Chemosensors

18 pages, 3807 KiB

Open AccessArticle

Dummy Template Molecularly Imprinted Polymers for Electrochemical Detection of Cardiac Troponin I: A Combined Computational and Experimental Approach

by Mohammad Sadegh Sadeghi Googheri, Davide Campagnol, Paolo Ugo, Samira Hozhabr Araghi and Najmeh Karimian

Chemosensors 2025, 13(1), 26; https://doi.org/10.3390/chemosensors13010026 - 20 Jan 2025

Viewed by 718

Abstract

Cardiac troponin I (cTnI) is a crucial biomarker for the early detection of acute myocardial infarction (AMI), playing a significant role in cardiac health assessment. Molecularly imprinted polymers (MIPs) are valued for their stability, ease of fabrication, reusability, and selectivity. However, using the [...] Read more.

Cardiac troponin I (cTnI) is a crucial biomarker for the early detection of acute myocardial infarction (AMI), playing a significant role in cardiac health assessment. Molecularly imprinted polymers (MIPs) are valued for their stability, ease of fabrication, reusability, and selectivity. However, using the analyte as a template can be costly, especially if the analyte is expensive. In such cases, a dummy template (DT) with similar chemico-physical properties can be useful. This study aimed to design a DT-MIP for cTnI detection using cytochrome c (Cyt c) as the template, combining computational and experimental approaches. Molecular docking identified binding sites on Cyt c and cTnI for poly(o-phenylenediamine) (5PoPD) pentamers. Interactions and binding energies were examined using all-atom molecular dynamics (MDs) simulations and structural interaction fingerprint (SIFt) calculations. A DT-MIP-modified electrode for cTnI detection was prepared by electropolymerizing o-PD in the presence of Cyt c as a dummy template. Electrochemical techniques monitored the electropolymerization, template removal, and binding of the target analyte. The experimental results showed that the DT-MIPs exhibited a high binding affinity for cTnI, consistent with the binding energies observed in MD simulations. The satisfactory correlation between experimental and computational results validated our model-based approach for the rational design of dummy template molecularly imprinted polymers. Full article

(This article belongs to the Special Issue Recent Advances in Electrode Materials for Electrochemical Sensing)

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32 pages, 7458 KiB

Open AccessArticle

Long-Term Evaluation of Mid-Cost Optical Particle Counters for PM2.5 Monitoring in an Underground Subway Station: Insights from a 15-Month Study

by Trieu-Vuong Dinh, Byeong-Gyu Park, Sang-Woo Lee, In-Young Choi, Da-Hyun Baek and Jo-Chun Kim

Chemosensors 2025, 13(1), 25; https://doi.org/10.3390/chemosensors13010025 - 20 Jan 2025

Viewed by 527

Abstract

A beta-ray attenuation monitor (BAM) is preferred as a reference instrument for monitoring particulate matter in the air due to its accuracy. However, BAM cannot be used in large numbers for spatial distribution monitoring because of its high investment cost. Thus, a mid-cost [...] Read more.

A beta-ray attenuation monitor (BAM) is preferred as a reference instrument for monitoring particulate matter in the air due to its accuracy. However, BAM cannot be used in large numbers for spatial distribution monitoring because of its high investment cost. Thus, a mid-cost optical particle counter (OPC) is an alternative solution for widespread use. However, its long-term performance with respect to various monitoring environments should be taken into account. In this study, six mid-cost OPCs were used to measure PM_2.5 concentrations at an underground subway station and compared with a reference BAM over 15 months. OPCs were placed in the waiting space and platforms to compare PM_2.5 concentrations and determine PM_2.5/PM₁₀ ratios. The reference BAM was installed on the platform. Error analysis revealed a significant discrepancy, with normalized errors exceeding 30%, between the 1-h average PM_2.5 concentrations recorded by the BAM and OPCs at the same location. In contrast, the 24-h average PM_2.5 concentrations measured by the BAM and OPCs at the same location showed similar patterns, with stronger correlations (r² = 0.80–0.93) compared to the 1-h averages (r² = 0.63–0.83). The normalized errors for the 24-h averages ranged from 13.9% to 21.2%, depending on seasonal variations. These findings suggest that OPCs can effectively monitor 24-h average PM_2.5 concentrations in an underground subway station over a year without additional calibration, making them a cost-effective option. In addition, 1-h average PM_2.5 concentrations varied across different sampling spaces and were influenced by PM_2.5/PM₁₀ ratios. Hence, when measuring the 1-h average mass concentration of PM_2.5, it is essential to consider PM characteristics and seasons. Full article

(This article belongs to the Section Analytical Methods, Instrumentation and Miniaturization)

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18 pages, 3529 KiB

Open AccessArticle

Intelligent Electrochemical Sensing: A New Frontier in On-the-Fly Coffee Quality Assessment

by Simone Grasso, Maria Vittoria Di Loreto, Alessandro Zompanti, Davide Ciarrocchi, Laura De Gara, Giorgio Pennazza, Luca Vollero and Marco Santonico

Chemosensors 2025, 13(1), 24; https://doi.org/10.3390/chemosensors13010024 - 18 Jan 2025

Viewed by 610

Abstract

Quality control is mandatory in the food industry and chemical sensors play a crucial role in this field. Coffee is one of the most consumed and commercialized food products globally, and its quality is of the utmost importance. Many scientific papers have analyzed [...] Read more.

Quality control is mandatory in the food industry and chemical sensors play a crucial role in this field. Coffee is one of the most consumed and commercialized food products globally, and its quality is of the utmost importance. Many scientific papers have analyzed coffee quality using different approaches, such as analytical and sensor analyses, which, despite their good performance, are limited to structured lab implementation. This study aims to evaluate the capability of a smart electrochemical sensor to discriminate among different beverages prepared using coffee beans with different moisture content (0%, 2%, >4%) and ground in three sizes (fine, medium and coarse). These parameters reflect real scenarios where coffee is produced and its quality influenced. The possibility of optimizing coffee quality in real time by tuning these parameters could open the way to intelligent coffee machines. A specific experimental setup has been designed, and the data has been analyzed using machine learning techniques. The results obtained from Principal Component Analysis (PCA) and Partial Least Square Discriminant Analysis (PLS-DA) show the sensor’s capability to distinguish between samples of different quality, with a percentage of correct classification of 86.6%. This performance underscores the potential benefits of this sensor for coffee quality assessment, enabling time and resource savings, while facilitating the development of analytical methods based on smart electrochemical sensors. Full article

(This article belongs to the Special Issue Electrochemical Sensor for Food Analysis)

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16 pages, 1090 KiB

Open AccessArticle

Effectiveness of an E-Nose Based on Metal Oxide Semiconductor Sensors for Coffee Quality Assessment

by Yhan S. Mutz, Samara Mafra Maroum, Leticia L. G. Tessaro, Natália de Oliveira Souza, Mikaela Martins de Bem, Loyane Silvestre Alves, Luisa Pereira Figueiredo, Denes K. A. do Rosario, Patricia C. Bernardes and Cleiton Antônio Nunes

Chemosensors 2025, 13(1), 23; https://doi.org/10.3390/chemosensors13010023 - 18 Jan 2025

Viewed by 599

Abstract

Coffee quality, which ultimately is reflected in the beverage aroma, relies on several aspects requiring multiple approaches to check it, which can be expensive and/or time-consuming. Therefore, this study aimed to develop and calibrate an electronic nose (e-nose) coupled with chemometrics to approach [...] Read more.

Coffee quality, which ultimately is reflected in the beverage aroma, relies on several aspects requiring multiple approaches to check it, which can be expensive and/or time-consuming. Therefore, this study aimed to develop and calibrate an electronic nose (e-nose) coupled with chemometrics to approach coffee-related quality tasks. Twelve different metal oxide sensors were employed in the e-nose construction. The tasks were (i) the separation of Coffea arabica and Coffea canephora species, (ii) the distinction between roasting profiles (light, medium, and dark), and (iii) the separation of expired and non-expired coffees. Exploratory analysis with principal component analysis (PCA) pointed to a fair grouping of the tested samples according to their specification, indicating the potential of the volatiles in grouping the samples. Moreover, a supervised classification employing soft independent modeling of class analogies (SIMCA), partial least squares discriminant analysis (PLS-DA), and least squares support vector machine (LS-SVM) led to great results with accuracy above 90% for every task. The performance of each model varies with the specific task, except for the LS-SVM models, which presented a perfect classification for all tasks. Therefore, combining the e-nose with distinct classification models could be used for multiple-purpose classification tasks for producers as a low-cost, rapid, and effective alternative for quality assurance. Full article

(This article belongs to the Special Issue Sensors for Food Testing, Environmental Analysis, and Medical Diagnostics)

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16 pages, 3458 KiB

Open AccessArticle

Influence of Sample Preparation on SERS Signal

by Isabela Bianchi-Carvalho, Marcelo José dos Santos Oliveira, Cibely Silva Martin, Santiago Sánchez-Cortés and Carlos José Leopoldo Constantino

Chemosensors 2025, 13(1), 22; https://doi.org/10.3390/chemosensors13010022 - 18 Jan 2025

Viewed by 363

Abstract

Carbendazim (MBC), a commonly used fungicide from the benzimidazole group, was applied in this study as a probe molecule to understand the influence of sample preparation on the SERS (surface-enhanced Raman scattering) signal. We applied the external standard method (ESM), preparing fresh Ag [...] Read more.

Carbendazim (MBC), a commonly used fungicide from the benzimidazole group, was applied in this study as a probe molecule to understand the influence of sample preparation on the SERS (surface-enhanced Raman scattering) signal. We applied the external standard method (ESM), preparing fresh Ag colloid samples (reduced by hydroxylamine) for each concentration and measuring with and without potassium nitrate (KNO₃) as an aggregation-inducing salt. The impact of sample dilution before or after the addition of the salt to the Ag colloid was also explored. SERS signals were correlated with Ag colloid aggregation observed via transmission electron microscopy (TEM), UV-Vis extinction, dynamic light scattering (DLS), and zeta potential, examining diffusion-limited cluster aggregation (DLCA) and reaction-limited cluster aggregation (RLCA) mechanisms. The optimal results were achieved without KNO₃, with more compact aggregates at lower concentrations and more branched ones at higher concentrations. Dilution of the Ag colloid before salt addition enabled lower detection limits than without any dilution. No SERS signal was observed when the salt was added before dilution. These findings emphasize that a consistent relationship between aggregate morphology and the SERS signal cannot be generalized across analytes. Analyte-specific properties play a crucial role in determining optimal aggregation conditions for SERS analysis. Full article

(This article belongs to the Special Issue Raman and Surface-Enhanced Raman Scattering Techniques in Analytical and Biomedical Fields)

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13 pages, 2197 KiB

Open AccessArticle

UV Hyperspectral Imaging and Chemometrics for Honeydew Detection: Enhancing Cotton Fiber Quality

by Mohammad Al Ktash, Mona Knoblich, Frank Wackenhut and Marc Brecht

Chemosensors 2025, 13(1), 21; https://doi.org/10.3390/chemosensors13010021 - 17 Jan 2025

Viewed by 468

Abstract

Cotton, the most widely produced natural fiber, is integral to the textile industry and sustains the livelihoods of millions worldwide. However, its quality is frequently compromised by contamination, particularly from honeydew, a substance secreted by insects that leads to the formation of sticky [...] Read more.

Cotton, the most widely produced natural fiber, is integral to the textile industry and sustains the livelihoods of millions worldwide. However, its quality is frequently compromised by contamination, particularly from honeydew, a substance secreted by insects that leads to the formation of sticky fibers, thereby impeding textile processing. This study investigates ultraviolet (UV) hyperspectral imaging (230–380 nm) combined with multivariate data analysis to detect and quantify honeydew contaminations in real cotton samples. Reference cotton samples were sprayed multiple times with honey solutions to replicate the natural composition of honeydew. Comparisons were made with an alternative method where samples were soaked in sugar solutions of varying concentrations. Principal component analysis (PCA) and quadratic discriminant analysis (QDA) effectively differentiated and classified samples based on honey spraying times. Additionally, partial least squares regression (PLS-R) was utilized to predict the honeydew content for each pixel in hyperspectral images, achieving a cross-validation coefficient of determination R² = 0.75 and root mean square error of RMSE = 0.8 for the honey model. By employing a realistic spraying method that closely mimics natural contamination, this study refines sample preparation techniques for improved evaluation of honeydew levels. In conclusion, the integration of hyperspectral imaging with multivariate analysis represents a robust, non-destructive, and rapid approach for real-time detection of honeydew contamination in cotton, offering significant potential for industrial applications. Full article

(This article belongs to the Special Issue Green Analytical Chemistry: Current Trends and Future Developments)

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14 pages, 2938 KiB

Open AccessArticle

QD/SnO₂ Photoactivated Chemoresistive Sensor for Selective Detection of Primary Alcohols at Room Temperature

by Maria Yu. Skrypnik, Vadim B. Platonov, Daria A. Kurtina, Oleg G. Sinyashin, Marina N. Rumyantseva and Roman B. Vasiliev

Chemosensors 2025, 13(1), 20; https://doi.org/10.3390/chemosensors13010020 - 16 Jan 2025

Viewed by 533

Abstract

Sensors based on nanocomposites of quantum dots (QDs) and wide-gap metal oxides are of exceptional interest for photoactivated detection of toxic and pollutant gases without thermal heating. However, the class of detecting gases has been limited almost exclusively to oxidizing gases like NO [...] Read more.

Sensors based on nanocomposites of quantum dots (QDs) and wide-gap metal oxides are of exceptional interest for photoactivated detection of toxic and pollutant gases without thermal heating. However, the class of detecting gases has been limited almost exclusively to oxidizing gases like NO₂. Here, we designed a photoactivated sensor for the selective detection of primary alcohols at room temperature using CdSe quantum dots coupled to a wide-gap SnO₂ semiconductor matrix. Our concept of the sensor operations is based on the photochemical reaction of primary alcohols via photoactivated QD-SnO₂ charge transfer and does not involve chemisorbed oxygen, which is traditional for the operation of metal oxide sensors. We demonstrated an efficient sensor response to C₁–C₄ primary alcohols of ppm concentration under photoexcitation with a yellow LED in the absence of a signal from other volatile organic compounds (VOCs). We believe that proposed sensor concept opens up new ways to design photoactivated sensors without heating for the detection of VOCs. Full article

(This article belongs to the Special Issue Recent Progress on Sensors and Smart Systems for In-Situ Gas Monitoring)

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32 pages, 13426 KiB

Open AccessReview

Non-Enzymatic Electrochemical Glucose Sensors Based on Metal Oxides and Sulfides: Recent Progress and Perspectives

by Haibing Zhu, Feng Shi, Maoying Peng, Ye Zhang, Sitian Long, Ruixin Liu, Juan Li and Zhanjun Yang

Chemosensors 2025, 13(1), 19; https://doi.org/10.3390/chemosensors13010019 - 16 Jan 2025

Viewed by 614

Abstract

With the sudden advancement of glucose biosensors for monitoring blood glucose levels for the prevention and diagnosis of diabetes, non-enzymatic glucose sensors have aroused great interest owing to their sensitivity, stability, and economy. Recently, researchers have dedicated themselves to developing non-enzymatic electrochemical glucose [...] Read more.

With the sudden advancement of glucose biosensors for monitoring blood glucose levels for the prevention and diagnosis of diabetes, non-enzymatic glucose sensors have aroused great interest owing to their sensitivity, stability, and economy. Recently, researchers have dedicated themselves to developing non-enzymatic electrochemical glucose sensors for the rapid, convenient, and sensitive determination of glucose. However, it is desirable to explore economic and effective nanomaterials with a high non-enzymatic catalysis performance toward glucose to modify electrodes. Metal oxides (MOs) and metal sulfides (MSs) have attracted extensive interest among scholars owing to their excellent catalytic activity, good biocompatibility, low cost, simple synthesis process, and controllable morphology and structure. Nonetheless, the exploitation of MOs and MSs in non-enzymatic electrochemical glucose sensors still suffers from relatively low conductivity and biocompatibility. Therefore, it is of significance to integrate MOs and MSs with metal/carbon/conducive polymers to modify electrodes for compensating the aforementioned deficiency. This review introduces the recent developments in non-enzymatic electrochemical glucose sensors based on MOs and MSs, focusing on their preparation methods and how their structural composition influences sensing performance. Finally, this review discusses the prospects and challenges of non-enzymatic electrochemical glucose sensors. Full article

(This article belongs to the Special Issue Dedicated to Professor Huangxian Ju and Professor Xueji Zhang on the Occasion of Their 60th Birthday for Their Outstanding Contributions to the Field of Chemical/Bio Sensors)

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14 pages, 5093 KiB

Open AccessArticle

In Situ Classification of Original Rocks by Portable Multi-Directional Laser-Induced Breakdown Spectroscopy Device

by Mengyang Zhang, Hongbo Fu, Huadong Wang, Feifan Shi, Saifullah Jamali, Zongling Ding, Bian Wu and Zhirong Zhang

Chemosensors 2025, 13(1), 18; https://doi.org/10.3390/chemosensors13010018 - 15 Jan 2025

Viewed by 550

Abstract

In situ rapid classification of rock lithology is crucial in various fields, including geological exploration and petroleum logging. Laser-induced breakdown spectroscopy (LIBS) is particularly well-suited for in situ online analysis due to its rapid response time and minimal sample preparation requirements. To facilitate [...] Read more.

In situ rapid classification of rock lithology is crucial in various fields, including geological exploration and petroleum logging. Laser-induced breakdown spectroscopy (LIBS) is particularly well-suited for in situ online analysis due to its rapid response time and minimal sample preparation requirements. To facilitate in situ raw rock discrimination analysis, a portable LIBS device was developed specifically for outdoor use. This device built upon a previous multi-directional optimization scheme and integrated machine learning to classify seven types of original rock samples: mudstone, basalt, dolomite, sandstone, conglomerate, gypsolyte, and shale from oil logging sites. Initially, spectral data were collected from random areas of each rock sample, and a series of pre-processing steps and data dimensionality reduction were performed to enhance the accuracy and efficiency of the LIBS device. Subsequently, four classification algorithms—linear discriminant analysis (LDA), K-nearest neighbor (KNN), support vector machine (SVM), and extreme gradient boosting (XGBoost)—were employed for classification discrimination. The results were evaluated using a confusion matrix. The final average classification accuracies achieved were 95.71%, 93.57%, 92.14%, and 98.57%, respectively. This work not only demonstrates the effectiveness of the portable LIBS device in classifying various original rock types, but it also highlights the potential of the XGBoost algorithm in improving LIBS analytical performance in field scenarios and geological applications, such as oil logging sites. Full article

(This article belongs to the Special Issue Application of Laser-Induced Breakdown Spectroscopy, 2nd Edition)

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17 pages, 3787 KiB

Open AccessReview

Recent Advances in DNA Systems for In Situ Telomerase Activity Detection and Imaging

by Shiyi Zhang, Wenjing Xiong, Shuyue Xu and Ruocan Qian

Chemosensors 2025, 13(1), 17; https://doi.org/10.3390/chemosensors13010017 - 15 Jan 2025

Viewed by 661

Abstract

Telomeres play a key role in maintaining chromosome stability and cellular aging. They consist of repetitive DNA sequences that protect chromosome ends and regulate cell division. Telomerase is a reverse transcriptase enzyme counteracts the natural shortening of telomeres during cell division by extending [...] Read more.

Telomeres play a key role in maintaining chromosome stability and cellular aging. They consist of repetitive DNA sequences that protect chromosome ends and regulate cell division. Telomerase is a reverse transcriptase enzyme counteracts the natural shortening of telomeres during cell division by extending them. Its activity is pivotal in stem cells and cancer cells but absent in most normal somatic cells. Recent advances in biosensor technologies have facilitated the in situ detection of telomerase activity, which is essential for understanding its role in aging and cancer. Techniques such as fluorescence, electrochemistry, and DNA nanotechnology are now being employed to monitor telomerase activity in living cells, providing real-time insights into cellular processes. DNA-based biosensors, especially those incorporating molecular beacons, DNA walkers, and logic gates, have shown promise for enhancing sensitivity and specificity in telomerase imaging. These approaches also facilitate the simultaneous analysis of related cellular pathways, offering potential applications in early cancer detection and precision therapies. This review explores recent developments in intracellular telomerase imaging, highlighting innovative approaches such as DNA-functionalized nanoparticles and multi-channel logic systems, which offer non-invasive, real-time detection of telomerase activity in complex cellular environments. Full article

(This article belongs to the Special Issue Dedicated to Professor Huangxian Ju and Professor Xueji Zhang on the Occasion of Their 60th Birthday for Their Outstanding Contributions to the Field of Chemical/Bio Sensors)

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11 pages, 11548 KiB

Open AccessArticle

On-Site Detection of Ca and Mg in Surface Water Using Portable Laser-Induced Breakdown Spectroscopy

by Yuanxin Wan, Shixiang Ma, Peichao Zheng, Xiande Zhao, Zhen Xing, Leizi Jiao, Hongwu Tian and Daming Dong

Chemosensors 2025, 13(1), 16; https://doi.org/10.3390/chemosensors13010016 - 14 Jan 2025

Viewed by 521

Abstract

Ca and Mg are key constituents in surface water that are essential nutrients and vital indicators of water hardness. Rapid on-site measurement of Ca and Mg concentrations in surface water is important. However, traditional laboratory detection methods are complex and time-consuming, and on-site [...] Read more.

Ca and Mg are key constituents in surface water that are essential nutrients and vital indicators of water hardness. Rapid on-site measurement of Ca and Mg concentrations in surface water is important. However, traditional laboratory detection methods are complex and time-consuming, and on-site detection is difficult. In this study, a portable surface water detection method was developed using laser-induced breakdown spectroscopy with a miniaturized spectrometer LIBS and a liquid jet device for sample introduction. The device enables the rapid online in situ measurement of elemental concentrations in the water. The limits of detection for the rapid on-site detection of Ca and Mg in surface water were 11.58 and 2.57 mg/L, respectively. We applied this method to assess the concentrations of Ca and Mg in authentic water samples collected from rivers and ponds. The recovery rates for Ca and Mg were 90.83–101.74% and 93.43–108.74%, respectively. This method is suitable for rapid, on-site, and highly sensitive monitoring of Ca and Mg concentrations in the environment. Full article

(This article belongs to the Special Issue Application of Laser-Induced Breakdown Spectroscopy, 2nd Edition)

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46 pages, 13824 KiB

Open AccessReview

Volatolomics for Anticipated Diagnosis of Cancers with Chemoresistive Vapour Sensors: A Review

by Abhishek Sachan, Mickaël Castro and Jean-François Feller

Chemosensors 2025, 13(1), 15; https://doi.org/10.3390/chemosensors13010015 - 13 Jan 2025

Viewed by 516

Abstract

The anticipated diagnosis of cancers and other fatal diseases from the simple analysis of the volatiles emitted by the body (volatolome) is getting closer and closer from becoming reality. The promises of vapour sensor arrays are to provide a rapid, reliable, non-invasive and [...] Read more.

The anticipated diagnosis of cancers and other fatal diseases from the simple analysis of the volatiles emitted by the body (volatolome) is getting closer and closer from becoming reality. The promises of vapour sensor arrays are to provide a rapid, reliable, non-invasive and ready-to-use method for clinical applications by making an olfactive fingerprint characteristic of people’s health state, to increase their chance of early recovery. However, the different steps of this complex and ambitious process are still paved with difficulties needing innovative answers. The purpose of this review is to provide a statement of the blocs composing the diagnostic chain to identify the improvements still needed. Nanocomposite chemo-resistive transducers have unique prospects to enhance both the selectivity and sensitivity to volatile biomarkers. The variety of their formulations offers multiple possibilities to chemical functionalization and conductive architectures that should provide solutions to discriminations and stability issues. A focus will be made on the protocols for the collection of organic volatile compounds (VOC) from the body, the choice of vapour sensors assembled into an array (e-nose), in particular, chemo-resistive vapour sensors, their principle, fabrication and characteristics, and the way to extract pertinent features and analyse them with suitable algorithms that are able to find and produce a health diagnosis. Full article

(This article belongs to the Special Issue Development of the Advanced Sensors Based on Functionalized Carbon Nanomaterials)

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11 pages, 4368 KiB

Open AccessArticle

A Phenyl-Modified Aggregation-Induced Phosphorescent Emission-Active Cationic Ru(II) Complex for Detecting Picric Acid in Aqueous Media

by Ruimin Chen, Qinglong Zhang, Liyan Zhang and Chun Liu

Chemosensors 2025, 13(1), 14; https://doi.org/10.3390/chemosensors13010014 - 11 Jan 2025

Viewed by 456

Abstract

A cationic Ru(II) complex Ru1 with 5-phenyl-2,2′-bipyridine as ligand was synthesized and fully characterized. Ru1 exhibits significant aggregation-induced phosphorescent emission (AIPE) activity in THF/H₂O. The AIPE property of Ru1 has been successfully used to detect picric acid (PA) in aqueous media. [...] Read more.

A cationic Ru(II) complex Ru1 with 5-phenyl-2,2′-bipyridine as ligand was synthesized and fully characterized. Ru1 exhibits significant aggregation-induced phosphorescent emission (AIPE) activity in THF/H₂O. The AIPE property of Ru1 has been successfully used to detect picric acid (PA) in aqueous media. Ru1 exhibits a sensitive luminescence quenching response to PA, with a high quenching constant (K_SV = 2.5 × 10⁴ M⁻¹) and a low limit of detection (LOD = 91 nM). In addition, Ru1 demonstrates high sensitivity and selectivity for detecting PA in different common water samples. The UV-vis absorption spectra and luminescence lifetime of Ru1 show an obvious change after the addition of PA into the Ru1 samples, indicating that the quenching process is a combination of dynamic and static quenching. The density functional theory calculations indicate that the mechanism for the detection of PA is photo-induced electron transfer. Full article

(This article belongs to the Special Issue Green Analytical Methods for Environmental and Food Analysis)

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16 pages, 4408 KiB

Open AccessArticle

Consequences of Surface Composition and Aggregation Conditions of Ag Nanoparticles on Surface-Enhanced Raman Scattering (SERS) of Pesticides

by Marcelo José dos Santos Oliveira, Gilia Cristine Marques Ruiz, Rafael Jesus Gonçalves Rubira, Santiago Sanchez-Cortes, Carlos José Leopoldo Constantino and Leonardo Negri Furini

Chemosensors 2025, 13(1), 13; https://doi.org/10.3390/chemosensors13010013 - 10 Jan 2025

Viewed by 517

Abstract

Surface-enhanced Raman scattering (SERS) is highly dependent on the adsorption of target molecules onto metallic surfaces, such as colloidal metallic nanoparticles. The selection of suitable substrates is crucial for optimizing SERS performance. Herein, we investigated the dependence of two pesticide SERS signals, thiabendazole [...] Read more.

Surface-enhanced Raman scattering (SERS) is highly dependent on the adsorption of target molecules onto metallic surfaces, such as colloidal metallic nanoparticles. The selection of suitable substrates is crucial for optimizing SERS performance. Herein, we investigated the dependence of two pesticide SERS signals, thiabendazole (TBZ) and carbendazim (MBC), on both Ag nanoparticles (reduced by hydroxylamine—AgH or citrate—AgCT) and the aggregation conditions induced by adding different salts (NaCl, KCl or KNO₃). In addition to SERS experiments, in order to assess the induced aggregation of the Ag nanoparticles, UV-Vis absorption spectroscopy, dynamic light scattering (DLS) and zeta potential were employed. For AgH, the use of salts did not yield the greatest effect in the presence of TBZ, as only with the pesticide was it possible to achieve the highest aggregation and greater intensity of the SERS signal. In contrast, with the MBC pesticide, the KNO₃ salt promoted the greatest aggregation state and was crucial for obtaining the most amplified SERS signal. The thicker coating layer of AgCT prevented the adsorption of both pesticides on the surface of the nanoparticles, which was achievable using salts containing Cl⁻ ions. Additionally, to obtain the SERS signal of MBC with AgCT, besides the presence of chlorinated salts, other adjustments were necessary, such as changing both the pH of the medium (from pH 5.8 to pH 8, for which MBC is in its neutral form) and the laser lines (from 785 to 514.5 nm). These findings demonstrated that although the pesticide molecules belong to the same chemical functional group, their detection was strongly influenced by the surface of the silver nanoparticles and the salts added. This highlights the specific nuances in detection depending on the method of Ag synthesis and the nature of the aggregating agents used. Full article

(This article belongs to the Special Issue Raman and Surface-Enhanced Raman Scattering Techniques in Analytical and Biomedical Fields)

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28 pages, 2156 KiB

Open AccessReview

Sensing and Degradation of Organophosphorus Compounds by Exploitation of Heat-Loving Enzymes

by Giuseppe Manco, Eros A. Lampitella, Nagendra S. K. Achanta, Giuliana Catara, Maria Marone and Elena Porzio

Chemosensors 2025, 13(1), 12; https://doi.org/10.3390/chemosensors13010012 - 9 Jan 2025

Viewed by 897

Abstract

The increasing incidence of organophosphate (OP) pesticide poisoning and the use of OP chemical warfare agents (CWA) in conflicts and terrorist acts need sustainable methods for sensing, decontamination, and detoxification of OP compounds. Enzymes can serve as specific, cost-effective biosensors for OPs. We [...] Read more.

The increasing incidence of organophosphate (OP) pesticide poisoning and the use of OP chemical warfare agents (CWA) in conflicts and terrorist acts need sustainable methods for sensing, decontamination, and detoxification of OP compounds. Enzymes can serve as specific, cost-effective biosensors for OPs. We will report on recent advancements in the use of carboxylesterases from the Hormone-Sensitive Lipase for the detection of OP compounds. In addition, enzymatic-based OP detoxification and decontamination offer long-term, environmentally friendly benefits compared to conventional methods such as chemical treatment, incineration, neutralization, and volatilization. Enzymatic detoxification has gained attention as an alternative to traditional OP-detoxification methods. This review provides an overview of the latest research on enzymatic sensing and detoxification of OPs, by exploiting enzymes, isolated from thermophilic/extremophilic Bacteria and Archaea that show exceptional thermal stability and stability in other harsh conditions. Finally, we will make examples of integration between sensing and decontamination systems, including protein engineering to enhance OP-degrading activities and detailed characterization of the best variants. Full article

(This article belongs to the Special Issue Advanced Enzyme-Based Sensors)

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35 pages, 4936 KiB

Open AccessReview

Multi-Template Molecularly Imprinted Polymeric Electrochemical Biosensors

by Meltem Agar, Maisem Laabei, Hannah S. Leese and Pedro Estrela

Chemosensors 2025, 13(1), 11; https://doi.org/10.3390/chemosensors13010011 - 8 Jan 2025

Viewed by 903

Abstract

Dual- or multi-template molecularly imprinted polymers have been an attractive research field for many years as they allow simultaneous detection of more than one target with high selectivity and sensitivity by creating template-specific recognition sites for multiple targets on the same functional monomer. [...] Read more.

Dual- or multi-template molecularly imprinted polymers have been an attractive research field for many years as they allow simultaneous detection of more than one target with high selectivity and sensitivity by creating template-specific recognition sites for multiple targets on the same functional monomer. Dual/multi-template molecular imprinting techniques have been applied to identify, extract, and detect many targets, from heavy metal ions to viruses, by different methods, such as high-performance liquid chromatography (HPLC), liquid chromatography–mass spectrometry (LC-MS), and piezoelectric, optical, and electrochemical methods. This article focuses on electrochemical sensors based on dual/multi-template molecularly imprinted polymers detecting a wide range of targets by electrochemical methods. Furthermore, this work highlights the use of these sensors for point-of-care applications, their commercialization and their integration with microfluidic systems. Full article

(This article belongs to the Special Issue Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2024)

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17 pages, 6065 KiB

Open AccessArticle

AIPE-Active Neutral Ir(III) Complexes as Bi-Responsive Luminescent Chemosensors for Sensing Picric Acid and Fe³⁺ in Aqueous Media

by Qinglong Zhang, Jiangchao Xu, Qiang Xu and Chun Liu

Chemosensors 2025, 13(1), 10; https://doi.org/10.3390/chemosensors13010010 - 8 Jan 2025

Viewed by 487

Abstract

Three neutral iridium complexes Ir1–Ir3 were synthesized using diphenylphosphoryl-substituted 2-phenylpyridine derivatives as the cyclometalating ligand and picolinic acid as the auxiliary ligand. They exhibited significant aggregation-induced phosphorescent emission (AIPE) properties in H₂O/THF and were successfully used as bi-responsive luminescent [...] Read more.

Three neutral iridium complexes Ir1–Ir3 were synthesized using diphenylphosphoryl-substituted 2-phenylpyridine derivatives as the cyclometalating ligand and picolinic acid as the auxiliary ligand. They exhibited significant aggregation-induced phosphorescent emission (AIPE) properties in H₂O/THF and were successfully used as bi-responsive luminescent sensors for the detection of picric acid (PA) and Fe³⁺ in aqueous media. Ir1–Ir3 possesses high efficiency and high selectivity for detecting PA and Fe³⁺, with the lowest limit of detection at 59 nM for PA and 390 nM for Fe³⁺. Additionally, the complexes can achieve naked-eye detection of Fe³⁺ in aqueous media. Ir1–Ir3 exhibit excellent potential for practical applications in complicated environments. The detection mechanism for PA is attributed to photo-induced electron transfer (PET) and Förster resonance energy transfer (FRET), and the detection mechanism for Fe³⁺ may be explained by PET and the strong interactions between Fe³⁺ and the complexes. Full article

(This article belongs to the Special Issue Advanced Real-Time On-Site Sensing Technologies for Food and Environment Analysis: 2nd Edition)

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14 pages, 4197 KiB

Open AccessArticle

Effects of Base Materials (α-Alumina and/or γ-Alumina) on Volatile Organic Compounds (VOCs)-Sensing Properties of Adsorption/Combustion-Type Microsensors

by Takeo Hyodo, Yuma Matsuura, Genki Inao, Takahiko Sasahara, Yasuhiro Shimizu and Taro Ueda

Chemosensors 2025, 13(1), 9; https://doi.org/10.3390/chemosensors13010009 - 7 Jan 2025

Viewed by 481

Abstract

The sensing properties of adsorption/combustion-type microsensors using 5 wt% Pt-loaded aluminas, which consist of two kinds of alumina (α-Al₂O₃ and γ-Al₂O₃), as sensing (catalytic) materials for ethanol and toluene, were investigated in air, and the mixing [...] Read more.

The sensing properties of adsorption/combustion-type microsensors using 5 wt% Pt-loaded aluminas, which consist of two kinds of alumina (α-Al₂O₃ and γ-Al₂O₃), as sensing (catalytic) materials for ethanol and toluene, were investigated in air, and the mixing effects of α-Al₂O₃ with γ-Al₂O₃ on the dynamic and static responses of the sensors were discussed in this study. The mixing of 50 wt% α-Al₂O₃ with γ-Al₂O₃ was the most effective in enhancing the dynamic responses to ethanol, which originated from the flash combustion behavior of ethanol and/or their partially decomposed products adsorbed on the sensing films from 150 °C to 450 °C, while further mixing of α-Al₂O₃ with γ-Al₂O₃ tended to increase the dynamic responses to toluene. On the other hand, the static responses to both ethanol and toluene, which arise from their catalytic combustion at elevated temperatures (450 °C), mainly increased with an increase in the addition of α-Al₂O₃ in the 5 wt% Pt-loaded aluminas. These results indicate that the synergistic effects of the catalytic activity and the thermal conductivity of the 5 wt% Pt-loaded aluminas are the most important for the sensing properties of these sensors to ethanol and toluene. Full article

(This article belongs to the Special Issue Advanced Chemical Sensors for Gas Detection)

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16 pages, 3069 KiB

Open AccessArticle

MOF(CuBDC)-Microcantilever IR Spectroscopy for Methane Sensing with High Sensitivity and Selectivity

by Seungwan Seo, Seok Bin Kwon and Yangkyu Park

Chemosensors 2025, 13(1), 8; https://doi.org/10.3390/chemosensors13010008 - 3 Jan 2025

Viewed by 715

Abstract

Methane, a greenhouse gas with 21 times the global warming potential of carbon dioxide, is increasingly subject to stringent emission regulations, driving the demand for high-performance methane sensors. This study proposes a novel IR spectroscopy technique based on a CuBDC-integrated microcantilever (CuBDC-microcantilever IR [...] Read more.

Methane, a greenhouse gas with 21 times the global warming potential of carbon dioxide, is increasingly subject to stringent emission regulations, driving the demand for high-performance methane sensors. This study proposes a novel IR spectroscopy technique based on a CuBDC-integrated microcantilever (CuBDC-microcantilever IR spectroscopy) for CH₄ sensing, offering exceptional sensitivity and selectivity. The metal-organic framework (MOF) CuBDC was synthesized on the microcantilever using a drop-and-dry method facilitated by an intense pulsed light technique. Characterization via scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy confirmed the successful formation of CuBDC on the microcantilever. The CuBDC-microcantilever IR spectroscopy demonstrated a significantly enhanced sensitivity, with a differential amplitude at the CH₄ characteristic peak approximately 13 times higher than that of a conventional Si microcantilever. Moreover, the limit of detection was determined to be as low as 14.05 ppm. The clear separation of the CH₄ characteristic peak from the water and acetone vapor peaks also emphasized the sensor’s high selectivity. These findings highlight the superior sensitivity and selectivity of the proposed sensor, positioning it as a promising platform for CH₄ detection in industrial and environmental applications. Full article

(This article belongs to the Special Issue Low-Cost Chemosenors for Applications in Environment, Health, Food, and Industry Process Control)

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18 pages, 7395 KiB

Open AccessArticle

Electrochemical Detection of Dopamine with Graphene Oxide Carbon Dots Modified Electrodes

by Omar Isaac Torres-Soto, Alejandro Vega-Rios, Rocio B. Dominguez and Velia Osuna

Chemosensors 2025, 13(1), 7; https://doi.org/10.3390/chemosensors13010007 - 3 Jan 2025

Viewed by 662

Abstract

In this work, the influence of surface functionalization due to synthesis conditions of graphene oxide quantum dots GOQDs was evaluated for dopamine (DA) detection. GOQDs were synthesized using HNO₃ (6 M or 8 M) through a liquid-phase oxidation method. The characterization (HRTEM, [...] Read more.

In this work, the influence of surface functionalization due to synthesis conditions of graphene oxide quantum dots GOQDs was evaluated for dopamine (DA) detection. GOQDs were synthesized using HNO₃ (6 M or 8 M) through a liquid-phase oxidation method. The characterization (HRTEM, FTIR, Raman, and XRD) and evaluation by amperometry (AMP) and differential pulse voltammetry (DPV) showed that GOQDs-8 synthesized with higher oxygen content were more sensitive and selective in DA detection than GOQDs-6. The synergistic effects of electrostatic attraction from glassy carbon electrode negatively charged surface, functionalization for inner-sphere mechanism, and edge effect from lower particle size resulted in amplified electrochemical signal achieving detection at nanomolar level using AMP and DPV. When evaluated using AMP, GCE/GOQDs-8 showed a sensitivity of 0.0422 μA μM^–1, a limit of detection (LOD) of 17.6 nM, a linear range from 0.1 to 100 μM, and minimal interference for uric acid, levodopa, and acetaminophen. In contrast, using DPV, the GCE/GOQDs-8 exhibited a sensitivity of 0.0616 μA μM^–1, a LOD of 506 nM, and a linear range from 0.1–30 μM with remarkable selectivity from all interferent species. The assay of GOQDs-8/GCE sensor in normal human serum proved to be feasible for the practical determination of DA. The recovery obtained was in the range of 94.1 to 112.8% with a relative standard deviation (RSD), n = 3 of less than 3.62%. The oxygen-rich material showed a promising performance that can be further improved with additional nanocarbon or conducting polymers supports. Full article

(This article belongs to the Special Issue Advanced Biomarkers (Glucose, Lactate, Uric Acid, Ketones, Cholesterol, Glutamate) Biosensors)

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16 pages, 4628 KiB

Open AccessArticle

A Reverse Design Method for Convective PCR Chips Featuring Precise Control of Steady-State Flow Fields

by Chenfei Li, Yaping Xie, Haochen Yong, Xin Zhao, Xingxing Ke and Zhigang Wu

Chemosensors 2025, 13(1), 6; https://doi.org/10.3390/chemosensors13010006 - 1 Jan 2025

Viewed by 830

Abstract

Convective Polymerase Chain Reaction (cPCR), owing to its enhanced thermal cycling efficiency, holds promise for application in the next generation of mainstream commercial PCR instruments. Despite its potential, existing capillary-based and annular reaction chamber designs encounter limitations in precisely controlling the internal flow [...] Read more.

Convective Polymerase Chain Reaction (cPCR), owing to its enhanced thermal cycling efficiency, holds promise for application in the next generation of mainstream commercial PCR instruments. Despite its potential, existing capillary-based and annular reaction chamber designs encounter limitations in precisely controlling the internal flow field, which poses a significant barrier to the progression of cPCR. To overcome these obstacles, this work innovatively proposes a cPCR chip utilizing a “racetrack-shaped” reaction chamber, along with a reverse design approach tailored to meet diverse reaction requirements. Through modeling and simulation, we accurately obtained the relationship between the design parameters and the average flow velocity of the cPCR chip with a “racetrack-shaped” reaction chamber. By capturing the motion of fluorescent particles using a high-speed camera, we acquired the velocity distribution of the actual flow field. Further, we utilized these relationships to conduct a reverse design. Ultimately, a reaction chamber was designed based on the actual amplification needs of 2019-nCoV and hepatitis B virus, and successful amplification was achieved using a self-developed temperature control platform. Full article

(This article belongs to the Special Issue Electrochemical Biosensors and Bioassays Based on Nanomaterials)

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4 pages, 158 KiB

Open AccessEditorial

New Trend: Application of Laser-Induced Breakdown Spectroscopy with Machine Learning

by Zhe Wang

Chemosensors 2025, 13(1), 5; https://doi.org/10.3390/chemosensors13010005 - 27 Dec 2024

Viewed by 817

Abstract

Laser-induced breakdown spectroscopy (LIBS) has long been regarded as the “future superstar” of chemical analysis [...] Full article

(This article belongs to the Special Issue Application of Laser-Induced Breakdown Spectroscopy)

25 pages, 3936 KiB

Open AccessArticle

Evaluation of Corrosion Potential Stability of Stainless Steels in Dilute Electrolyte Solution for Application to a Quasi-Reference Electrode Used in Electrochemical Sensing System

by Kyosuke Sawada, Shinji Okazaki, Tatsuki Inaba, Motohiro Sakuma and Koichi Azuma

Chemosensors 2025, 13(1), 4; https://doi.org/10.3390/chemosensors13010004 - 25 Dec 2024

Viewed by 519

Abstract

To evaluate the long term corrosion potential stability of stainless steel (SS) in environmental water, the corrosion potential of SUS304, SUS316, SUS316L, and SUS430 was measured for 1 week in a solution of 0.9 mM NaHCO₃ and 0.5 mM CaCl₂, [...] Read more.

To evaluate the long term corrosion potential stability of stainless steel (SS) in environmental water, the corrosion potential of SUS304, SUS316, SUS316L, and SUS430 was measured for 1 week in a solution of 0.9 mM NaHCO₃ and 0.5 mM CaCl₂, referred to as “sub-tap water.” The potential of the SSs upon initial immersion in sub-tap water was approximately 10 times less stable than the potentials of Fe and Cu. However, as immersion continued, the stability of the corrosion potential of the SS improved and became equivalent to those of Fe and Cu. The stability could be manipulated by pretreatment (pre-immersion) before samples were immersed in sub-tap water. The stability was increased by pre-immersion in an acidic solution but was reduced by a passivation treatment. The formation of iron oxides on the SS surface stabilized the potential, whereas surface enrichment with Cr led to instability. This behavior can also be inferred from a comparison of the polarization curves, where the passive current after the passivation treatment was the largest. This result is also speculatively attributed to the corrosion potential in sub-tap water decreasing over time after the passivation treatment. The charge transfer resistance likely contributes significantly to the potential stability, as indicated by an equivalent circuit analysis based on electrochemical impedance spectroscopy. The results showed that, when stabilizing the corrosion potential of SS, there is no need to reduce the charge transfer resistance as with existing reference electrodes. Stability is achieved when the surface thickness is such that the pseudo-capacitance in a dilute solution is less than 10 µF s^α−1cm⁻² and potential stability does not influence a few changes in the CPE₁ value after potential stability is achieved. The results of this study show that SS can be used as a quasi-reference electrode material. We expect the findings presented herein to strongly affect the development of electrochemical sensors that can be easily used in long term continuous measurements and in situ applications. Full article

(This article belongs to the Special Issue Low-Cost Chemosenors for Applications in Environment, Health, Food, and Industry Process Control)

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13 pages, 3128 KiB

Open AccessArticle

Laser-Induced Graphene-Based Gas Sensor with PEDOT:PSS/Gold–Platinum Nanocomposites for Highly Sensitive Detection of Methane

by Jiaying Sun, Zhuoru Huang, Xiaojing Zhang, Hangming Xiong, Weijie Yu, Shimeng Mou, Wenwu Zhu and Hao Wan

Chemosensors 2025, 13(1), 3; https://doi.org/10.3390/chemosensors13010003 - 25 Dec 2024

Viewed by 671

Abstract

Methane is a common intestinal gas that has been linked to a variety of gastrointestinal disorders. In this study, we prepared a LIG-based electrochemical sensor modified with PEDOT:PSS/Au-Pt nanocomposites for high-sensitivity methane detection. LIG’s high porosity, flexibility, and excellent electrical conductivity are beneficial [...] Read more.

Methane is a common intestinal gas that has been linked to a variety of gastrointestinal disorders. In this study, we prepared a LIG-based electrochemical sensor modified with PEDOT:PSS/Au-Pt nanocomposites for high-sensitivity methane detection. LIG’s high porosity, flexibility, and excellent electrical conductivity are beneficial for electrochemical detection. The PEDOT:PSS film is electrodeposited on the electrode surface to amplify the signal further. The synergistic effect of bimetallic nanocomposites can improve the electrochemical catalytic activity and increase the specific surface area and the advantages of active sites. The experimental results show that the LIG sensor has a wide linear detection range (2–500 ppm), a low detection limit (about 0.36 ppm), high sensitivity, and good repeatability. The sensor is easy to manufacture, is low-cost, operates at room temperature, has high sensitivity, has a low detection limit, and is expected to be used for methane breath detection in the future. Full article

(This article belongs to the Special Issue Advancements of Chemical and Biosensors in China—2nd Edition)

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13 pages, 79922 KiB

Open AccessPerspective

In Vivo Photoelectrochemical Analysis

by Li Li, Yueru Zhao, Cong Pan, Wenjie Ma and Ping Yu

Chemosensors 2025, 13(1), 2; https://doi.org/10.3390/chemosensors13010002 - 24 Dec 2024

Viewed by 731

Abstract

Microelectrode-based photoelectrochemical (PEC) technology is a novel and rapidly developing analytical method for the in vivo probing of neurochemical events in the brain, which is distinguished by its low background noise and high detection sensitivity. This mini-review focuses on recent advances in in [...] Read more.

Microelectrode-based photoelectrochemical (PEC) technology is a novel and rapidly developing analytical method for the in vivo probing of neurochemical events in the brain, which is distinguished by its low background noise and high detection sensitivity. This mini-review focuses on recent advances in in vivo PEC biosensors. We classify the key characteristics of PEC technology and elucidate its underlying principles. Furthermore, newly developed PEC neurochemical sensing methods for detecting various substances, including SO₂, antibiotics, metal ions, neurotransmitters, and thioalcohols, as well as cells are discussed. Finally, this review concludes with a comprehensive summary and perspectives on the emerging opportunities and challenges facing this field. Full article

(This article belongs to the Special Issue Dedicated to Professor Huangxian Ju and Professor Xueji Zhang on the Occasion of Their 60th Birthday for Their Outstanding Contributions to the Field of Chemical/Bio Sensors)

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20 pages, 5668 KiB

Open AccessArticle

Study of the Influence of Thermal Annealing of Ga-Doped ZnO Thin Films on NO₂ Sensing at ppb Level

by Benjamin Paret, Richard Monflier, Philippe Menini, Thierry Camps, Yohann Thimont, Antoine Barnabé and Lionel Presmanes

Chemosensors 2025, 13(1), 1; https://doi.org/10.3390/chemosensors13010001 - 24 Dec 2024

Viewed by 672

Abstract

In this paper, the sensitivity to sub-ppm NO₂ concentration of 50 nm thick Ga-doped ZnO (GZO) films grown by RF magnetron sputtering is studied. The films were annealed under dry air for 4 h at either 500 °C, 600 °C, or 700 [...] Read more.

In this paper, the sensitivity to sub-ppm NO₂ concentration of 50 nm thick Ga-doped ZnO (GZO) films grown by RF magnetron sputtering is studied. The films were annealed under dry air for 4 h at either 500 °C, 600 °C, or 700 °C. The increase in the annealing temperature leads to an improvement of the crystallinity while no significant evolution of the surface grain size is observed. The electrical resistance of the thin films was measured at 250 °C under neutral argon atmosphere, humid air reference atmosphere, and reference atmosphere polluted by 100 ppb of NO₂. An increase in sensitivity to NO₂ is noted for samples annealed at 600 °C, leading to a response R_NO2/R_air of ~10 for 100 ppb of NO₂. Finally, photoluminescence spectra are compared with their electrical resistance at 250 °C under the various atmospheres to understand this phenomenon. It is proposed that the origin of the NO₂ maximum sensitivity for films annealed at 600 °C is the consequence of a specific annihilation of point defects resulting in an increase in the relative concentration of oxygen vacancies, which improves selectivity toward NO₂. Full article

(This article belongs to the Special Issue Functional Nanomaterial-Based Gas Sensors)

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Chemosensors, Volume 13, Issue 1 (January 2025) – 26 articles

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