Chemosensors

14 pages, 845 KB

Open AccessArticle

Electronic Nose Profiling of Pet Foods for Brand and Flavor Discrimination with Preference Analysis

by Viktória Éles, Haruna Gado Yakubu, György Kövér, Hedvig Fébel, Róbert Romvári and George Bazar

Chemosensors 2026, 14(8), 180; https://doi.org/10.3390/chemosensors14080180 - 7 Aug 2026

Abstract

Electronic nose (EN) technology, based on electrochemical sensor arrays, has emerged as a rapid and objective tool for aroma characterization in food systems. This study investigated factors influencing cat food preference using physicochemical analysis, texture measurement, preference testing, and EN technology. Nine (9) [...] Read more.

Electronic nose (EN) technology, based on electrochemical sensor arrays, has emerged as a rapid and objective tool for aroma characterization in food systems. This study investigated factors influencing cat food preference using physicochemical analysis, texture measurement, preference testing, and EN technology. Nine (9) commercial cat foods from three brands (A: premium; B and C: medium price) with different flavors were evaluated. Proximate analysis revealed no significant differences (p > 0.05) in most nutrients, except crude fiber (CF) (p < 0.05), which was higher in lower-priced cat foods. Shear force showed a positive correlation with consumption (r = 0.72), while CF was negatively correlated (r = −0.52). Preference tests indicated that Brand A was most preferred, followed by Brand C, while Brand B was least preferred. Principal component analysis (PCA) identified variability in individual cat preferences, and one outlier cat was excluded. Discriminant analysis of EN data showed clear separation by brand rather than flavor, suggesting brand-related aroma profiles can be monitored rapidly through the digital odor fingerprint. Cat food acceptance is mainly driven by texture, CF content, and aroma rather than macronutrient composition. The results of the EN evaluation of cat food samples revealed the same group similarities and differences as the 8-month preference test performed with cats. Similar to this study, EN classification models can be developed using food preference data and the digital aroma fingerprints of foods. After validations, the EN models can be used as an effective tool to monitor the quality and assess new diets according to the known preferred odor fingerprint. Full article

(This article belongs to the Special Issue Applications of Electronic Nose (E-Nose) and Electronic Tongue (E-Tongue) in Food Quality: 2nd Edition)

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20 pages, 15353 KB

Open AccessArticle

Interpretable Spectral Transformer for Raman-Based Bacterial Identification Across Species and Strains

by Yijian Meng, Jesper B. Christensen, Carsten Thirstrup, Lucia Ronda Rute, Konstantinos Stergiou, Danylo Komisar, Oleksii Ilchenko, Ditte Rask Tornby, Thomas Emil Andersen, Hüsnü Aslan and Mikael Lassen

Chemosensors 2026, 14(8), 179; https://doi.org/10.3390/chemosensors14080179 - 4 Aug 2026

Abstract

Raman spectroscopy combined with machine learning offers a rapid, label-free approach for bacterial identification, but robust translation remains challenged by spectral variability, biological heterogeneity, and limited model interpretability. Here, we present an integrated evaluation of an optimized Spectral Transformer (ST) framework for Raman-based [...] Read more.

Raman spectroscopy combined with machine learning offers a rapid, label-free approach for bacterial identification, but robust translation remains challenged by spectral variability, biological heterogeneity, and limited model interpretability. Here, we present an integrated evaluation of an optimized Spectral Transformer (ST) framework for Raman-based bacterial classification benchmarked against a systematically optimized one-dimensional convolutional neural network (1D-CNN). The comparison was performed using a curated 36-class dataset comprising 15 Gram-negative bacterial entries, 15 Gram-positive bacterial entries, one non-bacterial microorganism, and five background/reference classes, enabling evaluation of both species-level and fine-grained bacterial classification. Under 15 dB noise-augmented evaluation, the ST achieved 80.6% ± 0.3% accuracy and a Matthews correlation coefficient (MCC) of 0.801 ± 0.003, outperforming the 1D-CNN baseline with 72.9% ± 0.3% accuracy and an MCC of 0.721 ± 0.003. Integrated Gradients analysis combined with attention map visualization enabled multi-level model interpretation, revealing that the ST’s improved robustness correlates with more bounded attribution patterns during misclassification, whereas the 1D-CNN’s feature attribution becomes scattered under noise perturbation. Importantly, this interpretability-driven analysis identified model-specific failure modes in the baseline architecture, including an over-reliance on non-specific spectral regions under noise, which can inform future data collection strategies and guide refinements to experimental protocols. These results demonstrate that attention-based spectral modeling improves Raman-based bacterial classification under noise-perturbed conditions while enabling multi-level interpretability that bridges model understanding with actionable feedback on experimental design and data quality requirements. Full article

(This article belongs to the Special Issue Spectroscopic Techniques for Chemical Analysis, 2nd Edition)

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17 pages, 4235 KB

Open AccessArticle

Rapid High-Throughput Screening of Curdlan-Producing Mutants via a Microscale Aniline Blue Colorimetric Assay

by Jiangtao Tian, Min Sun, Zeyun Lu, Xuexia Yang, Deming Jiang, Zhongyi Chang and Hongliang Gao

Chemosensors 2026, 14(8), 178; https://doi.org/10.3390/chemosensors14080178 - 3 Aug 2026

Abstract

Curdlan is an industrially important β-1,3-glucan with applications in the food, pharmaceutical, and biomaterial industries. However, the identification of high-yielding curdlan-producing strains is hindered by the absence of rapid and efficient screening methods. To address this limitation, we developed a systematically optimized integrated [...] Read more.

Curdlan is an industrially important β-1,3-glucan with applications in the food, pharmaceutical, and biomaterial industries. However, the identification of high-yielding curdlan-producing strains is hindered by the absence of rapid and efficient screening methods. To address this limitation, we developed a systematically optimized integrated microscale workflow combining 48-well plate fermentation with a quantitative aniline blue-based colorimetric assay in 96-well plates for high-throughput screening of curdlan-producing strains. Fermentation was miniaturized using 48-well plates, while curdlan quantification was performed in 96-well plates through formation of a curdlan–aniline blue complex. Key parameters were systematically optimized. Under optimal conditions, curdlan dissolved in 1.0 mol/L NaOH was reacted with 2.0 mg/mL aniline blue in 0.5 mol/L phosphate buffer (pH 7.0) for 90 min, and absorbance was measured at 550 nm. The assay demonstrated excellent linearity between curdlan concentration and absorbance (y = 1.0008x + 0.1536, R² = 0.9957, p < 0.001). To validate the method, curdlan yields from nine mutants derived from ATCC31749 were determined using both gravimetric and colorimetric approaches, revealing a strong correlation (R² = 0.8683, p < 0.001), that confirmed the assay’s reliability for rapid screening. Application of this platform to 132 UV-mutagenized strains identified nine mutants with enhanced curdlan production. The best-performing strain, UV150824-02, produced 46.8 ± 0.08 g/L curdlan, an 11.4% increase over the wild-type strain ATCC31749 (41.6 ± 1.54 g/L), and maintained stable curdlan production over nine laboratory passages (coefficient of variation = 2.72%). This method significantly improves the efficiency of mutagenesis-based strain screening and provides a practical and efficient tool for accelerating strain improvement in industrial polysaccharide fermentation. Full article

(This article belongs to the Special Issue Recent Advances in Chemical Sensors for Biological Detection and Environmental Monitoring: Fundamental Science and Applications)

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45 pages, 3070 KB

Open AccessReview

Applications of Electronic Nose Technology in Tea Processing: A Comprehensive Review

by Guangyao Ying, Huili Xia and Jun Li

Chemosensors 2026, 14(8), 177; https://doi.org/10.3390/chemosensors14080177 - 3 Aug 2026

Abstract

Tea quality is fundamentally determined by the complex biochemical transformations occurring during manufacturing. Traditional sensory evaluation, while essential, suffers from inherent subjectivity and cannot meet the demands of modern, industrial-scale production monitoring. This review critically examines the application of electronic nose (E-nose) technology [...] Read more.

Tea quality is fundamentally determined by the complex biochemical transformations occurring during manufacturing. Traditional sensory evaluation, while essential, suffers from inherent subjectivity and cannot meet the demands of modern, industrial-scale production monitoring. This review critically examines the application of electronic nose (E-nose) technology throughout the tea-processing pipeline, covering multiple transducer technologies including metal oxide semiconductor (MOS) sensors, quartz crystal microbalance (QCM) sensors, conducting polymer (CP) sensors, and emerging chemiresistive platforms. Particular emphasis is placed on the E-nose’s capacity for real-time, non-destructive monitoring of key processing stages, including withering, rolling, fermentation, and drying. We analyze how optimized sensor arrays capture dynamic volatile organic compound (VOC) evolution, enabling the precise identification of optimal processing endpoints, especially in black tea fermentation control. Furthermore, this review evaluates how advanced pattern recognition algorithms (such as deep learning models) and multi-sensor data fusion strategies enhance the robustness and accuracy of process monitoring. By correlating E-nose response patterns with critical biochemical markers and traditional taster metrics, this paper demonstrates the technology’s pivotal role in transitioning tea manufacturing from experience-based craftsmanship to data-driven automation, ultimately ensuring superior product consistency and efficiency. Full article

(This article belongs to the Special Issue Gas Sensors: Recent Advances and Future Challenges)

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16 pages, 2023 KB

Open AccessArticle

Detection of Trace Fluoranthene in Marine Environments Using a PANI/Nano-Fe₃O₄-Based Immunosensor

by Xiaochun Han, Xuan Wang, Runze Liu, Junjie Yin, Zhiqiang Ai, Ruiyuan Xue, Qixue Liao and Huili Hao

Chemosensors 2026, 14(8), 176; https://doi.org/10.3390/chemosensors14080176 - 3 Aug 2026

Abstract

In this study, an electrochemical immunosensor based on polyaniline/nano-Fe₃O₄ (PANI/Nano-Fe₃O₄) nanocomposite (PANI/Nano-Fe₃O₄/Anti-FLA/BSA/GCE) was developed for the highly sensitive and selective detection of trace levels of fluoranthene (FLA) in marine environments. Fluoranthene antibodies [...] Read more.

In this study, an electrochemical immunosensor based on polyaniline/nano-Fe₃O₄ (PANI/Nano-Fe₃O₄) nanocomposite (PANI/Nano-Fe₃O₄/Anti-FLA/BSA/GCE) was developed for the highly sensitive and selective detection of trace levels of fluoranthene (FLA) in marine environments. Fluoranthene antibodies (Anti-FLA) were covalently immobilized on a glassy carbon electrode (GCE) modified with PANI/Nano-Fe₃O₄ via an EDC/NHS activation strategy, enabling specific recognition of FLA based on the antigen–antibody binding mechanism. The performance of the sensor was systematically optimized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV). The results demonstrated a linear inverse relationship between peak current (I_p) and FLA concentration in the range of 0.5~80 ng/mL, with a regression equation of I = −1.55C + 174.602 (R² = 0.996). The limit of detection (LOD) was as low as 0.354 ng/mL (S/N = 3). In real seawater sample analysis, spiked recovery tests at three representative sites in the Maowei Sea, Guangxi, yielded recoveries of 95.44%~97.51%, with RSDs below 3%, confirming the sensor’s resistance to matrix interference. The synergistic effect of the porous conductive network of PANI and the high specific surface area of Nano-Fe₃O₄ significantly amplified the electrochemical signal, while the molecular specificity of the antibody ensured targeted recognition. This sensor provides a novel and effective approach for the on-site rapid detection of polycyclic aromatic hydrocarbon (PAH) pollutants in complex marine environments, offering both high sensitivity and selectivity. Full article

(This article belongs to the Topic Electrochemical Analysis/Electrochemical Sensors in Bioanalytical Applications and Environmental Monitoring)

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13 pages, 12553 KB

Open AccessArticle

An Extended-Gate Ion-Sensitive Field-Effect Transistor Based on Aptamer Capture for Ultrasensitive Detection of Tetracycline in River Water Samples

by Qinwen Wang, Yiqing Wang, Yang Huang and Jidong Jiang

Chemosensors 2026, 14(8), 175; https://doi.org/10.3390/chemosensors14080175 - 3 Aug 2026

Abstract

The widespread use of tetracycline (TC) has resulted in its frequent occurrence in aquatic environments because of incomplete metabolism and continuous release, raising increasing concerns regarding water quality and environmental safety. Reliable determination of trace TC in real water samples remains challenging owing [...] Read more.

The widespread use of tetracycline (TC) has resulted in its frequent occurrence in aquatic environments because of incomplete metabolism and continuous release, raising increasing concerns regarding water quality and environmental safety. Reliable determination of trace TC in real water samples remains challenging owing to its low concentration and the complex sample matrix. In this work, an aptamer-functionalized extended-gate ion-sensitive field-effect transistor (EG-ISFET) was developed for sensitive TC detection. The sensing interface was constructed by immobilizing a TC-specific aptamer on a Ta₂O₅ extended gate. Upon target recognition, aptamer folding redistributes the interfacial charge, thereby modulating the surface potential of the extended gate and producing a measurable field-effect response. The proposed sensor exhibits a broad linear detection range from 1 pM to 1 μM with a detection limit of 0.33 pM. To facilitate practical applications, a compact plug-and-play point-of-care testing (POCT) platform integrating the EG-ISFET sensor was further developed for rapid on-site analysis. The portable system demonstrated satisfactory accuracy and reliability for the determination of TC in river water samples, highlighting its potential for environmental monitoring and point-of-use water quality assessment. 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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19 pages, 4242 KB

Open AccessArticle

Silver/Magnetite Modified Carbon Paste Electrode for Arsenic (III) Quantification

by Diana E. Soto-Nájera, María Teresa Alarcón-Herrera, José Rafael Irigoyen-Campuzano and Liliana Reynoso-Cuevas

Chemosensors 2026, 14(8), 174; https://doi.org/10.3390/chemosensors14080174 - 28 Jul 2026

Abstract

In this study, a carbon paste electrode modified with silver and magnetite nanoparticles was used to quantify arsenic via square-wave anodic stripping voltammetry. Under optimized parameters, a deposition potential of −0.4 V for a period of 70 s, the setup achieved a linear [...] Read more.

In this study, a carbon paste electrode modified with silver and magnetite nanoparticles was used to quantify arsenic via square-wave anodic stripping voltammetry. Under optimized parameters, a deposition potential of −0.4 V for a period of 70 s, the setup achieved a linear quantification range from 0 to 40 µg L⁻¹ of As (III) (R² = 0.982). Electrochemical characterization was performed using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The evaluated arsenic quantification framework encompasses the World Health Organization (WHO) limit and the Mexican maximum permissible level for arsenic in drinking water (10 µg L⁻¹), as well as arsenic concentrations frequently reported in groundwater wells throughout northern Mexico. Key advantages of this electrode include its low fabrication cost, ease of operation, and analytical stability spanning a 30-day period. Additionally, selectivity tests revealed that Cu(II) masked the arsenic stripping signal at a 1:1 Cu(II): arsenic concentration ratio, whereas no modification of the target signal was observed in the presence of cadmium. Full article

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

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28 pages, 52596 KB

Open AccessArticle

TCM-USP: An Adaptive and Interpretable Framework for Rapid, Traceable Preliminary Quantification of Active Constituents in Traditional Chinese Medicines Using Biomimetic Sensor Data

by Xuemei Yin, Pengfei Song, Xiao Luo, Yu Bai, Yuang Wang, Xin Hu, Haiyan Wang, Daji Ergu, Juanjuan Zhang and Fangyao Liu

Chemosensors 2026, 14(8), 173; https://doi.org/10.3390/chemosensors14080173 - 27 Jul 2026

Abstract

Biomimetic sensors offer a rapid route for estimating active constituent contents in Chinese medicinal materials, but their practical use at procurement sites and production workshops is constrained by small and skewed datasets, repeated task-specific model configuration, and the limited operational traceability of many [...] Read more.

Biomimetic sensors offer a rapid route for estimating active constituent contents in Chinese medicinal materials, but their practical use at procurement sites and production workshops is constrained by small and skewed datasets, repeated task-specific model configuration, and the limited operational traceability of many nonlinear models. This study proposes the Traditional Chinese Medicine Unified Sensor-based Prediction (TCM-USP) framework for traceable preliminary screening rather than confirmatory laboratory quantification. The same modeling workflow was applied across different medicinal material–sensor combinations and integrates controlled symbolic feature construction with density-aware robust partial least squares modeling. The framework was evaluated on six prediction tasks involving five medicinal materials and three sensor types. TCM-USP achieved higher

R^{2}

values than raw-feature PLS in all six tasks and achieved the highest

R^{2}

among the evaluated models in four tasks. Although SVR or GPR achieved higher

R^{2}

values in the remaining two tasks, TCM-USP generated compact prediction formulas directly expressed in terms of the original sensor readings, enabling independent calculation, audit, and rapid batch-level decision support. These results support the feasibility of TCM-USP for traceable preliminary screening across the investigated small-sample and low-dimensional sensor tasks, while pharmacopoeial methods remain necessary for confirmatory quantification. Full article

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

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29 pages, 9523 KB

Open AccessArticle

N,S-Donor Triazole–Thione-Modified Graphite Paste Electrode for Selective Voltammetric Detection of Cu(II) in Environmental Waters

by Nigora Qutlimurotova, Dilsora Axmadova, Dilnoza Ismailova, Jasur Tursunqulov, Rukhiya Qutlimurotova, Lola Yusupova, Sholpan Yespenbetova and Nargiza Atakulova

Chemosensors 2026, 14(8), 172; https://doi.org/10.3390/chemosensors14080172 - 25 Jul 2026

Abstract

A simple and cost-effective graphite paste electrode modified with 5-(4-aminophenyl)-4-amino-1,2,4-triazole-3(2H)-thione was developed for the selective voltammetric determination of Cu(II) ions in environmental water samples. The N,S-donor ligand was [...] Read more.

A simple and cost-effective graphite paste electrode modified with 5-(4-aminophenyl)-4-amino-1,2,4-triazole-3(2H)-thione was developed for the selective voltammetric determination of Cu(II) ions in environmental water samples. The N,S-donor ligand was incorporated into a graphite–polystyrene matrix without the use of nanomaterials, providing a reproducible and straightforward electrode fabrication route. Scanning electron microscopy revealed a rough, porous surface morphology with an enhanced electroactive surface area of 0.065 cm², approximately twice the geometric area. Electrochemical impedance spectroscopy confirmed diffusion-controlled mass transport, while cyclic voltammetry indicated quasi-reversible behaviour of the Cu(II)/Cu(0) redox system with a linear dependence of peak current on the square root of the scan rate. Differential pulse voltammetry under optimised conditions (0.1 mol·L⁻¹ H₂SO₄, pH 1.0–1.2) yielded a linear analytical response over the concentration range of 0.01–0.4 μmol·L⁻¹ (R² = 0.99507), with a limit of detection of 0.02 μmol·L⁻¹ and a limit of quantification of 0.06 μmol·L⁻¹—well below the WHO guideline for copper in drinking water. The sensing mechanism involves selective N,S-bidentate coordination of Cu(II) at the electrode surface, followed by electrochemical reduction, as supported by FT-IR spectroscopic evidence. The sensor demonstrated good selectivity toward Cu(II) in the presence of common interfering metal ions at up to 20-fold excess. The method was successfully validated against ICP-OES (recovery 99.8%, RSD < 0.33%) and confirmed by spike–recovery experiments (99.0–99.5%), confirming its practical applicability for trace-level environmental monitoring. The modified electrode retained approximately 93% of its initial response after 30 consecutive measurements and 91% after 14 days of storage, demonstrating good operational stability. Full article

(This article belongs to the Topic Electrochemical Analysis/Electrochemical Sensors in Bioanalytical Applications and Environmental Monitoring)

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17 pages, 10402 KB

Open AccessArticle

In Situ Fabrication of Controlled Porous Manifold Coupled with Non-Planar Microelectrodes for Microfluidic Biosensors

by Najamuddin Naveed Khaja, Sushma Yadav, Niranjan Haridas Menon, Sreerag Kaaliveetil, Guangliang Liu, Yu-Hsuan Cheng, Kathleen McEnnis and Sagnik Basuray

Chemosensors 2026, 14(8), 171; https://doi.org/10.3390/chemosensors14080171 - 25 Jul 2026

Abstract

The demand for a versatile and portable point-of-use (POU) sensor platform has surged due to the pandemic, especially in countries with limited medical laboratory facilities. We recently unveiled a portable, non-planar, interdigitated, flow-through, porous electrode platform that automatically measures electrochemical impedance spectroscopy (EIS) [...] Read more.

The demand for a versatile and portable point-of-use (POU) sensor platform has surged due to the pandemic, especially in countries with limited medical laboratory facilities. We recently unveiled a portable, non-planar, interdigitated, flow-through, porous electrode platform that automatically measures electrochemical impedance spectroscopy (EIS) signals from various biomarkers. However, the packed powder exhibited a loss of performance over time due to displacement, leaching, and poor stability. Herein, we modified the packing strategy by synthesizing the sensing material within the channel, thereby improving adhesion, structural integrity, and stability. Leveraging the exceptional thermal stability, mechanical strength, and chemical resistance of polyimide (PI), we developed a novel fabrication approach that combines liquid-phase inversion and breath-figure techniques to create a porous PI manifold with single-walled carbon nanotubes (SWCNTs) under varying humidity conditions. Scanning electron microscope (SEM) analysis revealed that lower relative humidity (RH) conditions yield larger but less uniformly distributed pores, leading to increased channel pressure. The manifold demonstrated exceptional stability under rigorous flow conditions, withstanding a high flow rate of 30 µL/min while maintaining consistent pressure-EIS responses. The device produced a measurable proof-of-concept impedance response following exposure to a femtomolar concentration of complementary target ssDNA in 1× PBS within 15 min. A formal limit of detection was not determined in the present study. We developed a mechanically stable sensor design with improved durability under repeated flow conditions by systematically optimizing synthesis conditions and manifold configuration. This innovative fabrication strategy demonstrates the importance of packing methodology in sensor design and paves the way for robust, scalable, and efficient diagnostic solutions in resource-limited settings. Full article

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

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31 pages, 2382 KB

Open AccessReview

Aptamer/Nanozyme Chemical Sensors for On-Site Glyphosate Determination in Agricultural Runoff: Classification, Operating Principles, and Analytical Applicability

by Meiqing Jin, Qingwei Zhou and Li Fu

Chemosensors 2026, 14(8), 170; https://doi.org/10.3390/chemosensors14080170 - 23 Jul 2026

Abstract

This critical perspective review first classifies glyphosate-sensing platforms and then evaluates their analytical applicability to agricultural runoff. Platforms are divided at the primary level into optical and electrochemical transduction, because these families measure different physical signals and have different sources of matrix interference. [...] Read more.

This critical perspective review first classifies glyphosate-sensing platforms and then evaluates their analytical applicability to agricultural runoff. Platforms are divided at the primary level into optical and electrochemical transduction, because these families measure different physical signals and have different sources of matrix interference. They are then grouped by the process that produces selectivity or signal change: direct interaction or metal coordination, affinity recognition by aptamers, antibodies, or molecularly imprinted polymers, catalytic modulation by enzymes or nanozymes, and separation or preconcentration before detection. This hierarchy distinguishes recognition chemistry from transduction method and device configuration. The review next defines four intended analytical applications—trace surveillance, runoff event screening, spill triage, and laboratory-adjacent confirmation—and compares them in terms of matrix, target concentration range, sample preparation, reporting metrics, and quality control requirements. Glyphosate occurs in dissolved and particle-associated forms, degrades mainly to AMPA, and coexists with phosphate, glufosinate, divalent cations, natural organic matter, and suspended sediment. Consequently, the lowest reported LOD is rarely the sole criterion for selecting a method. Matrix-matched calibration, spike recovery, selectivity, response time, storage stability, reader requirements, and invalid result rules determine whether an assay is suitable for a specified analytical application. The most defensible near-term approach combines matrix-specific sample preparation, platform-specific controls, and LC-MS/MS confirmation when results are regulatory, contested, or close to a decision threshold. Full article

(This article belongs to the Special Issue Chemical Sensors for Bio-Medical and Environmental Applications, 3rd Edition)

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13 pages, 6812 KB

Open AccessArticle

Preventing Drug-Facilitated Sexual Assault: A Smartphone-Readout Lateral Flow Assay for GBL Detection in Water and Saliva

by Jordi Roig-Rubio, Carmen Coll, Salvador Gil, Pau Arroyo, José A. Sáez and Pablo Gaviña

Chemosensors 2026, 14(7), 169; https://doi.org/10.3390/chemosensors14070169 - 21 Jul 2026

Abstract

The rising prevalence of Drug-Facilitated Sexual Assault (DFSA) underscores the urgent need for rapid, sensitive, and selective analytical tools. Among the most concerning substances are γ-hydroxybutyric acid (GHB) and its precursor γ-butyrolactone (GBL), both of which pose significant forensic challenges due to their [...] Read more.

The rising prevalence of Drug-Facilitated Sexual Assault (DFSA) underscores the urgent need for rapid, sensitive, and selective analytical tools. Among the most concerning substances are γ-hydroxybutyric acid (GHB) and its precursor γ-butyrolactone (GBL), both of which pose significant forensic challenges due to their rapid metabolism and narrow detection windows. While detection methods for GHB have advanced, the monitoring of GBL remains less explored. This study reports the extended application of a fluorescein-based chemosensor previously validated for GHB for the selective detection of GBL in aqueous media and synthetic saliva. The probe operates via fluorescence quenching proportional to GBL concentration, achieving detection limits well below toxicological thresholds. Mechanistic investigations reveal that the recognition process is driven by an acid–base equilibrium and the reversible opening of the fluorescein lactone ring, with the 2-aminonaphthoxazole moiety playing a pivotal role. The sensor exhibits high selectivity against common DFSA-related interferents. Furthermore, the system was integrated into a portable lateral flow assay coupled with a smartphone-based readout, providing a cost-effective and user-friendly platform. Meeting the WHO “ASSURED” criteria, this methodology represents a promising tool for forensic, clinical, and preventive applications against chemical submission. Full article

(This article belongs to the Section Applied Chemical Sensors)

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14 pages, 4539 KB

Open AccessArticle

A Co²⁺ Fluorescent Probe Based on Surface Complexation for On-Site Feed Detection

by Jingjing He, Min Ye, Huiting Lian and Xuexia Lin

Chemosensors 2026, 14(7), 168; https://doi.org/10.3390/chemosensors14070168 - 16 Jul 2026

Abstract

As a core component of vitamin B12, Co²⁺ is closely associated with the health, life performance, and productivity of ruminants. Therefore, the selective and sensitive detection of Co²⁺ is of great significance. In this work, using the Au–S bond as an [...] Read more.

As a core component of vitamin B12, Co²⁺ is closely associated with the health, life performance, and productivity of ruminants. Therefore, the selective and sensitive detection of Co²⁺ is of great significance. In this work, using the Au–S bond as an “anchor”, a ternary nanocomposite (CDs-AuNPs-GSH) with synergistic functions was constructed by combining gold nanoparticles (AuNPs) with glutathione (GSH) through hydrogen bonding and electrostatic interactions with functional groups on the surface of carbon dots (CDs). The resulting nanocomposite was employed as a fluorescence sensor for Co²⁺ detection. Under optimal conditions at pH 6.0, the sensor exhibited a good linear relationship over the Co²⁺ concentration range of 0.5–125.0 mM, with a limit of detection (LOD) of 0.38 mM. The interaction mechanism between Co²⁺ and the composite was systematically investigated using various characterization methods. The results indicated that Co²⁺, owing to its strong coordination ability, enriches on the surface of the composite, subsequently triggering dynamic fluorescence quenching via an electron transfer pathway. The sensor was successfully applied to determine Co²⁺ in mixed livestock and poultry feed samples, with recovery rates ranging from 89.4% to 103.9%, demonstrating its potential for on-site detection in feed analysis. Full article

(This article belongs to the Special Issue Fluorescent Probes for Highly Sensitive Ion and Compound Detection)

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16 pages, 830 KB

Open AccessArticle

Geographical and Seasonal Differentiation Along with Quality Evaluation of Lavender Essential Oil Through Volatile Profiling

by Cornelia Veronica Floare-Avram, Olivian Marincas, Dana Alina Magdas and Ioana Feher

Chemosensors 2026, 14(7), 167; https://doi.org/10.3390/chemosensors14070167 - 16 Jul 2026

Abstract

The study aimed to characterize Romanian lavender essential oils (LEOs) according to geographical regions and harvested years by combining gas chromatography–mass spectrometry (GC/MS) with chemometric analysis and quality evaluation. Sixty-four LEO samples were collected from three Romanian areas (Moldova, Transylvania, Muntenia) during three [...] Read more.

The study aimed to characterize Romanian lavender essential oils (LEOs) according to geographical regions and harvested years by combining gas chromatography–mass spectrometry (GC/MS) with chemometric analysis and quality evaluation. Sixty-four LEO samples were collected from three Romanian areas (Moldova, Transylvania, Muntenia) during three consecutive years (2023–2025). GC–MS profiling identified 45 volatile compounds, with linalool, linalyl acetate, 1,8-cineole as predominant constituents. Oil quality was assessed using both a quality scoring algorithm based on characteristic volatile compounds and compliance with the ISO 3515:2002 standard. Most samples were classified as very good quality according to the proposed quality score, whereas only three samples fully complied with all ISO requirements. Pearson correlation analysis revealed significant positive associations among several biosynthetically related compounds, indicating identical variation within the volatile fingerprint. Linear discriminant analysis (LDA) successfully discriminated samples according to both geographical origin and harvest year, identifying characteristic combinations of volatile compounds responsible for sample classification. The results demonstrate that the overall volatile fingerprint, rather than individual compounds, provides a reliable basis for the authentication and differentiation of Romanian lavender essential oils. The combined GC–MS and chemometric approach represents an effective tool for quality evaluation, geographical traceability and authenticity assessment of lavender essential oils. Full article

(This article belongs to the Special Issue Advanced Chemometric Methods for Analytical Applications)

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18 pages, 18384 KB

Open AccessArticle

Enhanced Oxygen Vacancies in Ni-Doped SnO₂ Nanorods via Aerosol-Assisted Chemical Vapor Deposition for Low-Concentration Hydrogen Detection

by Peng Chen, Xin Zhang, Jiacheng Liu, Xu Li, Min Chen and Qingji Wang

Chemosensors 2026, 14(7), 166; https://doi.org/10.3390/chemosensors14070166 - 15 Jul 2026

Abstract

Hydrogen is a clean energy carrier essential for carbon neutrality, but its invisible and odorless nature poses significant safety risks, particularly during low-concentration leaks. Although metal oxide semiconductor (MOS) sensors offer fast response and high sensitivity, their ability to detect ppb-level hydrogen remains [...] Read more.

Hydrogen is a clean energy carrier essential for carbon neutrality, but its invisible and odorless nature poses significant safety risks, particularly during low-concentration leaks. Although metal oxide semiconductor (MOS) sensors offer fast response and high sensitivity, their ability to detect ppb-level hydrogen remains limited. In this work, we present a high-performance hydrogen gas sensor based on nickel-doped tin dioxide (Ni-SnO₂) nanorods, directly grown on planar electrodes via aerosol-assisted chemical vapor deposition (AACVD). By optimizing the Ni doping ratio and nanorod morphology, the 3 wt% Ni-SnO₂ sensor achieves a low detection limit of 100 ppb for H₂, demonstrating promising potential for low-concentration hydrogen detection. Moreover, the sensor exhibits outstanding selectivity, with a response to 100 ppm H₂ nearly six times higher than that to the next most responsive interfering gas (NH₃). Comprehensive XPS and Raman analyses reveal that Ni doping introduces abundant oxygen vacancies and lattice defects, which are the key origins of the enhanced sensing performance. Notably, the 3 wt% Ni-SnO₂ sensor strikes an optimal balance between lattice defects and structural stability, delivering both high sensitivity and good moisture resistance with minimal baseline drift over weeks of operation. This work establishes a facile and scalable AACVD strategy for engineering defect-rich SnO₂ nanostructures, enabling sub-ppm hydrogen detection with high selectivity and long-term stability—addressing a critical gap in practical hydrogen safety monitoring. Full article

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

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4 pages, 167 KB

Open AccessEditorial

Colorimetric and Fluorescent Sensors: Current Status and Future Development

by Kien Wen Sun and Muthaiah Shellaiah

Chemosensors 2026, 14(7), 165; https://doi.org/10.3390/chemosensors14070165 - 15 Jul 2026

Abstract

Chemosensors for diverse analytes have become a significant research topic experiencing innovative real-time development [...] Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensors: Current Status and Future Development)

36 pages, 10377 KB

Open AccessReview

Sensing and Optical Imaging of Ferroptosis-Related Molecular Events in Acute Ischemic Stroke: Mechanisms, Technologies and Translational Perspectives

by Ru Wang, Jinghang Li, Siqi Huang, Yuguang Lv, Zhiling Hou and Nuan Wen

Chemosensors 2026, 14(7), 164; https://doi.org/10.3390/chemosensors14070164 - 14 Jul 2026

Abstract

Reperfusion after acute ischemic stroke (AIS) triggers a series of ferroptosis-related molecular events, including iron dyshomeostasis, oxidative/nitrative stress, antioxidant depletion, and membrane lipid peroxidation. Conventional ferroptosis assays mainly rely on ex vivo or endpoint measurements, limiting their ability to dynamically monitor the spatiotemporal [...] Read more.

Reperfusion after acute ischemic stroke (AIS) triggers a series of ferroptosis-related molecular events, including iron dyshomeostasis, oxidative/nitrative stress, antioxidant depletion, and membrane lipid peroxidation. Conventional ferroptosis assays mainly rely on ex vivo or endpoint measurements, limiting their ability to dynamically monitor the spatiotemporal evolution of these events during ischemia–reperfusion. Recent advances in chemical sensing and optical imaging have enabled in situ detection of key ferroptosis-related nodes, such as Fe²⁺/labile iron pool, ROS/ONOO⁻, GSH/Cys/GPX4, H₂S/Cys–Met metabolism, and lipid peroxidation. In this review, we summarize sensing targets, reaction-based probe design, near-infrared and two-photon imaging, photoacoustic imaging, and multimodal validation strategies for AIS-related ferroptosis. Representative probes for H₂O₂, ONOO⁻, H₂S, Fe²⁺, and lipid peroxidation are discussed in the context of cellular models, oxygen-glucose deprivation/reoxygenation, middle cerebral artery occlusion/reperfusion, and in vivo brain imaging. We emphasize that a single probe signal cannot independently confirm ferroptosis and should be interpreted together with GPX4/ACSL4 alterations, MDA/4-HNE levels, tissue injury, neurological outcomes, and Fer-1/Lip-1 rescue experiments. Finally, we discuss current challenges, including limited tissue penetration, blood–brain barrier delivery, quantitative stability, probe safety, and clinical translation, and highlight future directions involving ratiometric, NIR/NIR-II, two-photon, multitarget, and imaging-guided validation strategies. Full article

(This article belongs to the Special Issue Advanced Optical Imaging Technologies and Fluorescent Probes)

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23 pages, 10805 KB

Open AccessReview

Functional Materials for Molecular POCT in Infectious Disease Detection: Advances and Regulatory Perspectives

by Yan Tan, Haonan Wu, Junjun Lan, Ting Qian, Xin Zhou, Shiyang Zhao and Hui Wang

Chemosensors 2026, 14(7), 163; https://doi.org/10.3390/chemosensors14070163 - 14 Jul 2026

Abstract

On-site nucleic acid analysis for infectious diseases can be rapidly achieved through molecular point-of-care testing (molecular POCT), which plays an indispensable role in early pathogen identification, timely clinical intervention, and public health emergency response. Performance improvements in such systems are largely driven by [...] Read more.

On-site nucleic acid analysis for infectious diseases can be rapidly achieved through molecular point-of-care testing (molecular POCT), which plays an indispensable role in early pathogen identification, timely clinical intervention, and public health emergency response. Performance improvements in such systems are largely driven by innovations in functional materials that refine nucleic acid extraction, amplification, and signal output. This article reviews recent developments in functional materials deployed in molecular POCT, with emphasis on nucleic acid capture matrices, amplification-promoting agents, and signal transduction components. From a medical device regulatory standpoint, we examine how material characteristics shape key analytical indicators, including sensitivity and specificity, and discuss critical risks such as off-target amplification and batch inconsistency. Finally, we outline future directions, highlighting cross-disciplinary cooperation to reconcile technological innovation with risk control for translating advanced materials into high-performance molecular POCT products. Full article

(This article belongs to the Special Issue Rapid Point-of-Care Testing Technology and Application (Second Edition))

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14 pages, 3157 KB

Open AccessArticle

COC Chip-Integrated Zinc Finger Protein Array for PCR-Free Detection of RASSF1A Promoter Methylation

by Hye Yeon Jang, Sthitodhi Ghosh, Chong H. Ahn, Narendhar Chandrasekar, Michael Taeyoung Hwang and Moon-Soo Kim

Chemosensors 2026, 14(7), 162; https://doi.org/10.3390/chemosensors14070162 - 13 Jul 2026

Abstract

The detection of RASSF1A (Ras-associated domain family 1 isoform A) promoter methylation in body fluids can offer a powerful tool for the early diagnosis of bladder cancer. Zinc finger proteins (ZFPs) serve as sequence-specific recognition elements for targeting double-stranded DNA sequences. Here, we [...] Read more.

The detection of RASSF1A (Ras-associated domain family 1 isoform A) promoter methylation in body fluids can offer a powerful tool for the early diagnosis of bladder cancer. Zinc finger proteins (ZFPs) serve as sequence-specific recognition elements for targeting double-stranded DNA sequences. Here, we report a cyclic olefin copolymer (COC) chip-integrated ZFP array-based molecular sensor that bypasses the need for bisulfite conversion and PCR amplification to recognize the specific site of DNA methylation in the RASSF1A promoter. Building upon the SEER-LAC (SEquence-Enabled Reassembly of β-Lactamase) framework, we engineered a dual-recognition split-enzyme system in which a COC chip-immobilized ZFP array confers sequence specificity while a co-recruited methyl-binding domain (MBD) enforces methylation-dependent gating, together driving the proximity-induced reconstitution of functional β-lactamase at methylated target loci. Accordingly, this sensor specifically reassembles and restores enzymatic activity only in the presence of specific methylated DNA in the RASSF1A promoter region. We demonstrate that this dual-component array effectively differentiates methylation status with high specificity. Given its rapid turnaround and non-PCR-based mechanism, this system can be well-suited for developing diagnostic assays for bladder cancer, offering a potential alternative to conventional epigenetic screening methods. Full article

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

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