose (E-nose), discriminating against the aromatic profile of white rice (WR), and validate it with sensory analysis and gas chromatography. The results of the sensory analysis showed a decrease in positive fruity and sweet aromas of some volatile compounds such as hexanal and nonanal, among others, and an increase in roasted aromas due to the appearance of furans and furanones compounds, which is probably associated with socarrat formation. The acrylamide content increased by 33.8–48.3% as the intensity of the thermal treatment rose. The higher value of acrylamide (179.5 ng g−1) was achieved in P. The E-nose was sensitive to changes in the aromatic profile, and the PCA analysis explained 85.7% and 91.6% of the variance for WR and P, respectively. Furthermore, a strong clustering in the thermal treatments was observed, which is related to the composition of volatile compounds. Full article
(This article belongs to the Collection Recent Advances in Multifunctional Sensing Technology for Gas Analysis)
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20 pages, 1476 KiB  
Review
New Trends in Uric Acid Electroanalysis
by Ligia Chelmea, Mihaela Badea, Ioan Scarneciu, Marius Alexandru Moga, Lorena Dima, Patrizia Restani, Cecilia Murdaca, Daniel Ciurescu and Laura Elena Gaman
Chemosensors 2023, 11(6), 341; https://doi.org/10.3390/chemosensors11060341 - 09 Jun 2023
Cited by 1 | Viewed by 1608
Abstract
Considering the increasing incidence of hyperuricemia and oxidative stress-related diseases, quantification of uric acid has become essential. Therefore, the evolution on sensing devices being favorable, these questions are more often addressed to the field of medical researchers. As for many metabolites, (bio)sensors provide [...] Read more.
Considering the increasing incidence of hyperuricemia and oxidative stress-related diseases, quantification of uric acid has become essential. Therefore, the evolution on sensing devices being favorable, these questions are more often addressed to the field of medical researchers. As for many metabolites, (bio)sensors provide a reliable method for screening and evaluation of uric acid status. Due to the numerous categories of (bio)sensors available, choosing the appropriate one is a challenge. This study reviews the scientific information concerning the most suitable (bio)sensors for quantification of uric acid, presenting a list of sensors from the last decade, categorized by configurations and materials. In addition, this review includes a comparison of sensors according to their interference behavior and sensitivity, offering an objective perspective for identifying devices that are suitable for clinical applications. Full article
(This article belongs to the Special Issue Electrochemical Sensors for Food Control, Environmental Analysis, and Diagnosis in Medicine)
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11 pages, 5240 KiB  
Article
A Simple Method to Fabricate the Highly Sensitive SERS Substrate by Femtosecond Laser-Based 3D Printer
by Woong Kim, Woochang Kim, Doyeon Bang, Jinsung Park and Wonseok Lee
Chemosensors 2023, 11(6), 340; https://doi.org/10.3390/chemosensors11060340 - 08 Jun 2023
Cited by 1 | Viewed by 1742
Abstract
Surface-enhanced Raman spectroscopy (SERS) is a potent technique for analyzing and detecting various targets, including toxic ions, pesticides, and biomarkers, at the single-molecule level. The efficiency of SERS techniques relies heavily on the underlying SERS substrate, which is primarily responsible for the strong [...] Read more.
Surface-enhanced Raman spectroscopy (SERS) is a potent technique for analyzing and detecting various targets, including toxic ions, pesticides, and biomarkers, at the single-molecule level. The efficiency of SERS techniques relies heavily on the underlying SERS substrate, which is primarily responsible for the strong induction of localized plasmon resonance on nanostructures. Noble metals such as gold and silver were commonly used to fabricate SERS substrates, leveraging the electromagnetic mechanism (EM) to enhance the Raman signal. However, chemically synthesized nanoparticle-based SERS substrates suffer from low uniformity and reproducibility. Furthermore, the high cost associated with noble metals makes most SERS substrates expensive to produce. In this study, we present a straightforward method for fabricating a highly uniform and reproducible SERS substrate using a femtosecond laser-based 3D printer. Notably, our method offers good cost competitiveness since it requires only a minimal amount of gold coating for the SERS signal. Moreover, the proposed method exhibits exceptional versatility in SERS analysis and detection, catering to numerous targets in the field. Full article
(This article belongs to the Special Issue Chemosensors in Biological Challenges)
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13 pages, 1508 KiB  
Article
An Electrochemical Sensor for Trimethoprim Based on a Magnetic Molecularly Imprinted Carbon Paste Electrode
by Peng Liu, Ruiying Zhang, Liyan Zheng and Qiue Cao
Chemosensors 2023, 11(6), 339; https://doi.org/10.3390/chemosensors11060339 - 08 Jun 2023
Cited by 4 | Viewed by 1245
Abstract
In order to achieve simple, rapid, and highly sensitive detection of trimethoprim (TMP), a magnetic molecularly imprinted carbon paste electrode (MCPE) was prepared by drop-coating magnetic molecularly imprinted polymer (MIP@Fe3O4@MWNTs) on the surface of reduction graphene oxide (rGO)/MCPE doped [...] Read more.
In order to achieve simple, rapid, and highly sensitive detection of trimethoprim (TMP), a magnetic molecularly imprinted carbon paste electrode (MCPE) was prepared by drop-coating magnetic molecularly imprinted polymer (MIP@Fe3O4@MWNTs) on the surface of reduction graphene oxide (rGO)/MCPE doped with Fe3O4@MWNTs. The introduction of multi-walled carbon nanotubes (MWNTs) and rGO served as dual signal-amplification materials, which can improve the response sensitivity of the sensor. In addition, the magnetic interaction between the substrate electrode and the molecularly imprinted material was beneficial to increasing the stability of the sensor. As expected, the electrochemical sensor not only showed sensitivity and selectivity for the detection of TMP, but it also possessed good stability. The detection range for TMP was 4.0 × 10−9~5.0 × 10−4 mol/L, and the detection limit was 1.2 × 10−9 mol/L. The response performance varied within 10% when the sensor was placed for more than 2 months and used more than 60 times. The spiked recoveries of TMP in environmental water samples, urine samples, and pharmaceuticals (drugs) were between 91% and 110%, and the relative standard deviation (RSD) was within 5%. Full article
(This article belongs to the Special Issue Nanoparticles in Chemical and Biological Sensing)
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14 pages, 3743 KiB  
Article
Laser-Induced Graphene on Optical Fibre: Towards Simple and Cost-Effective Electrochemical/Optical Lab-on-Fibre Bioplatforms
by Laura L. Ferreira, Rafael A. Ribeiro, António J. S. Fernandes, Florinda M. Costa, Carlos Marques and Nuno F. Santos
Chemosensors 2023, 11(6), 338; https://doi.org/10.3390/chemosensors11060338 - 07 Jun 2023
Cited by 4 | Viewed by 1333
Abstract
A 3D graphene foam made of interconnected multilayer graphene flakes was produced on optical fibres (OF) by laser-induced transformation of a polyimide (PI) film coated on the OF cladding. This material, known as laser-induced graphene (LIG), was explored in the electrochemical detection and [...] Read more.
A 3D graphene foam made of interconnected multilayer graphene flakes was produced on optical fibres (OF) by laser-induced transformation of a polyimide (PI) film coated on the OF cladding. This material, known as laser-induced graphene (LIG), was explored in the electrochemical detection and quantification of dopamine (DA) at physiologically relevant concentrations in the presence of the most relevant interfering molecules in biological fluids, ascorbic acid (AA) and uric acid (UA). The measured limit of detection is 100 nM, the linear range is 0.1 to 5.0 μM and a maximum sensitivity of 5.0 µA µM−1 cm−2 was obtained for LIG decorated with Pt nanoparticles (NPs). Moreover, immunity to AA and UA interference and to fouling was attained by decorating the LIG electrode with Pt NPs and coating it with Nafion. These figures of merit underline the potential of these sensors for the quantification of physiologically relevant concentrations of DA in biological fluids, paving the way for the development of hybrid electrochemical/optical sensing actuating platforms in a lab-on-fibre configuration, with relevant applications in biomedical engineering. The advantages of this hybrid arrangement include the possibility of in situ counterproofing, extended measuring ranges, photoelectrochemical detection and the probing of inaccessible places. This elegant approach can also provide a simple and cost-effective way to fabricate biomedical devices with extended functionality, such as medical optical probes with added electrochemical capabilities and optogenetics combined with local electrochemical detection, among others. Full article
(This article belongs to the Special Issue Low-Cost Chemo/Bio-Sensors Based on Nanomaterials)
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17 pages, 4399 KiB  
Article
Graphene-Based Electrodes for Monitoring of Estradiol
by Auwal M. Musa, Janice Kiely, Richard Luxton and Kevin C. Honeychurch
Chemosensors 2023, 11(6), 337; https://doi.org/10.3390/chemosensors11060337 - 06 Jun 2023
Viewed by 1464
Abstract
This study explores the potential use of graphene-based electrodes in the electrochemical determination of estradiol using amperometric techniques as a simple, enzyme-free approach. Graphene, a carbon-based nanomaterial, has been extensively investigated in materials science as a sensing material. Its remarkable properties, such as [...] Read more.
This study explores the potential use of graphene-based electrodes in the electrochemical determination of estradiol using amperometric techniques as a simple, enzyme-free approach. Graphene, a carbon-based nanomaterial, has been extensively investigated in materials science as a sensing material. Its remarkable properties, such as its high electron mobility and conductivity, robust mechanical characteristics, and good surface-to-volume ratio, have led to its adoption in numerous applications, including electrochemical sensing. Estradiol is a crucial sex hormone that affects metabolism and reproduction. However, excessive amounts may disrupt endocrine functions. Electrochemical sensors suffer from electrode fouling, leading to passivation that ultimately affects performance. We exploit the inherent properties of various types of graphene-based electrodes, including graphene screen-printed electrodes (GHSPE), electrochemically exfoliated graphene-modified electrodes (EEFGHSPE), and 3D graphene foam screen-printed electrodes (3D-GFSPE), for the amperometric studies. The electrochemical properties and structural characteristics of these sensors are evaluated using cyclic voltammetry and scanning electron microscopy. The analytical performance of these sensors is at an applied potential of +0.65 V (vs. Ag/AgCl) over the concentration range 0.83 to 4.98 μM estradiol. Sensitivities of 0.151 µAµM−1 cm−2, 0.429 µAµM−1 cm−2, and 0.273 µA µM−1 cm−2, with detection limits of 0.0041 µM, 0.097 µM, and 0.018 µM (S/N = 3), are found for GHPSPE, 3D-GFSPE and EEFGHSPE, respectively. The possibility of amperometrically determining the estradiol levels in a potable tap water sample are then investigated over the concentration range 0.83–4.98 µM. Full article
(This article belongs to the Special Issue Advances in Screen-Printed Electrode & Electrochemical Sensor Applications)
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13 pages, 2321 KiB  
Article
Ammonia Sensor Based on Co2+/SCN− Modified Core-Shell MCM-41 for Rapid Naked-Eye Colorimetric Detection
by Songtao Liu, Kaixin Wei, Fuqiang Cheng, Yongsheng Li and Min Xue
Chemosensors 2023, 11(6), 336; https://doi.org/10.3390/chemosensors11060336 - 06 Jun 2023
Cited by 1 | Viewed by 1108
Abstract
Mesoporous silica materials have been widely used as gas adsorbents due to their excellent adsorption ability, large specific surface area, simple preparation process, and convenient functionalization. In this study, a core–shell mesoporous material MCM-41@SiO2 was synthesized and functionalized by CoCl2, [...] Read more.
Mesoporous silica materials have been widely used as gas adsorbents due to their excellent adsorption ability, large specific surface area, simple preparation process, and convenient functionalization. In this study, a core–shell mesoporous material MCM-41@SiO2 was synthesized and functionalized by CoCl2, and subsequently KSCN, to prepare an ammonia adsorbent. The adsorbent was proved to possess high surface area, good sphericity, uniform size, good dispersibility, and high adsorption capability following DLS, SEM, TEM, and a static adsorption study. Moreover, the successful functionalization and thermal stability were confirmed by FT-IR, XPS, and TGA. The material was then used to fabricate a glass tube sensor for the rapid naked-eye detection of ammonia gas. The sensor showed good performance in terms of sensing speed, selectivity, accuracy, and reusability. Within 5 s, NH3 could be detected by the discoloration, and a wide NH3 concentration from 20 to 1000 ppm could be detected. It also showed a good linear relationship between discoloration length and ammonia concentration. A reversible color change from blue to yellow indicated the presence of NH3, which was attributed to the formation and disassembly of ammonia-containing complex [Co(NH3)6(NCS)2]. With fast adsorption, naked-eye sensing properties, and good selectivity, the sensor holds good promise for indoor NH3 sensing and other more complicated situations. Full article
(This article belongs to the Section Nanostructures for Chemical Sensing)
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24 pages, 3050 KiB  
Review
Micro-Magnetofluidic System for Rare Cell Analysis: From Principle to Translation
by Kangfu Chen and Zongjie Wang
Chemosensors 2023, 11(6), 335; https://doi.org/10.3390/chemosensors11060335 - 06 Jun 2023
Cited by 4 | Viewed by 1574
Abstract
Rare cells play essential roles in the initiation and progression of diseases and therefore their analysis is of great interest. The micro-magnetofluidic system is one of the emerging platforms that have been proposed for the rapid, sensitive, and cost-effective analysis of rare cells. [...] Read more.
Rare cells play essential roles in the initiation and progression of diseases and therefore their analysis is of great interest. The micro-magnetofluidic system is one of the emerging platforms that have been proposed for the rapid, sensitive, and cost-effective analysis of rare cells. Given its unprecedented throughput, micro-magnetofluidic systems have attracted substantial research interest in the last decade—multiple designs have been proposed, validated, and even advanced to the stage of clinical trials. This mini review aims to provide a timely summary of the relevant progress in the field thus far. We reviewed the concepts and realizations of micro-magnetofluidic devices based on the interaction between nanoparticles and on-chip micro-magnets. Their real-world applications in rare cell analysis were also highlighted and explained. In addition, we discussed the major challenges in the development and translation of micro-magnetofluidic into the clinic, including multi-marker capability and large-scale manufacturability. Full article
(This article belongs to the Special Issue Electrochemical Biosensors and Bioassays Based on Nanomaterials)
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24 pages, 11289 KiB  
Review
N-Doped Graphene and Its Derivatives as Resistive Gas Sensors: An Overview
by Ali Mirzaei, Somalapura Prakasha Bharath, Jin-Young Kim, Krishna K. Pawar, Hyoun Woo Kim and Sang Sub Kim
Chemosensors 2023, 11(6), 334; https://doi.org/10.3390/chemosensors11060334 - 05 Jun 2023
Cited by 7 | Viewed by 1573
Abstract
Today, resistance gas sensors which are mainly realized from metal oxides are among the most used sensing devices. However, generally, their sensing temperature is high and other materials with a lower operating temperature can be an alternative to them. Graphene and its derivatives [...] Read more.
Today, resistance gas sensors which are mainly realized from metal oxides are among the most used sensing devices. However, generally, their sensing temperature is high and other materials with a lower operating temperature can be an alternative to them. Graphene and its derivatives with a 2D structure are among the most encouraging materials for gas-sensing purposes, because a 2D lattice with high surface area can maximize the interaction between the surface and gas, and a small variation in the carrier concentration of graphene can cause a notable modulation of electrical conductivity in graphene. However, they show weak sensing performance in pristine form. Hence, doping, and in particular N doping, can be one of the most promising strategies to enhance the gas-sensing features of graphene-based sensors. Herein, we discuss the gas-sensing properties of N-doped graphene and its derivatives. N doping can induce a band gap inside of graphene, generate defects, and enhance the conductivity of graphene, all factors which are beneficial for sensing studies. Additionally, not only is experimental research reviewed in this review paper, but theoretical works about N-doped graphene are also discussed. Full article
(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)
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19 pages, 11372 KiB  
Review
Recent Progress in Fluorescent Probes for the Detection and Research of Hydrogen Sulfide in Cells
by Weier Liang, Yong Zhang, Shaoqing Xiong and Dongdong Su
Chemosensors 2023, 11(6), 333; https://doi.org/10.3390/chemosensors11060333 - 04 Jun 2023
Cited by 1 | Viewed by 1857
Abstract
Hydrogen sulfide (H2S) is a gaseous signaling molecule that plays an important role in regulating various physiological activities in biological systems. As the fundamental structural and functional unit of organisms, cells are closely related to the homeostasis of their internal environment. [...] Read more.
Hydrogen sulfide (H2S) is a gaseous signaling molecule that plays an important role in regulating various physiological activities in biological systems. As the fundamental structural and functional unit of organisms, cells are closely related to the homeostasis of their internal environment. The levels of H2S in different organelles maintain a certain balance, and any disruption of this balance will lead to various functional abnormalities that affect the health of organisms. Fluorescent imaging technology provides unique merits, such as simplicity, non-invasiveness, and real-time monitoring, and has become a powerful approach for the detection of molecules in biological systems. Based on the special physicochemical properties of H2S, numerous H2S-specific fluorogenic probes have been designed with different recognition mechanisms that enable rapid and accurate detection of H2S in cells. Therefore, this review briefly illustrates the design strategies, response principles, and biological applications of H2S-specific fluorescent probes and aims to provide relevant researchers with insight for future research. Full article
(This article belongs to the Special Issue A Theme Issue in Honor of Dr. Richard Horobin—Cell or Organelle Selective Fluorescent Probes: Their Design, Mechanism, Modeling and Application)
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17 pages, 7443 KiB  
Article
A ‘Turn-On’ Carbamazepine Sensing Using a Luminescent SiO2/-(CH2)3NH2/-C6H5 + Rh6G System
by Halyna Yankovych, Erika Dutková, Viktoriia Kyshkarova, Miroslava Vaclavikova and Inna Melnyk
Chemosensors 2023, 11(6), 332; https://doi.org/10.3390/chemosensors11060332 - 04 Jun 2023
Cited by 1 | Viewed by 1016
Abstract
Carbamazepine is a crucial medication used to treat nervous system disorders, and its low level of absorption in the human body suggests that a significant amount of it may be present in sewage water. Consequently, this pioneering research deals with the synthesis and [...] Read more.
Carbamazepine is a crucial medication used to treat nervous system disorders, and its low level of absorption in the human body suggests that a significant amount of it may be present in sewage water. Consequently, this pioneering research deals with the synthesis and application of a luminescent sensor based on rhodamine 6 G-modified bifunctional silica particles for the determination of carbamazepine. The sensing material was fabricated in one step by the sol–gel technique and the dye was adsorbed onto the surface from an alcohol solution. The composition, morphology and size of functionalized silica particles were determined by physico-chemical methods. The material’s features provide the possibility of its application as a sensing material for carbamazepine determination at a variety of concentrations. The sensor possesses a linear response towards carbamazepine in the concentration range of 0.8–200.0 μM with a limit of detection (LOD) of 17.9 μM and a limit of quantification (LOQ) of 59.7 μM and has demonstrated reliable quantification over a wide range of concentrations, from therapeutic to high fatal concentrations. Additionally, the sensing mechanism has been proposed, which involves the formation of hydrogen bonding between carbamazepine and Rhodamine 6G immobilized bifunctional silica particles. Full article
(This article belongs to the Special Issue Smart Chemosensors for Biosensing and Bioimaging)
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15 pages, 3239 KiB  
Article
Development of Sensitive Electrochemical Sensor Based on Chitosan/MWCNTs-AuPtPd Nanocomposites for Detection of Bisphenol A
by En Han, Yingying Pan, Lei Li, Yuan Liu, Yuan Gu and Jianrong Cai
Chemosensors 2023, 11(6), 331; https://doi.org/10.3390/chemosensors11060331 - 03 Jun 2023
Cited by 1 | Viewed by 1231
Abstract
An electrochemical sensor based on AuPtPd trimetallic nanoparticles functionalized multi-walled carbon nanotubes coupled with chitosan modified glassy carbon electrode (GCE/CS/MWCNTs-AuPtPd) was proposed for the rapid detection of bisphenol A (BPA). AuPtPd trimetallic nanoparticles were first assembled on MWCNTs to obtain MWCNTs-AuPtPd nanocomposite. Then, [...] Read more.
An electrochemical sensor based on AuPtPd trimetallic nanoparticles functionalized multi-walled carbon nanotubes coupled with chitosan modified glassy carbon electrode (GCE/CS/MWCNTs-AuPtPd) was proposed for the rapid detection of bisphenol A (BPA). AuPtPd trimetallic nanoparticles were first assembled on MWCNTs to obtain MWCNTs-AuPtPd nanocomposite. Then, the MWCNTs-AuPtPd was further dispersed on the chitosan-modified electrode surface to fabricate the GCE/CS/MWCNTs-AuPtPd sensor. Due to the superior catalytic properties of MWCNTs-AuPtPd and the good film formation of chitosan, the constructed sensor displayed good performances for BPA detection. The structural morphology of CS/MWCNTs-AuPtPd was characterized in many ways, such as SEM, TEM and UV-vis. The designed sensor showed a linear relationship in concentration range from 0.05 to 100 µM for BPA detecting, and the detection limit was 1.4 nM. The GCE/CS/MWCNTs-AuPtPd was further used to realize the detection of BPA in food samples, and the recovery was between 94.4% and 103.6%. Those results reflected that the electrochemical sensor designed by CS/MWCNTs-AuPtPd nanocomposites was available, which could be used for the monitoring of food safety. Full article
(This article belongs to the Section Nanostructures for Chemical Sensing)
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14 pages, 3848 KiB  
Article
Gold Nanocluster-Based Fluorescent Sensor Array for Antibiotic Sensing and Identification
by Mengjiao Mo, Haoyi Yuan, Jingyu Zhang, Jian Wang, Ying Liu, Juanjuan Peng and Lingzhi Zhao
Chemosensors 2023, 11(6), 330; https://doi.org/10.3390/chemosensors11060330 - 03 Jun 2023
Cited by 4 | Viewed by 1165
Abstract
Antibiotic contamination has become a serious global problem due to abuse and misuse. Therefore, it is important to develop an efficient detection method to monitor the rational use of antibiotics. In this study, fluorescent gold nanoclusters with 11-mercaptoundecanoic acid as ligands (MUA-AuNCs) were [...] Read more.
Antibiotic contamination has become a serious global problem due to abuse and misuse. Therefore, it is important to develop an efficient detection method to monitor the rational use of antibiotics. In this study, fluorescent gold nanoclusters with 11-mercaptoundecanoic acid as ligands (MUA-AuNCs) were synthesized by a one-step method firstly. Rare earth ions (Re3+) can enhance the fluorescence of MUA-AuNCs through inducing the aggregation of MUA-AuNCs, but antibiotics decrease the fluorescence of the Re3+-MUA-AuNCs to different degrees through coordination with Re3+ and competitive absorption with AuNCs. Therefore, a sensor array was obtained on the basis of the above mechanism, which can detect and discriminate six different antibiotics with a detection range from 40 to 300 μM. A 100% correct classification was achieved. The fluorescent sensor array showed high selectivity for tetracycline antibiotics and good anti-interference performance was demonstrated. Combined with pattern recognition methods, the proposed sensor array can be used for the discrimination of different antibiotics and binary antibiotic mixtures. Furthermore, the excellent performance of this sensor array in quantitation and blind sample recognition further validates its potential for practical applications. Full article
(This article belongs to the Special Issue A Theme Issue in Honor of Dr. Richard Horobin—Cell or Organelle Selective Fluorescent Probes: Their Design, Mechanism, Modeling and Application)
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20 pages, 5761 KiB  
Article
A Sensor for Electrochemical pH Monitoring Based on Laser-Induced Graphene Modified with Polyfolate
by Vytautas Žutautas, Romualdas Trusovas, Aivaras Sartanavičius, Karolis Ratautas, Algirdas Selskis and Rasa Pauliukaite
Chemosensors 2023, 11(6), 329; https://doi.org/10.3390/chemosensors11060329 - 02 Jun 2023
Cited by 2 | Viewed by 1352
Abstract
A laser-induced graphene (LIG) modified with chitosan (Chit) and conducting polymer polyfolate (PFA) was used as a base to develop a flat and flexible pH sensor. LIGs were formed using two different irradiation wavelengths of 355 nm and 532 nm. Depending on the [...] Read more.
A laser-induced graphene (LIG) modified with chitosan (Chit) and conducting polymer polyfolate (PFA) was used as a base to develop a flat and flexible pH sensor. LIGs were formed using two different irradiation wavelengths of 355 nm and 532 nm. Depending on the wavelengths, the obtained electrodes were named LIG355 and LIG532. Microscopic imaging revealed that the bare LIG electrode surface had rough structures after laser treatment giving hydrophilic properties, and that PFA forms fibre-like structures on Chit coated LIG. Electrochemical investigation with the redox probe demonstrated that diffusion is a limiting process at the bare and modified LIG electrodes. A capacitive behaviour was observed from electrochemical impedance spectra at bare electrodes, showing a rather rough interface at LIG355 but a microporous one at LIG532. The developed flat and flexible electrode was sensitive to pH in the region from 6.0 to 9.0. In the studied pH range, the sensitivity was 27.86 ± 0.81 for PFA/Chit/LIG355 and 30.32 ± 0.50 mV/pH for PFA/Chit/LIG532 with moderate stability for a period of more than two months. Full article
(This article belongs to the Section Applied Chemical Sensors)
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11 pages, 2507 KiB  
Article
Plasma-Sputtered Growth of Ni-Pd Bimetallic Nanoparticles on Carbon Nanotubes for Toluene Sensing
by Selene Acosta, Juan Casanova-Chafer, Eduard Llobet, Axel Hemberg, Mildred Quintana and Carla Bittencourt
Chemosensors 2023, 11(6), 328; https://doi.org/10.3390/chemosensors11060328 - 02 Jun 2023
Viewed by 1214
Abstract
The properties of carbon nanotubes (CNTs) can be effectively tailored by decorating their surface with metal nanoparticles. For the decoration, first plasma functionalization is used to add oxygen chemical groups to the CNTs surface. Afterwards, the Ox-CNTs are decorated with Ni-Pd bimetallic nanoparticles [...] Read more.
The properties of carbon nanotubes (CNTs) can be effectively tailored by decorating their surface with metal nanoparticles. For the decoration, first plasma functionalization is used to add oxygen chemical groups to the CNTs surface. Afterwards, the Ox-CNTs are decorated with Ni-Pd bimetallic nanoparticles using plasma sputtering deposition, a clean, fast, and environmentally friendly functionalization method. The grafted oxygen groups serve as nucleation sites for the growth of the bimetallic nanoparticles. Finally, the Ni-Pd nanoparticle-decorated CNTs are assessed as a sensing layer for the detection of toluene. Full article
(This article belongs to the Special Issue Chemical Sensors for Bio-Medical and Environmental Applications)
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13 pages, 1866 KiB  
Article
Spray-On Colorimetric Sensors for Distinguishing the Presence of Lead Ions
by Priyanka Shiveshwarkar and Justyn Jaworski
Chemosensors 2023, 11(6), 327; https://doi.org/10.3390/chemosensors11060327 - 02 Jun 2023
Cited by 1 | Viewed by 1446
Abstract
Sprayable stimuli-responsive material coatings represent a new class of detection system which can be quickly implemented to transform a surface into a color-responsive sensor. In this work, we describe a dipicolylamine-terminated diacetylene-containing amphiphile formulation for spray coating on to a simple paper substrate [...] Read more.
Sprayable stimuli-responsive material coatings represent a new class of detection system which can be quickly implemented to transform a surface into a color-responsive sensor. In this work, we describe a dipicolylamine-terminated diacetylene-containing amphiphile formulation for spray coating on to a simple paper substrate to yield disposable test strips that can be used to detect the presence of lead ions in solution. We find the response to be very selective to only lead ions and that the sensitivity can be modulated by altering the UV curing time after spraying. Sensitive detection to at least 0.1 mM revealed a clear color change from a blue to red phase. This represents the first demonstration of a spray-on sensor system capable of detection of lead ions in solution. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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16 pages, 3265 KiB  
Article
Au Nanoparticles on 4-Thiophenol-Electrodeposited Carbon Surfaces for the Simultaneous Detection of 8-Hydroxyguanine and Guanine
by Niloufar Soltani, Qusai Hassan, Meissam Noroozifar and Kagan Kerman
Chemosensors 2023, 11(6), 326; https://doi.org/10.3390/chemosensors11060326 - 02 Jun 2023
Viewed by 1152
Abstract
In this proof-of-concept study, gold nanoparticles (AuNPs) were immobilized on glassy carbon electrode (GCE) surfaces using a surface-anchored diazonium salt of 4-aminothiophenol (GCE-Ph-S-AuNPs). X-ray photoelectron spectroscopy (XPS) studies confirmed the attachment of the AuNPs via 4-thiophenol onto the surface of the modified electrode. [...] Read more.
In this proof-of-concept study, gold nanoparticles (AuNPs) were immobilized on glassy carbon electrode (GCE) surfaces using a surface-anchored diazonium salt of 4-aminothiophenol (GCE-Ph-S-AuNPs). X-ray photoelectron spectroscopy (XPS) studies confirmed the attachment of the AuNPs via 4-thiophenol onto the surface of the modified electrode. Differential pulse voltammetry (DPV) was performed for the simultaneous determination of guanine (G) and 8-hydroxyguanine (8-OH-G). The calibration curves were linear up to 140 µM and 60 µM with a limit of detection of 0.02 µM and 0.021 µM for G and 8-OH-G, respectively. Moreover, chronoamperometric studies were carried out for the determination of diffusion coefficients of 8-OH-G and G. The GCE-Ph-S-AuNPs were also applied in genomic DNA-spiked samples for the determination of G and 8-OH-G with recovery rates between 98.5% and 103.3%. The novel electrochemical surface provided a potential platform for the sensitive detection of 8-OH-G related to oxidative stress-induced DNA damage in clinical studies. Full article
(This article belongs to the Collection Electrochemical Biosensors for Medical Diagnosis)
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15 pages, 3849 KiB  
Article
High Sensitivity Low-Temperature Hydrogen Sensors Based on SnO2/κ(ε)-Ga2O3:Sn Heterostructure
by Aleksei Almaev, Nikita Yakovlev, Viktor Kopyev, Vladimir Nikolaev, Pavel Butenko, Jinxiang Deng, Aleksei Pechnikov, Petr Korusenko, Aleksandra Koroleva and Evgeniy Zhizhin
Chemosensors 2023, 11(6), 325; https://doi.org/10.3390/chemosensors11060325 - 01 Jun 2023
Cited by 4 | Viewed by 1411
Abstract
The structural and gas-sensitive properties of n-N SnO2/κ(ε)-Ga2O3:Sn heterostructures were investigated in detail for the first time. The κ(ε)-Ga2O3:Sn and SnO2 films were grown by the halide vapor phase epitaxy [...] Read more.
The structural and gas-sensitive properties of n-N SnO2/κ(ε)-Ga2O3:Sn heterostructures were investigated in detail for the first time. The κ(ε)-Ga2O3:Sn and SnO2 films were grown by the halide vapor phase epitaxy and the high-frequency magnetron sputtering, respectively. The gas sensor response and speed of operation of the structures under H2 exposure exceeded the corresponding values of single κ(ε)-Ga2O3:Sn and SnO2 films within the temperature range of 25–175 °C. Meanwhile, the investigated heterostructures demonstrated a low response to CO, NH3, and CH4 gases and a high response to NO2, even at low concentrations of 100 ppm. The current responses of the SnO2/κ(ε)-Ga2O3:Sn structure to 104 ppm of H2 and 100 ppm of NO2 were 30–47 arb. un. and 3.7 arb. un., correspondingly, at a temperature of 125 °C. The increase in the sensitivity of heterostructures at low temperatures is explained by a rise of the electron concentration and a change of a microrelief of the SnO2 film surface when depositing on κ(ε)-Ga2O3:Sn. The SnO2/κ(ε)-Ga2O3:Sn heterostructures, having high gas sensitivity over a wide operating temperature range, can find application in various fields. Full article
(This article belongs to the Collection Sustainable Metal Oxide Materials for Sensing Applications)
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13 pages, 1691 KiB  
Article
Dilute-and-Shoot-Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry for Pteridine Profiling in Human Urine and Its Association with Different Pathologies
by Claudia Giménez-Campillo, Marta Pastor-Belda, Natalia Arroyo-Manzanares, Natalia Campillo, Blanca del Val Oliver, José Zarauz-García, Luis Sáenz and Pilar Viñas
Chemosensors 2023, 11(6), 324; https://doi.org/10.3390/chemosensors11060324 - 01 Jun 2023
Viewed by 1320
Abstract
Pteridines are a group of compounds synthesised by many living organisms that are involved in the metabolism of many cofactors and vitamins. Their concentration in biological fluids may be altered by various pathologies such as cancer or inflammatory bowel disease, urine being the [...] Read more.
Pteridines are a group of compounds synthesised by many living organisms that are involved in the metabolism of many cofactors and vitamins. Their concentration in biological fluids may be altered by various pathologies such as cancer or inflammatory bowel disease, urine being the main route of excretion. In this study, three lumazines and ten pterins were analysed in their native oxidation state using high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Their high concentration in urine samples and their good ionisation behaviour allow the use of the dilute-and-shoot method by simple filtration of the urine prior to chromatographic analysis. The final method offers excellent linearity, sensitivity and precision parameters, and a total of 135 urine samples were analysed from patients with some relevant information such as faecal calprotectin (FCP) levels, common diseases such as diabetes, hypertension and dyslipidaemia and immunological diseases such as inflammatory bowel disease (IBD). The pteridine profile was related to FCP levels without showing any correlation. In addition, pteridine levels were compared between healthy subjects and IBD, diabetic, hypertensive and dyslipidaemic patients, and significant differences were found between the two groups for some of the pteridines. Full article
(This article belongs to the Special Issue Diversity in Sensing Applications of Porphyrin or Other Macrocyclic Compound-Based Materials)
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13 pages, 2432 KiB  
Article
Polymeric Composite including Magnetite Nanoparticles for Hydrogen Peroxide Detection
by Maria Roniele Felix Oliveira, Pilar Herrasti, Roselayne Ferro Furtado, Airis Maria Araújo Melo and Carlucio Roberto Alves
Chemosensors 2023, 11(6), 323; https://doi.org/10.3390/chemosensors11060323 - 01 Jun 2023
Cited by 2 | Viewed by 1124
Abstract
The combination of a biopolymer and a conductive polymer can produce new materials with improved physico-chemical and morphological properties that enhance their use as sensors. Magnetite nanoparticles (MN) can be further introduced to these new matrices to improve the analytical performance. This study [...] Read more.
The combination of a biopolymer and a conductive polymer can produce new materials with improved physico-chemical and morphological properties that enhance their use as sensors. Magnetite nanoparticles (MN) can be further introduced to these new matrices to improve the analytical performance. This study aimed to evaluate the electrocatalytic response of nanocomposites formed by the introduction of MN to polypyrrole (PPy) doped in the presence of cashew gum polysaccharide (CGP) and in the presence of carboxymethylated cashew gum polysaccharide (CCGP). Characterization of the nanocomposites was carried out via transmission electron microscopy (TEM) and infrared spectroscopy (FTIR) and showed that the absorption band of the blend was shifted to a higher frequency in the nanocomposites, indicating the intermolecular interaction between the blend and nanoparticles. The electrocatalytic performance of the nanocomposites was evaluated by applying a constant potential of −0.7 V with successive additions of H2O2 (1 mmol L−1) in 10 mmol L−1 phosphate buffer under agitation at pH 7.5. The nanocomposite formed by the introduction of MN to polypyrrole doped with cashew gum polysaccharide (PPy(cgp)–MN) displayed excellent electrocatalytic surface properties, with high H2O2 specificity, a linear response (R2 = 0.99), high sensitivity (0.28 µmol L−1), and a low H2O2 detection limit (0.072 mmol L−1). Full article
(This article belongs to the Special Issue Electrochemical Biosensors and Bioassays Based on Nanomaterials)
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