Chemosensors

35 pages, 3865 KiB

Open AccessReview

Sensors and Biosensors as Viable Alternatives in the Determination of Contaminants in Corn: A Review (2021–2025)

by Lívia M. P. Teodoro, Letícia R. G. Lacerda, Penelopy Costa e Santos, Lucas F. Ferreira and Diego L. Franco

Chemosensors 2025, 13(8), 299; https://doi.org/10.3390/chemosensors13080299 (registering DOI) - 9 Aug 2025

Abstract

Corn is one of the most produced cereals in the world and exerts a significant economic impact on a billion-dollar market. It is utilized globally as a food source for humans and livestock and as a source of carbohydrates, fiber, vitamins, minerals, and [...] Read more.

Corn is one of the most produced cereals in the world and exerts a significant economic impact on a billion-dollar market. It is utilized globally as a food source for humans and livestock and as a source of carbohydrates, fiber, vitamins, minerals, and antioxidants, and also for fuel production and industrial products. However, their production is adversely affected by chemical contamination, primarily by mycotoxins, pesticides, and trace elements. Sensors and biosensors have become reliable alternatives to traditional spectroscopic and chromatographic methods for detecting these substances to enhance processes from harvesting to consumption. Here, we thoroughly evaluated studies on sensors and biosensors as alternatives to the growing demand for the determination of these contaminants as point-of-care devices in the past five years. This review reports innovative systems, using cutting-edge technology in expanded interdisciplinary research, supported by computational simulations to elucidate the interaction/reaction prior to experimentation, exploring the latest developments in nanostructures to create devices with excellent analytical performance. Many systems meet the demands of multiple and simultaneous determinations with fast results, in loco analyses with portable devices connected to personal smartphones, and simple operations to assist farmers, producers, and consumers in monitoring product quality throughout each stage of corn production. Full article

(This article belongs to the Special Issue Electrochemical Sensors and Biosensors for Food, Environmental and Biomedical Analysis)

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22 pages, 2235 KiB

Open AccessReview

Resistive-Based Nanostructured CeO₂ Gas Sensors: A Review

by Mahmoud Torkamani Cheriani, Ali Mirzaei and Jae-Hun Kim

Chemosensors 2025, 13(8), 298; https://doi.org/10.3390/chemosensors13080298 (registering DOI) - 9 Aug 2025

Viewed by 26

Abstract

Air pollution and the emission of toxic gases represent a critical global concern, posing significant threats to human health and environmental stability. Resistive gas sensors are widely employed to detect toxic gases, owing to their cost-effectiveness, high stability, sensitivity, and swift dynamics. Among [...] Read more.

Air pollution and the emission of toxic gases represent a critical global concern, posing significant threats to human health and environmental stability. Resistive gas sensors are widely employed to detect toxic gases, owing to their cost-effectiveness, high stability, sensitivity, and swift dynamics. Among various sensing materials, comparatively less attention has been paid to CeO₂ despite its good catalytic activity and high stability. In this review paper, we are focusing on CeO₂ gas sensors in pristine, doped, decorated, and composite forms. Using numerous examples, we have shown the great potential of CeO₂ for gas sensing. The main features of CeO₂ as a gas sensor include excellent environmental stability, the abundance of oxygen vacancies, high mechanical strength, cost-effectiveness, and good catalytic activity. However, low electrical conductivity is the main shortage of CeO₂ as a gas sensor. With a high emphasis on the sensing mechanism, we believe that this review paper is highly useful for researchers working in this field. Full article

(This article belongs to the Special Issue Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2025)

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16 pages, 2496 KiB

Open AccessArticle

Silicon Nanowires Sensor Modified with Cu (II) Phthalocyanine Derivative for Phosphate Monitoring

by Milaine Jebali, Zina Fredj, Sameh Daboussi, Mounir Ben Ali and Mohamed Hassen

Chemosensors 2025, 13(8), 297; https://doi.org/10.3390/chemosensors13080297 (registering DOI) - 9 Aug 2025

Viewed by 48

Abstract

This study reports the development of a highly sensitive electrochemical sensor for phosphate ion detection, utilizing silicon nanowires (SiNWs) as the transducing elements and a novel copper (II) phthalocyanine-acrylate polymer adduct (Cu (II) Pc-PAA) as the functional sensing layer. Silicon nanowires were fabricated [...] Read more.

This study reports the development of a highly sensitive electrochemical sensor for phosphate ion detection, utilizing silicon nanowires (SiNWs) as the transducing elements and a novel copper (II) phthalocyanine-acrylate polymer adduct (Cu (II) Pc-PAA) as the functional sensing layer. Silicon nanowires were fabricated via metal-assisted chemical etching (MACE) with etching durations of 15, 25, 35, 45, and 60 min. The SiNWs etched for 15 min exhibited the highest sensitivity, showing superior electrochemical performance. Functionalized SiNWs were systematically evaluated for phosphate ion (HPO₄²⁻) detection over a wide concentration range (10⁻¹⁰ to 10⁻⁶ M) using Mott–Schottky measurements. The surface morphology of the SiNWs was thoroughly characterized before and after Cu (II) Pc-PAA layer functionalization. The sensing material was analyzed using contact angle goniometry and scanning electron microscopy (SEM), confirming both its uniform distribution and effective immobilization. The sensor displayed a Nernstian behavior with a sensitivity of 28.25 mV/Decade and an exceptionally low limit of detection (LOD) of 1.5 nM. Furthermore, the capacitive sensor exhibited remarkable selectivity toward phosphate ions, even in the presence of potentially interfering anions such as Cl⁻, NO₃⁻, SO₄²⁻ and ClO₄⁻. These results confirm the sensor’s high sensitivity, selectivity, and fast response, underscoring its suitability for environmental phosphate ion monitoring. Full article

(This article belongs to the Special Issue Electrochemical Sensors and Biosensors for Food, Environmental and Biomedical Analysis)

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13 pages, 686 KiB

Open AccessArticle

Development and Validation of an HPLC-MS/MS Method for Quantifying Deoxynivalenol and Zearalenone Biomarkers in Dried Porcine Blood Spots

by Isadora Fabris Laber, Cristina Tonial Simões, Cristiane Rosa da Silva, Luara Medianeira de Lima Schlösser, Janine Alves Sarturi, Luriane Medianeira Carossi Leal, Renê Valmor Theobald and Carlos Augusto Mallmann

Chemosensors 2025, 13(8), 296; https://doi.org/10.3390/chemosensors13080296 (registering DOI) - 9 Aug 2025

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Abstract

Deoxynivalenol (DON) and zearalenone (ZEN) are common mycotoxins in animal feeds, and their metabolites can be detected in exposed animals. Traditional methods focus on mycotoxin detection in feed, whereas biomarker-based approaches are used for evaluating individual exposure. This study aimed to develop and [...] Read more.

Deoxynivalenol (DON) and zearalenone (ZEN) are common mycotoxins in animal feeds, and their metabolites can be detected in exposed animals. Traditional methods focus on mycotoxin detection in feed, whereas biomarker-based approaches are used for evaluating individual exposure. This study aimed to develop and validate a multi-analyte method for the detection of biomarkers of ZEN, DON, and their metabolites α-zearalanol (α-ZAL), zearalanone (ZAN), deepoxy-DON (DOM-1), and 3-acetyl-DON (3-ADON) in swine using dried blood spots (DBSs) on qualitative filter paper. Analysis was performed using high-performance liquid chromatography–tandem mass spectrometry. Blank blood samples from three male pigs were fortified with 20, 40, and 60 μg/L of each analyte. Aliquots of 40 μL were spotted onto filter paper and then extracted and analyzed. Method validation included evaluating limits of detection and quantification, linearity, matrix effects, recovery, repeatability, intermediate precision, and selectivity. All analytes were detectable in DBS. Also, ZEN, ZAN, DON, and DOM-1 met all validation criteria, with recovery values of 89.10%, 79.79%, 101.50%, and 79.50%, respectively. Both α-ZAL and 3-ADON showed lower recoveries (74.66% and 58.66%). The method was successfully validated for simultaneous analysis of ZEN, ZAN, DON, and DOM-1 in swine DBS, offering a practical and minimally invasive tool for biomonitoring mycotoxin exposure. Full article

(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges (Third Edition))

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16 pages, 1719 KiB

Open AccessArticle

Geographical Origin Classification of Oolong Tea Using an Electronic Nose: Application of Machine Learning and Gray Relational Analysis

by Sushant Kaushal, Priya Rana, Chao-Chin Chung and Ho-Hsien Chen

Chemosensors 2025, 13(8), 295; https://doi.org/10.3390/chemosensors13080295 - 8 Aug 2025

Viewed by 148

Abstract

Taiwan accounts for 90% of the total oolong tea production and enjoys a good global reputation for its quality. In recent years, oolong tea from neighboring countries has been imported into Taiwan and sold as Taiwanese oolong at high prices. This study aimed [...] Read more.

Taiwan accounts for 90% of the total oolong tea production and enjoys a good global reputation for its quality. In recent years, oolong tea from neighboring countries has been imported into Taiwan and sold as Taiwanese oolong at high prices. This study aimed to rapidly classify oolong tea from four geographical origins (Taiwan, Vietnam, China, and Indonesia) using an electronic nose (E-nose) combined with machine learning. Color measurements were also conducted to support the classification. The electronic nose (E-nose) was utilized to analyze the aroma profiles of tea samples. To classify the samples, five machine learning models—linear discriminant analysis (LDA), support vector machine (SVM), K-nearest neighbor (KNN), artificial neural network (ANN), and random forest (RF)—were developed using 70% of the dataset for training and tested on the remaining 30%. Gray relational analysis (GRA) was applied to measure the relationship between sensor responses and reference tea origins. Multivariate analysis of variance (MANOVA) indicated a statistically significant effect of tea origin on color parameters, as confirmed by both Pillai’s trace and Wilks’ Lambda (Λ) tests (p = 0.000 < 0.05). Among the tested models, LDA and ANN achieved the highest overall classification accuracy (98.33%), with ANN outperforming in the discrimination of Taiwanese oolong tea, achieving 98.89% accuracy. GRA presented higher gray relational grade (GRG) values for Taiwanese tea samples compared to other origins and identified sensors S4, S6, and S14 as the dominant contributors. In conclusion, the E-nose combined with machine learning provides a rapid, non-destructive, and effective approach for geographical origin classification of oolong tea. Full article

(This article belongs to the Special Issue Applications of Electronic Nose (E-Nose) and Electronic Tongue (E-Tongue) in Food Quality)

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12 pages, 5808 KiB

Open AccessArticle

A High-Precision Hydrogen Sensor Array Based on Pt-Modified SnO₂ for Suppressing Humidity and Oxygen Interference

by Meile Wu, Zhixin Wu, Hefei Chen, Zhanyu Wu, Peng Zhang, Lin Qi, He Zhang and Xiaoshi Jin

Chemosensors 2025, 13(8), 294; https://doi.org/10.3390/chemosensors13080294 - 7 Aug 2025

Viewed by 163

Abstract

Humidity and oxygen have significant impacts on the accuracy of hydrogen detection, especially for metal oxide semiconductor sensors at room temperature. Addressing this challenge, this study employs a screen-printed 1 × 2 resistive sensor array made from an identical 1 wt.% platinum-modified tin [...] Read more.

Humidity and oxygen have significant impacts on the accuracy of hydrogen detection, especially for metal oxide semiconductor sensors at room temperature. Addressing this challenge, this study employs a screen-printed 1 × 2 resistive sensor array made from an identical 1 wt.% platinum-modified tin oxide nanoparticle material. Fabrication variability between the two sensing elements was intentionally leveraged to enhance array output differentiation and information content. Systematic hydrogen-sensing tests were conducted on the array under diverse oxygen and moisture conditions. Three distinct feature types—the steady-state value, resistance change, and area under the curve—were extracted from the output of each array element. These features, integrated with their quotient, formed a nine-feature vector matrix. A multiple linear regression model based on this array output was developed and validated for hydrogen prediction, achieving a coefficient of determination of 0.95, a mean absolute error of 125 ppm, and a mean relative standard deviation of 7.07%. The combined information of the array provided significantly more stable and precise hydrogen concentration predictions than linear or nonlinear models based on individual sensor features. This approach offers a promising path for mass-producing highly interference-resistant, precise, and stable room-temperature hydrogen sensor arrays. Full article

(This article belongs to the Section Materials for Chemical Sensing)

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16 pages, 3021 KiB

Open AccessReview

Microfluidic Paper-Based Sensors and Their Applications for Glucose Sensing

by Phan Gia Le and Sungbo Cho

Chemosensors 2025, 13(8), 293; https://doi.org/10.3390/chemosensors13080293 - 7 Aug 2025

Viewed by 216

Abstract

Recently, the incidence of diabetes has increased across all socioeconomic groups, with a notable increase in developing countries. Although advances in medical devices have enhanced healthcare accessibility, these benefits remain largely out of reach for individuals residing in remote areas. Concurrently, a variety [...] Read more.

Recently, the incidence of diabetes has increased across all socioeconomic groups, with a notable increase in developing countries. Although advances in medical devices have enhanced healthcare accessibility, these benefits remain largely out of reach for individuals residing in remote areas. Concurrently, a variety of devices have been created to detect glucose biomarkers. Among these, microfluidic paper-based sensors have received substantial attention due to their affordability, disposability, and ease of production. Research on microfluidic paper-based glucose sensors has become particularly prominent owing to their considerable potential and wide applicability, especially in the integration of artificial intelligence and machine learning in glucose sensor processing. This review aims to examine recent advancements and progress in the development of microfluidic paper-based glucose sensors over the past five years, highlighting their advantages, limitations, and prospects. The sensors combined with artificial intelligence and machine learning have potential for future applications. Full article

(This article belongs to the Special Issue Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2025)

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16 pages, 2057 KiB

Open AccessArticle

Comparison of Two Derivative Methods for the Quantification of Amino Acids in PM_2.5 Using GC-MS/MS

by Jungmin Jo, Na Rae Choi, Eunjin Lee, Ji Yi Lee and Yun Gyong Ahn

Chemosensors 2025, 13(8), 292; https://doi.org/10.3390/chemosensors13080292 - 7 Aug 2025

Viewed by 193

Abstract

Amino acids (AAs), a type of nitrogen-based organic compounds in the atmosphere, are directly and indirectly related to climate change, and as their link to allergic diseases becomes more known, the need for quantitative analysis of ultrafine dust (PM_2.5) will become [...] Read more.

Amino acids (AAs), a type of nitrogen-based organic compounds in the atmosphere, are directly and indirectly related to climate change, and as their link to allergic diseases becomes more known, the need for quantitative analysis of ultrafine dust (PM_2.5) will become increasingly necessary. When sensing water-soluble AAs using a gas chromatograph combined with a tandem mass spectrometer (GC-MS/MS), derivatization should be considered to increase the volatility and sensitivity of target analytes. In this study, two methods were used to compare and evaluate 13 AA derivatives in PM_2.5 samples: N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide with 1% tert-butyldimethylchlorosilane (MTBSTFA w/1% t-BDMCS), which is preferred for silylation, and ethyl chloroformate (ECF) with methanol (MeOH) for chloroformate derivatization. The most appropriate reaction conditions for these two derivative methods, such as temperature and time, and the analytical conditions of GC-MS/MS for the qualitative and quantitative analysis of AAs were optimized. Furthermore, the calibration curve, detection limit, and recovery of both methods for validating the quantification were determined. The two derivative methods were applied to 23 actual PM_2.5 samples to detect and quantify target AAs. The statistical significances between pairwise measurements of individual AAs detected by both methods were evaluated. This study will help in selecting and utilizing appropriate derivative methods for the quantification of individual AAs in PM_2.5 samples. Full article

(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges (Third Edition))

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14 pages, 6958 KiB

Open AccessArticle

A pH-Responsive Liquid Crystal-Based Sensing Platform for the Detection of Biothiols

by Xianghao Meng, Ronghua Zhang, Xinfeng Dong, Zhongxing Wang and Li Yu

Chemosensors 2025, 13(8), 291; https://doi.org/10.3390/chemosensors13080291 - 6 Aug 2025

Viewed by 198

Abstract

Biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), are crucial for physiological regulation and their imbalance poses severe health risks. Herein, we developed a pH-responsive liquid crystal (LC)-based sensing platform for detection of biothiols by doping 4-n-pentylbiphenyl-4-carboxylic acid (PBA) into [...] Read more.

Biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), are crucial for physiological regulation and their imbalance poses severe health risks. Herein, we developed a pH-responsive liquid crystal (LC)-based sensing platform for detection of biothiols by doping 4-n-pentylbiphenyl-4-carboxylic acid (PBA) into 4-n-pentyl-4-cyanobiphenyl (5CB). Urease catalyzed urea hydrolysis to produce OH⁻, triggering the deprotonation of PBA, thereby inducing a vertical alignment of LC molecules at the interface corresponding to dark optical appearances. Heavy metal ions (e.g., Hg²⁺) could inhibit urease activity, under which condition LC presents bright optical images and LC molecules maintain a state of tilted arrangement. However, biothiols competitively bind to Hg²⁺, the activity of urease is maintained which enables the occurrence of urea hydrolysis. This case triggers LC molecules to align in a vertical orientation, resulting in bright optical images. This pH-driven reorientation of LCs provides a visual readout (bright-to-dark transition) correlated with biothiol concentration. The detection limits of Cys/Hcy and GSH for the PBA-doped LC platform are 0.1 μM and 0.5 μM, respectively. Overall, this study provides a simple, label-free and low-cost strategy that has a broad application prospect for the detection of biothiols. Full article

(This article belongs to the Special Issue Feature Papers on Luminescent Sensing (Second Edition))

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15 pages, 630 KiB

Open AccessArticle

Application of a Low-Cost Electronic Nose to Differentiate Between Soils Polluted by Standard and Biodegradable Hydraulic Oils

by Piotr Borowik, Przemysław Pluta, Miłosz Tkaczyk, Krzysztof Sztabkowski, Rafał Tarakowski and Tomasz Oszako

Chemosensors 2025, 13(8), 290; https://doi.org/10.3390/chemosensors13080290 - 5 Aug 2025

Viewed by 164

Abstract

Detection of soil pollution by petroleum products is necessary to remedy threats to economic and human health. Pollution by hydraulic oil often occurs through leaks from forestry machinery such as harvesters. Electronic noses equipped with gas sensor arrays are promising tools for applications [...] Read more.

Detection of soil pollution by petroleum products is necessary to remedy threats to economic and human health. Pollution by hydraulic oil often occurs through leaks from forestry machinery such as harvesters. Electronic noses equipped with gas sensor arrays are promising tools for applications of pollution detection and monitoring. A self-made, low-cost electronic nose was used for differentiation between clean and polluted samples, with two types of oils and three levels of pollution severity. An electronic nose uses the TGS series of gas sensors, manufactured by Figaro Inc. Sensor responses to changes in environmental conditions from clean air to measured odor, as well as responses to changes in sensor operation temperature, were used for analysis. Statistically significant response results allowed for the detection of pollution by biodegradable oil, while standard mineral oil was difficult to detect. It was demonstrated that the TGS 2602 gas sensor is most suitable for the studied application. LDA analysis demonstrated multidimensional data patterns allowing differentiation between sample categories and pollution severity levels. Full article

(This article belongs to the Special Issue Electronic Nose and Electronic Tongue for Substance Analysis)

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16 pages, 2634 KiB

Open AccessArticle

Optimized SILAR Growth of Vertically Aligned ZnO Nanorods for Low-Temperature Acetone Detection

by Brahim Ydir, Amine Ajdour, Mouad Soumane, Iulia Antohe, Gabriel Socol, Luiza-Izabela Toderascu, Driss Saadaoui, Imade Choulli, Radouane Leghrib and Houda Lahlou

Chemosensors 2025, 13(8), 289; https://doi.org/10.3390/chemosensors13080289 - 5 Aug 2025

Viewed by 268

Abstract

Vertically oriented morphologies of the semiconducting metal oxide (SMO) surface provide a simple and effective means of enhancing gas sensor performance. We successfully synthesized explicitly aligned ZnO nanorods using a simple automated SILAR technique to improve acetone detection. In this work, we found [...] Read more.

Vertically oriented morphologies of the semiconducting metal oxide (SMO) surface provide a simple and effective means of enhancing gas sensor performance. We successfully synthesized explicitly aligned ZnO nanorods using a simple automated SILAR technique to improve acetone detection. In this work, we found that vertically oriented morphologies, such as well-aligned ZnO nanorods, can significantly enhance the sensor response due to an increase in specific active area and electron mobility, allowing a faster response to changes in the gas environment. The optimal operating temperature for our ZnO nanorod-based sensors in detecting acetone gas is 260 °C. At this temperature, the sensors exhibit a 96% response with a rapid response time of just 3 s. The improved sensing performance is attributed to both electronic and chemical sensitization mechanisms, which enhance the formation of active sites and shorten electron diffusion paths. Full article

(This article belongs to the Special Issue Functionalized Material-Based Gas Sensing)

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17 pages, 3360 KiB

Open AccessArticle

Efficient and Selective Multiple Ion Chemosensor by Novel Near-Infrared Sensitive Symmetrical Squaraine Dye Probe

by Sushma Thapa, Kshitij RB Singh and Shyam S. Pandey

Chemosensors 2025, 13(8), 288; https://doi.org/10.3390/chemosensors13080288 - 4 Aug 2025

Viewed by 206

Abstract

A novel near-infrared (NIR) squaraine-based chemosensor, SQ-68, has been designed and synthesized for the sensitive and selective detection of Cu²⁺ and Ag⁺ ions, offering a compact solution for multi-analyte sensing. SQ-68 demonstrates high selectivity, with its performance influenced by the [...] Read more.

A novel near-infrared (NIR) squaraine-based chemosensor, SQ-68, has been designed and synthesized for the sensitive and selective detection of Cu²⁺ and Ag⁺ ions, offering a compact solution for multi-analyte sensing. SQ-68 demonstrates high selectivity, with its performance influenced by the solvent environment: It selectively detects Cu²⁺ in acetonitrile and Ag⁺ in an ethanol–water mixture. Upon binding with either ion, SQ-68 undergoes significant absorption changes in the NIR region, accompanied by visible color changes, enabling naked-eye detection. Spectroscopic studies confirm a 1:1 binding stoichiometry with both Cu²⁺ and Ag⁺, accompanied by hypochromism. The detection limits are 0.09 μM for Cu²⁺ and 0.38 μM for Ag⁺, supporting highly sensitive quantification. The sensor’s practical applicability was validated in real water samples (sea, lake, and tap water), with recovery rates ranging from 73–95% for Cu²⁺ to 59–99% for Ag⁺. These results establish SQ-68 as a reliable and efficient chemosensor for environmental monitoring and water quality assessment. Its dual-analyte capability, solvent-tunable selectivity, and visual detection features make it a promising tool for rapid and accurate detection of heavy metal ions in diverse aqueous environments. Full article

(This article belongs to the Special Issue Chemosensors Based on Advanced Materials for Environmental Detection and Monitoring)

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14 pages, 1443 KiB

Open AccessArticle

Mid-Infrared Spectroscopy with Variable Selection for the Rapid Quantification of Amylose Content in Starch

by Jingyue Qiao, Hongwei Wang, Jianing Bai, Yimin Liu, Xiaocheng Liu, Yanyan Zhang and Leiming Yuan

Chemosensors 2025, 13(8), 287; https://doi.org/10.3390/chemosensors13080287 - 4 Aug 2025

Viewed by 222

Abstract

Amylose content significantly influences the technological, quality, and nutritional properties of starchy foods. This study developed a rapid, non-destructive method to quantify amylose content in starch using mid-infrared (MIR) spectroscopy combined with chemometric techniques. Manually prepared starch mixtures with varying amylose levels were [...] Read more.

Amylose content significantly influences the technological, quality, and nutritional properties of starchy foods. This study developed a rapid, non-destructive method to quantify amylose content in starch using mid-infrared (MIR) spectroscopy combined with chemometric techniques. Manually prepared starch mixtures with varying amylose levels were scanned to obtain MIR spectra, which were preprocessed using smoothing and z-score normalization to reduce operational variability. Three variable selection methods, including bootstrap soft shrinkage (BOSS), competitive adaptive reweighted sampling (CARS), and uninformative variable elimination (UVE), were applied to select the useful spectra. A partial least square (PLS) model was then constructed to correlate selected spectral data with amylose content. The results revealed that the number and position of selected variables differed across different optimization methods, which influenced the model’s performance. It is worth noting that the optimized PLS model significantly reduced the root mean squared error of cross-validation (RMSECV) and improved prediction accuracy in 50 runs. In particular, the CARS-PLS model showed superior performance, achieving a correlation coefficient (R_p) of 0.964 and a root mean squared error of prediction (RMSEP) of 4.59, a 60% improvement over the original PLS model, which had an RMSEP of 11.56. These results highlight MIR spectroscopy’s potential, combined with optimized chemometric models, for accurate amylose quantification in food quality control. Full article

(This article belongs to the Special Issue Spectroscopic Techniques for Chemical Analysis)

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29 pages, 3037 KiB

Open AccessReview

Methods for GC/MS Analysis of the Most Commonly Seized Drugs of Abuse and Their Metabolites in Biological Samples

by Ivan Kojić, Violeta M. Đurović, Yulia A. Smyatskaya, Nemanja Brkljača, Angi E. Skhvediani, Andrey V. Vasin, Ksenija Stojanović and Saša D. Đurović

Chemosensors 2025, 13(8), 286; https://doi.org/10.3390/chemosensors13080286 - 4 Aug 2025

Viewed by 403

Abstract

Gas chromatography with mass spectrometry (GC-MS) is a common analytical technique used for identifying and quantifying drugs of abuse, as well as their metabolites, extracted from biological samples. Depending on the properties of the analyzed compounds, particularly in the case of metabolites, derivatization [...] Read more.

Gas chromatography with mass spectrometry (GC-MS) is a common analytical technique used for identifying and quantifying drugs of abuse, as well as their metabolites, extracted from biological samples. Depending on the properties of the analyzed compounds, particularly in the case of metabolites, derivatization is often necessary. In this article, we will address the definition, properties, sample preparation, and GC-MS analysis of the most common drugs of abuse in their native (seized) form and their metabolites in biological samples (urine, blood, hair, and tissue). Drugs that will be described are: amphetamines and their derivatives, cannabinoids, cocaine, opioids, lysergide (LSD), benzodiazepines, gamma-hydroxybutyric acid (GHB), phencyclidine (PCP), mescaline, psilocin, and psilocybin. The literature review showed that the analysis of the drugs of abuse requires a simple extraction procedure and analysis with or without derivatization. However, the analysis of the metabolites requires removing the interferences from the matrix (proteins, other compounds, water, and other species that may interfere with the analysis or contaminate the GC-MS). This review article will provide insights into the available procedures for sample preparation and analytical methods, helping authors gain the necessary information and select the desired procedure for analysis. Full article

(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges (Third Edition))

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37 pages, 3005 KiB

Open AccessReview

Printed Sensors for Environmental Monitoring: Advancements, Challenges, and Future Directions

by Amal M. Al-Amri

Chemosensors 2025, 13(8), 285; https://doi.org/10.3390/chemosensors13080285 - 4 Aug 2025

Viewed by 409

Abstract

Environmental monitoring plays a key role in understanding and mitigating the effects of climate change, pollution, and resource mismanagement. The growth of printed sensor technologies offers an innovative approach to addressing these challenges due to their low cost, flexibility, and scalability. Printed sensors [...] Read more.

Environmental monitoring plays a key role in understanding and mitigating the effects of climate change, pollution, and resource mismanagement. The growth of printed sensor technologies offers an innovative approach to addressing these challenges due to their low cost, flexibility, and scalability. Printed sensors enable the real-time monitoring of air, water, soil, and climate, providing significant data for data-driven decision-making technologies and policy development to improve the quality of the environment. The development of new materials, such as graphene, conductive polymers, and biodegradable substrates, has significantly enhanced the environmental applications of printed sensors by improving sensitivity, enabling flexible designs, and supporting eco-friendly and disposable solutions. The development of inkjet, screen, and roll-to-roll printing technologies has also contributed to the achievement of mass production without sacrificing quality or performance. This review presents the current progress in printed sensors for environmental applications, with a focus on technological advances, challenges, applications, and future directions. Moreover, the paper also discusses the challenges that still exist due to several issues, e.g., sensitivity, stability, power supply, and environmental sustainability. Printed sensors have the potential to revolutionize ecological monitoring, as evidenced by recent innovations such as Internet of Things (IoT) integration, self-powered designs, and AI-enhanced data analytics. By addressing these issues, printed sensors can develop a better understanding of environmental systems and help promote the UN sustainable development goals. Full article

(This article belongs to the Section Electrochemical Devices and Sensors)

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13 pages, 1316 KiB

Open AccessArticle

Molecularly Imprinted Electrochemical Sensor Electrodes Based on Poly-Pyrrole for Sensitive Detection of Morphine in Wastewater

by Pranaya Charkravarthula and Amos Mugweru

Chemosensors 2025, 13(8), 284; https://doi.org/10.3390/chemosensors13080284 - 4 Aug 2025

Viewed by 265

Abstract

Morphine is an opioid extracted from the poppy plant and highly effective for moderate to severe pain management. Development of techniques to measure the concentration of this highly addictive drug in various matrices is very important. This work was aimed at the development [...] Read more.

Morphine is an opioid extracted from the poppy plant and highly effective for moderate to severe pain management. Development of techniques to measure the concentration of this highly addictive drug in various matrices is very important. This work was aimed at the development of a sensitive electrochemical method for detection of morphine in wastewater. Molecularly imprinted (MIP) electrodes were made by the electro-polymerization process using pyrrole as a monomer. Electro-polymerization was performed on glassy carbon electrodes in the presence of morphine before the extraction of the entrapped morphine molecules. Various techniques were employed to monitor the polymerization and response of the fabricated electrodes toward morphine. These techniques included Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). The morphine concentration was determined using SWV and CV by measuring the change in the redox peak current of [Fe(CN)₆]^−3/−4. These MIP electrode sensors were used to analyze morphine concentrations between 0 and 80.0 nM solution. The SWV showed a wider linear response region than CV. The detection limit using SWV was found to be 1.9 nM, while using CV, the detection limit was 2.75 nM. This MIP electrode sensor exhibited specificity when other closely related molecules were included and hence has potential as a cheap alternative technique for analysis of morphine. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymer (MIP) Sensors)

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13 pages, 1484 KiB

Open AccessArticle

A Long-Wavelength Fluorescent Probe for Efficient Dual-Color Imaging of Boronic-Acid-Containing Agents in Living Cells

by Shinya Takada, Honghuo Du, Naoya Kondo, Anna Miyazaki, Fumiko Hara, Shizuyo Horiyama, Takashi Temma and Masayori Hagimori

Chemosensors 2025, 13(8), 283; https://doi.org/10.3390/chemosensors13080283 - 4 Aug 2025

Viewed by 373

Abstract

In boron neutron capture therapy (BNCT), the intracellular localization and concentration of boron-10 atoms significantly influence therapeutic efficacy. Although various boronic-acid-targeted fluorescent probes have been developed to evaluate BNCT agents, most of these probes emit at short wavelengths and are, therefore, incompatible with [...] Read more.

In boron neutron capture therapy (BNCT), the intracellular localization and concentration of boron-10 atoms significantly influence therapeutic efficacy. Although various boronic-acid-targeted fluorescent probes have been developed to evaluate BNCT agents, most of these probes emit at short wavelengths and are, therefore, incompatible with common nuclear-staining reagents such as Hoechst 33342 and 4′,6-diamidino-2-phenylindole (DAPI). While our previously reported probe, BS-631, emitted fluorescence above 500 nm, it exhibited limitations in terms of reaction rate and fluorescence intensity. To address these issues, we developed a boronic-acid-targeted fluorescent probe with a longer emission wavelength, rapid reactivity, and strong fluorescence intensity. Herein, we designed and synthesized BTTQ, a probe based on a 2-(2-hydroxyphenyl)benzothiazole core structure. BTTQ exhibited immediate fluorescence upon reaction with 4-borono-L-phenylalanine (BPA), with an emission wavelength of 567 nm and a sufficiently high fluorescence quantum yield for detection. BTTQ quantitatively detected BPA with high sensitivity (quantification limit of 10.27 µM), suitable for evaluating BNCT agents. In addition, BTTQ exhibited selective fluorescence for BPA over metal cations. Importantly, BTTQ enabled fluorescence microscopic imaging of intracellular BPA distribution in living cells co-stained with Hoechst 33342. These results suggest that BTTQ is a promising fluorescent probe for the evaluation of future BNCT agents. Full article

(This article belongs to the Special Issue Advancements and Emerging Applications of Fluorescent Probes for Sensing and Imaging)

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15 pages, 3714 KiB

Open AccessArticle

Application of Graphite Electrodes Prepared from Waste Zinc−Carbon Batteries for Electrochemical Detection of Xanthine

by Milan B. Radovanović, Ana T. Simonović, Marija B. Petrović Mihajlović, Žaklina Z. Tasić and Milan M. Antonijević

Chemosensors 2025, 13(8), 282; https://doi.org/10.3390/chemosensors13080282 - 2 Aug 2025

Viewed by 174

Abstract

Waste from zinc−carbon batteries poses a serious environmental protection problem. One of the main problems is also the reliable and rapid determination of some compounds that may be present in food and beverages consumed worldwide. This study addresses these problems and presents a [...] Read more.

Waste from zinc−carbon batteries poses a serious environmental protection problem. One of the main problems is also the reliable and rapid determination of some compounds that may be present in food and beverages consumed worldwide. This study addresses these problems and presents a possible solution for the electrochemical detection of xanthine using carbon from spent batteries. Cyclic voltammetry and differential pulse voltammetry are electrochemical methods used for the detection of xanthine. The techniques used demonstrate the mechanism of xanthine oxidation in the tested environment. A linear correlation was found between the oxidation current peaks and the xanthine concentration in the range of 5·10⁻⁷ to 1·10⁻⁴ M, as well as the values for the limit of detection and the limit of quantification, 7.86·10⁻⁸ M and 2.62·10⁻⁷ M, respectively. The interference test shows that the electrode obtained from waste Zn-C batteries has good selectivity, which means that the electrode can be used for xanthine determination in the presence of various ions. The data obtained show that carbon sensors from used zinc−carbon batteries can be used to detect xanthine in real samples. Full article

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

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15 pages, 3579 KiB

Open AccessArticle

Dual-Control-Gate Reconfigurable Ion-Sensitive Field-Effect Transistor with Nickel-Silicide Contacts for Adaptive and High-Sensitivity Chemical Sensing Beyond the Nernst Limit

by Seung-Jin Lee, Seung-Hyun Lee, Seung-Hwa Choi and Won-Ju Cho

Chemosensors 2025, 13(8), 281; https://doi.org/10.3390/chemosensors13080281 - 2 Aug 2025

Viewed by 295

Abstract

In this study, we propose a bidirectional chemical sensor platform based on a reconfigurable ion-sensitive field-effect transistor (R-ISFET) architecture. The device incorporates Ni-silicide Schottky barrier source/drain (S/D) contacts, enabling ambipolar conduction and bidirectional turn-on behavior for both p-type and n-type configurations. Channel polarity [...] Read more.

In this study, we propose a bidirectional chemical sensor platform based on a reconfigurable ion-sensitive field-effect transistor (R-ISFET) architecture. The device incorporates Ni-silicide Schottky barrier source/drain (S/D) contacts, enabling ambipolar conduction and bidirectional turn-on behavior for both p-type and n-type configurations. Channel polarity is dynamically controlled via the program gate (PG), while the control gate (CG) suppresses leakage current, enhancing operational stability and energy efficiency. A dual-control-gate (DCG) structure enhances capacitive coupling, enabling sensitivity beyond the Nernst limit without external amplification. The extended-gate (EG) architecture physically separates the transistor and sensing regions, improving durability and long-term reliability. Electrical characteristics were evaluated through transfer and output curves, and carrier transport mechanisms were analyzed using band diagrams. Sensor performance—including sensitivity, hysteresis, and drift—was assessed under various pH conditions and external noise up to 5 V_pp (i.e., peak-to-peak voltage). The n-type configuration exhibited high mobility and fast response, while the p-type configuration demonstrated excellent noise immunity and low drift. Both modes showed consistent sensitivity trends, confirming the feasibility of complementary sensing. These results indicate that the proposed R-ISFET sensor enables selective mode switching for high sensitivity and robust operation, offering strong potential for next-generation biosensing and chemical detection. Full article

(This article belongs to the Section Electrochemical Devices and Sensors)

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21 pages, 2240 KiB

Open AccessReview

A Review of Fluorescent pH Probes: Ratiometric Strategies, Extreme pH Sensing, and Multifunctional Utility

by Weiqiao Xu, Zhenting Ma, Qixin Tian, Yuanqing Chen, Qiumei Jiang and Liang Fan

Chemosensors 2025, 13(8), 280; https://doi.org/10.3390/chemosensors13080280 - 2 Aug 2025

Viewed by 318

Abstract

pH is a critical parameter requiring precise monitoring across scientific, industrial, and biological domains. Fluorescent pH probes offer a powerful alternative to traditional methods (e.g., electrodes, indicators), overcoming limitations in miniaturization, long-term stability, and electromagnetic interference. By utilizing photophysical mechanisms—including intramolecular charge transfer [...] Read more.

pH is a critical parameter requiring precise monitoring across scientific, industrial, and biological domains. Fluorescent pH probes offer a powerful alternative to traditional methods (e.g., electrodes, indicators), overcoming limitations in miniaturization, long-term stability, and electromagnetic interference. By utilizing photophysical mechanisms—including intramolecular charge transfer (ICT), photoinduced electron transfer (PET), and fluorescence resonance energy transfer (FRET)—these probes enable high-sensitivity, reusable, and biocompatible sensing. This review systematically details recent advances, categorizing probes by operational pH range: strongly acidic (0–3), weakly acidic (3–7), strongly alkaline (>12), weakly alkaline (7–11), near-neutral (6–8), and wide-dynamic range. Innovations such as ratiometric detection, organelle-specific targeting (lysosomes, mitochondria), smartphone colorimetry, and dual-analyte response (e.g., pH + Al³⁺/CN⁻) are highlighted. Applications span real-time cellular imaging (HeLa cells, zebrafish, mice), food quality assessment, environmental monitoring, and industrial diagnostics (e.g., concrete pH). Persistent challenges include extreme-pH sensing (notably alkalinity), photobleaching, dye leakage, and environmental resilience. Future research should prioritize broadening functional pH ranges, enhancing probe stability, and developing wide-range sensing strategies to advance deployment in commercial and industrial online monitoring platforms. Full article

(This article belongs to the Special Issue Advancements and Emerging Applications of Fluorescent Probes for Sensing and Imaging)

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18 pages, 2092 KiB

Open AccessArticle

Predicting Adsorption Performance Based on the Properties of Activated Carbon: A Case Study of Shenqi Fuzheng System

by Zhilong Tang, Bo Chen, Wenhua Huang, Xuehua Liu, Xinyu Wang and Xingchu Gong

Chemosensors 2025, 13(8), 279; https://doi.org/10.3390/chemosensors13080279 - 1 Aug 2025

Viewed by 183

Abstract

This work aims to solve the problem of product quality fluctuations caused by batch-to-batch variations in the adsorption capacity of activated carbon during the production of traditional Chinese medicine (TCM) injections. In this work, Shenqi Fuzheng injection was selected as an example. Diluted [...] Read more.

This work aims to solve the problem of product quality fluctuations caused by batch-to-batch variations in the adsorption capacity of activated carbon during the production of traditional Chinese medicine (TCM) injections. In this work, Shenqi Fuzheng injection was selected as an example. Diluted Shenqi Extract (DSE), an intermediate in the production process of Shenqi Fuzheng injection, was adsorbed with different batches of activated carbon. The adsorption capacities of adenine, adenosine, calycosin-7-glucoside, and astragaloside IV in DSE were selected as evaluation indices for activated carbon absorption. Characterization methods such as nitrogen adsorption, X-ray photoelectron spectrum (XPS), and Fourier transform infrared (FTIR) were chosen to explore the quantitative relationships between the properties of activated carbon (i.e., specific surface area, pore volume, surface elements, and spectrum) and the adsorption capacities of these four components. It was found that the characteristic wavelengths from FTIR characterization, i.e., 1560 cm⁻¹, 2325 cm⁻¹, 3050 cm⁻¹, and 3442 cm⁻¹, etc., showed the strongest correlation with the adsorption capacities of these four components. Prediction models based on the transmittance at characteristic wavelengths were successfully established via multiple linear regression. In validation experiments of models, the relative errors of predicted adsorption capacities of activated carbon were mostly within 5%, indicating good predictive ability of the models. The results of this work suggest that the prediction method of adsorption capacity based on the mid-infrared spectrum can provide a new way for the quality control of activated carbon. Full article

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

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33 pages, 2747 KiB

Open AccessReview

Biochar-Derived Electrochemical Sensors: A Green Route for Trace Heavy Metal Detection

by Sairaman Saikrithika and Young-Joon Kim

Chemosensors 2025, 13(8), 278; https://doi.org/10.3390/chemosensors13080278 - 1 Aug 2025

Viewed by 234

Abstract

The increasing demand for rapid, sensitive, and eco-friendly methods for the detection of trace heavy metals in environmental samples, attributed to their serious threats to health and the environment, has spurred considerable interest in the development of sustainable sensor materials. Toxic metal ions, [...] Read more.

The increasing demand for rapid, sensitive, and eco-friendly methods for the detection of trace heavy metals in environmental samples, attributed to their serious threats to health and the environment, has spurred considerable interest in the development of sustainable sensor materials. Toxic metal ions, namely, lead (Pb²⁺), cadmium (Cd²⁺), mercury (Hg²⁺), arsenic (As³⁺), and chromium, are potential hazards due to their non-biodegradable nature with high toxicity, even at trace levels. Acute health complications, including neurological, renal, and developmental disorders, arise upon exposure to such metal ions. To monitor and mitigate these toxic exposures, sensitive detection techniques are essential. Pre-existing conventional detection methods, such as atomic absorption spectroscopy (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS), involve expensive instrumentation, skilled operators, and complex sample preparation. Electrochemical sensing, which is simple, portable, and eco-friendly, is foreseen as a potential alternative to the above conventional methods. Carbon-based nanomaterials play a crucial role in electrochemical sensors due to their high conductivity, stability, and the presence of surface functional groups. Biochar (BC), a carbon-rich product, has emerged as a promising electrode material for electrochemical sensing due to its high surface area, sustainability, tunable porosity, surface rich in functional groups, eco-friendliness, and negligible environmental footprint. Nevertheless, broad-spectrum studies on the use of biochar in electrochemical sensors remain narrow. This review focuses on the recent advancements in the development of biochar-based electrochemical sensors for the detection of toxic heavy metals such as Pb²⁺, Cd²⁺, and Hg²⁺ and the simultaneous detection of multiple ions, with special emphasis on BC synthesis routes, surface modification methodologies, electrode fabrication techniques, and electroanalytical performance. Finally, current challenges and future perspectives for integrating BC into next-generation sensor platforms are outlined. Full article

(This article belongs to the Special Issue Green Electrochemical Sensors for Trace Heavy Metal Detection)

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13 pages, 2146 KiB

Open AccessArticle

Radical TTM-DMODPA for Ascorbic Acid Non-Catalytic Visual Detection

by Qingmei Zhong, Huixiang Zong, Xiaohui Xie, Xiaomei Rong and Chuan Yan

Chemosensors 2025, 13(8), 277; https://doi.org/10.3390/chemosensors13080277 - 27 Jul 2025

Viewed by 345

Abstract

Ascorbic acid (AA) plays a multidimensional role in human physiological and pathological processes, and the detection of its urinary concentration facilitates the diagnosis of metabolic or kidney diseases. Visual detection exhibits minimal reliance on instrumentation and is suitable for on-site analysis in routine [...] Read more.

Ascorbic acid (AA) plays a multidimensional role in human physiological and pathological processes, and the detection of its urinary concentration facilitates the diagnosis of metabolic or kidney diseases. Visual detection exhibits minimal reliance on instrumentation and is suitable for on-site analysis in routine settings. Current visual colorimetric detection methods typically rely on enzymatic or nanozyme-based catalysis. Organic neutral radicals bearing unpaired electrons represent a class of materials exhibiting intrinsic responsiveness to redox stimuli. The tris (2,4,6-trichlorophenyl) methyl (TTM) radical has attracted widespread attention for its adjustable optical properties and sensitive response to external redox stimuli. We synthesized a novel radical TTM-DMODPA and applied it for non-catalytic colorimetric detection of AA. It not only enables quantitative AA measurement via UV-vis spectroscopy (linear range: 1.25–75 μmol/L, LOD: 0.288 μmol/L) but also facilitates instrument-free visual detection using smartphone cameras (linear range: 0–65 μmol/L, LOD: 1.46 μmol/L). This method demonstrated satisfactory performance in the measurement of AA in actual urine samples. Recovery rates ranged from 97.8% to 104.1%. Consequently, this work provides a portable and effective method for assessing AA levels in actual urine samples. Full article

(This article belongs to the Section (Bio)chemical Sensing)

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11 pages, 3086 KiB

Open AccessArticle

A Carbazole-Based Aggregation-Induced Emission “Turn-On” Sensor for Mercury Ions in Aqueous Solution

by Remya Radha, Mohammed S. Valliyengal and Mohammad H. Al-Sayah

Chemosensors 2025, 13(8), 276; https://doi.org/10.3390/chemosensors13080276 - 25 Jul 2025

Viewed by 532

Abstract

The development of rapid detection methods to identify mercury ions in aqueous solutions is crucial for effectively monitoring environmental contamination. Fluorescent chemical sensors offer a fast and reliable approach to detect and analyze these metal ions. In this study, a sensor utilizing aggregation-induced [...] Read more.

The development of rapid detection methods to identify mercury ions in aqueous solutions is crucial for effectively monitoring environmental contamination. Fluorescent chemical sensors offer a fast and reliable approach to detect and analyze these metal ions. In this study, a sensor utilizing aggregation-induced emission (AIE) is introduced as a ’turn-on’ fluorescent sensor specifically designed for mercury ions in aqueous solutions. The sensor, based on carbazole, forms aggregates in aqueous solutions, resulting in a significant 800% enhancement of its fluorescence signal. When elemental iodine is added to the solution, the fluorescence of the aggregates is quenched by 90%. However, upon subsequent addition of mercury ions, the fluorescence is regenerated, and the intensity of the emission signal is directly proportional to the concentration of the ions across a wide concentration range. The carbazole-iodine complex acts as a fluorescent probe, enabling the detection of mercury ions in aqueous solutions. Full article

(This article belongs to the Special Issue Advanced Colorimetric and Fluorescent Sensors and Their Application in Detection, 2nd Edition)

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36 pages, 22778 KiB

Open AccessReview

Enzyme-Based Single Solid-State Nanochannel Biosensors

by L. Miguel Hernández Parra, Omar Azzaroni and Waldemar A. Marmisollé

Chemosensors 2025, 13(8), 275; https://doi.org/10.3390/chemosensors13080275 - 25 Jul 2025

Viewed by 276

Abstract

Sensing technologies play a critical role in healthcare, not only for diagnosis and treatment but especially for prevention and early intervention. Recent advances in biology, medicine, and materials science have expanded the landscape of measurable biological markers and enabled the development of nanotechnology-based [...] Read more.

Sensing technologies play a critical role in healthcare, not only for diagnosis and treatment but especially for prevention and early intervention. Recent advances in biology, medicine, and materials science have expanded the landscape of measurable biological markers and enabled the development of nanotechnology-based biosensing platforms. Among the most prominent strategies in biosensing are those that take inspiration from nature, particularly through the integration of biological components such as enzymes. This review focuses on the intersection between enzymatic catalysis and single solid-state nanochannel (SSN) technologies as a promising approach for the development of advanced biosensing devices. We provide an overview of the historical background, current state of the art, and major achievements in enzyme-based biosensors and artificial nanochannel platforms, highlighting their synergistic potential. Particular attention is given to the challenges associated with enzyme integration into artificial environments, including stability and functionality retention, and the strategies employed to overcome them. Finally, we discuss the prospects and limitations of combining enzymes with SSNs, aiming to inspire future research in this emerging and multidisciplinary field. Full article

(This article belongs to the Special Issue Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2025)

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18 pages, 2943 KiB

Open AccessArticle

Urban Precipitation Scavenging and Meteorological Influences on BTEX Concentrations: Implications for Environmental Quality

by Kristina Kalkan, Vitaly Efremov, Dragan Milošević, Mirjana Vukosavljev, Nikolina Novakov, Kristina Habschied, Kresimir Mastanjević and Brankica Kartalović

Chemosensors 2025, 13(8), 274; https://doi.org/10.3390/chemosensors13080274 - 24 Jul 2025

Viewed by 383

Abstract

This study provides an assessment of BTEX compounds—benzene, toluene, ethylbenzene, and xylene isomers—in urban precipitation collected in the city of Novi Sad, Republic of Serbia, during autumn and winter 2024, analyzed by gas chromatography-mass spectrometry (GC-MS). By combining chemical analysis with meteorological observations [...] Read more.

This study provides an assessment of BTEX compounds—benzene, toluene, ethylbenzene, and xylene isomers—in urban precipitation collected in the city of Novi Sad, Republic of Serbia, during autumn and winter 2024, analyzed by gas chromatography-mass spectrometry (GC-MS). By combining chemical analysis with meteorological observations and HYSPLIT backward trajectory modeling, the study considers the mechanisms of BTEX removal from the atmosphere via wet scavenging and highlights the role of local weather conditions and long-range atmospheric transport in pollutant concentrations. During the early observation period (September to late November), average concentrations were 0.45 µg/L benzene, 3.45 µg/L ethylbenzene, 4.0 µg/L p-xylene, 2.31 µg/L o-xylene, and 1.32 µg/L toluene. These values sharply dropped to near-zero levels in December for benzene, ethylbenzene, and xylenes, while toluene persisted at 1.12 µg/L. A pronounced toluene spike exceeding 6 µg/L on 28 November was likely driven by transboundary air mass transport from Central Europe, as confirmed by trajectory modeling. The environmental risks posed by BTEX deposition, especially from toluene and xylenes, underline the need for regulatory frameworks to include precipitation as a pathway for pollutant deposition. It should be clarified that the identified risk primarily concerns aquatic organisms, due to the potential for BTEX infiltration into surface waters and subsequent ecotoxicological impacts. Incorporating such monitoring into EU policies can improve protection of air, water, and ecosystems. Full article

(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges (Third Edition))

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15 pages, 2518 KiB

Open AccessArticle

Ligand Differentiation Ability of Insect Odorant Receptors in Heterologously Expressed Cells as Potential Biosensor Elements

by Rui Zhou, Yuji Sukekawa, Sawako Niki, Eri Kuroda, Ryohei Kanzaki, Shigehiro Namiki and Hidefumi Mitsuno

Chemosensors 2025, 13(8), 273; https://doi.org/10.3390/chemosensors13080273 - 23 Jul 2025

Viewed by 432

Abstract

The extensive diversity of volatile organic compounds, along with their minor structural variations, presents significant challenges in the development of chemosensory-based biosensors. Previously, we generated sensor cells expressing insect odorant receptors (ORs) in Sf21 cells, demonstrating their potential as cell-based odorant sensor elements. [...] Read more.

The extensive diversity of volatile organic compounds, along with their minor structural variations, presents significant challenges in the development of chemosensory-based biosensors. Previously, we generated sensor cells expressing insect odorant receptors (ORs) in Sf21 cells, demonstrating their potential as cell-based odorant sensor elements. However, it remains unclear whether the selectivity of cells expressing ORs in vitro for diverse compounds aligns with the receptor’s in vivo performance, aside from the response to target compounds. To address this, we assessed the ligand responses of sensor cells expressing ORs from Drosophila melanogaster using a high-throughput calcium imaging system. Our results demonstrate that in vitro receptor responses exhibit ligand selectivity comparable to in vivo conditions across different chemical categories. Broadly tuned OR-expressing sensor cells (Or13a, Or47a, and Or98a) displayed differential affinities, whereas the narrowly tuned Or56a-expressing sensor cells selectively responded to geosmin. Moreover, cell responses varied with subtle differences in chemical structure, including carbon chain length and functional group positioning. These findings provide valuable insights into insect OR–ligand interactions in vitro, demonstrating that receptor selectivity in sensor cells closely mirrors in vivo conditions. In addition to this consistency, our results highlight the subtle ligand differentiation capabilities of sensor cells enabling fluorescence-based visualization of receptor–ligand interactions. Full article

(This article belongs to the Special Issue Low-Cost Chemosensors for Applications in Environment, Health, Food, and Industry Process Control, 2nd Edition)

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63 pages, 4971 KiB

Open AccessReview

Electrochemical Nanosensors Applied to the Assay of Some Food Components—A Review

by Aurelia Magdalena Pisoschi, Florin Iordache, Loredana Stanca, Petronela Mihaela Rosu, Nicoleta Ciocirlie, Ovidiu Ionut Geicu, Liviu Bilteanu and Andreea Iren Serban

Chemosensors 2025, 13(8), 272; https://doi.org/10.3390/chemosensors13080272 - 23 Jul 2025

Viewed by 641

Abstract

Nanomaterials’ special features enable their extensive application in chemical and biochemical nanosensors for food assays; food packaging; environmental, medicinal, and pharmaceutical applications; and photoelectronics. The analytical strategies based on novel nanomaterials have proved their pivotal role and increasing interest in the assay of [...] Read more.

Nanomaterials’ special features enable their extensive application in chemical and biochemical nanosensors for food assays; food packaging; environmental, medicinal, and pharmaceutical applications; and photoelectronics. The analytical strategies based on novel nanomaterials have proved their pivotal role and increasing interest in the assay of key food components. The choice of transducer is pivotal for promoting the performance of electrochemical sensors. Electrochemical nano-transducers provide a large active surface area, enabling improved sensitivity, specificity, fast assay, precision, accuracy, and reproducibility, over the analytical range of interest, when compared to traditional sensors. Synthetic routes encompass physical techniques in general based on top–down approaches, chemical methods mainly relying on bottom–up approaches, or green technologies. Hybrid techniques such as electrochemical pathways or photochemical reduction are also applied. Electrochemical nanocomposite sensors relying on conducting polymers are amenable to performance improvement, achieved by integrating redox mediators, conductive hydrogels, and molecular imprinting polymers. Carbon-based or metal-based nanoparticles are used in combination with ionic liquids, enhancing conductivity and electron transfer. The composites may be prepared using a plethora of combinations of carbon-based, metal-based, or organic-based nanomaterials, promoting a high electrocatalytic response, and can accommodate biorecognition elements for increased specificity. Nanomaterials can function as pivotal components in electrochemical (bio)sensors applied to food assays, aiming at the analysis of bioactives, nutrients, food additives, and contaminants. Given the broad range of transducer types, detection modes, and targeted analytes, it is important to discuss the analytical performance and applicability of such nanosensors. Full article

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

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13 pages, 1704 KiB

Open AccessArticle

Rapid High-Accuracy Quantitative Analysis of Water Hardness by Combination of One-Point Calibration Laser-Induced Breakdown Spectroscopy and Aerosolization

by Ting Luo, Weihua Huang, Riheng Chen, Furong Chen, Jinke Chen, Zhenlin Hu and Junfei Nie

Chemosensors 2025, 13(8), 271; https://doi.org/10.3390/chemosensors13080271 - 23 Jul 2025

Viewed by 300

Abstract

Water quality should be tested to ensure it is acceptable for the healthy growth of plants and animals, and water hardness is one of the important testing indexes. Herein, a novel approach was proposed to achieve high accuracy and rapid quantitative analyses of [...] Read more.

Water quality should be tested to ensure it is acceptable for the healthy growth of plants and animals, and water hardness is one of the important testing indexes. Herein, a novel approach was proposed to achieve high accuracy and rapid quantitative analyses of water hardness by combining one-point calibration laser-induced breakdown spectroscopy (OPC–LIBS) and aerosolization. First, the water samples are aerosolized via the aerosol generation device and the LIBS spectra of aerosols are obtained. Then, a modified OPC–LIBS model is used to determine the elemental contents of the aerosols via LIBS spectra, in which the plasma temperature is calculated using the Multi-Element Saha–Boltzmann (ME–SB) plot. One suitable standard liquid sample (the concentrations of Ca, Mg, and Sr were 50 mg/L, 50 mg/L, and 500 mg/L, respectively) was selected to evaluate the quantitative performance of the modified OPC–LIBS. Then, the Ca and Mg concentrations in the three real water samples (from the Yangtze River, reservoir, and underground) were detected and quantified by the proposed method, and the quantitative results of three LIBS calibration methods were compared with that of inductively coupled plasma optical emission spectroscopy (ICP–OES). The average relative error of Ca and Mg found in the OPC–LIBS results was lower by 22.23% than the internal standard method and 14.50% lower than the external standard method. The method combining modified OPC–LIBS and aerosolization can achieve high-precision rapid quantification of water hardness detection, which provides a new path for rapid detection of water hardness and is expected to make online detection a reality in the water quality testing field. Full article

(This article belongs to the Special Issue Laser-Induced Breakdown Spectroscopy for Component Analysis in Food and Environmental Samples)

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16 pages, 1519 KiB

Open AccessArticle

Rare Earth Element Detection and Quantification in Coal and Rock Mineral Matrices

by Chet R. Bhatt, Daniel A. Hartzler and Dustin L. McIntyre

Chemosensors 2025, 13(8), 270; https://doi.org/10.3390/chemosensors13080270 - 23 Jul 2025

Viewed by 596

Abstract

As global demand for rare earth elements (REEs) increases, maintaining the production and supply chain is critical. Technologies capable of being used in the field and in situ in the subsurface for rapid REE detection and quantification facilitates the efficient mining of known [...] Read more.

As global demand for rare earth elements (REEs) increases, maintaining the production and supply chain is critical. Technologies capable of being used in the field and in situ in the subsurface for rapid REE detection and quantification facilitates the efficient mining of known resources and exploration of new and unconventional resources. Laser-induced breakdown spectroscopy (LIBS) is a promising technique for rapid elemental analysis both in the laboratory and in the field. Multiple articles have been published evaluating LIBS for detection and quantification of REEs; however, REEs in their natural deposits have not been adequately studied. In this work, detection and quantification of two REEs, La and Nd, have been studied in both synthetic and natural mineral matrices at concentrations relevant to REE extraction. Measurements were performed on REE-containing rock and coal samples (natural and synthetic) utilizing different LIBS instruments and techniques, specifically a commercial benchtop instrument, a custom benchtop instrument (single- and double-pulse modes), and a custom LIBS probe currently being developed for in situ, subsurface, borehole wall detection and quantification of REEs. Plasma expansion, emission intensity, detection limits, and double-pulse signal enhancement were studied. The limits of detection (LOD) were found to be 10/14 ppm for La and 15/25 ppm for Nd in simulated coal/rock matrices in single-pulse mode. Signal enhancement of 3.5 to 6-fold was obtained with double-pulse mode as compared to single-pulse operation. Full article

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

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