Chemosensors

21 pages, 3317 KB

Open AccessArticle

Microcontact-Printed Flexible Electrodes for Label-Free Electrochemical Detection of Lung Cancer Biomarker

by Alberto G. Silva-Junior, Abdelhamid Errachid, Nadia Zine, Marie Hangouet, Guy Raffin, Michelly C. Pereira, Maria D. L. Oliveira and Cesar A. S. Andrade

Chemosensors 2025, 13(11), 377; https://doi.org/10.3390/chemosensors13110377 (registering DOI) - 27 Oct 2025

Abstract

Lung cancer remains one of the deadliest cancers worldwide, which highlights the urgent need for new diagnostic tools to detect reliable biomarkers. To enable scalable and cost-effective production, we developed reusable PDMS stamps patterned with electrodes to print flexible electrodes on PET substrates [...] Read more.

Lung cancer remains one of the deadliest cancers worldwide, which highlights the urgent need for new diagnostic tools to detect reliable biomarkers. To enable scalable and cost-effective production, we developed reusable PDMS stamps patterned with electrodes to print flexible electrodes on PET substrates using a microcontact printing (µCP) approach. PET was chosen not only for its flexibility but also as a more sustainable alternative to conventional rigid materials. On these electrodes, three sensing platforms were tested for neuron-specific enolase (NSE) detection: APTES-based monolayers, electrospun PVA/alginate nanofibers, and electropolymerized polypyrrole (PPy) films. Voltammetric and fluorescence/AFM analyses confirmed that all three platforms could recognize the target analyte, with the PPy-CdTe configuration showing the strongest signal variation. Impedance spectroscopy further supported this finding, revealing a clear linear correlation between charge transfer resistance (RCT) and NSE concentration. The PPy-CdTe sensor demonstrated high sensitivity and consistent performance for NSE detection, achieving a detection limit (LOD) of 8.05 pg·µL⁻¹ and a quantification limit (LOQ) of 26.84 pg·µL⁻¹. Full article

(This article belongs to the Special Issue Advanced Biosensors for Diagnostic Applications)

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13 pages, 1813 KB

Open AccessArticle

Highly Selective and Stable Electrochemical Sensor for Hydrogen Peroxide—Application in Cosmetics Quality Control

by Totka Dodevska, Dobrin Hadzhiev and Nina Dimcheva

Chemosensors 2025, 13(11), 376; https://doi.org/10.3390/chemosensors13110376 (registering DOI) - 25 Oct 2025

Abstract

Nowadays, electrochemical sensors have become a popular topic in cosmetics quality control. A simple and stable electrochemical sensor for hydrogen peroxide (H₂O₂) was developed on the basis of a rhodium-modified glassy carbon electrode (Rh/GCE). A quick, one-step, reproducible, and [...] Read more.

Nowadays, electrochemical sensors have become a popular topic in cosmetics quality control. A simple and stable electrochemical sensor for hydrogen peroxide (H₂O₂) was developed on the basis of a rhodium-modified glassy carbon electrode (Rh/GCE). A quick, one-step, reproducible, and cost-effective electrodeposition procedure was applied to modify GCE with Rh nanoparticles. The sensor shows a high selectivity for H₂O₂ at a low applied potential of −0.1 V (vs. Ag/AgCl, 3 M KCl), with an excellent stability and good repeatability (RSD = 3.2%; n = 5). The modified electrode Rh/GCE demonstrates a high sensitivity of 172.24 ± 1.95 μA mM⁻¹ cm⁻² (n = 3), a linear response to H₂O₂ between 5 and 1000 µM, and a detection limit estimated to be 1.2 µM. Furthermore, Rh/GCE has been successfully used to measure H₂O₂ concentrations in hair dye and antiseptic solution, yielding satisfactory recovery rates. These findings highlight the potential of the Rh/GCE for the reliable quantitative detection of H₂O₂ in complex cosmetics matrices. Full article

(This article belongs to the Special Issue Nanostructured Materials for Electrochemical Sensing)

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13 pages, 648 KB

Open AccessArticle

Environmental Sustainability Study for the Determination of Ketoprofen in the Presence of Its Main Photo-Degradation Products in River Water Using Solid-Contact Electrodes

by Ali Altharawi and Sherif A. Abdel-Gawad

Chemosensors 2025, 13(11), 375; https://doi.org/10.3390/chemosensors13110375 (registering DOI) - 24 Oct 2025

Abstract

A major objective in recent years has been the use of membrane sensors for the purpose of monitoring and recognizing environmental pollutants in pharmaceuticals. Ketoprofen (KTP) is likely to be found in the environment, particularly in surface water bodies like rivers, because of [...] Read more.

A major objective in recent years has been the use of membrane sensors for the purpose of monitoring and recognizing environmental pollutants in pharmaceuticals. Ketoprofen (KTP) is likely to be found in the environment, particularly in surface water bodies like rivers, because of its extensive use in medicine. The photodegradability of KTP and the prolonged exposure of river water to sunlight may facilitate its photodegradation. To measure KTP along with its main photo-degradation products, three membrane electrodes were fabricated using different plasticizers. Dioctyl phthalate (DOP), dibutyl sebacate (DBS), and o-nitrophenyloctyl ether (o-NPOE) membrane electrodes were constructed for the selective analysis of the investigated medication. The fabricated sensors were prepared using tetraoctyl ammonium chloride as an ion-pairing agent. A linear range of 1 × 10⁻⁵ M to 1 × 10⁻¹ M was shown by the electrodes. The slopes (in mV/decade) for the DOP, DBS, and o-NPOE membranes were −58.80 ± 0.90, −57.90 ± 0.80, and −56.80 ± 1.10, respectively. All test parameters were refined to enhance electrochemical performance. The synthesized membranes were successfully utilized to accurately measure KTP amidst its primary photodegradants. The fabricated sensors were effectively utilized to measure KTP in river water samples without requiring pre-treatment processes. 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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14 pages, 1123 KB

Open AccessArticle

Portable MOS Electronic Nose Screening of Virgin Olive Oils with HS-SPME-GC–MS Corroboration: Classification and Estimation of Sunflower-Oil Adulteration

by Ramiro Sánchez, Fernando Díaz and Lina Melo

Chemosensors 2025, 13(10), 374; https://doi.org/10.3390/chemosensors13100374 - 21 Oct 2025

Abstract

Extra virgin olive oil (EVOO) can degrade during production or storage to virgin olive oil (VOO) or lampante olive oil (LOO). Fraud can also occur during commercialisation through the adulteration of EVOO (Ad-EVOO) with cheaper sunflower oil (SFO). Therefore, rapid screening techniques for [...] Read more.

Extra virgin olive oil (EVOO) can degrade during production or storage to virgin olive oil (VOO) or lampante olive oil (LOO). Fraud can also occur during commercialisation through the adulteration of EVOO (Ad-EVOO) with cheaper sunflower oil (SFO). Therefore, rapid screening techniques for quality control are needed. We evaluated an electronic nose (EN) with chemometrics—linear discriminant analysis (LDA), artificial neural-network discriminant analysis (ANN-DA), and partial least-squares regression (PLS)—in two scenarios: (i) classification into four classes (EVOO, VOO, LOO, and Ad-EVOO adulterated with 25% w/w SFO); and (ii) Ad-EVOO series containing 5–40% w/w SFO. Classes were corroborated by HS-SPME-GC-MS, with elevated (E)-2-hexenal and 3-hexen-1-ol in EVOO and increases in nonanal, ethyl acetate, and 2-propanol in deteriorated oils. Using the EN, LDA separated the classes, and ANN-DA achieved 90% accuracy under cross-validation, with the greatest confusion between VOO and LOO. In adulteration, discrimination emerged from 20% SFO, and PLS estimated %Ad-EVOO with R²pred = 0.972 (RMSEC/RMSEP = 8.059/5.627). In conclusion, the EN provides objective, rapid, and non-destructive screening that supports sensory panels and chromatographic analyses during reception and storage in industrial settings. Full article

(This article belongs to the Special Issue Detection of Volatile Organic Compounds in Complex Mixtures)

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16 pages, 2760 KB

Open AccessArticle

Simple Moisture Sensing Element Using Carbon Nanotube Composite Paper

by Takahide Oya, Tadashi Saito, Yuma Morita and Koya Arai

Chemosensors 2025, 13(10), 373; https://doi.org/10.3390/chemosensors13100373 - 16 Oct 2025

Abstract

We propose a unique moisture sensing element (including humidity sensor) using carbon nanotube (CNT) composite paper. The CNT composite paper is a composite material consisting of CNTs and cellulose paper, which can be easily produced using a method based on the Japanese washi [...] Read more.

We propose a unique moisture sensing element (including humidity sensor) using carbon nanotube (CNT) composite paper. The CNT composite paper is a composite material consisting of CNTs and cellulose paper, which can be easily produced using a method based on the Japanese washi papermaking process. Since this composite paper contains CNTs, it is a conductive paper. In addition, the cellulose fibers that make up the paper are known to show a volume change of up to 35% with humidity. The proposed moisture sensing element uses this volume change and the electrical resistance derived from the CNT network contained in the composite paper. Through various experiments, it was confirmed that the electrical resistance of the CNT composite paper changes in response to moisture of various sizes, such as water droplets and vapors (humidity). It was concluded that these changes were the result of the volume change of paper fibers due to moisture, which greatly affected the structure of the CNT network contained within the composite paper. The results of this study will be useful for the practical application of simple and flexible paper-based moisture sensing elements in the near future. Full article

(This article belongs to the Special Issue Application of Carbon Nanotubes in Sensing)

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12 pages, 1973 KB

Open AccessArticle

A Simple Second-Derivative Image-Sharpening Algorithm for Enhancing the Electrochemical Detection of Chlorophenol Isomers

by Shuo Duan, Yong Wen, Fangquan Xia and Changli Zhou

Chemosensors 2025, 13(10), 372; https://doi.org/10.3390/chemosensors13100372 - 16 Oct 2025

Abstract

Electrochemical detection is widely used in environmental, health, and food analysis due to its portability, low cost, and high sensitivity. However, when analytes with similar redox potentials coexist, overlapping voltammetric signals often occur, which compromises detection accuracy and sensitivity. In this study, a [...] Read more.

Electrochemical detection is widely used in environmental, health, and food analysis due to its portability, low cost, and high sensitivity. However, when analytes with similar redox potentials coexist, overlapping voltammetric signals often occur, which compromises detection accuracy and sensitivity. In this study, a simple second-derivative image sharpening (IS) algorithm is applied to the electrochemical detection of chlorophenol (CP) isomers with similar redox behaviors. Specifically, a graphene-modified electrode was employed for the electrochemical detection of two chlorophenol isomers: ortho-CP (o-CP) and meta-chlorophenol (m-CP) in the range from 1.0 to 10.0 μmol/L. After image-sharpening, the peak potential difference between o- and m-CP increased from 0.08 V to 0.12 V. The limits of detection (LOD) for o-CP and m-CP decreased from 0.6 to 0.9 μmol/L to 0.12 and 0.31 μmol/L, respectively. The corresponding sensitivities also improved from 0.92 to 1.35 A/(mol L⁻¹) to 4.11 and 3.71 A/(mol L⁻¹), respectively. Moreover, the sharpened voltammograms showed enhanced peak resolution, facilitating visual discrimination of the two isomers. These results demonstrate that image sharpening can significantly improve peak shape, peak separation, sensitivity, and detection limit in electrochemical analysis. The obtained algorithm is computationally efficient (<30 lines of C++ (Version 6.0)/OpenCV, executable in <1 ms on an ARM-M0 microcontroller) and easily adaptable to various programming environments, offering a promising approach for data processing in portable electrochemical sensing systems. Full article

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

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15 pages, 3319 KB

Open AccessArticle

Next-Generation Airborne Pathogen Detection: Flashing Ratchet Potential in Action

by Yazan Al-Zain, Mohammad Bqoor, Maha Albqoor and Lujain Ismail

Chemosensors 2025, 13(10), 371; https://doi.org/10.3390/chemosensors13100371 - 16 Oct 2025

Abstract

A novel airborne pathogen detection method, based on Flashing Ratchet Potential (FRP) and Electric Current Spectroscopy (ECS), is presented. The system employs a precisely engineered asymmetric electrode array to generate controlled directional transport of oxygen ions (O₂⁻•), produced via thermionic [...] Read more.

A novel airborne pathogen detection method, based on Flashing Ratchet Potential (FRP) and Electric Current Spectroscopy (ECS), is presented. The system employs a precisely engineered asymmetric electrode array to generate controlled directional transport of oxygen ions (O₂⁻•), produced via thermionic emission and three-body electron attachment. As these ions interact with airborne particles in the detection zone, measurable perturbations in the ECS profile emerge, yielding distinct spectral signatures that indicate particle presence. Proof-of-concept experiments, using standardized talcum powder aerosols as surrogates for viral-scale particles, established optimal operating parameters of 6 V potential and 600 kHz modulation frequency, with reproducible detection signals showing a relative shift of 4.5–13.4% compared to filtered-air controls. The system’s design concept incorporates humidity-resilient features, intended to maintain stability under varying environmental conditions. Together with the proposed size selectivity (50–150 nm), this highlights its potential robustness for real-world applications. To the best of our knowledge, this is the first demonstration of an open-air electro-ratchet transport system coupled with electric current spectroscopy for bioaerosol monitoring, distinct from prior optical or electrochemical airborne biosensors, highlighting its promise as a tool for continuous environmental surveillance in high-risk settings such as hospitals, airports, and public transit systems. Full article

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

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15 pages, 1511 KB

Open AccessArticle

NIR and MIR Spectroscopy for the Detection of Adulteration of Smoking Products

by Zeb Akhtar, Ihtesham ur Rehman, Cédric Delporte, Erwin Adams and Eric Deconinck

Chemosensors 2025, 13(10), 370; https://doi.org/10.3390/chemosensors13100370 - 16 Oct 2025

Abstract

This study explores the application of Mid-Infrared (MIR) and Near-Infrared (NIR) spectroscopy combined with various multivariate calibration techniques to detect the presence of cannabis in tobacco samples and tobacco in herbal smoking products. Both MIR and NIR spectra were recorded for self-prepared samples, [...] Read more.

This study explores the application of Mid-Infrared (MIR) and Near-Infrared (NIR) spectroscopy combined with various multivariate calibration techniques to detect the presence of cannabis in tobacco samples and tobacco in herbal smoking products. Both MIR and NIR spectra were recorded for self-prepared samples, followed by data exploration using Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA), and the calculation of binary classification models with Soft Independent Modelling of Class Analogy (SIMCA) and Partial Least Squares-Discriminant Analysis (PLS-DA). PCA demonstrated a clear differentiation between tobacco samples containing and not containing cannabis. On the other hand, based on PCA, only NIR was able to distinguish herbal smoking products adulterated and not adulterated with tobacco. HCA further clarified these results by revealing distinct clusters within the data. Modelling results indicated that MIR and NIR spectroscopy, particularly when paired with preprocessing techniques like Standard Normal Variate (SNV) and autoscaling, demonstrated high classification accuracy in SIMCA and PLS-DA, achieving correct classification rates of 90% to 100% for external test sets. Comparison of MIR and NIR revealed that NIR spectroscopy resulted in slightly more accurate models for the screening of tobacco samples for cannabis and herbal smoking products for tobacco. The developed approach could be useful for the initial screening of tobacco samples for cannabis, e.g., in a night life setting by law enforcement, but also for inspectors visiting shops selling tobacco and/or herbal smoking products. Full article

(This article belongs to the Section Optical Chemical Sensors)

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20 pages, 5256 KB

Open AccessArticle

Electrochemical Approach to the Determination of Gallic Acid with Bismuth-Based Carbon Electrodes

by Ivana Škugor Rončević, Marijo Buzuk, Josipa Dugeč, Jure Vasilj, Marija Pustak and Nives Vladislavić

Chemosensors 2025, 13(10), 369; https://doi.org/10.3390/chemosensors13100369 - 14 Oct 2025

Abstract

The synergistic combination of bismuth and its compounds with the exceptional properties of single-walled carbon nanotubes (SWCNT) was investigated as a sensing platform for the sensitive detection of gallic acid and as a standard for the determination of total phenol. Four bismuth-based electrodes [...] Read more.

The synergistic combination of bismuth and its compounds with the exceptional properties of single-walled carbon nanotubes (SWCNT) was investigated as a sensing platform for the sensitive detection of gallic acid and as a standard for the determination of total phenol. Four bismuth-based electrodes were used for this purpose: SWCNT with bismuth (SWCNT/Bi) or bismuth (III) oxide (SWCNT/Bi₂O₃) and bismuth or bismuth (III) oxide electrodeposited on a glassy carbon electrode (ELF/Bi and ELF/Bi₂O₃), which were morphologically characterized by scanning electron microscopy. Cyclic voltammetry in phosphate electrolyte at different pH values revealed that the SWCNT/Bi₂O₃ electrode exhibited optimal performance for the analytical determination of gallic acid at pH 3. Surface-active carbon nanotubes facilitate the adsorption and accumulation of gallic acid, while the addition of Bi₂O₃ improves electron transfer, resulting in a synergistic enhancement of the oxidation signal. Square-wave voltammetry with SWCNT/Bi₂O₃ electrodes also provided reliable and accurate results and proved to be suitable for the quantitative determination of gallic acid with wide linearity (0.2–80 µM) and sensitivities of 12.5, 2.35, and 0.385 µA µmol⁻¹ dm³ for low, medium, and high concentration ranges, respectively. The limit of detection was 0.06 µmol dm⁻³. Finally, the electrode was successfully applied for gallic acid determination in various seeds. Full article

(This article belongs to the Special Issue Progress of Photoelectrochemical Analysis and Sensors)

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17 pages, 3452 KB

Open AccessArticle

Room Temperature Sub-ppm NO₂ Gas Sensor Based on Ag/SnS₂ Heterojunction Driven by Visible Light

by Ding Gu, Jun Dong, Wei Liu and Xiaogan Li

Chemosensors 2025, 13(10), 368; https://doi.org/10.3390/chemosensors13100368 - 10 Oct 2025

Abstract

As industrial waste gas, nitrogen dioxide (NO₂) is a serious hazard to air pollution and human health, and there is a pressing demand for developing high-performance NO₂ gas sensors. Tin disulfide (SnS₂), a representative two-dimensional metal sulfide characterized [...] Read more.

As industrial waste gas, nitrogen dioxide (NO₂) is a serious hazard to air pollution and human health, and there is a pressing demand for developing high-performance NO₂ gas sensors. Tin disulfide (SnS₂), a representative two-dimensional metal sulfide characterized by a significant specific surface area, a suitable electron band gap, and an easily tunable layered structure, shows a broad application prospect in gas sensing applications. Nevertheless, SnS₂-based gas sensors suffer from poor sensitivity, which seriously hinders their application in room temperature gas sensing. In this study, Ag/SnS₂ heterojunction nanomaterials were synthesized by an in situ reduction approach. The findings reveals that the gas-sensitive response of the Ag/SnS₂ nanocomposites at room temperature under visible light irradiation can achieve 10.5 to 1 ppm NO₂, with a detection limit as low as 200 ppb, which realizes the room-temperature detection of Sub-ppm NO₂. Meanwhile, the sensor exhibits good selectivity, reproducibility (cyclic stability > 95%). The improved gas sensitivity of the Ag/SnS₂ sensor can be due to the synergistic effect of the carrier separation at the Ag/SnS₂ Schottky junction and the localized surface plasmon resonance (LSPR) of Ag nanoparticles. The LSPR effect significantly enhances light absorption and surface-active site density, facilitating trace NO₂ detection at room temperature. This study provides the foundation for the subsequent development of room temperature layered metal sulfide gas sensors. Full article

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

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36 pages, 3836 KB

Open AccessReview

Carbon Nanotube-Based Chemical Sensors: Sensing Mechanism, Functionalization and Applications

by Jie Tang, Ruirui Li, Subhan Mahmood, Jiying Li and Shun Yao

Chemosensors 2025, 13(10), 367; https://doi.org/10.3390/chemosensors13100367 - 10 Oct 2025

Cited by 1

Abstract

Carbon nanotubes (CNTs) have opened new routes in the field of chemical sensing due to their unparalleled electrical conductivity, high surface area, and versatile functionalization capabilities. This review systematically examined the latest advancements in CNT-based chemical sensors, with a focus on their sensing [...] Read more.

Carbon nanotubes (CNTs) have opened new routes in the field of chemical sensing due to their unparalleled electrical conductivity, high surface area, and versatile functionalization capabilities. This review systematically examined the latest advancements in CNT-based chemical sensors, with a focus on their sensing mechanism, functionalization strategies, and applications. A spotlight was cast on the wide-ranging applications of CNT-based chemical sensors, spanning environmental analysis, drug detection, healthcare, food quality control, gases detection, strain sensing, etc. Finally, through a comprehensive SWOT analysis, the strengths, weaknesses, opportunities, and existing threats, along with emerging trends of CNTs in the sensing field, were elucidated. This review systematically summarized the applications of CNTs across six major fields, highlighting more than 60 CNT-based sensing materials. We aim to provide a forward-looking perspective on how CNTs will continue to shape the future of chemical sensing. Full article

(This article belongs to the Special Issue Application of Carbon Nanotubes in Sensing)

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16 pages, 5153 KB

Open AccessArticle

Fabrication and Characterization of a Portable and Electrochemical System for Field Determination of Nitrate in Coastal Seawater

by Xiaoling He, Hong Wei, Tian Ouyang, Ziwen Xu, Taoda Liu, Ying Cheng, Ziman Ma, Wenyan Tao and Dawei Pan

Chemosensors 2025, 13(10), 366; https://doi.org/10.3390/chemosensors13100366 - 9 Oct 2025

Abstract

Nitrate, as one of the important nutrients in seawater, influences the constant ratio of nitrogen to phosphorus, which is closely related to phytoplankton survival. In this work, a Cu-nanosphere-modified gold microwire electrode was used as the working electrode for determining nitrate in an [...] Read more.

Nitrate, as one of the important nutrients in seawater, influences the constant ratio of nitrogen to phosphorus, which is closely related to phytoplankton survival. In this work, a Cu-nanosphere-modified gold microwire electrode was used as the working electrode for determining nitrate in an artificial seawater sample with salinity of 35‰ by a differential pulse voltammetry technique. Under the optimized conditions, the detection linear range is from 1 μM to 2000 μM, the limit of detection is 0.33 μM, and the response time for a single sample is 5 min. Then, to reduce the influence of factors such as temperature, humidity, and microbial environment during sample transporting on the nitrate concentration in real seawater, a portable electrochemical system was introduced for on-site detection. Rapid field determination results show that nitrate levels correlate with tides, proving the portable system’s reliability. Full article

(This article belongs to the Special Issue Photoelectrochemical and Surface Plasmon Resonance Sensors: Current Status and Future Perspectives)

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16 pages, 2895 KB

Open AccessArticle

Reverse Titration Using Tablets for Accurate Water Hardness Measurement with Improved Resistance to Interference

by Chinonso Henry Ezeoke, Zubi Sadiq, Seyed Hamid Safiabadi Tali and Sana Jahanshahi-Anbuhi

Chemosensors 2025, 13(10), 365; https://doi.org/10.3390/chemosensors13100365 - 8 Oct 2025

Abstract

We report a novel tablet-based reverse titration system for rapid, point-of-use measurement of water hardness, overcoming key limitations of conventional EDTA titration. Reagents are encapsulated in pullulan matrix giving two separate tablets. The first tablet contains the Eriochrome black T (EBT) and N [...] Read more.

We report a novel tablet-based reverse titration system for rapid, point-of-use measurement of water hardness, overcoming key limitations of conventional EDTA titration. Reagents are encapsulated in pullulan matrix giving two separate tablets. The first tablet contains the Eriochrome black T (EBT) and N-cyclohexyl-3-aminopropanesulfonic acid (CAPS) buffer, while the second encapsulates ethylenediaminetetraacetic acid (EDTA) disodium salt dihydrate. The system employs a trimodal detection strategy: qualitative screening via immediate color change with the EBT tablet, semi-quantitative estimation through combined tablet dissolution and adjusting the sample volume to a reference level, and quantitative determination using reverse titration, where water is gradually added until the red wine endpoint appears. This approach enhances interference tolerance from competing metal ions and improves accuracy over traditional methods. Testing with real water samples showed excellent agreement with standard titration. The tablets remain stable for over seven months, and the system eliminates the need for skilled personnel, laboratory equipment, or bulky instrumentation. This low-cost, user-friendly, and interference-tolerant platform enables rapid and accurate water hardness assessment at the point of use. Full article

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

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16 pages, 2105 KB

Open AccessArticle

Synthesis of CSA-Capped Poly(aniline-co-aniline-2-sulfonic acid) Spherical Nanoparticles for Gas Sensor Applications

by Ki-Hyun Pyo, Ji-Sun Kim, Yoon Hee Jang and Jin-Yeol Kim

Chemosensors 2025, 13(10), 364; https://doi.org/10.3390/chemosensors13100364 - 4 Oct 2025

Abstract

We synthesized emeraldine salts of poly(aniline-co-aniline-2-sulfonic acid) capped with camphorsulfonic acid (CSA), forming spherical nanoparticles (NPs), i.e., CSA-capped P(ANi-co-ASNi), and demonstrated their efficacy as gas sensor elements. The synthesized core–shell spherical NPs, averaging 265 nm in diameter, feature a CSA shell with a [...] Read more.

We synthesized emeraldine salts of poly(aniline-co-aniline-2-sulfonic acid) capped with camphorsulfonic acid (CSA), forming spherical nanoparticles (NPs), i.e., CSA-capped P(ANi-co-ASNi), and demonstrated their efficacy as gas sensor elements. The synthesized core–shell spherical NPs, averaging 265 nm in diameter, feature a CSA shell with a porous thin-film morphology, characterized by the uneven distribution of fine particulate domains across the outer surface of the positively charged P(ANi-co-ASNi) cores. This uniquely heterogeneous shell architecture facilitates stable charge transport at the core–shell interface, enhances resistance to ambient humidity, and promotes efficient interaction with organic gas molecules. The CSA-capped P(ANi-co-ASNi) sensors reliably detected low concentrations of acetone (1–5 ppm) and water vapor (1–28% RH) under ambient conditions. Furthermore, the sensors exhibited superior stability across varying temperature, humidity, and cyclic performance, outperforming conventional pure PANiNi. Full article

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

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15 pages, 1190 KB

Open AccessArticle

Tropical Weathering Effects on Neat Gasoline: An Analytical Study of Volatile Organic Profiles

by Khairul Osman, Naadiah Ahmad Mazlani, Gina Francesca Gabriel, Noor Hazfalinda Hamzah, Rogayah Abu Hassan, Dzulkiflee Ismail and Wan Nur Syuhaila Mat Desa

Chemosensors 2025, 13(10), 363; https://doi.org/10.3390/chemosensors13100363 - 3 Oct 2025

Abstract

Gasoline is the most common ignitable liquid used to initiate fires, making its detection and identification in fire debris crucial for determining incendiary origins. Fire debris is typically collected after extinguishment and safety clearance, often resulting in gasoline weathering, especially when delayed. Most [...] Read more.

Gasoline is the most common ignitable liquid used to initiate fires, making its detection and identification in fire debris crucial for determining incendiary origins. Fire debris is typically collected after extinguishment and safety clearance, often resulting in gasoline weathering, especially when delayed. Most research on gasoline weathering has been conducted in controlled laboratory settings in temperate climates. However, the effects of tropical conditions on the rate of gasoline weathering and the resulting chemical composition of volatiles remain largely unexplored. Understanding how tropical environmental factors alter gasoline weathering is essential for accurate fire debris interpretation in such regions. This study investigates how tropical climates impact gasoline weathering indoors and outdoors. Weathered samples were prepared by volume reduction method, gradually evaporating gasoline from 10% to 95%. Indoor samples were exposed to room temperature, while outdoor samples were left in open space under natural tropical conditions. Gas Chromatography/Mass Spectrometry (GC-MS) analysis revealed chromatographic shifts in heavier compounds (C₃–C₄ alkylbenzenes) compared to lighter ones like toluene as weathering progressed. Correlation between indoor and outdoor samples was high (>0.970) at 10–50% weathering but declined (<0.600) at 90–95%, indicating differing patterns. All target compounds remained detectable across all samples. Full article

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

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13 pages, 4976 KB

Open AccessArticle

Nanostructured CeO₂-C Derived from Ce-BDC Precursors for Room-Temperature Ammonia Sensing

by Liang Wang, Manyi Liu, Shan Ren, Xiankang Zhong, Bofeng Bai, Shouning Chai, Chi He and Xinzhe Li

Chemosensors 2025, 13(10), 362; https://doi.org/10.3390/chemosensors13100362 - 3 Oct 2025

Abstract

The prompt and reliable detection of NH₃ leakage at room temperature (RT) is considered important for safety assurance and sustainable production. Although chemiresistive NH₃ sensors feature low cost and structural simplicity, their practical application is hindered by high operating temperatures and [...] Read more.

The prompt and reliable detection of NH₃ leakage at room temperature (RT) is considered important for safety assurance and sustainable production. Although chemiresistive NH₃ sensors feature low cost and structural simplicity, their practical application is hindered by high operating temperatures and inadequate selectivity. Metal–organic frameworks (MOFs) and their derivatives offer a promising approach to address these limitations. In this work, Ce-BDC precursors with tunable particle sizes and crystallinity were synthesized by adjusting the raw material concentration. Controlled pyrolysis yielded a series of CeO₂-C-X (X = 0.5, 1, 1.5, 2) materials with nanosized particles. Among them, the CeO₂-C-1 sensor delivered a high response of 82% toward NH₃ under 40% relative humidity at RT. Moreover, it possessed excellent selectivity, repeatability, and rapid response-recovery behavior compared with the other samples. CeO₂-C-1 also remained stable under varying oxygen and humidity conditions, demonstrating high applicability. The superior sensing properties may be attributed to its high specific surface area and optimized mesoporous structure, which facilitated efficient gas adsorption and reaction. These findings demonstrated that precise control of MOF precursors and the structure in CeO₂ nanomaterials was critical for achieving high-performance gas sensing and established Ce-MOF-derived CeO₂ as a promising sensing material for NH₃ detection at RT. Full article

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

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12 pages, 980 KB

Open AccessArticle

HS-SPME-GC-MS Volatile Profile of “Aglio Rosso di Sulmona” (Sulmona Red Garlic) Floral Scape

by Samantha Reale, Rossella Ferretti, Alessandra Biancolillo, Valter Di Cecco, Luciano Di Martino, Marco Di Santo and Angelo Antonio D’Archivio

Chemosensors 2025, 13(10), 361; https://doi.org/10.3390/chemosensors13100361 - 2 Oct 2025

Abstract

Garlic (Allium Sativum L.) is a source of organosulphur compounds with well-known sensorial and biological activity. Organosulphur precursors of garlic aroma are also detected in the plant leaves, but limited literature on this subject is available. This study is aimed at the [...] Read more.

Garlic (Allium Sativum L.) is a source of organosulphur compounds with well-known sensorial and biological activity. Organosulphur precursors of garlic aroma are also detected in the plant leaves, but limited literature on this subject is available. This study is aimed at the characterization of the volatile profile of the floral scapes of Sulmona red garlic (aglio rosso di Sulmona) cultivated in the Abruzzo region (Italy). Floral scapes are manually removed from the plant before flowering and used as an ingredient of local gastronomy. The organosulphur volatile profile of the scapes is investigated by HS-SPME-GC-MS and compared to that provided by the clove. The GC-MS chromatogram of garlic clove, which is characterized by the predominant contribution of a few organosulphur organic compounds, is significantly more intense than that of the scapes. Almost all the organosulphur compounds contributing to the clove aroma were detected in the scape volatile profile, which, however, exhibits a more balanced contribution of major and minor organo sulphur compounds. Moreover, a significantly higher relative abundance of terpenes and aldehydes is observed in the scape aroma. The geographical/varietal origin of clove seeds (Sulmona versus Spain or France) and cultivation area interactively influence the aroma profile of Sulmona red garlic scapes. Full article

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

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13 pages, 2151 KB

Open AccessArticle

Profiling Hydrogen-Bond Conductance via Fixed-Gap Tunnelling Sensors in Physiological Solution

by Biao-Feng Zeng, Canyu Yan, Ye Tian, Yuxin Yang, Long Yi, Shiyang Fu, Xu Liu, Cuifang Kuang and Longhua Tang

Chemosensors 2025, 13(10), 360; https://doi.org/10.3390/chemosensors13100360 - 2 Oct 2025

Abstract

Hydrogen bonding, a prevalent molecular interaction in nature, is crucial in biological and chemical processes. The emergence of single-molecule techniques has enhanced our microscopic understanding of hydrogen bonding. However, it is still challenging to track the dynamic behaviour of hydrogen bonding in solution, [...] Read more.

Hydrogen bonding, a prevalent molecular interaction in nature, is crucial in biological and chemical processes. The emergence of single-molecule techniques has enhanced our microscopic understanding of hydrogen bonding. However, it is still challenging to track the dynamic behaviour of hydrogen bonding in solution, particularly under physiological conditions where interactions are significantly weakened. Here, we present a nanoscale-confined, functionalised quantum mechanical tunnelling (QMT) probe that enables continuous monitoring of electrical fingerprints of single-molecule hydrogen bonding interactions for over tens of minutes in diverse solvents, including polar physiological solutions, which reveal reproducible multi-level conductance distributions. Moreover, the functionalised QMT probes have successfully discriminated between L(+)- and D(−)-tartaric acid enantiomers by resolving the conductance difference. This work uncovers dynamic single-molecule hydrogen bonding processes within confined nanoscale spaces under physiological conditions, establishing a new paradigm for probing molecular hydrogen-bonding networks in supramolecular chemistry and biology. Full article

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

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17 pages, 2793 KB

Open AccessArticle

Full-Spectrum LED-Driven Underwater Spectral Detection System and Its Applications

by Yunfei Li, Jun Wei, Shaohua Cheng, Tao Yu, Hong Zhao, Guancheng Li and Fuhong Cai

Chemosensors 2025, 13(10), 359; https://doi.org/10.3390/chemosensors13100359 - 1 Oct 2025

Abstract

Spectral detection technology offers non-destructive, in situ, and high-speed capabilities, making it widely applicable for detecting biological and chemical samples and quantifying their concentrations. Water resources, essential to life on Earth, are widely distributed across the planet. The application of spectral technology to [...] Read more.

Spectral detection technology offers non-destructive, in situ, and high-speed capabilities, making it widely applicable for detecting biological and chemical samples and quantifying their concentrations. Water resources, essential to life on Earth, are widely distributed across the planet. The application of spectral technology to underwater environments is useful for wide-area water resource monitoring. Although spectral detection technology is well-established, its underwater application presents challenges, including waterproof housing design, power supply, and data transmission, which limit widespread application of underwater spectral detection. Furthermore, underwater spectral detection necessitates the development of compatible computational methods for sample classification or regression analysis. Focusing on underwater spectral detection, this work involved the construction of a suitable hardware system. A compact spectrometer and LEDs (400 nm–800 nm) were employed as the detection and light source modules, respectively, resulting in a compact system architecture. Extensive tests confirmed that the miniaturized design-maintained system performance. Further, this study addressed the estimation of total phosphorus (TP) concentration in water using spectral data. Samples with varying TP concentrations were prepared and calibrated against standard detection instruments. Subsequently, classification algorithms applied to the acquired spectral data enabled the in situ underwater determination of TP concentration in these samples. This work demonstrates the feasibility of underwater spectral detection for future in situ, high-speed monitoring of aquatic biochemical indicators. In the future, after adding UV LED light source, more water quality parameter information can be obtained. Full article

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

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