Chemosensors doi: 10.3390/chemosensors14060136

Authors: Zhenyu Wang Yu Mu Haizhen Ding Yuxin Wang Jing Zhao

Triethylamine (TEA), a widely used volatile organic compound (VOC), poses severe threats to environmental safety and human health upon accidental leakage, making the development of high-performance TEA detection techniques urgently needed. Herein, we report a Sn-based metal–organic framework (Sn-MOF) constructed from 4,5-dichloroimidazole ligands synthesized via a solvothermal approach. The resulting MOF-derived SnO2 materials were obtained by calcination at 400–600 °C, yielding SnO2 with tunable specific surface area and surface defect-site density. Structural and surface characterizations revealed that the materials consist of primary nanoparticles in the range of 10–50 nm, forming aggregated particles of 1–2 µm. The gas sensing performance toward TEA was systematically evaluated. The SnO2-400 °C sensor exhibited the highest response (S = 85.0) to 100 ppm TEA at 190 °C, with a low detection limit of 1 ppm, superior selectivity, good repeatability, and excellent long-term stability. The observed performance variation was attributed to the combined effects of specific surface area, abundant defect-associated surface sites, and suitable mesoporous structure. This work not only provides a high-performance TEA sensor for industrial and food safety monitoring but also offers a rational strategy for designing MOF-derived metal oxide gas sensors with tailored microstructures and surface defect chemistry.

Chemosensors doi: 10.3390/chemosensors14060137

Authors: Nada K. H. Alzahrani Naha Meslet Alsebaii Fatmah M. Alshareef Azhaar T. Alsaggaf Mohamed A. El Hamd A. Al Solami Najwa Ali Asiri Eman Alsolmy Wejdan T. Alsaggaf

A pyranochromene-based ligand, 2-amino-4-(4-chlorophenyl)-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-carbonitrile (ACLPh-PC-3-CN), was employed as a chelating modifier for the electrochemical determination of Cd(II) in water samples. ACLPh-PC-3-CN was co-immobilized with Nafion on a glassy carbon electrode to form a stable ACLPh-PC-3-CN/Nafion film that combines ligand-based coordination with cation-exchange-assisted preconcentration of Cd2+ at the electrode surface. The Cd(II) response at the modified electrode was characterized by cyclic voltammetry and differential pulse anodic stripping voltammetry, and the data support a predominantly 1:1 Cd(II)–ligand interaction at the interface under the selected conditions. At an optimized pH of 6.0, the sensor provided a linear calibration range from 16.21 to 56.72 μM, with a detection limit of 0.60 μM and a quantification limit of 2.0 μM, and showed good precision (repeatability 2.3% RSD, reproducibility 3.1% RSD) and short-term stability (94% of the initial response after 14 days). The ACLPh-PC-3-CN/Nafion-modified electrode tolerated common inorganic ions and surfactant species (≤5% signal change) and was successfully applied to the determination of Cd(II) in tap water and Red Sea water, affording recoveries between 98.7% and 101%. While the current detection limit is higher than typical guideline values for Cd in drinking water, the proposed sensor compares favorably with several reported electrochemical Cd(II) sensors in terms of simplicity, precision, and matrix tolerance, and represents a useful platform for coordination-based electrochemical sensing of cadmium in environmental water samples.

Chemosensors doi: 10.3390/chemosensors14060135

Authors: Alfonso Shin Marc J. Madou Lawrence Kulinsky Elliot E. Hui Rie Nakajima Philip Felgner

The rapid emergence of SARS-CoV-2 variants underscores the need for accurate, rapid, and affordable diagnostic tools, particularly in resource-limited settings. An isothermal amplification-based assay was developed integrating reverse-transcriptase recombinase polymerase amplification (RT-RPA), T7 transcription, and duplex-specific nuclease (DSN)-mediated detection for variant discrimination. The assay targets three genomic regions: a conserved region within ORF1a and two variant regions, ORF1a (Δ3675–3677) and the S gene (Δ69–70), enabling differentiation between the Wuhan-Hu-1 reference isolate and the B.1.1.7 variant. The method demonstrated high specificity and a limit of detection of 200 copies per sample using low-cost instrumentation. DSN-mediated cleavage improved discrimination between matched and mismatched RNA targets while enabling signal amplification through target recycling. The assay requires minimal laboratory infrastructure, relying on a heat block and fluorescent plate reader. These results demonstrate a scalable and cost-effective strategy for SARS-CoV-2 variant screening with potential as a future strategy for pathogen screening and variant surveillance.

Chemosensors doi: 10.3390/chemosensors14060134

Authors: Jiayi Guo Hong-Bo Cui Dong Liu Chunzhi Li Guijian Guan Ming-Yong Han

Benefiting from tunable emission from ultraviolet to near-infrared windows, long luminescence lifetimes, and exceptional photostability, rare earth (RE)-doped nanomaterials overcome the limitations of conventional dyes and quantum dots, enabling deep-tissue, high-resolution, and low-background imaging. As multifunctional fluorescent probes, RE-doped nanomaterials are driving the development of next-generation biomedical imaging. This review summarizes recent advances in the structural design of RE-doped nanomaterials, surface engineering for biocompatibility, and targeting strategies for improved performance, and highlights their integration into advanced imaging modalities, including NIR-I/II fluorescence, FLIM, PAI, super-resolution STED, multimodal FL/MRI/CT, X-ray-excited luminescence, and persistent luminescence. Meanwhile, mechanistic insights, material innovations, and comparative advantages are discussed. Furthermore, challenges related to quantum yield, scalable synthesis, imaging resolution, and clinical translation are considered, while future directions—centered on multifunctional probe design, NIR-II imaging, and AI-assisted data analysis—are proposed, offering a versatile platform for precise multimodal imaging with significant potential to advance early diagnosis, personalized therapy, and clinical applications.

Chemosensors doi: 10.3390/chemosensors14060133

Authors: Liqin Cui Kun Fan Jia Ma Yun Lu Yanfang Wang Jiao Yang

Melamine, characterized by its high nitrogen content, has been illegally added to food and feed to falsely increase apparent protein levels. However, melamine and its metabolites pose serious risks to human and animal health, including kidney stones, renal failure, and even death, as well as potential carcinogenic effects. Therefore, accurate detection of trace melamine is of great importance and urgency. Electrochemical sensors based on nanomaterials have been widely used for melamine detection due to their high sensitivity, good selectivity, rapid response, and simple operation. In this work, a composite nanosheet-structured electrode was fabricated, and a dense layer of gold nanoparticles was modified on its surface to enhance electrochemical performance. Cyclic voltammetry and electrochemical impedance spectroscopy measurements indicated that this electrode exhibited highly sensitive electrochemical properties. In addition, differential pulse voltammetry was employed for melamine detection, and the results showed a wide linear range of 20–500 nM with an LOD of 4.7 nM. The proposed electrode enabled the detection of melamine in milk samples, exhibiting good anti-interference ability and long-term stability.

Chemosensors doi: 10.3390/chemosensors14060132

Authors: Rafael Mendes Coelho Thaís Machado Lima Patrick Wander Endlich Priscila Izabela Soares Ângelo Rafael Machado Geycson Figueiredo Dias Arnaldo César Pereira Diego Leoni Franco Lucas Franco Ferreira

Hormones regulate numerous physiological processes and are essential for maintaining metabolic homeostasis. Accurate hormone quantification is crucial for the diagnosis and monitoring of endocrine and metabolic disorders. Electrochemical biosensors have recently emerged as promising platforms for hormone detection, offering simplicity, rapid response, cost-effectiveness, and high sensitivity compared to conventional techniques such as chromatography and mass spectrometry. This review summarizes the advances in electrochemical biosensors for detecting clinically relevant hormones, including cortisol, estrogen, progesterone, thyroid-stimulating hormone, parathyroid hormone, prolactin, and insulin, since 2010. Particular attention has been paid to developments in electrode modification strategies, including nanomaterials, redox enzymes, and novel recognition elements, which significantly improve the sensitivity and selectivity. These advances enable hormone detection at lower concentrations in various biological and environmental matrices. Despite these promising developments, challenges related to sensor stability, fabrication costs, and regeneration procedures limit their large-scale commercialization. Future research should focus on improving robustness, optimizing immobilization strategies, and integrating innovative materials to enhance the analytical performance. Continued collaboration among researchers, engineers, and healthcare professionals is essential. With ongoing technological progress, electrochemical biosensors are expected to play an important role in clinical diagnosis, point-of-care testing, and personalized medicine.

Chemosensors doi: 10.3390/chemosensors14060131

Authors: Yanting Tang Jingyao Liu Bowen Zhou Lanpeng Guo Hua-Yao Li Huan Liu

Colloidal quantum dots (CQDs) are ideal for room-temperature gas sensors due to their high surface area, abundant dangling bonds, and excellent film-forming properties. However, the underlying conduction mechanism remains unclear, lacking in-depth analysis of gas–solid charge transfer and carrier transport, which hinders the rational design of high-performance gas sensors. To address this, we fabricated a PbS colloidal quantum dot thin-film transistor (TFT) gas sensor that enables in situ analysis of carrier concentration and mobility via gate voltage modulation. We systematically measured the variations in conductivity, carrier concentration, and mobility with NO2 concentration and established a normalized weight variation model. The results show that the conductivity increase upon NO2 exposure is primarily due to the rise in carrier concentration induced by gas adsorption. At low concentrations (below 0.5 ppm), the response is dominated by mobility variation. This work provides a physically meaningful theoretical framework for understanding the conduction mechanism.

Chemosensors doi: 10.3390/chemosensors14060129

Authors: Alhumaidi B. Alabbas Sherif A. Abdel-Gawad

Particularly in regions experiencing rapid industrial and healthcare development, the presence of pharmaceutical residues in wastewater is becoming an increasingly pressing environmental concern. In this study, an analytical method was developed to quantify lisinopril (LIS), ramipril (RAM), and enalapril (ENA) in wastewater while being both sensitive and inexpensive. To improve the precision and accuracy of the measurements, propranolol (PRO) was used as an internal standard. To achieve dual preconcentration and enhanced sensitivity, the method integrates filed amplified sample stacking (FASS) with solid-phase extraction (SPE) before capillary electrophoresis (CE) in a synergistic way. Important experimental factors such the composition of the background electrolyte (BGE), pH, injection settings, stacking efficiency, and selection of the SPE sorbent were meticulously calibrated. Under ideal circumstances, the SPE-CE-FASS method demonstrated remarkable linearity within the concentration range of 10–1000 ng L−1 (R2 > 0.999), an outstanding level of accuracy (intra- and inter-day RSD < 6%), and satisfactory recovery percents (90–97%) in real wastewater samples. This method offers an eco-friendly and cost-effective alternative to liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) by reducing waste, using less solvent, and providing enough sensitivity for trace-level analysis. Hence, it is very suitable for the regular monitoring of angiotensin converting enzyme (ACE) inhibitors in complex wastewater matrices.

Chemosensors doi: 10.3390/chemosensors14060130

Authors: Alessandra De Lorenzi Pezzolo Paolo Stoppa Andrea Pietropolli Charmet

In this work, the Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectra of 30 specimens of Soft Stone of the Berici Hills (Vicenza, Italy) are analyzed by multivariate tools to characterize their different varieties. This calcareous material shows different characteristics regarding colour, hardness, and type and quantity of included fossils that led to various denominations and classifications. By performing a Principal Component Analysis in the 900–1220 cm−1 spectral range, four main groups could be identified in the dataset investigated: Oligocene stones (White and Coloured Vicenza) and Eocene ones (Yellow and Grey Nanto-like, and Nanto p.d.). The spectral features due to the non-carbonate content of the samples (in particular those of quartz, montmorillonite, kaolinite and sanidine) are discussed and employed to characterize the different groups. An appropriate characterization of the three most represented groups is then proposed by means of a Soft Independent Modelling of Class Analogy (SIMCA). This model also proved useful to get information on the samples left out (the Nanto p.d. sample and the five with hybrid characteristics, Grigio Alpi and Pietra del Mare).

Chemosensors doi: 10.3390/chemosensors14060128

Authors: Jiawei Zou Juan Dong Zhuo Tang Wei Wang Feng Du

RNA aptamer sensors are promising for environmental and clinical detection, but their poor stability limits practical application. Here, we developed a tRNA-fused strategy to enhance the stability of unmodified RNA aptamer sensors. The tRNA scaffold was fused to the 3′ end of Spinach aptamer to construct tRNA-Spinach. In vitro stability assays showed that tRNA-Spinach retained 50% of its initial fluorescence for 84 days at 25 °C (60% humidity), a 7-fold improvement compared with native Spinach (12 days). The tRNA-fused strategy also doubled the in vivo half-life of Spinach from 20 min to 40 min in KM mice. Based on this strategy, a tobramycin sensor was constructed, which exhibited a LOD of 30 nM, a linear range of 30–100 nM (R2 = 0.9905). The biosensor could be detected with a handheld UV lamp within 10 min. This tRNA-fused strategy enables room-temperature storage of RNA aptamer sensors without chemical modification, providing a scalable and cost-effective platform for point-of-care diagnostics in resource-limited settings.

Chemosensors doi: 10.3390/chemosensors14060127

Authors: Xiangyu Ren Rundong Wang Yiru Zhang Mengjin Zhai Yukun Qin Wenhao Liao Anjie Cao Yuan Chen Bingkai Han

Metalloporphyrins play an important role in biomedicine, catalysis, and energy, among other fields, due to their structural complexity and functional diversity. In this study, GO was used as the precursor support and chitosan was employed to reduce and functionalize GO into chitosan-functionalized rGO. Furthermore, metalloporphyrins were covalently linked to the amino side chains of chitosan via an amide crosslinking method, and a series of metalloporphyrin–chitosan-functionalized rGO nanocomposites were designed and synthesized. A set of poly(metalloporphyrin–chitosan)-functionalized rGO working electrodes was constructed by drop-coating onto glassy carbon electrodes, and their electrocatalytic performance toward dopamine was investigated in PBS solution. Finally, zinc(II) porphyrin, with the best performance, was selected as the core catalytic unit to fabricate an enzyme-free dopamine sensor. Under optimal working conditions, the sensor exhibited a sensitivity of 0.30 mA mM−1cm−2, a linear detection range of 0.001~1.0 mM, and a low detection limit of 0.05 μM (S/N = 3). The sensor showed anti-interference ability against various interfering ions and electroactive substances, as well as good stability and repeatability.

Chemosensors doi: 10.3390/chemosensors14060126

Authors: Zeqi Yu Xinyu Sun Yanan Niu Chaoyu Song Yukang Sun Yuguang Lv

Elucidating structure–activity relationships in semiconductor photocatalysis has been significantly impeded by the inherent limitations of ensemble-averaged characterization techniques, which obscure the spatiotemporal heterogeneity intrinsic to catalytic surfaces. Single-molecule fluorescence microscopy (SMFM) surmounts this bottleneck by offering nanometer-scale spatial resolution coupled with the capacity to resolve single-turnover events. Herein, we provide a comprehensive overview of the State-of-the-Art applications of fluorogenic probe-coupled SMFM in deciphering the microscopic mechanisms governing photocatalysis. We begin by delineating the operational principles of total internal reflection fluorescence (TIRF) microscopy and categorizing the response mechanisms of three distinct classes of fluorogenic probes: oxidative (e.g., Amplex Red, APF), reductive (e.g., Resazurin, DN-BODIPY), and acidic (e.g., furfuryl alcohol, thiophene) reporters. Subsequently, we highlight seminal studies wherein SMFM has been leveraged to visualize facet-dependent charge separation on model photocatalysts—including TiO2, BiOBr, and InSe—to map the dynamic activity associated with surface defects and to precisely locate active sites during photoelectrochemical water splitting. Finally, we critically assess the prevailing technical challenges, such as limitations in probe specificity and background interference, while offering a perspective on prospective avenues for methodological refinement. This review is intended to serve as a methodological cornerstone for advancing mechanistic understanding in photocatalysis and for guiding the rational design of high-performance catalysts.

Chemosensors doi: 10.3390/chemosensors14060125

Authors: Yan-Chi Tseng Chih-Hsin Chen

Hydrogen sulfide (H2S) is a toxic and biologically relevant gas, necessitating sensitive and interference-resistant detection methods for environmental monitoring. Here, we develop a donor–acceptor molecular platform incorporating a polarized conjugated double bond bridge and demonstrate its application, using YG2 as the representative probe, as a dual-peak ratiometric UV–Vis sensor for H2S. UV–Vis spectroscopy, supported by 1H NMR analysis, indicates HS--induced interaction with the conjugated linkage, leading to disruption of π-conjugation, suppression the intramolecular charge-transfer (ICT) band at 409 nm, and enhancing the locally excited (LE) band at 279 nm. The ratiometric parameter log(Abs279/Abs409) affords a linear response over the concentration range of 1.0 × 10−6–1.0 × 10−4 M with a detection limit of 8.3 × 10−7 M, providing approximately an order-of-magnitude improvement in analytical sensitivity compared with single-wavelength methods, and the reaction reaches completion within ~10 s. YG2 exhibits excellent selectivity toward H2S over common anions and enables accurate quantification in real water samples, with recoveries of 95.43–105.86% and relative standard deviations (RSDs) of 0.56–9.58%. These results suggest that YG2 is a rapid, self-calibrating, and spectroscopically interpretable ratiometric probe suitable for reliable H2S detection in complex aqueous environments.

Chemosensors doi: 10.3390/chemosensors14060124

Authors: Ming-Yu Zhong Yue Gu Jie Lu Hao He Ming-Zhu Deng Meng-Li Li Cheng-Cheng Li Hao-Xue Li Li Mi Zheng Xu Fang Zhang Guo-Song Chen Yin-Zhu Wang

In most ratiometric electrochemiluminescence (ECL) sensors, the utilization of different co-reactants for anodic and cathodic ECL luminophores, along with a broad potential scanning range, restricts their practical applications. Herein, we first reported dual-cathodic potential-resolved ECL from nitrogen/sulfur-codoped carbon dots (N,S-CDs) and mercaptopropionic acid-functionalized copper nanoclusters (MPA-Cu NCs) using their common co-reactant K2S2O8 within a potential range of 0 to −2 V, and developed a ratiometric ECL biosensor for miRNA-155 analysis. Initially, the ECL peak of MPA-Cu NCs at approximately −2 V on the electrode was quenched through resonance energy transfer (RET) by methylene blue. Subsequently, trace target miRNA-155 was converted into abundant output DNA via a DNA walker mechanism. In the presence of Pb2+, partial DNA was cleaved to remove methylene blue, thereby restoring the ECL intensity of MPA-Cu NCs. Furthermore, the cleaved DNA fragments sparked rolling circle amplification (RCA), which ultimately facilitated the loading of N,S-CDs onto the electrode surface, generating an ECL peak at approximately −1 V. As the concentration of miRNA-155 increased, both ECL signals rose simultaneously but with different magnitudes. The fabricated ratiometric ECL sensor achieved a linear detection range for miRNA-155 from 10 aM to 0.1 nM, with a limit of detection of 2.91 aM. Overall, this study offers a new strategy for constructing dual-cathodic ratiometric ECL biosensors and provides a promising approach for early disease diagnosis.

Chemosensors doi: 10.3390/chemosensors14060123

Authors: Yuyang Li Zhengying Wang Shuangyang Kuang Keyuan Ding Xiaotian Zhu Xiaoyan Wei

The trace water content in industrial oil critically affects the operational stability and service life of industrial equipment and serves as a key indicator for evaluating oil quality. Therefore, the rapid, sensitive, and visual detection of trace water in oil is of great engineering significance for equipment condition monitoring and early fault warning. Existing detection methods predominantly rely on precision instruments; although they enable quantitative analysis, their operational procedures are complicated and time-consuming, which are unsuitable for on-site real-time monitoring. Consequently, there is an urgent need for a novel trace water detection sensor that offers high sensitivity, visualization, and adaptability to oil-phase environments. Herein, a coplanar electrode alternating current electroluminescent (ACEL) sensor is developed for the visual detection of trace water in oil. The ACEL sensor features a multilayer structure comprising a substrate layer, a coplanar electrode layer, and a humidity-sensitive luminescent layer. The humidity-sensitive luminescent layer consists of humidity-sensitive hydrogel and ZnS: Cu electroluminescent powder, forming a loose and porous film that enables high-sensitivity humidity sensing and simultaneously electroluminescent visual signal output. The sensing mechanism study reveals that variations in trace water content modulate the dielectric properties of the humidity-sensitive layer, which further affect the electroluminescent intensity of the ACEL sensor. In addition, the ACEL sensor enables the rapid, naked-eye recognition of humidity changes under trace water conditions without the need for precision instruments, achieving a rapid response time of 3 s and a detection limit as low as 60 ppm, all making it applicable for different types of industrial oils. Thus, this ACEL sensor features a novel detection mechanism, excellent universality, fast response, and ease of operation, offering a new visual sensing strategy for trace water detection in industrial oil and holding broad prospects for practical applications.

Chemosensors doi: 10.3390/chemosensors14060122

Authors: Lihua Jiang Miaoyang Chen Jun Zhu Gang Chen Shaohua Huang Haitao Xu

Electrochemical sensing provides an alternative approach for the trace detection of bioactive substances in fruits. However, the complex matrix in fruit tissues, the coexistence of multiple active components, and the varied pH environments limit the sensing performance and accurate quantitative detection of conventional electrochemical sensors. Herein, a dual-mode electrochemical sensor based on a Co3O4@N-MWCNTs modified glassy carbon electrode was developed for the sequential detection of quercetin, rutin, and glucose in fruits under acidic and alkaline conditions. The as-prepared electrode exhibited improved charge transfer efficiency and favorable electrocatalytic activity toward the three target analytes. Under optimal conditions, the sensor displayed wide linear ranges of 0.5~70 μM for quercetin and 0.5~5 μM for rutin in acidic environment, with low detection limits of 0.124 μM and 0.045 μM, respectively. In alkaline environment, the detection limit for glucose was determined to be 8.86 μM. Moreover, four combined machine learning models with feature selection algorithms were established, among which the CARS-RFE+RFR model achieved the best prediction accuracy and robustness for multicomponent quantification. Furthermore, the proposed sensing system was applied to the rapid determination of quercetin, rutin, and glucose in real litchi samples, with recoveries ranging from 98.4% to 105.4%. This study provides a feasible electrochemical strategy for multicomponent detection in complex plant matrices, showing good applicability for rapid on-site analysis in agricultural and food-related applications.

Chemosensors doi: 10.3390/chemosensors14050121

Authors: Bowen Wang Yuhan Guo Tao Chen Maojin Tian

Bacterial infections pose a persistent global threat to public health, driving the demand for rapid, sensitive, and specific detection technologies applicable to disease diagnosis, food safety, and environmental monitoring. Conventional methods like plate culture and polymerase chain reaction are often hampered by lengthy procedures, dependence on complex instrumentation, and requirements for specialized personnel. The emergence of nanozymes and nanomaterials with enzyme-like catalytic activities has introduced a paradigm shift in biosensing, offering superior stability, cost-effectiveness, and tunable functionality compared to their natural counterparts. This review provides a comprehensive and systematic analysis of the latest advancements in nanozyme-mediated bacterial detection. It is structured around the primary signal transduction modalities: colorimetric, fluorescence, electrochemical, and surface-enhanced Raman scattering (SERS) analyses. For each approach, we outline the fundamental design principles, which commonly integrate a synergistic cascade of specific recognition, catalytic signal amplification, and signal readout, and present representative applications for detecting key pathogens like Staphylococcus aureus, Salmonella, and Listeria monocytogenes in complex samples. We evaluate and contrast the advantages, analytical performance, and appropriateness of these different platforms for various practical scenarios. Finally, we address current challenges, including achieving high specificity in complex matrices, precise modulation of nanozyme activity, and method standardization. Perspectives on future research directions aimed at developing next-generation, high-performance, and potentially portable bacterial detection systems are also provided.

Chemosensors doi: 10.3390/chemosensors14050120

Authors: Li-Ke Wang Xin-Ru Chen Tong-Yu Lin Yong-Liang Ban Zeng-Chen Liu Hua-Li Jia Hong Wang Yu-Bao Lan

Chirality is a cornerstone of biological systems and pharmaceutical activity, driving a critical need for rapid and sensitive enantioselective analytical methods. Covalent organic frameworks (COFs) have emerged as versatile porous materials, and their chiral counterparts, chiral COFs (CCOFs), uniquely combine high surface area, pre-designable pores, and a confined chiral microenvironment, making them exceptional platforms for enantioselective fluorescence sensing. This review systematically summarizes recent advances in the construction and application of CCOFs for enantioselective fluorescence sensing. We first outline the primary synthetic strategies for CCOFs, including direct synthesis, post-synthetic modification, and chiral induction. Subsequently, based on the direction of fluorescence signal change upon analyte binding, we classify the sensing mechanisms into three categories: “turn-off” (quenching via static complexation or photoinduced electron transfer), “turn-on” (enhancement through rigidification or suppression of electron transfer), and ratiometric (self-calibrating dual-emission response). Representative examples for the detection of amino acids, amino alcohols, terpenes, and saccharides are highlighted for each mode. Special emphasis is placed on structure–property relationships, such as the synergistic roles of hydrogen bonding, π–π stacking, and framework confinement in amplifying enantioselectivity. Finally, we discuss current challenges and future perspectives, including the rational design of ratiometric sensors, integration into practical devices, and the convergence with machine learning to advance the field of smart chiral sensing.

Chemosensors doi: 10.3390/chemosensors14050119

Authors: Marcel Cedric Deussi Ngaha Hamdi Ben Halima Nicole Jaffrezic-Renault

Per- and polyfluoroalkyl substances (PFAS) have been extensively used for many years in the manufacturing of industrial and commercial goods. Their toxicity and their extensive use, stability, durability, persistence, and bioaccumulation are responsible for the contamination of water, soil, air, and food, causing significant harm to human health and the environment. The objective of this chapter is to evaluate the ability of advanced (bio)sensing strategies for the sensitive, accurate, rapid, simple, and low-cost detection of PFAS in drinking water and the environment. We address advanced bio(sensing) strategies by emphasizing the electrochemical (bio)sensing strategies and the optical bio(sensing) strategies. The principle of each method, the mechanisms involved in the detection, the linear range, the limit of detection, and the applicability are underlined. Finally, this review outlines the major challenges and outlook to move advanced (bio)sensing strategies from the laboratory stage to practical applications in the environment, food, and health.

Chemosensors doi: 10.3390/chemosensors14050118

Authors: Yize Zhang Youhong Zeng Lingxuan Liu Lei Wang Hao Chen Yatan Yuan Yingying Ding Guijun Miao Lulu Zhang Xianbo Qiu

Different from isothermal amplification, for polymerase chain reaction (PCR), highly reliable valving for PCR chamber, significantly shortened thermal cycling time, and concise multiplexed detection are always challenges for microfluidic-based devices. Here, we present a real-time, centrifugal, plastic microfluidic chip for multiplexed PCR detection specifically based on the mechanism of cooperating valving. To achieve consistent amplification, a concise dual-valving strategy was developed. Instantly melted wax is centrifuged and completely filled into the narrow channel and hole to act as the compact wax valve. Meanwhile, an elastic and sticky membrane is depressed to seal the hole to act as the membrane valve. The wax valve is protected by the membrane valve from being damaged by both mechanical deformation and thermal corroding caused by the hot vapor with high pressure from the PCR chamber. A double-sided heating strategy is adopted to reduce the thermal cycling time; meanwhile, a balanced mechanism is used to achieve real-time amplification by rotating the centrifugal chip between the heating and detection positions in turn. As a proof-of-concept, the performance of the centrifugal chip with four parallel units is demonstrated by successfully detecting purified DNA templates or the extracted DNA templates from cells as well within 20 min.

Chemosensors doi: 10.3390/chemosensors14050117

Authors: Michele Penza

This Special Issue based on eight Articles/Reviews focuses on low-cost chemical sensor technologies, bio-chemical sensors, advanced active materials, sensing nanomaterials, sensor nodes, wireless sensor networks for chemical sensing, functional characterization, miniaturized transducers, advanced proofs of concept, and chemical detection applications. Promising advanced materials such as metal oxide nanostructures, carbon nanomaterials, composite heterostructures, multilayered coatings, and more have been explored for chemical sensing applications and environmental sustainability. Sensing solutions have been applied in the context of bio-chemical detection and gas monitoring, representing the current state of the art.

Chemosensors doi: 10.3390/chemosensors14050116

Authors: Wenhao Bi Dongxin Shi Feifei Wang Yuxiao Song Jing Sun Chenyu Jiang

In recent years, pesticides have been widely applied in the commercial cultivation of traditional Chinese medicinal plants to increase the yield of medicinal materials. Xinhui dried tangerine peel (Citri Reticulatae Pericarpium), a common ingredient in traditional Chinese medicine, utilizes the citrus peel as its medicinal part. During cultivation, the peel is directly exposed to pesticides, making it susceptible to pesticide residue accumulation. To enable the rapid identification of pesticide types and their targeted removal, this study integrated laser-induced breakdown spectroscopy with ensemble learning algorithms. Three lightweight neural network models—1D-CNN, Res-CNN, and LIBS-UNet—were developed and trained using either a single loss function or a composite loss function. The 1D-CNN, Res-CNN, and LIBS-UNet models achieved accuracies of 97.50% and 98.69%, 95.00% and 95.73%, and 74.06% and 76.88% for the single loss and composite loss functions, respectively. During the model ensemble stage, individual models were weighted according to their classification accuracy and test similarity matrices. Through this approach, the pesticide identification accuracy reached 99.99%. This study demonstrates that ensemble learning can effectively integrate the strengths of multiple weak classifiers, thereby significantly enhancing classification performance and providing a novel approach for the rapid detection of pesticide residues in traditional Chinese medicine ingredients.

Chemosensors doi: 10.3390/chemosensors14050115

Authors: Roqaya Mohamed Elnagar Gul Shahzada Khan Irshad Ul Haq Bhat Suad Ahmed Rashdan Awal Noor

The literature collected from various search engines and high-quality scientific databases reveals that amino acid (AA)-functionalized nanoparticles have emerged as a promising field for selective detection and remediation of heavy metals (HMs). Among the various nanoparticles (NPs), gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) have drawn considerable attention, attributed to their unique optical, catalytic, and surface plasmon resonance properties. Functionalization with amino acids significantly enhances nanoparticle stability, biocompatibility, and metal-binding affinity through diverse functional groups. AA-functionalized AuNPs, including glycine, cystine, leucine, methionine, tyrosine, aspartic acid, histidine, and lysine-capped systems, exhibit tunable selectivity toward heavy metal ions. Bifunctionalization strategies further enhance sensitivity by inducing nanoparticle aggregation or signal amplification. Beyond single amino acids, polypeptides and protein-functionalized AuNPs offer enhanced molecular recognition and multivalent binding, expanding their applicability in complex matrices. Similarly, amino acid-functionalized AgNPs, such as those capped with similar amino acids stated above, exhibit strong interactions with heavy metals, AA bifunctionalization, and bimetallic nanoparticles (BNPs), particularly amino acid-functionalized Au–Ag systems, which combine the advantages of both metals, leading to improved sensitivity, selectivity, and signal strength. Although these advances have been made, a major gap remains in the systematic comparison of different amino acids, peptides, and bimetallic systems under real-world conditions. This gap can be addressed by standardized testing methods, clearer structure–function relationships and combined experimentation to guide the rational design of more efficient AA-functionalized nanoparticles.

Chemosensors doi: 10.3390/chemosensors14050114

Authors: Shunpei Hitosugi Noriko Ueda Hiroki Narita Haruki Minami Takayuki Okano Yoichi Aoki Rieko Takahashi Hisatake Okada

Chemical probe-based pattern analysis offers a powerful approach for evaluating complex mixtures, particularly in non-target sensing scenarios where components are unknown or where multivariate interactions, such as those involved in taste perception, dominate the response behavior. However, its broader applicability has been limited by challenges in generating sufficiently diverse probe sets and in acquiring multidimensional response data from large probe arrays. In this study, we address both limitations by constructing a high-capacity sensing platform that integrates artificial DNA-derived chemical probes with conventional fluorescent probes. Artificial DNA probes were synthesized following established modular assembly methods, enabling large-scale generation of structurally diverse sensing elements. An imaging-based detection instrument—combining controlled excitation and high-resolution fluorescence capture—was developed to simultaneously quantify color and intensity responses from up to 88 probes. We applied this system to the analysis of 20 taste-related compounds, demonstrating clear discrimination based on multidimensional fluorescence patterns. Furthermore, systematic evaluation of probe number versus classification accuracy revealed that increased probe diversity substantially enhances non-target discrimination performance, supporting the value of using low-specificity artificial DNA probes in high-density arrays. These results establish a versatile and scalable platform for non-target pattern analysis and highlight the importance of probe multiplicity in complex mixture sensing.

Chemosensors doi: 10.3390/chemosensors14050113

Authors: Robert Ruginescu Roberta Maria Banciu Szilveszter Gáspár Cristina Purcarea Alina Vasilescu

Water toxicity screening requires sensitive tools to rapidly detect environmental pollutants. While complex analytical methods accurately determine known contaminants, fast screening tests utilizing biological processes, such as photosynthesis, are increasingly being developed to evaluate the toxicity of environmental waters. We describe the isolation of the psychrotolerant Coccomyxa sp. LT4 from Scarisoara Ice Cave (Romania), representing the first report of green algae inhabiting this type of environment, and provide a preliminary assessment of its isolated thylakoids as novel biorecognition components for water toxicity screening. Photosynthetic activity and diuron sensitivity were measured amperometrically and compared with thylakoids from the reference cyanobacterium Synechococcus elongatus PCC 7942. The bioreceptor’s response to various pollutants and water salinities was also investigated. The microalgal thylakoids were more sensitive to diuron than the reference thylakoids, generated stable photocurrents across a broad salinity range and, when lyophilized with sucrose, retained their activity for over two years at −20 °C. Consequently, these thylakoids, isolated from a cold-environment microalga, provide a promising basis for developing biosensors for in situ toxicity screening in low-temperature aquatic ecosystems.

Chemosensors doi: 10.3390/chemosensors14050112

Authors: Rawan H. Alansari Esraa M. Bakhsh Kalsoom Akhtar Lenah R. Altamimi Gul Aslam Khan Sher Bahadar Khan

Using orange peels as a biowaste, fluorescent N-CDs were prepared simply and rapidly through a one-step microwave-assisted method and urea as a nitrogen source. The synthesized N-CDs exhibited a high QY value of 47.12% compared to CDs prepared using different methods. Moreover, the N-CDs have good pH and thermal stability. N-CDs exhibited high sensitivity toward Fe(III), Hg(I), and Hg(II) ions with low LOD values of about 0.0555, 0.15379, and 0.02505 μM, respectively. This approach is hopeful for the large-scale formation of N-CDs and could encourage their utilization as fluorescent chemosensors due to their affordability, simplicity, high efficiency, and environmental friendliness.

Chemosensors doi: 10.3390/chemosensors14050111

Authors: Syrine Behi Atef Thamri Juan Casanova-Chafer Nicolas Karageorgos Perez Eduard Llobet Adnane Abdelghani

Volatile Organic Compounds (VOCs) are important indicators of environmental pollution and metabolic activity, making their sensitive and selective detection highly relevant for applications in health monitoring and air quality assessment. Graphene, owing to its exceptional charge transport properties, large surface area, and tunable surface chemistry, is a promising candidate for advanced gas and VOCs sensing. Here we report chemoresistive sensors based on pristine graphene and graphene decorated with platinum (Pt), palladium (Pd), and gold (Au) nanoparticles toward both aromatic (benzene, toluene, and xylene) and non-aromatic (ethanol, methanol, and acetone) vapor compound detection. The detection is achieved at room temperature, and the results demonstrate that graphene functionalized with noble metal nanoparticles shows significant enhancements in sensitivity compared to pristine graphene, mainly against ethanol, toluene and xylene vapors for the Au–graphene sensors. A comparative study with Multi-Walled Carbon Nanotube (MWCNT) sensors decorated with the same type of nanoparticles revealed clear advantages of graphene, attributed to the microstructure and porous structure of graphene powders, which facilitate efficient charge transfer upon vapor adsorption.

Chemosensors doi: 10.3390/chemosensors14050109

Authors: Zhuoxian Weng Yongjie Xu Weina Li Xunhe Huang Liangjie Luo Zhiwei Liu Xiaonan Zhang

Wuhua Yellow Chicken (WYC) is a Guangdong heritage breed known for its characteristic “three yellow” phenotype and distinctive meat flavour. Despite its commercial importance, data on muscle flavour chemistry remain scarce. In this study, 180 one-day-old chicks (90 cocks, 90 hens, 18 replicates of 5 chickens per sex) were raised to 20 weeks under cage conditions, after which slaughter traits, meat physicochemical indices, proximate composition, amino acid and fatty acid profiles, and volatile compounds were measured. Cocks were heavier and had higher eviscerated yields and leg muscle percentages, whereas hens accumulated more abdominal fat (6.47–0.46%, p < 0.01). Shear force was greater in cock breast muscle (2.86–2.13 kg·f, p < 0.01), indicating firmer texture. Cock breast muscle contained more crude protein (26.89%) and less crude fat. Amino acid totals were identical between sexes (21.10 g/100 g), with all six essential amino acids surpassing FAO/WHO reference values; lysine scored highest (168%). Unsaturated fatty acid proportions were 63.33% (cocks) and 66.64% (hens), with PUFA/SFA ratios of 61.95% and 53.60%, respectively. Gas chromatography-mass spectrometry identified 10 volatile compounds in cocks and 14 in hens; aldehydes dominated in both, with hexanal alone accounting for over 50%. Hen muscle contained a richer volatile profile, including additional ketone and ester compounds. These data collectively confirm that WYC is nutritionally dense, organoleptically appealing, and well-suited for further breed promotion.

Chemosensors doi: 10.3390/chemosensors14050110

Authors: Asma E. Althagafi Ekram Y. Danish Amna N. Khan M. Aslam M. Tahir Soomro

The extensive use of 2,4-dichlorophenoxyacetic acid (2,4-D) in agriculture has led to water contamination and associated health risks, highlighting the need for eco-friendly detection strategies. Herein, Fe3O4 nanoparticles were green-synthesized for the first time using an aqueous extract of Rumex nervosus (R. nervosus) as a natural reducing and stabilizing agent and successfully employed for the electrochemical sensing of 2,4-D, representing the first reported application of R. nervosus-mediated Fe3O4 nanoparticles for this purpose. The phytochemical composition of the extract and synthesized R-Fe3O4 nanoparticles were systematically characterized. The R-Fe3O4-modified glassy carbon electrode (GCE) was evaluated for charge transfer properties using electrochemical impedance spectroscopy (EIS). Cyclic voltammetry (CV) showed no redox peak for 2,4-D at the bare GCE, whereas R-Fe3O4/GCE exhibited a distinct reduction peak at ~−1.5 V in 0.1 M phosphate buffer (pH 7), attributed to reductive dechlorination. Square-wave voltammetry (SWV) exhibited a linear response over the concentration range of 50–325 µM with a detection limit of 3.35 µM for 2,4-D. Although this performance is slightly above the guideline limits recommended by the World Health Organization (~0.14 µM) and the United States Environmental Protection Agency (~0.32 µM), it is suitable for the routine monitoring of elevated 2,4-D levels in environmental samples. The sensor demonstrated high selectivity with negligible interference and satisfactory recoveries of 96.6–98.3% in real water samples.

Chemosensors doi: 10.3390/chemosensors14050108

Authors: Seo-Yeon Kim Hyun-Jun Dong Jaehan Jung

Humidity sensors are widely employed in diverse fields such as healthcare, agriculture, construction, and the storage of food and pharmaceuticals. In these areas, accurate and reliable humidity monitoring is essential to ensure appropriate environmental conditions and prevent material degradation or device malfunction. Recently, organic–inorganic hybrid materials have emerged as promising platforms for humidity sensing, as they integrate the complementary properties of both organic and inorganic components. Notably, hybrid materials with three-dimensional architectures have received growing attention owing to their large specific surface area, which affords enhanced reactivity and improved sensing performance. In this review, recent progress in humidity sensors based on organic–inorganic hybrid materials is summarized, with particular emphasis on three-dimensional hybrid architectures. The analysis suggests that 3D hybrid architectures can enhance sensing performance by improving water adsorption and charge transport pathways. Overall, the potential and significance of organic–inorganic hybrid architectures for the development of high-performance humidity sensors are critically discussed.

Chemosensors doi: 10.3390/chemosensors14050107

Authors: Tudor-Alexandru Filip Vlad-Andrei Scarlatache Alin Dragomir Georgiana Prodan-Chiriac Marius-Andrei Olariu

Innovations in nanomaterial science, engineering and printing technologies have increasingly driven advances in electrochemical sensing. Screen-printed electrodes (SPEs) have become a versatile, low-cost, and scalable solution for developing portable electrochemical detection platforms. However, their analytical performance remains intrinsically limited by surface area, electron transfer efficiency, and the immobilization of biomolecules. Recent developments in nanostructured materials, ranging from two-dimensional (2D) materials such as graphene, MXenes, and transition metal dichalcogenides, to one-dimensional nanostructures and hybrid nanocomposites, have transformed the signal transduction landscape of SPE-based electrochemical sensors. Integration of nanomaterials into SPEs has successfully transformed their analytical capabilities, but the diversity of materials and modification strategies has made it difficult to consolidate current knowledge in the field. Strategies that integrate nanomaterials via ink formulation, surface modification, or in situ growth have yielded sensors with unprecedented sensitivity, reproducibility, and selectivity across various chemical and biological targets. This review offers a cross-material synthesis of how nanomaterial engineering transforms the electrochemical performance of SPEs. By integrating insights across morphology, interfacial chemistry, and device-level behavior, it establishes a unified perspective that has been missing from the current literature and clarifies the design principles driving next-generation SPE-based sensing platforms.

Chemosensors doi: 10.3390/chemosensors14050106

Authors: Jie Gao Weiwei Zhang Hangming Qi Xu Tao Qian Yu Xianming Kong Kundan Sivashanmugan

A flexible paper-based surface-enhanced Raman scattering substrate with a hydrophobic surface was fabricated through a simple route. The Ag nanoparticle was modified on filter paper through the in situ growth method. The hydrophobic filter paper/Ag substrate was prepared via soaking in 10−8 g/mL of 1-dodecanethiol with a 12 h growth time. The hydrophobic filter paper/Ag substrate exhibits excellent flexibility and hydrophobic properties with a contact angle of 130.2°. The diffusion of the aqueous solution was significantly suppressed on the hydrophobic filter paper/Ag substrate. The hydrophobic filter paper/Ag substrate could simultaneously improve the SERS signal and fluorescence of the analyte, and that was successfully used for detecting thiram from edible oil with a limit of detection at 1.8 × 10−8 M and monitoring melamine in aqueous solution. The hydrophobic filter paper/Ag substrate is a flexible, economical, and convenient method for detecting harmful ingredients from oil by SERS.

Chemosensors doi: 10.3390/chemosensors14050105

Authors: Vahideh Ilbeigi Younes Valadbeigi Štefan Matejčík

Formalin, a commercial aqueous solution typically containing 37% formaldehyde, often includes a few percent methanol to inhibit polymerization. Nevertheless, formaldehyde readily forms polymerization products such as glycols, dimethoxy (acetal), and methoxyalcohol (hemiacetal) derivatives, making their analysis important. In this work, we employ ion mobility spectrometry (IMS) for qualitative and quantitative detection of these species and demonstrate that analysis is not feasible using the standard IMS reactant ion, H3O+(H2O)n. Protonation by H3O+(H2O)n induces loss of water or methanol, preventing stable detection of the intact derivatives. Hence, ammonia was introduced as a dopant to replace H3O+(H2O)n with NH4+(H2O)n in the ionization region, thereby shifting the ionization mechanism from proton transfer to ammonium attachment. A high-temperature injection port was also designed to enable the analysis of both liquid samples and their corresponding headspace. Using the developed method, we identified both acetal and hemiacetal derivatives in commercial formaldehyde solution, while only the more volatile acetal species were detected in the headspace. Quantitative analysis yielded a limit of detection (LOD) of 1.9 ppm and a linear range of 5.5–120 ppm for solution measurements. Importantly, the method provides reliable detection in the presence of substantial humidity, an environment in which many polymer-based sensors fail due to severe moisture interference. Overall, ammonia-doped IMS offers a robust and humidity-tolerant platform for characterizing formaldehyde polymerization products in both the gas and liquid phases.

Chemosensors doi: 10.3390/chemosensors14050104

Authors: Zixian Wu Hui Zhou You Zhou

Unsafe food poses a significant threat to global public health and the economy, making the early detection of food spoilage an ongoing and critical imperative. Herein, we report the design of a straightforward and highly effective fluorescence sensor for monitoring histamine (HI), a key biomarker of food deterioration, utilizing the direct interaction between the analyte and the sensor. We demonstrate that the inherently weak luminescent covalent organic framework (COF), TpPa-1, functions as a highly responsive “turn-on” luminescent switch in the presence of HI. Upon interaction with HI, the luminescence of TpPa-1 is significantly enhanced; this phenomenon is attributed to the generation of anionic N− species via the deprotonation of the N−H unit, which effectively suppresses the electron transfer pathway from the nitrogen lone pair to the COF backbone. The TpPa-1 sensor exhibits excellent sensitivity and reproducibility for HI detection. Furthermore, we developed a reusable, fluorescent COF-based film that displays a distinct, naked-eye visible color transition from red to yellow-green upon exposure to histamine, establishing a robust platform for rapid, and preliminary food quality assessment. This work presents a novel, COF-based strategy for HI detection, offering substantial significance for public health and food safety monitoring.

Chemosensors doi: 10.3390/chemosensors14050103

Authors: Mona A. Abdel Rahman Hazim Mohammed Ali Mohammed Gamal Lobna Mohammed Abd Elhalim Mai Mohamed Abd El-Aziz Rehab Moussa Tony

Multivariate calibration methods have proven to be helpful in interpreting complex spectral data, particularly in the simultaneous analysis of pharmaceutical mixtures. In this study, three chemometric-assisted spectrophotometric methods were developed and validated for the simultaneous assessment of flunixin meglumine (FM) and florfenicol (FF), namely, multivariate curve resolution–alternating least squares (MCR-ALS), artificial neural networks (ANNs), and partial least squares (PLS). These methods were successfully utilized to address the significant spectral overlap between FM and FF in their combined dose form, enabling simultaneous quantification without prior chromatographic separation. Statistical analysis was conducted to compare the performance of the proposed methods to that of a published HPLC method, and the results showed no significant variation in trueness or precision. The proposed methods were validated according to ICH guidelines, showing high sensitivity, low LOD and LOQ, and excellent precision (%RSD < 2.0%). Furthermore, they were evaluated for environmental sustainability using the analytical greenness (AGREE) metric and the complex modified green analytical procedure index (Complex MoGAPI), which provided a greenness score of 0.7 and a total sustainability score of 80. These results demonstrate the applicability of the proposed chemometric methods as straightforward, effective, and ecologically beneficial substitutes for regular quality control analysis.

Chemosensors doi: 10.3390/chemosensors14050102

Authors: José Manuel Olmos José Antonio González-Franco Joaquín Ángel Ortuño

This review examines the reported research on the potential responses of ion-selective electrodes over time when exposed to sudden changes in the concentration of the primary ion (ion initially present in the ion-selective electrode membrane) and/or foreign interfering ions. Particular attention is given to the responses of liquid- and plasticized polymeric membrane-based ion-selective electrodes to foreign ions. The review provides an in-depth discussion of the theoretical models proposed to describe transient potential signals obtained experimentally with these ion-selective electrodes. In chronological order, the different contributions are presented and commented on in terms of their assumptions and mathematical treatments. The final equations obtained in each case, as well as some stages of their derivations, are presented. Additionally, the various models are classified and critically commented upon. Lastly, the review discusses the analytical applications reported for identifying and quantifying ions using the transient potential signals.

Chemosensors doi: 10.3390/chemosensors14050101

Authors: Maria I. Ikim Varvara A. Demina Elena Y. Spiridonova Egor D. Baldin Olusegun J. Ilegbusi Leonid I. Trakhtenberg

Indium oxide was mechanically activated, and its effect on the operation of semiconductor gas-sensitive devices was evaluated. The structural and morphological characteristics of In2O3 following mechanical activation were examined. The powder treatment produced a defective particle surface structure, enhanced specific surface area, and improved material diffusion properties. Experimental evidence indicates a substantial enhancement in the reactivity of indium oxide with diverse gases, stemming from alterations in grain structure and the formation of novel adsorption sites. The results obtained demonstrate that mechanoactivation is a promising technological tool for the development of energy-efficient sensors.

Chemosensors doi: 10.3390/chemosensors14040100

Authors: Fabiola Eugelio Marcello Mascini Federico Fanti Sara Palmieri Michele Del Carlo

Background: Sensors and mass spectrometry (MS) are frequently used in combination for food safety and quality assessment, yet their functional integration lacks a formal methodological framework. This review categorizes the synergies between these technologies into distinct Relational Connections. Methodology: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 155 original research articles published between 2015 and 2025 were systematically analyzed. Records were identified via the Scopus database within the food science domain. Experimental meta-data, including extraction protocols, instrumental configurations (ionization source, mass analyzer, cost tier), and chemometric strategies, were extracted to identify core methodological patterns. Statistical associations were quantified using chi-squared tests with Cramer’s V effect sizes. Results: Five Relational Connections were identified: (1) MS as reference for sensor validation (25.2%); (2) MS-sensor correlative analysis (10.3%); (3) MS quantifying data to train predictive sensor models (6.5%); (4) MS identifying targets for sensor detection (7.1%); and (5) MS enabling sensor classification models (51.0%). Technology pairing is governed by a three-level hierarchy: analyte polarity determines the ionization source (V = 0.69), required precision determines the mass analyzer (V = 0.64), and cost/availability constraints shape the practical integration strategy. Gas Chromatography (GC)-MS is predominantly coupled with Electronic Noses for volatile profiling (86% of classification studies), while Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) pairs with biosensors for contaminant analysis (74% of reference validation studies). Systematic analysis of the full pairing matrix reveals that 75% of theoretically possible MS-sensor combinations remain unexplored or underrepresented, identifying both technical boundaries and innovation frontiers. Discussion: The findings clarify the strategic logic behind technology pairings, demonstrating that MS provides the quantitative molecular data required for sensor training. The hierarchical decision framework and identification of underexplored pairings provide an evidence-based guide for designing future integrated food analysis systems.

Chemosensors doi: 10.3390/chemosensors14040099

Authors: Sarra Takita Alexei Nabok Magdi H. Mussa Abdalrahem Shtawa Anna Lishchuk David P. Smith

Prostate cancer (PCa) remains one of the most prevalent urological malignancies worldwide, with early and accurate diagnosis being critical for improving patient outcomes. Traditional screening approaches, such as digital rectal examination and prostate-specific antigen (PSA) testing, have long served as frontline tools; however, their limited specificity and sensitivity contribute to high rates of false positives, unnecessary biopsies, and overtreatment. Recent UK guidelines and international consensus increasingly question the role of PSA-based population screening, advocating for risk-stratified pathways and multiparametric MRI as first-line investigations. In parallel, advances in molecular biology have identified promising cancer-specific biomarkers, such as prostate cancer antigen 3 (PCA3) and transmembrane protease serine 2 (TMPRSS2:ERG), that outperform PSAs in terms of specificity and prognostic value. These developments have catalysed innovation in biosensor technologies, enabling rapid, cost-effective, and non-invasive detection of single and multiplex biomarkers in urine and serum. Electrochemical and optical affinity-based biosensors offer transformative potential for the development of personalised point-of-care platforms and diagnostics, reducing the reliance on invasive procedures and improving clinical decision-making. The latter can be augmented with artificial intelligence (AI) tools. This review critically examines the limitations of PSAs, synthesises evidence on novel biomarkers and imaging-led strategies, and evaluates the design, performance, and translational challenges of biosensor-based assays. Furthermore, it outlines future directions, including standardisation, large-scale clinical validation, and integration of multiplex biosensors with AI for precision diagnostics. By bridging molecular insights with engineering innovations, these approaches promise to redefine PCa screening and enable accurate, patient-centred care.

Chemosensors doi: 10.3390/chemosensors14040098

Authors: Xinyu Lu Jin Wang Jiahao Zhou Wenwen Tu Junru Zhou Tianxiang Wei

Quantitative detection of alkaline phosphatase (ALP) activity is crucial in clinical diagnosis and bioanalysis. Herein, we have developed a highly sensitive electrochemiluminescence (ECL) biosensor that employs a biomimetic zirconia interface as its core sensing platform. The interface was constructed by immobilizing o-phosphorylethanolamine (PEA) onto zirconium oxide nanofilms (ZrO2NFs), forming a surface rich in Zr-O-P bonds. This design mimics phosphate recognition and enzyme-triggered dephosphorylation processes, where ALP catalyzes the hydrolysis of these bonds, triggering a direct switch in the ECL signal from Ru(bpy)32+-loaded gold nanocage (Ru-AuNCs) emitters. This sensor achieves a wide linear range of 0.100–100 U/L and a low detection limit down to 0.0899 U/L. Its practical utility was validated through the accurate detection of ALP in fetal bovine serum samples, confirming high recovery and reliability. This strategy highlights the potential of biomimetic zirconia interfaces in developing robust biosensors for early disease diagnosis.

Chemosensors doi: 10.3390/chemosensors14040097

Authors: Yili Yuan Qing Kang Xusheng Wang Wensheng Liu Jialei Du

Surface plasmon resonance (SPR) is a label-free, real-time biosensing technology with high sensitivity for the detection of biomolecular interactions. This review highlights recent advances in SPR biosensors for the detection of SARS-CoV-2. First, we outline design strategies, especially advanced plasmonic nanostructures and precise surface functionalization, that improve the specificity and binding affinity to viral targets. Next, we cover signal amplification methods, such as nanoparticle conjugation and plasmonic photothermal effects, which enhance the sensitivity for low-abundance viral components. Subsequently, we conducted a comparative analysis of SPR biosensors alongside traditional and emerging detection approaches for SARS-CoV-2, elucidating their individual merits and drawbacks. We also discuss how machine learning improves data interpretation and diagnostic accuracy. Finally, we discuss the current challenges and future development directions, particularly for clinical diagnostics, epidemic monitoring, and public health security. These advances support faster, more reliable, and accessible diagnostics for current and future viral outbreaks.

Chemosensors doi: 10.3390/chemosensors14040096

Authors: Shih-Rong Lin Yan-Chiao Mao Ahai C. Lua Hsuan-Wei Huang Jun-Jen Liu Yu-Chih Shen

Synthetic cathinones are among the most frequently encountered classes of new psychoactive substances, and many occur as structural isomers sharing identical molecular formulas and highly similar mass-spectral features. Among them, substituted cathinones with the molecular formula C12H17NO (MW 191 Da) present particular analytical challenges because of their similar chromatographic behavior and overlapping ionization patterns. This study evaluated a combined EI-GC-MS and ESI-LC-MS/MS workflow, incorporating derivatization with trifluoroacetic anhydride (TFAA) and acetic anhydride (AA), for the differentiation of ten MW 191 Da isomers. TFAA-derivatized GC-MS enabled preliminary classification of the isomers, although several EMC and MEC analogs remained only partially resolved. AA derivatization improved the separation of unresolved isomers under slower oven temperature conditions, demonstrating the value of alternative acylation for enhancing chromatographic discrimination. LC-MS/MS provided complementary confirmation for several analytes, but some isomers remained difficult to distinguish because of shared product ions and peak fusion in mixed-standard analysis. Overall, this study establishes a practical analytical workflow for distinguishing MW 191 Da substituted cathinone isomers and highlights both the strengths and limitations of combining derivatization-based GC-MS with LC-MS/MS confirmation in routine forensic or clinical laboratories.

Chemosensors doi: 10.3390/chemosensors14040095

Authors: Yifan Qi Shuwen Yan Jianrong Chai Tingrui Wang Yuming Wang

Medicine–food homology (MFH) substances, which possess both medicinal and edible properties, have garnered widespread attention in the global health context of the new era. The MFH industry has experienced explosive growth and has gradually become a key supporting aspect of TCM modernization. However, due to the pollution of the modern environment, the content of pollutants in MFH products has been increasing, raising concerns regarding quality, safety, and efficacy control. Traditional quality-analysis technologies struggle to meet the needs of rapid on-site detection because of their dependence on large instruments and the complexity of operation. This dilemma has propelled advances in sensor technology. With its advantages of high sensitivity, real-time detection, and portability, sensor technology has become a key technical support for quality control and supervision in the field of MFH. In this review, we comprehensively categorize the mainstream sensor types used for analysis in the field of MFH, including intelligent sensors, optics, electrochemistry, biosensors, etc. This review outlines their research status, elaborates on their primary application directions and corresponding core technologies, discusses current challenges (including stability, interference, and cost), and presents future perspectives. Overall, sensor-based technologies offer a promising and scalable solution for the quality control of MFH products, addressing critical challenges such as stability, interference, and cost. With ongoing advances in intelligent sensing, optics, electrochemistry, and biosensing platforms, these methods are poised to play an increasingly vital role in ensuring the safety, efficacy, and quality consistency of MFH products amid growing environmental pressures.

Chemosensors doi: 10.3390/chemosensors14040094

Authors: Ziyi Cheng Mei Zhang Huijun Yuan Jingjing Liu Yongzhuo Zhang

The exploration of deep-sea microorganisms is transitioning from ex situ laboratory analysis to in situ real-time monitoring. While in situ technologies offer unprecedented access to microbial activities in their natural extreme habitats, they face a critical, yet often overlooked, bottleneck: the absence of a robust metrological framework. This lack of standardized calibration, traceability, and reference materials results in data that are often irreproducible, device-specific, and incomparable across studies, severely undermining scientific discovery and resource assessment. This review provides a systematic analysis of the current landscape of deep-sea microbial detection technologies, categorizing them by their operational principles and critically evaluating their performance, limitations, and metrological readiness. By synthesizing the technological challenges with the principles of metrology, we identify the fundamental gap between advanced sensing capabilities and the lack of in situ measurement standards. To bridge this gap, we propose an innovative “laboratory simulation–in situ detection–remote calibration” trinity calibration system. This framework establishes a complete metrological traceability chain tailored for extreme deep-sea conditions, aiming to transform isolated sensor data into globally comparable, scientifically robust, and industrially actionable information, thereby paving the way for precision deep-sea biology and governance.

Chemosensors doi: 10.3390/chemosensors14040093

Authors: Wenjie Bi Jinmiao Zhu Bin Zheng Shiwei Yang Chengzhi Ruan Siyu Yu Xinran Li Yinuo Xu Hongyu Yu Yafei Xu Shantang Liu

In this study, Ag-functionalized porous ZnO nanocomposites were successfully synthesized via pyrolysis of Ag-loaded ZIF-8 precursors. The structural and surface properties of the materials were systematically characterized using XRD, XPS, FESEM, and HRTEM analyses. A gas sensor fabricated from the optimized 3.0 wt% Ag–ZnO sample exhibited a significantly enhanced response (Ra/Rg = 103) toward 100 ppm acetone at an operating temperature of 275 °C, which is approximately 2.51 times greater than that of pristine ZnO. The sensor also demonstrated rapid response/recovery times (6 s/7 s), excellent linearity over a wide concentration range (500 ppb–200 ppm), good selectivity against common interfering VOCs, and stable performance, with over 95% response retention after 30 days. The improved sensing performance is attributed to the hierarchical porous structure derived from ZIF-8 and the increased oxygen vacancy concentration and chemisorbed oxygen species induced by Ag loading, which collectively increase surface reaction activity. This work provides an effective strategy for constructing noble metal-modified porous ZnO materials for sensitive and reliable acetone detection.

Chemosensors doi: 10.3390/chemosensors14040092

Authors: Wenxuan Li Dongxin Shi Feifei Wang Yuxiao Song Yong Yang Jing Sun Chenyu Jiang

Cavity ring-down spectroscopy has significant potential for detecting trace volatile organic compounds, owing to its long absorption path and high sensitivity. However, in practical measurements, noise severely decreases the accuracy of decay curves and the reliability of concentration retrieval. To address this, we developed a deep learning-based denoising model called decay-upsampling FC-Net. Experimental results showed that the model improved the signal-to-noise ratio from 13.86 dB to 26.79 dB and processed a single decay curve in only 0.000207 s on average. Moreover, under high-noise conditions, it determined the ring-down time more accurately than conventional methods. This study provides an effective signal processing solution to enhance the practical reliability of Cavity ring-down spectroscopy gas detection systems.

Chemosensors doi: 10.3390/chemosensors14040091

Authors: Zhenghe Li Zhonghang Xia Huiming Ji Yiwen Zhang

To detect volatile organic compounds, fabricating gas sensors with high sensitivity, excellent selectivity, low detection limits, and good long-term stability is critical. Herein, Er1/3Yb1/3La1/3FeO3 medium-entropy material was synthesized via the sol–gel method and characterized in terms of its morphological, structural, and chemical properties. The medium-entropy design induces significant lattice distortion and increased oxygen vacancies, leading to higher adsorbed oxygen content and hole concentration on the material surface, which enhances the activity of gas-sensing reactions. The Er1/3Yb1/3La1/3FeO3 sensor exhibits a response of 13.2 toward 10 ppm of butanone gas at the optimum operating temperature of 192 °C, which is nearly three times the response of the ErFeO3 sensor (4.5), along with excellent selectivity to butanone gas, a low detection limit (0.5 ppm), and long-term stability. Moreover, the applied magnetic fields improve the ordering of magnetic moments in both Er1/3Yb1/3La1/3FeO3 and O2 molecules, which facilitates gas adsorption and electron transfer, and further boosts the gas-sensing performance. The response of the Er1/3Yb1/3La1/3FeO3 sensor toward 10 ppm butanone is enhanced to 21.3 under the applied magnetic field of 680 mT, which improves the selectivity toward butanone. This work provides a novel material design strategy for the detection of VOCs and a feasible magnetic field-assisted approach for optimizing the gas-sensing performance of perovskite ferrite materials.

Chemosensors doi: 10.3390/chemosensors14040090

Authors: Sabri Ouni Eslam Elkalla Sumera Khizar Abdelhamid Elaissari Abdelhamid Errachid Nicole Jaffrezic-Renault

Methanol (MeOH) is widely used in industry and is highly toxic when ingested. In this work, a new micro-conductometric transducer is functionalized with magnetic Fe3O4 nanoparticles capped with Artemisia Herba Alba (AHA) extract. The resulting AHA-Fe3O4 nanoparticles, crystallized in the cubic spinel phase, exhibit an average crystallite size of 6 nm. These nanoparticles were homogeneously dispersed within an electrodeposited chitosan film on interdigitated electrodes for conductometric measurements. The gas-sensing behavior of the films was evaluated at room temperature toward methanol, ethanol, and acetone vapors. For methanol, the sensor shows response times (tRes) ranging from 9 to 12 s depending on the analyte concentration, with a detection limit of 600 ppm in the gas phase. The methanol sensor presents a sensitivity 30 times lower for acetone and 3.7 times lower for ethanol. The sensor exhibited stable detection sensitivity over two months, under intermittent storage at 4 °C. Methanol was detected in the headspace of commercial product samples, in good agreement with the producer’s value.

Chemosensors doi: 10.3390/chemosensors14040089

Authors: Zijian Wu Ying Chen Ming Li Pengcheng Xu Xinxin Li

Detection of formaldehyde is of great significance for environmental monitoring and public health. Although amino-modified MOF nanomaterials have been widely adopted to improve the gas-sensing properties for hazardous gases, the fundamental enhancement mechanism is still insufficiently clarified, especially for formaldehyde-sensing material. In this work, the adsorption enthalpies of formaldehyde on UiO-66 and UiO-66-NH2 were quantitatively extracted via MEMS variable-temperature adsorption experiments, yielding values of −21.8 and −45.9 kJ/mol, respectively. The results demonstrate that amino-modified UiO-66-NH2 enables reversible adsorption between physisorption and chemisorption, which is more favorable for gas-sensing applications. Furthermore, a formaldehyde sensor was fabricated based on a MEMS resonant microcantilever. Gas-sensing performance tests indicate that the UiO-66-NH2-based sensor displays a remarkable response to 0.5–10 ppm formaldehyde with a detection limit of 17 ppb and high selectivity. The significantly improved sensing performance experimentally validates the reasonability of the proposed mechanism. This work provides a reliable strategy for revealing the sensitivity enhancement mechanism and developing high-performance MOF-based formaldehyde sensors.

Chemosensors doi: 10.3390/chemosensors14040088

Authors: Ana-Raluca Măghinici Andreea-Loredana Comănescu Andrei-Daniel Geman Constantin Apetrei

Nonsteroidal anti-inflammatory drugs such as phenylbutazone (PBZ) are among the most widely used medications globally due to their effectiveness in relieving pain and reducing inflammation. This study aims to detect PBZ with metallic particle-based electrochemical sensors using cyclic voltammetry (CV) in the presence of catechol as a redox probe. The approach focuses on evaluating the electrochemical behaviour of PBZ under different experimental conditions and optimizing the detection parameters to develop a simple, rapid, and cost-effective analytical method suitable for this pharmaceutical compound in lab practice. CV was performed using four types of screen-printed electrodes, each modified with different transitional metal particles, in potassium ferrocyanide/potassium ferricyanide, catechol, and catechol-PBZ solutions to study the electrochemical response and detection capability for PBZ. The best performance characteristics were obtained for the sensor modified with Ir particles that detect PBZ, with a linearity range of 0.01 to 1.00 μM and a detection limit of 1.53 nM. Additionally, Fourier-transform infrared spectroscopy (FT-IR) was used to characterize the PBZ in pharmaceuticals. The method using an iridium-modified sensor developed in this study allows the accurate detection of PBZ in pharmaceuticals with a relative error lower than 4%.

Chemosensors doi: 10.3390/chemosensors14040086

Authors: Wei Yang Jinpeng Ma Guandong Wang

Brucellosis is a globally prevalent zoonosis that causes abortion and infertility in livestock, leading to substantial economic losses. Sensitive and reliable quantification of Brucella antibodies, particularly at trace levels, is critical for early diagnosis. In this work, an electrochemical immunosensor was developed by integrating electric field-assisted antigen immobilization with an electrode platform. The electrode was first electrochemically pretreated to improve interfacial reproducibility, and then sequentially modified with L-cysteine and glutaraldehyde to construct an antigen-coupling layer. During antigen immobilization, a custom-built electric field device was applied to regulate the interfacial arrangement of Brucella antigens. The fabrication process was characterized by scanning electron microscopy and cyclic voltammetry, and the analytical performance was evaluated by electrochemical impedance spectroscopy and voltammetric measurements. Under the optimized conditions, the proposed immunosensor exhibited a linear response to Brucella antibodies over the range of 1 × 10−6–10 IU/mL, with a correlation coefficient of 0.99 and a detection limit of 2.04 × 10−7 IU/mL. The sensor also showed acceptable specificity, repeatability, and short-term storage stability, with recoveries of 93.15–99.14% in spiked milk samples. These results indicate that electric field-assisted immobilization can serve as a useful interfacial regulation strategy for Brucella immunosensing and support the analytical feasibility of the proposed platform under controlled experimental conditions. Further validation in more complex biological matrices is still required.

Chemosensors doi: 10.3390/chemosensors14040087

Authors: Marta Guembe-Garcia Lisa Rita Magnaghi Guglielmo Emanuele Franceschi Antonio Bova Raffaela Biesuz

Error in Figure 7a [...]

Chemosensors doi: 10.3390/chemosensors14040085

Authors: Wafa Al-Gethami

This study presents the post-synthetic functionalization of Ni-Co bimetallic nanoparticles (NPs) with a β-cyclodextrin (β-CD) framework using a green synthesis approach with Illicium verum (Star anise) extract. The synthesized nanocomposite was verified using physicochemical characterization techniques such as FTIR, XRD, Zeta potential, DLS, SEM, and TEM. This surface modification successfully yielded a stable core–shell architecture with a reduced crystallite size of 29.5 nm, compared to 41.2 nm for bare Ni-Co NPs. The β-CD coating shifted the Zeta potential from −33.07 mV to −27.65 mV, establishing an electro-steric stabilization mechanism. Sensing performance toward Cd2+ ions was evaluated via the QCM-D technique. The Ni-Co/β-CD nanocomposite demonstrated a superior sensitivity of 34.72 Hz/mM and a remarkably low limit of detection (LOD) of 17.3 µM, representing a 27-fold enhancement over the bare Ni-Co NPs (LOD: 472.2 µM). The mechanical signature, characterized by negative dissipation shifts and a high acoustic ratio (ΔD/Δf = 79.410 × 10−6), confirms an analyte-induced conformational rigidification driven by a host–guest interaction mechanism. These findings establish a robust method of producing bio-based, “smart” nanocomposites for high-precision environmental sensing.

Chemosensors doi: 10.3390/chemosensors14040084

Authors: Beatriz Hatta-Sakoda M. Monica Giusti Luis E. Rodriguez-Saona Luis Condezo-Hoyos

A digital colorimetric method (ACETimage), which utilizes aldol condensation, crotonization, and resinification, was developed and validated to quantify acetaldehyde in the head fraction of Pisco distillation. The optimal conditions for the reaction were as follows: the head Pisco samples were placed in headspace vials, 20% w/w NaOH was added, and the mixture was boiled in water for 2 min. The Color Grab app was used to capture and analyze images of the reactions, with a screen brightness intensity of 0.5, within a maximum post-reaction time of 10 min. The Euclidean distance (ED-RGB) was the color parameter most sensitive to changes, showing a linear correlation with the square of acetaldehyde concentration, with R2 values ranging from 0.9926 to 0.9976. The limit of detection (LOD) and limit of quantification (LOQ) for the ACETimage method were determined to be 30 and 95.3 mg/L, respectively. A significant correlation was observed between the acetaldehyde content measured using ACETimage and gas chromatography (Spearman’s r = 0.9373). Bland–Altman analysis indicated that the differences between the two methods were within the 95% limits of agreement. ACETimage offers a rapid, cost-effective, and user-friendly solution for monitoring acetaldehyde levels during Pisco distillation, enabling easy implementation in production environments, both artisanal and industrial, with minimal sample preparation and limited personnel training.

Chemosensors doi: 10.3390/chemosensors14040083

Authors: Nicole Jaffrezic-Renault Jin-Ming Lin

This Special Issue, entitled “Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2025”, collates 13 review papers that present state-of-the-art findings and future challenges regarding research on gas sensors, chemical sensors, and biosensors [...]

Chemosensors doi: 10.3390/chemosensors14040082

Authors: Sanket Kadam Rohit Ketkar Wen Tai Li Muthaiah Shellaiah Basheer Aazaad Nabanita Sadhukhan Ming Chang Lin Sadeecha Wani Ganesh Chaturbhuj

The use of one-step products and their applications in sensory applications has gained much importance. Herein, Schiff’s base fluorescent turn-on sensor, namely FBTS, was synthesised via a condensation reaction between 6-fluorobenzo[d]thiazol-2-amine and 2-hydroxybenzaldehyde. The probe FBTS exhibits an intense “turn-on” blue fluorescence upon binding to Al3+ ions in a dimethyl sulfoxide–water (DMSO–H2O (8:2, v/v)) medium. From photoluminescence (PL) titrations, the detection limit (LOD) for Al3+ is estimated to be 0.14 microM, and the Benesi–Hildebrand plot-based association constant (Ka) of 5.4 × 104 M−1 confirm a strong association between FBTS and Al3+. Negligible interference is observed in the presence of other metal ions. From the pH effect studies, the optimal pH range for Al3+ detection is 7–9. The recyclable reversibility of FBTS + Al3+ complex has been demonstrated via the sodium salt of ethylenediaminetetraacetic acid (Na2-EDTA) chelation. A Job’s plot and interrogations, such as high-resolution mass spectrometry (HR-MS), 1H-nuclear magnetic resonance (NMR) titration, and density functional theory (DFT), verified the 1:1 stoichiometry of binding between FBTS and Al3+. Based on multiple analyses, the binding mode and mechanism have been detailed. In addition, the practical application of FBTS for detecting Al3+ is demonstrated using the strip paper method, fish analysis, spiked real sample analysis, and cellular imaging.

Chemosensors doi: 10.3390/chemosensors14040081

Authors: Xinhua Shi Xinru Zhao Xiaofan An Meng Gao

Hydrogen peroxide (H2O2) plays a very vital role in industrial and biological processes, but its high concentration may cause health hazards. Therefore, accurate detection of H2O2 is crucial for chemical and biological sensing applications. In this work, a ratiometric fluorescent probe was developed using a core–shell structural silica nanoparticle for the detection of H2O2. Firstly, a silica core structure with red fluorescence emission was constructed by encapsulating a Schiff base compound (SD). Afterwards, a mesoporous silica shell was fabricated, and the AIE featured fluorophore with a H2O2 response character was covalently linked on the surface of the mesoporous shell layer. As recognition sites on the shell, blue-emitting TB molecules specifically identified H2O2 through their phenylboronic acid ester group. The blue fluorescence of core–shell structural nanoprobes would be quenched in the presence of H2O2, while red fluorescence remained unchanged, ensuring the high sensitivity and specificity of the ratio sensing. This design has demonstrated significant potential for the reliable monitoring of hydrogen peroxide in biological and environmental applications.

Chemosensors doi: 10.3390/chemosensors14040080

Authors: Shelly Hafira Nikma Budi Riza Putra Mohamad Rafi Eti Rohaeti Munawar Khalil Wulan Tri Wahyuni

Ground clove bud adulteration with cheaper materials, such as clove stem and soil, poses a significant threat to spice quality and consumer trust. This study introduces a novel, alternative analytical method for the authentication and detection of adulteration in ground clove bud samples. The approach combines voltammetric fingerprinting using a multi-walled carbon nanotube-modified electrode with robust chemometric analysis. Cyclic voltammetry of clove bud samples revealed anodic peaks above +0.5 V and a smaller cathodic peak between +0.5 and −0.3 V vs. Ag/AgCl, suggesting the presence of electroactive compounds. Voltammograms were obtained for authentic clove bud samples sourced from three major Indonesian production regions (South Sulawesi, North Maluku, and East Java), showing varying redox peak intensities. Chemometric analysis, specifically Partial Least Squares Discriminant Analysis (PLS-DA), was successfully employed to differentiate clove bud samples by geographical origin, and Principal Component Analysis (PCA) was used to discriminate authentic clove bud samples from adulterants. Furthermore, Partial Least Squares Regression (PLSR) was utilized to quantify adulteration levels, predicting adulterant concentration (10–100% w/w) using electrochemical signal intensities. The PLSR method exhibited strong linearity between observed and predicted values, confirming its robustness. This proposed method offers a simple, portable, and practical approach for the quality control of ground clove bud. The combination of rapid voltammetric measurement and chemometric modelling provides a valuable and practical tool to prevent fraud and ensure the integrity of the spice trade.

Chemosensors doi: 10.3390/chemosensors14040079

Authors: Alhumaidi B. Alabbas Sherif A. Abdel-Gawad

Pharmaceutical residues in aquatic environments represent a significant pollution concern, particularly in regions experiencing rapid healthcare and industrial growth. This study presents a sensitive and environmentally sustainable analytical method for monitoring paracetamol (PAR), ibuprofen (IBU), and diclofenac sodium (DIC) in pharmaceutical wastewater from Al-Kharj Governorate, Saudi Arabia. The method integrates off-line solid-phase extraction (SPE) with field-amplified sample stacking (FASS) prior to capillary electrophoresis (CE), enabling effective dual preconcentration and enhanced detection sensitivity. Key parameters affecting separation and enrichment, including background electrolyte composition, pH, injection conditions, stacking efficiency, and SPE sorbent selection, were systematically optimized. Under optimal conditions, the SPE–CE–FASS method demonstrated excellent linearity (r2 ≥ 0.997) over the concentration range of 10–1000 ng L−1, with strong precision (intra- and inter-day RSD ≤ 6%) and high recoveries (91.8–98.5%) in pharmaceutical wastewater samples. Matrix-based limits of detection were 4.0 ng L−1 for PAR, 3.5 ng L−1 for IBU, and 3.0 ng L−1 for DIC. The method was successfully applied to real wastewater samples, where all target analytes were detected at environmentally relevant concentrations. Owing to its low solvent consumption, reduced waste generation, and high sensitivity, the proposed SPE–CE–FASS method offers a reliable, cost-effective, and environmentally friendly approach for routine monitoring of pharmaceutical residues in complex wastewater matrices.

Chemosensors doi: 10.3390/chemosensors14040078

Authors: Hongbo Lin Taiqun Yang Lei Li Lang Liu

Fluorescent metal nanoclusters show great promise in heavy metal ion sensing. Herein, a bimetallic nanocluster (GSH-Au/Ag NCs) with orange fluorescence was synthesized through a facile one-pot method. The synthesized GSH-Au/Ag NCs displayed optimal excitation and emission peaks at 275 and 610 nm, respectively. The incorporation of silver can enhance the fluorescence of metal nanoclusters. The fluorescence of as-synthesized GSH-Au/Ag NCs can be significantly quenched by Hg2+ and Cu2+, and a “on–off” fluorescent probe was designed. The detection conditions, including pH and the concentration of the probe, were optimized. The respective detection limits for Hg2+ and Cu2+ ions under optimal detection conditions are estimated to be 40 nM and 33 nM, over the linear range of 100–1200 nM. Furthermore, a ratiometric fluorescent probe was prepared by mixing quinine sulfate and as-synthesized GSH-Au/Ag NCs. Hg2+ and Cu2+ can effectively quench the red fluorescence of GSH-Au/Ag NCs, whereas the blue fluorescence of quinine sulfate remains invariant. This leads to measurable changes in the RGB values of the resulting fluorescence images. The ratio (R/B) exhibits a linear relationship with the concentration of Hg2+ and Cu2+, enabling the determination of its concentration by analyzing RGB values in fluorescence images. This visual detection method significantly reduces both assay time and cost, making it suitable for on-site detection of heavy metal ions in water samples.

Chemosensors doi: 10.3390/chemosensors14040077

Authors: Juan Ma Hong Li Siyu Huang Xiaojing Hu Tingjuan Xia Dongyun Zheng

In the present study, an amperometric aflatoxin B1 sensor was constructed via modifying a nano-graphite carbon paste microelectrode with a cationic surfactant of cetyltrimethylammonium bromide (CTAB) and a perfluorosulfonic acid resin of Nafion through a simple and controllable electrochemical scanning method. The experiment results show that CTAB–Nafion composite film has a good catalytic effect on the electrochemical response of aflatoxin B1. The electrocatalytic mechanism was investigated with the aid of different analytical techniques, including square wave voltammetry, electrochemical impedance spectroscopy, chronocoulometry, energy-dispersive spectroscopy and scanning electron microscopy. Under the optimal conditions, the linear range of the sensor is from 0.1 nM to 100 nM, and its detection limit and sensitivity are 20 pM (S/N = 3) and (24.9 ± 1.51) μA/nM, respectively. The accurate and rapid detection of aflatoxin B1, which has strong carcinogenicity, is of great significance for food quality monitoring and the protection of human health. Therefore, finally, the sensor was used to detect the concentration of aflatoxin B1 in milk and soy sauce samples, and the favorable recovery results indicated its good application prospects.

Chemosensors doi: 10.3390/chemosensors14030076

Authors: Yuxuan Liu Tianzeng Huang Yang Chen Gaowa Xing Hongmei Cao Daixin Ye

A novel sensitive and selective electrochemiluminescence (ECL) sensor using nitrogen-doped graphyne as the platform was proposed for kanamycin (KAN) detection. First, nitrogen-doped graphyne nanomaterial (1N-GY) with high conductivity was synthesized using a high-energy ball milling method. Compared with ordinary graphyne, the addition of nitrogen atoms can improve the conductivity of the material and reduce the electronic migration energy barrier. Then it was used as a substrate material of the ECL sensor, not only increasing the conductivity of the biosensor but also improving the sensitivity of the ECL sensor by providing more immobilization space for the luminescent probe of Nafion-coated mesoporous silica adsorbed Ru(bpy)32+ (mSiO2@Nafion@Ru(bpy)32+). On this basis, mSiO2@Nafion@Ru(bpy)32+ functionalized DNA probes were used as luminescent and capture probes to specifically recognize different concentrations of KAN to produce ECL signals. Under optimal conditions, the proposed ECL sensor exhibited good linearity (10−12–10−6 M KAN) and a low detection limit of 1.08 pM. The prepared biosensor with good stability and selectivity successfully detected KAN in honey and milk samples, with spiked recovery rates ranging from 98% to 111.79%. This method not only expands the application of 1N-GY as a novel graphitic material in ECL biosensors but also provides an effective way to check antibiotics in dairy products.

Chemosensors doi: 10.3390/chemosensors14030075

Authors: Daniela Partene Iulia Gabriela David Mihaela-Carmen Cheregi Emilia-Elena Iorgulescu Hassan Noor

Antibiotics are used primarily in human and veterinary medicine to treat various infections. They have also found applications in animal farms and aquaculture as growth promotors, with the aim of increasing food production. Their uncontrolled use can lead to increased bacterial resistance to antibiotics as well as other adverse effects. Unfortunately, these can reach and accumulate in the environment. Thus, their sensitive and selective detection from various matrices, using inexpensive and portable instruments, is becoming an increasing necessity. Electrochemical techniques are a viable alternative in this regard, and carbon paste electrodes (CPEs) present electrochemical and economic characteristics that recommend them as versatile devices for this purpose. Therefore, this paper is a comprehensive synthesis of the information presented in the last 10 years in the literature regarding CPEs developed for the analysis of antibiotics in different samples. Methods for obtaining different modified CPEs and their performances in detecting compounds belonging to different classes of antibiotics were discussed and priorities for future development were suggested. Through this review, researchers interested in the (electro)analysis of antibiotics will gain information about the advantages and limitations of using CPEs and the efforts made in the last decade to improve their performance.

Chemosensors doi: 10.3390/chemosensors14030074

Authors: Diego Leoni Franco Lucas Franco Ferreira

The premise of electrochemical sensors and biosensors is based on a miniaturized device that can provide precise, highly reliable results with sensitivity and selectivity that is comparable to or even better than the current gold standards [...]

Chemosensors doi: 10.3390/chemosensors14030073

Authors: Julian Joppich Andreas Schütze Christian Bur

Technological solutions might be of great importance for reducing food waste. In the scope of this article, gas sensor systems for assessing the edibility of food have been studied, which can help to avoid food losses by suggesting consumption before spoilage or by separating infected fruits from fresh ones. Several series of measurements with various foodstuffs were conducted to develop methods that enable the identification of possible use cases in which gas sensors could be used to assess food condition as well as methods to calibrate such sensor systems. This paper presents results for oranges as an important target for grocery stores. The fruit headspace was measured by gas sensors, reference data were acquired using human assessment (appearance, odor, edibility) and gas chromatography–mass spectrometry (GC-MS) analysis. Data evaluation shows correlations between the performance of individual sensors for a technical assessment of fruit condition with marker substances identified by GC-MS, e.g., limonene for damaged oranges. Models were derived that are, in general, able to quantify the edibility or to classify defects/mold, but limitations in the applicability/transferability, e.g., between orange varieties, were also identified. With the knowledge gained, important steps could be taken towards an application-oriented setup, and recommendations regarding the sensors used, food trained, and calibration methods applied are derived.

Chemosensors doi: 10.3390/chemosensors14030072

Authors: Apinya Ketkong Kheamrutai Thamaphat Thana Sutthibutpong Noppadon Nuntawong Fueangfakan Chutrakulwong

Sensitive and on-site detection of pesticide residues remains a critical challenge for food safety, particularly in developing regions where rapid screening tools are urgently needed. Herein, we report a flexible surface-enhanced Raman scattering (SERS) platform based on triangular silver nanoplates (TSNPs) integrated onto a polydimethylsiloxane (PDMS) substrate, enabling sensitive and conformal detection of paraquat residues on agricultural surfaces. TSNPs were synthesized via a seed-mediated photochemical growth method and formulated into a TSNP ink, which was directly deposited onto oxygen-plasma-treated and thiol-functionalized PDMS substrates. Owing to the highly anisotropic geometry and sharp edges of TSNPs, the flexible SERS substrate exhibits strong localized surface plasmon resonance (LSPR) enhancement and mechanically stable electromagnetic hot spots. Systematic optimization of TSNP optical absorbance revealed that uniform nanoplate distribution and optimal hotspot density were achieved at an absorbance of 2.0. The SERS performance was evaluated using rhodamine 6G under front-side and back-side illumination configurations, demonstrating good signal reproducibility and a detection limit of approximately 10−5 M. Notably, back-side illumination through the PDMS layer provided superior SERS responses due to improved optical transmission and light–matter interaction. The practical applicability was further demonstrated through back-side SERS detection of paraquat on aluminum foil as a model surface, achieving a lowest detectable concentration of 5 × 10−6 M, followed by damage-free detection on Chinese pear peels. This work highlights a reliable and nondestructive flexible SERS platform for on-site pesticide residue monitoring.

Chemosensors doi: 10.3390/chemosensors14030071

Authors: Lichao Liu Huihui Zhu Xuefeng Gu Ping Hu Yang Chen Pengjia Qi Kai Liu

As wearable electronic products have been integrated into daily life, flexible pressure sensors, which convert pressure into electrical signals, have become a research focus because of their cross-industry application potential. Despite an increasing number of related studies, the systematic integration of discussions on sensing mechanisms, performance regulation, and multiscenario adaptability remains to be explored. In this paper, core sensing mechanisms such as piezoresistive, capacitive, piezoelectric, and triboelectric mechanisms are systematically reviewed; key performance indicators, including sensitivity, response time, and linearity, are analyzed; construction strategies for diverse substrates and conductive functional materials are explored; and applications in healthcare, human–computer interaction, and electronic skin are elaborated on. The aim of these analyses is to provide practical insights into the development and design of flexible pressure sensors, thus providing a useful reference for advancing these technologies and expanding their cross-domain use.

Chemosensors doi: 10.3390/chemosensors14030070

Authors: Yanting Tang Xinyi Chen Huanhuan Zhang Lanpeng Guo Hua-Yao Li Huan Liu

The growing demand for intelligent environmental monitoring is driving the advancement of high-performance, low-cost, and highly integrated gas sensors. Silicon-compatible semiconductor gas sensors provide a promising platform to achieve this goal by leveraging their compatibility with complementary metal–oxide semiconductor (CMOS) processes. The established mass-manufacturing capabilities of micro-electromechanical systems (MEMS) and the high sensitivity and signal amplification characteristics of field effect transistors (FETs) in recent years have made the development of next-generation sensing devices feasible. In this review, we systematically summarize the latest advances in silicon-compatible gas sensors, with a focus on MEMS and FET technologies. We discuss their sensing mechanisms and performance optimization strategies, and further highlight the evolution of gas sensor technology toward on-chip intelligent olfactory systems that integrate sensing, computing, and storage capabilities.

Chemosensors doi: 10.3390/chemosensors14030069

Authors: Alhumaidi B. Alabbas Sherif A. Abdel-Gawad

The continuous discharge of pharmaceutical residues into aquatic environments has raised significant environmental concerns due to their persistence and incomplete removal during wastewater treatment. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most frequently detected pharmaceutical contaminants in industrial effluents. In this study, a sensitive and selective analytical method was developed for the simultaneous determination of ketoprofen (KTP), meloxicam (MEL), and celecoxib (CEL) in pharmaceutical wastewater using micellar electrokinetic chromatography (MEKC) combined with off-line solid-phase extraction (SPE). A high-volume SPE procedure (1000 mL sample) followed by evaporation and reconstitution provided a theoretical enrichment factor of approximately 10,000. Under optimised conditions, complete separation was achieved in less than 10 min. The method exhibited excellent linearity over a range of 0.5–20 µg/mL (r2 > 0.999), with limits of detection in wastewater ranging from 14 to 18 ng/L. Accuracy and precision complied with ICH Q2(B) guidelines, and recoveries from spiked wastewater samples ranged from approximately 99% to 101%, indicating efficient extraction and minimal analyte loss. The validated method was successfully applied to real pharmaceutical wastewater samples, demonstrating its suitability for the routine monitoring of trace-level NSAIDs in complex industrial matrices.

Chemosensors doi: 10.3390/chemosensors14030068

Authors: Teresė Kondrotaitė-Intė Domas Pirštelis Laisvidas Striška Antanas Zinovičius Inga Morkvėnaitė Arūnas Ramanavičius

This study investigates the combined effect of electrodeposited gold nanoparticles (AuNPs) and AuNP–polypyrrole (PPy)-modified Saccharomyces cerevisiae on electrochemical glucose sensing. AuNPs were deposited onto electrode surfaces by cyclic voltammetry, and the resulting interfaces were characterized using atomic force microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. AFM analysis confirmed increased surface roughness and height variability after deposition, indicating substantial restructuring of the electrode interface. Electrochemical measurements showed that AuNP deposition altered interfacial charge storage and transfer and increased the measured charge-transfer resistance. Glucose sensing was evaluated in a ferricyanide-mediated system using yeast layers with or without AuNP and PPy modification over a 0–60 mM concentration range. All configurations exhibited saturating, non-linear glucose responses described by Hill fitting. Among the evaluated yeast-modified electrodes, the AuNP–PPy modified yeast produced the strongest glucose-induced current increase and the best low-concentration performance, achieving a limit of detection of 0.540 mM, compared with 1.016 mM and 1.330 mM for single-modified layers and 3.360 mM for unmodified yeast. These results show that combining AuNP electrodeposition with AuNP–PPy yeast modification improves interfacial properties and enhances mediator-assisted electrochemical glucose sensing.

Chemosensors doi: 10.3390/chemosensors14030067

Authors: Yiyuan Zhang Chen Zhou Jiaxin Li Evgeny Kovtunets

A novel acridine-based fluorescent sensor (Sensor ANT) for the highly selective and sensitive detection of cyanide ions (CN−) was rationally designed and synthesized via the conjugation reaction of acridine-9-amine with 3-nitrophenyl isothiocyanate. The sensing mechanism is triggered by the specific interaction between exogenous CN− and the hydrogen-bonding moieties within the sensor’s molecular framework, which induces a distinct fluorescence quenching response. Systematic titration experiments confirmed that Sensor ANT exhibits rapid response kinetics, excellent selectivity, and reliable qualitative/quantitative detection capabilities toward CN−. Complementary biocompatibility assays, including in vitro cellular imaging and in vivo zebrafish experiments, further verified the promising application potential of this sensor in practical and biological detection scenarios. The detection limit (DL) of Sensor ANT for CN− was calculated to be 2.89 × 10−7 M, with a 1:1 binding stoichiometry and a binding constant of 1.95 × 104 M−1. These findings demonstrate that Sensor ANT represents a robust candidate for CN− detection in environmental and biological systems.

Chemosensors doi: 10.3390/chemosensors14030066

Authors: Elena Cassera Anna Angeleri Michela Sturini Emanuele Ferrari Andrea Capucciati

The growing demand for sustainable, biocompatible, and multifunctional sensing materials has intensified interest in melanin and its derivatives, including melanin-inspired polymers and composites. Melanin is a naturally occurring biopolymer whose intricate structure and diverse chemical composition give rise to a remarkable combination of optical, electrical, and chemical properties. Key physicochemical characteristics, such as broadband optical absorption, hydration-dependent conductivity, redox activity, and metal ion coordination, are closely linked to melanin’s signal transduction capabilities and underpin its relevance in sensing applications. Recent advances in melanin-based sensing technologies encompass pH, humidity, chemical, biological, and optical platforms, with particular emphasis on hybrid systems incorporating graphene, silicon, or nanomaterials, and printable or wearable device architectures. These developments have enabled enhanced performance and broadened potential application fields. However, persistent challenges, including intrinsic heterogeneity, limited selectivity, relatively low electrical conductivity, and poor long-term operational stability, still limit practical implementation. Emerging molecular engineering and advanced fabrication strategies are being developed to address these limitations. Together, these findings position melanin as a versatile, eco-compatible, and functionally rich material, with a significant potential to underpin the next generation of sustainable sensing technologies.

Chemosensors doi: 10.3390/chemosensors14030065

Authors: Davron Sh. Kurbanov Komiljon R. Yakubov Vinoth Kumar Kazi Selvarajan Premkumar Mihhail Klopov Rustam B. Bazarbayev Smagul Zh. Karazhanov

This study presents a unified first-principles investigation of CO2, NO2, SO2, and H2O adsorption on Al2O3 (001), TiO2 (001), and SiO2 (001) surfaces, establishing the first cross-material, chemically consistent benchmark for oxide–gas interactions. Calculated adsorption energies reveal strong chemisorption of SO2 and NO2 on Al2O3 and TiO2, moderate H2O binding—particularly on TiO2 where hydroxylation is favored—and generally weak CO2 interactions across all surfaces. Bader charge analysis provides atom-resolved insight into these trends, showing substantial electron transfer and pronounced oxygen-site polarization for strongly adsorbing gases, in contrast to the minimal charge redistribution characteristic of physisorbed CO2. These charge-transfer signatures distinguish binding mechanisms, clarify the origins of material-specific selectivity, and link adsorption to expected variations in surface conductivity and sensor response. The combined energetic and electronic analysis also reveals competitive effects between humidity and CO2 on surface hydroxylation and local electronic structure, a phenomenon critical for realistic sensing environments but previously unaddressed. Overall, this work delivers a rigorous comparative framework for understanding gas interactions with technologically relevant oxides and provides a solid foundation for future studies involving defects, dopants, surface reconstructions, and advanced functionalization strategies for environmental monitoring and energy-conversion devices.

Chemosensors doi: 10.3390/chemosensors14030064

Authors: Jorge A. Uc-Martín Roberto G. Ramírez-Chavarría

High concentrations of ionized ammonia (NH4+) have been increasingly reported in municipal drinking water systems, posing a severe public health risk as excessive ingestion can lead to life-threatening conditions. Despite its importance, there is a significant lack of sensing technologies designed for continuous-flow monitoring outside laboratory settings, particularly those providing a robust, low-cost methodology suitable for resource-limited environments. To address these challenges, in this work, we report the development of an impedance sensor featuring a 3D-printed housing (3D-IS) for monitoring aqueous ionized ammonia (NH4+). The sensing electrodes, composed of zinc oxide and graphite, allow for the detection of concentrations 10 times lower and 60 times higher than current environmental limits. Its innovative, optimized design, analogous to that of industrial pressure gauges, highlights its potential for use in continuous water flow conditions outside the laboratory, such as water treatment plants. The level of NH4+ in water is monitored by changes in impedance magnitude, with optimal performance observed at a frequency of 100 kHz. At this frequency, the impedance magnitude decreased by nearly two orders of magnitude as the NH4+ concentration increased from 0 to 1 μM. Under these optimized conditions, the sensor exhibited a sensitivity of 2 kΩ/log(μM) and a linearity exceeding 90%. Furthermore, we propose an equivalent circuit model that accurately describes the experimental data, explaining the transduction process. We also describe, from an electrical perspective, the phenomenon of adsorption on the sensor’s transducer surface, thereby ensuring the device’s selectivity. The sensor was evaluated using dilutions of a standard ammonium solution for IC in distilled water, as well as with real groundwater samples, obtaining ∼99.7% of correlation with ion chromatography and a limit of detection of 2 μM. Finally, our device can provide information relatively quickly, with the added advantage of stable response under continuous-flow and real conditions, making it an attractive option for integration into a field sensor node.

Chemosensors doi: 10.3390/chemosensors14030063

Authors: Maksim V. Lipskikh Elena I. Korotkova Alina V. Erkovich Margarita S. Mamina Muhammad Saqib Olga I. Lipskikh Pradip K. Kar

The blood serum that was used in the original publication [...]

Chemosensors doi: 10.3390/chemosensors14030062

Authors: Yonatan Uziel Natan Orlov Loay Atamneh Offer Schwartsglass Shimshon Belkin Aharon J. Agranat

Chemical monitoring of pollutants and hazardous materials in water supply systems traditionally depends on centralized laboratories, advanced instrumentation, and trained personnel, limiting accessibility and preventing real-time, on-site analysis. This work presents an alternative cost-effective, field-deployable approach that uses genetically engineered bioluminescent bioreporters, encapsulated in self-sufficient alginate capsules and integrated with an optoelectronic detection circuit, to detect and quantify target materials in water. We have developed a scalable single-channel prototype featuring four sensing tracks—two for sample measurement, one for clean water, and one for a standard reference solution. The latter employs the standard ratio (SR) method to ensure robust quantification, compensating for batch variability and environmental effects. System characterization showed high uniformity across tracks. Validation with nalidixic acid (NA) demonstrated reliable quantitative performance, with a blind test estimation of 5.6 mg/L for a true concentration of 5 mg/L, well within the calibration error range. Additional sensitivity testing confirmed detection of mitomycin C (MMC) at concentrations as low as 50 µg/L. Overall, the results highlight the potential of bacterial chemical sensing as a practical and scalable tool for real-time, in situ water quality monitoring networks.

Chemosensors doi: 10.3390/chemosensors14030061

Authors: Miha Kim Yunkwang Oh Sun-Seek Min Keekwang Kim Moonil Kim

Herein, RATSGO (Real-time Automated Training and Sensing for Gas Odor), a fully automated live-animal olfactory training platform, for the detection of GBL as a sexual assault-facilitating drug is reported. The system integrates four distinct operant conditioning-based training paradigms, all executed without human intervention, to enhance learning speed, consistency, and scalability. Using this fully automated framework, four rats were trained to identify γ-butyrolactone (GBL). Three of the four animals successfully reached the predefined learning completion criterion, whereas one failed to meet the criterion. Across 320 automated trials, the GBL rats achieved a mean detection accuracy of 90%, with sensitivity and specificity values of 97% and 82%, respectively. The corresponding positive and negative predictive values (PPV and NPV) were 85% and 96%. When challenged with GBL diluted in drinking water (180 trials), performance remained high, yielding 88% accuracy, 89% sensitivity, 87% specificity, 85% PPV, and 90% NPV. Similarly, in experiments involving GBL mixed with whisky (200 trials), the rats demonstrated robust recognition capability, achieving 90% overall accuracy, perfect sensitivity (100%), 84% specificity, 79% PPV, and 100% NPV. Importantly, odor discrimination performance was preserved when reassessed four months after the completion of training, indicating strong long-term retention of the learned odor representations. Collectively, these findings confirm that the RATSGO system supports rapid, stable, and precise odor learning, underscoring its promise as a practical and extensible biological sensing platform for chemical detection applications.

Chemosensors doi: 10.3390/chemosensors14030060

Authors: Nesrine Hafiene Rayhane Zribi Claudia Espro Carlos Vázquez-Vázquez Noureddine Bouguila Giovanni Neri

In this paper, a study on the development of indium-doped CuxS heterojunction-based conductometry sensors is presented. To fabricate the sensors, thick films of In-CuxS heterojunctions were sprayed directly on the alumina sensing platform provided with interdigitated Pt electrodes. The effect of the doping level with different nominal amounts of InCl3 additive (0%, 3%, and 5%) on the structural, morphological and optical properties of CuxS films was first studied by XRD, AFM, UV-Vis and Raman spectroscopy. Moreover, the electrical and sensing characteristics towards low concentrations of hydrogen sulfide (H2S) in air were investigated. The tests carried out clearly demonstrated the positive effect of In doping on the H2S sensing performance of CuxS. The 5%-doped CuxS sensor showed the highest sensitivity to the target gas compared to the other sensor, as well as good stability and selectivity properties.

Chemosensors doi: 10.3390/chemosensors14030059

Authors: Mingzhi Jiao Junqiang Huang Fukao Jia Bin Bai Yu Huo

This work presents an enhanced sensing framework for MEMS gas sensors based on tunable-amplitude periodic modulation, enabling multi-state excitation and feature enrichment without increasing the number of sensing elements. A multi-level periodic driving scheme is introduced to realize sensor virtualization, and the resulting multi-state responses are processed using a short-term baseline-tracking algorithm and a dislocated sparse-sampling strategy to improve feature discrimination. A lightweight multilayer perceptron (MLP) classifier is subsequently optimized and deployed on a field-programmable gate array (FPGA)-based accelerator to enable gas recognition under constrained hardware resources. Experimental results obtained from ternary mixtures of CH4, CO, and H2 demonstrate a classification accuracy of 98.5%, accompanied by a 60% reduction in model size and a fivefold improvement in computational speed on the FPGA accelerator.

Chemosensors doi: 10.3390/chemosensors14030058

Authors: Taoyou Zhou Jingjie Fan Pengyu Zhang Yun Wang Xiangxiang Wang Lining Bao Mingjian Yi Yuxian Guo Bai Sun Lingtao Kong Shuguang Zhu

Dichloromethane, as a widely used highly volatile industrial solvent, has neurotoxicity and hepatotoxicity and is suspected of being a carcinogen to humans. Therefore, it is necessary to develop a detection method that is more convenient for users, responds faster and is more efficient than traditional analytical techniques. In cataluminescence (CTL) technology, as a promising alternative, the performance of CTL sensors critically depends on the design of high-performance sensitive materials. In this study, by rationally designing two typical metal–organic frameworks (MOFs), UIO-66 (zirconium-based) and HKUST-1 (copper-based), UIO-66/HKUST-1 nanocomposites for dichloromethane CTL detection were prepared by using a simple hydrothermal method. The experimental results show that when the composition ratio of UIO-66 is 2%, this composite exhibits the strongest CTL response to dichloromethane. Under optimized conditions, this sensor exhibits high selectivity, excellent stability (RSD = 3.98%), and a rapid response advantage for dichloromethane. The response time and recovery time are 5 and 19 s, respectively. It shows a good linear relationship within the concentration range of 8.4–84 ppm, along with a detection limit as low as 1.71 ppm. Analysis indicates that the enhanced performance stems from the formation of high-concentration oxygen vacancies and significantly strengthened synergistic effects at the UIO-66/HKUST-1 composite. This increases the concentration of surface reactive oxygen species, thereby providing more active sites for catalytic reactions. This work provides a robust and efficient sensing strategy for dichloromethane detection.

Chemosensors doi: 10.3390/chemosensors14030057

Authors: Yan Ke Ge Cao Ningning Zhou Min Yang Tianhong Huang Jiali Xiong Zhujun Li Chuhong Zhu

Surface-enhanced Raman scattering (SERS) technology, with its high sensitivity and fingerprinting capability, has shown broad application prospects in environmental monitoring, food safety, biomedicine, and other fields. Electrospinning technology can produce flexible nanofiber membranes with high specific surface area and three-dimensional porous structures, providing an ideal platform for constructing high-performance SERS substrates for multiphasic analysis. This review systematically summarizes the fabrication strategies of fiber-based SERS substrates by using electrospinning technology, classified from three perspectives: material composition (polymer-based, ceramic-based, carbon fiber-based, and metal-based), spatial configuration (inner, surface, and inner-surface), and temporal sequence of plasmonic nanostructure (pre-synthesis, pre-reduction, post-reduction, post-modification, etc.). Furthermore, the sampling methods and measurement approaches of such substrates in liquid-phase, solid-phase, and gas-phase detection are discussed, with a focus on their applications in environmental pollution monitoring, food safety inspection, microbial identification, and biomedical diagnostics. Finally, the comparison of different preparation strategies and potential future directions are discussed, which could offer helpful guidance for the design and application of high-performance flexible SERS substrates.

Chemosensors doi: 10.3390/chemosensors14030056

Authors: Yu-Meng Dai Weidong Ruan Hong-Wei Li

This study reports the precise synthesis of red-emitting gold–silver bimetallic nanoclusters (Au-AgNCs) via a one-pot hydrothermal method using thiolactic acid as both the ligand and reducing agent. The Au-AgNCs possess an average diameter of 1.85 nm and exhibit strong fluorescence emission at 687 nm. Furthermore, they display notable assembly-induced emission enhancement (AIEE) properties. Upon assembly with bovine serum albumin (BSA), their fluorescence quantum yield significantly increases from 2.50% to 7.78%. Then Au-AgNCs@BSA assembly was employed as a ratiometric fluorescence sensor for the detection of chlortetracycline (CTC). In the presence of CTC, the original red emission of the assembly at 687 nm remained stable, while a new blue emission emerged at 420 nm and intensified progressively with CTC concentration. The ratio of the two emission intensities (I420/I687) exhibited an excellent linear correlation with CTC concentration over the range of 0.10 to 15 μM, with a limit of detection (LOD) of 20 nM. Notably, the sensor demonstrated exceptional selectivity for CTC, showing negligible response to common interfering substances such as metal ions, anions, amino acids, and crucially, other tetracycline antibiotics (tetracycline, oxytetracycline, and doxycycline). The practical applicability of the sensor was validated through the determination of spiked CTC in real water samples, achieving satisfactory recovery rates. In conclusion, this work accomplishes two key objectives: the development of novel AIEE-active Au-Ag bimetallic nanoclusters and the design of an efficient ratiometric sensing strategy. This approach enables the highly selective and sensitive detection of CTC, offering a promising tool for environmental monitoring.

Chemosensors doi: 10.3390/chemosensors14030055

Authors: César Iván Romo-Sáenz Nancy Edith Rodríguez-Garza Ana Laura Delgado-Miranda Diana Laura Clark-Perez Beatriz Elena Castro-Valenzuela Celia María Quiñones-Flores Alva Rocío Castillo-González Andrés Garcia Patricia Tamez-Guerra Ricardo Gomez-Flores

Red blood cells represent a widely used cellular model in cytotoxicity studies, particularly in hemocompatibility assessments. As enucleated cells, which are abundant and easily accessible in both humans and animals, red blood cells allow for rapid, reproducible, and low-cost evaluation of the toxicity of bioactive compounds, whether natural, synthetic, or nanoparticulate. From a functional perspective, the red blood cell membrane is highly sensitive to physical and chemical environmental changes (osmolarity, temperature, pH, and the presence of oxidizing agents). This sensitivity makes red blood cells an effective biosensor for detecting membrane damage, hemolysis, oxidative stress, methemoglobin formation, and aggregation processes. Therefore, in vitro tests using red blood cells allow for the preliminary evaluation in preclinical development, particularly for the early screening of cytotoxicity, membrane-disruptive effects, and hemocompatibility of small molecules, nanomaterials, and blood-contacting biomaterials. These techniques include hemocompatibility tests, evaluation of oxidative and osmotic damage, and evaluation of erythrocyte aggregation and function. However, the use of red blood cells as a cytotoxicity model also has significant limitations. As anucleate cells, erythrocytes lack organelles such as nuclei, mitochondria, or lysosomes, which prevents the evaluation of their effects on key intracellular processes such as protein synthesis, cell signaling, apoptosis, or endoplasmic reticulum stress. This lack of cellular complexity limits their usefulness as a sole model in studies of systemic toxicity or tissue-specific cytotoxicity. These tools offer an effective preliminary approach to anticipating risks in biomedical and pharmacological research.

Chemosensors doi: 10.3390/chemosensors14030054

Authors: Yilin Chen Xiaofei Weng Guanglu Lei Hao Jiang Wei Zheng Jun Zhang Xianghong Liu

Low-temperature (including room-temperature) gas sensors are crucial for energy-efficient and safe detection applications. In this study, we report the synthesis of In2O3-sensitized NiO nanoparticles (NPs) for NO2 detection. The NiO/In2O3 hybrid materials were obtained by pyrolysis of Ni/In bimetallic metal–organic framework (MOF) nanosheets (NSs) fabricated through ultrasonic synthesis and cation exchange. Gas sensing tests revealed that the In2O3 sensitization significantly enhances the NO2 sensing performance of NiO, enabling a response of 1.5 at room temperature (RT) and an optimal response at 100 °C. The NiO/In2O3 sensor demonstrates enhanced selectivity toward NO2, an ultra-low detection limit (41 ppb), and long-term stability. This study presents an effective MOF-derived route for developing high-performance low-power gas sensors.

Chemosensors doi: 10.3390/chemosensors14030053

Authors: İsmail Oran Halil İbrahim Özdemir Turgay Yılmaz Kılıç Hilmiye Deniz Ertuğrul Uygun Hakan Gökalp Uzun Barış Kılıçaslan Evrim Şimşek Yusuf Ali Altuncı Şadiye Mıdık Ali Murat Ergin

Objective: The performance of chrono-impedance measurement, a novel electrochemical method for determining free fatty acids (FA), was evaluated in a real-world clinical setting. Methods: Patients presenting to the emergency department with chest pain or discomfort were included. Routine diagnostic tests were performed in accredited laboratories. Chrono-impedance was measured using a screen-printed carbon electrode connected to a dedicated potentiostat. Serum total free-FA levels were determined by gas chromatography with flame ionization detection. Results: Among 104 patients, 21 received a specific diagnosis, while the remaining 83 patients were discharged with non-specific pain. Mean free-FA level was 0.9 ± 0.6 mM. Palmitic, linoleic, stearic, oleic, and arachidonic acids accounted for 74.9% of total free FAs. Impedance plots showed a characteristic logarithmic increase over time for all patients. When instantaneous impedance values at four different time points (10, 100, 376.6, and 500 s) were examined, a significantly strong correlation was observed between impedance and FA molarity (r = 0.8312, 0.9897, 0.9947, and 0.9951) and FA weight (r = 0.9572, 0.9878, 0.9996, and 0.9998), respectively. Conclusions: Chrono-impedance demonstrated a very high correlation with total free-FA levels in real patient samples.

Chemosensors doi: 10.3390/chemosensors14020052

Authors: Paul J. Gates

The analysis of intact phosphine ligands and phosphino organometallic complexes by mass spectrometry is problematic due to the reactivity of phosphorous(III) leading to rapid oxidation and decomposition of the ligands and complexes. Traditionally, the preferred ionisation method for this problematic class of analytes is electrospray ionisation. However, electrospray is often performed in protic solvents which can promote oxidation of the analyte, especially for those that are already prone to oxidation. This study presents the application of chip-based nanospray ionisation for the analysis of these classes of analyte. Nanospray operates at significantly reduced voltages compared to electrospray and at room temperature and, most importantly, is compatible with a wider range of solvents—included non-protic solvents like toluene and THF. The success of this methodology is initially demonstrated by analysis of the commercial ligand DPPE and then by analysis of a wide range of synthetic phosphine ligands and phosphino organometallic complexes produced in-house at the School of Chemistry, University of Bristol. In all cases, the resulting mass spectra are dominated by intact molecular species with only a small number of oxidised products being observed. In some cases, cationated ions are also observed along with some minor fragmentation or decomposition of the complexes.

Chemosensors doi: 10.3390/chemosensors14020051

Authors: Nana Ma Xueling Dong Ruinan Li Chuang Du Yawen Wang Jiaxin Bai Run Ran Xulin Liu Dianshuo Zhang Haikui Zou

Heparin (Hep) and its clinical antidote protamine (PRO) play essential yet antagonistic roles in anticoagulant therapy, necessitating reliable analytical tools to monitor their levels and interactions. Herein, we report that coptisine chloride (COP), a natural isoquinoline alkaloid, acts as an aggregation-induced emission (AIE) sensor enabling dual-responsive fluorescence modulation toward Hep and PRO. Owing to its rigid polycyclic and intrinsically twisted molecular framework, COP displays typical AIE behavior. In a DMSO/PBS mixture (PBS fraction = 99%, v/v), COP forms strongly emissive aggregates with Hep through electrostatically driven complexation, allowing sensitive Hep detection with a limit of detection (LOD) of 0.70 μg/mL. Subsequent competitive binding of PRO to Hep disrupts the COP–Hep aggregates, giving rise to fluorescence quenching and reversible PRO sensing (LOD: 0.49 μg/mL). Theoretical calculations together with multiple characterization techniques reveal an aggregation–disaggregation mechanism governing the dual fluorescence modulation. Moreover, COP achieves accurate Hep quantification in spiked diluted human serum, affording satisfactory linearity and recoveries (LOD = 0.71 μg/mL; recoveries 98.3–101.6%). These results demonstrate that COP, a structurally simple natural AIE luminogen, serves as a sustainable, biocompatible, and accessible tool for reversible Hep and PRO analysis in complex media.

Chemosensors doi: 10.3390/chemosensors14020050

Authors: Feng-Lian Ma Jia-Nan Wang Xue-Teng Guo Hang Lv Jia-Jia Fan Gui-Juan Ma Li-Hua Tang Yi Lv Yong-Jie Yu

This study focuses on the Helan Mountain East Foothills region of Ningxia, a typical continental climate wine-growing area, with Cabernet Sauvignon grapes as the subject. It combines trimethylsilyl derivatization–Gas Chromatography–Mass Spectrometry (TMS-GC-MS) technology and the independently developed AntDAS-GCMS data analysis platform. The aim was to systematically characterize the temporal dynamics of primary and secondary polar metabolites throughout the entire growth cycle of Cabernet Sauvignon in this region. Results identified 50 metabolites exhibiting significant differences (fold change ≥1, p < 0.05) across growth stages, primarily comprising organic acids (18), sugars (7), and amino acids (13). Metabolite accumulation demonstrated distinct stage-specific patterns: organic acids (e.g., tartaric acid, malic acid) peaked before veraison and then declined significantly, while sugars (e.g., fructose) exhibited a marked increase in abundance during the late maturation stage. The underlying mechanisms of the relevant metabolic pathways require further validation through multi-omics approaches. This study elucidates the dynamic characteristics of primary and secondary metabolites throughout the entire growth stages of Cabernet Sauvignon in the region of Ningxia. It provides data support for understanding the metabolic basis of flavor development in grapes from this area and offers practical references for quality regulation and harvest timing optimization in local grape cultivation management.

Chemosensors doi: 10.3390/chemosensors14020049

Authors: Marco Costa Sabrina Di Masi Giuseppe Egidio De Benedetto

Integrating environmental sustainability into chemical sensor research is no longer optional and must be addressed at the laboratory scale, where material selection, fabrication strategies, and end-of-life management are defined. Although chemical sensors benefit from miniaturization and disposable architectures, their environmental footprint extends beyond the device geometry to include the electrode substrates, functional coatings and auxiliary materials. In this context, sensors based on molecularly imprinted polymers (MIPs), which are entirely synthetic and artificially engineered materials, pose specific sustainability challenges related to material choice, processing, regeneration and disposal. Addressing these aspects in a systematic and quantitative manner is therefore essential to aligning high analytical performance with sustainable sensor design. This review surveys and critically discusses the strategies currently adopted to improve the environmental sustainability of MIP-based sensors, covering key stages of the MIP sensor lifecycle, including monomer and crosslinker selection, fabrication routes, operational aspects, and end-of-life management. Representative approaches such as the use of bioderived polymerization components, low-impact solvents, cleaner analyte removal methods, and low-energy polymerization techniques are analyzed, highlighting their advantages, limitations, and cost-related trade-offs. To move beyond the qualitative assessment of greenness, sustainability is addressed through Lifecycle Assessment (LCA) and AGREE-based metrics, highlighting the importance of functional units, use phase inventories, and regeneration strategies in reducing overall environmental impacts. The review concludes by proposing actionable guidelines to support the transition of MIP-based sensors from sustainable laboratory fabrication to real-world environmental monitoring applications.

Chemosensors doi: 10.3390/chemosensors14020048

Authors: Reagan Aviha Gymama Slaughter

Diabetes continues to impose significant global health and economic burdens, driving the demand for robust, enzyme-free glucose sensors capable of reliable operation under physiological conditions. Here, we report the development of a high-performance nonenzymatic glucose sensor based on laser-induced graphene (LIG) modified with zinc oxide (ZnO) and platinum (Pt) nanostructures. ZnO was electrodeposited onto LIG with modulation potential and deposition duration systematically optimized. The ZnO/LIG electrodes were characterized electrochemically using potassium ferricyanide and evaluated for glucose oxidation in phosphate-buffered solution. Subsequent electrodeposition of Pt under analogous optimized conditions yielded a ternary Pt/ZnO/LIG architecture with enhanced electrocatalytic activity. Sensor performance was assessed by cyclic voltammetry and chronoamperometry, with hydrodynamic conditions optimized for maximal response. The Pt/ZnO/LIG sensor demonstrated a high sensitivity of 37.125 µA mM−1 cm−2, a wide linear dynamic range (0.5–10 mM; 12–28 mM), and a low detection limit of 77.78 µM. The electrode exhibited excellent reproducibility, long-term stability over 7 weeks, and strong selectivity against common interfering species. Robust performance was also confirmed through real sample testing, highlighting its applicability in physiologically relevant matrices. These findings highlight the Pt/ZnO/LIG platform as a promising candidate for next-generation enzyme-free glucose monitoring systems for clinical and point-of-care diabetes management.

Chemosensors doi: 10.3390/chemosensors14020047

Authors: David Camejo Miguel Rodriguez-Escalante Parashu Nyaupane Helena Diez-y-Riega Carlos E. Manzanares

In this investigation, the local mode model for C-H overtone transitions in hydrocarbons and the thermal lens (TL) technique are used to obtain vibrational overtone spectra and subsequent analysis of hydrocarbon impurities in liquid solutions. The experimental thermal lens design enables the detection of hydrocarbon solutes in trace amounts within a hydrocarbon solvent by exciting two distinct vibrational overtones. To exemplify the method, we present the thermal lens signal corresponding to the (Δυ = 6) overtone of benzene or naphthalene as impurities in solvents such as n-hexane or iso-octane. The lowest composition recorded for benzene in n-hexane was 0.005%, while for naphthalene in n-hexane it was 0.001%. Additionally, we explore more sensitive experiments where the (Δυ = 5) transition of the impurity is detected concurrently with the (Δυ = 6) transition of the solvent. This analytical method can also be adapted for use with saturated alcohols in solution contaminating hydrocarbon solvents.

Chemosensors doi: 10.3390/chemosensors14020046

Authors: Wenting Shang Peipei Zhou Mengxue Liu Guangxia Lv Mengqi Sun Yanxia Li Xiangying Meng

Electrochemical biosensors have emerged as indispensable detection tools with rapid advancements in recent years, offering high sensitivity, specificity, and cost-effectiveness for quantifying diverse analytes, including amino acids, proteins, pathogens, cells, antigens, and organic/inorganic compounds, thereby advancing analytical detection technologies across multiple fields. Aptamers, synthetic in vitro-evolved ligands with exceptional binding affinity and stability, serve as superior biorecognition elements for electrochemical sensing interfaces. Compared with other bioreceptors such as antibodies, they are generally easier and faster to produce, more uniform between batches, and easier to modify chemically; they also maintain greater stability than protein antibodies or enzymes across varying pH, temperature, and ionic conditions, enabling targeted recognition and measurable signal transduction. This review systematically summarizes recent advances in electrochemical aptasensors across three core domains: biomedical diagnostics (covering tumor markers, infectious disease pathogens, cardiovascular and metabolic biomarkers), food safety monitoring (targeting antibiotics, mycotoxins, foodborne pathogens, and pesticide residues), and environmental hazard detection (including heavy metals, toxic compounds, and biotoxins). Key technological innovations such as nanomaterial modification, signal amplification strategies, and novel sensor architectures are highlighted. Additionally, it critically discusses prominent challenges, including complex matrix interference, limited aptamer repertoires, poor reproducibility, and lack of standardization, along with future prospects. This work aims to provide a comprehensive reference for the rational design, optimization, and clinical/field application of next-generation electrochemical aptasensing technologies.

Chemosensors doi: 10.3390/chemosensors14020045

Authors: Mohamed Abd-El Baset Nuha Y. Elamin Mohamed R. Elamin Soad S. Alzahrani Rasha M. Kamel Reda F. M. Elshaarawy Ahmed Shahat

A novel chemosensor has been developed for the accurate and sensitive detection of Hg2+ ions in industrial wastewater. This sensor uses a stick-like nanocellulose architecture synthesized via a green method. The unique morphology and surface area of nanocellulose make it an ideal mesoporous substrate for immobilizing the chromophore 1-(benzothiophenyl)-3-(benzooxazolyl)-2-((4-bromophenyl)diazenyl)propane-1,3-dione (azo-dione ligand, ADOL). Comprehensive characterization of the fabricated chemosensor and its nanocellulose base was carried out using FTIR, SEM, TEM, BET surface area, and XRD to evaluate their structural and morphological properties. Spectrophotometric parameters, including pH, response time, selectivity, and sensitivity, were extensively optimized to ensure optimal sensing performance, enabling detection of Hg2+ at very low concentrations. Method validation was performed in accordance with ICH (International Council for Harmonisation) guidelines, confirming the reliability of the sensor in terms of limit of detection (LOD), limit of quantification (LOQ), linearity, and precision. The spectrophotometric method achieved a highly sensitive LOD of 9.07 µg L−1. Moreover, the ADOL chemosensor demonstrated excellent reusability, maintaining performance over five cycles following regeneration with 0.1 M thiourea, underscoring its sustainability. Finally, the sensor exhibited outstanding performance in detecting Hg2+ across various industrial wastewater samples, highlighting its practical applicability, exceptional selectivity, and high sensitivity for real-world environmental monitoring.

Chemosensors doi: 10.3390/chemosensors14020044

Authors: Dan-Marius Mustață Ioana Ionel Daniel Bisorca Venera-Stanca Nicolici

Roadside public transport stops represent localized air pollution hotspots where short-term exposure may differ substantially from levels reported by urban background monitoring. This study investigates the application of low-cost air quality sensors for long-term characterization of particulate matter and gaseous pollutants in a traffic-dominated urban microenvironment. The novelty of this work lies in the combined use of collocated low-cost sensors, energy-independent solar-powered deployment, height-resolved placement representative of different breathing zones, and integrated statistical and predictive analysis to resolve exposure-relevant pollutant dynamics at a single transport stop. Hourly concentrations of particulate matter (PM) PM1, PM2.5, PM10, nitrogen dioxide (NO2), and ozone (O3) were measured over one year at a roadside transport stop adjacent to a four-lane urban road carrying approximately 30,000 vehicles per day. Measurements were obtained using two collocated low-cost sensor units based on optical particle sensing for particulate matter and electrochemical sensing for gases, together with concurrent meteorological observations. Strong agreement between the two particulate matter sensors supported the use of averaged concentrations. Mean PM2.5 concentrations were substantially higher in winter (32.4 µg/m3) than in summer (10.4 µg/m3), indicating pronounced seasonal variability. PM1 and PM2.5 exhibited closely aligned temporal patterns, while PM10 showed greater variability. NO2 displayed sharp diurnal peaks associated with traffic activity, whereas O3 exhibited opposing seasonal and diurnal behavior and was negatively correlated with both PM2.5 (r = −0.32) and NO2 (r = −0.29). One-hour-ahead predictive models incorporating meteorological and temporal variables achieved coefficients of determination up to 0.84. The results demonstrate that energy-independent low-cost sensor systems can robustly capture temporal patterns, pollutant interactions, and short-term predictability in localized roadside environments relevant to exposure assessment.

Chemosensors doi: 10.3390/chemosensors14020043

Authors: Aurelia Magdalena Pisoschi Loredana Stanca Florin Iordache Iuliana Ionascu Iuliana Gajaila Ovidiu Ionut Geicu Liviu Bilteanu Andreea Iren Serban

Pesticides are applied to promote performances in the agricultural field, sustaining crop productivity by counteracting the damages induced by pests and weeds. Under conditions of uncontrolled application, their negative influences exerted on soil, water and biodiversity mean contamination of food and impact on human health. The reactive oxygen species generation induced by pesticides impair the antioxidant protective ability. For humans, pesticides can have cytotoxic, carcinogenic, and mutagenic potential. They can be classified relying on the chemical structure or on the targeted organism. Optical sensors are based on UV-Vis absorption, fluorescence, chemiluminescence, surface plasmon resonance or Raman scattering. Based on their coloring features, nanomaterials are used in optical sensing platforms. They impart high specific surface area, small sizes, facility of surface modification by biorecognition elements (enzyme, antibody, aptamer, molecularly-imprinted polymer) and promote sensitivity and selectivity in biosensing platforms. The present paper highlights the performances of the optical sensing platforms in pesticide assay. Relevant novel applications are discussed critically, following the attempts to improve analytical features of chemical and biochemical sensors. Critical comparison of the techniques is performed in the last section. Advances in nanofabrication like the inclusion of novel nanomaterials and optimizing data interpretation by integration of algorithms can further enhance performances.

Chemosensors doi: 10.3390/chemosensors14020042

Authors: Tarek Sekrafi Mosaab Echabaane Ahmadou Ly Marc Debliquy Chérif Dridi Driss Lahem

The green synthesis of zinc oxide nanoparticles (ZnO NPs) using Retama raetam leaf extract via microwave irradiation was investigated. The biosynthesized NPs were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV-Vis spectrophotometry. An XRD pattern confirmed the formation of a hexagonal wurtzite structure. An FTIR analysis indicated the interactions of the NPs with bioactive molecules involved in their synthesis. SEM and STEM imaging determined the morphology of the NPs with an average size of 14 nm. Furthermore, the biosynthesized ZnO NPs were used as a sensitive layer for detecting volatile organic compounds (VOCs) at low concentrations ranging from 0.5 to 5 ppm. The response sensor measured at an optimum operating temperature of 250 °C and 50% relative humidity (RH). The sensor exhibited a strong response to 5 ppm ethanol (325%), a detection limit as low as 4 ppb and an excellent stability across varying humidity levels.

Chemosensors doi: 10.3390/chemosensors14020041

Authors: Xiuhua You Zhijun Li Youjiao Wu Xinhua Ma Yiwei Wang Shurong Tang Wei Chen

A new fluorescence detection method for PO43− was developed through the in situ synthesis of cadmium sulfide quantum dots (CdS QDs). Without PO43−, the CdS QDs could not be effectively formed by only the S2− and Cd2+ in the solution. As a stabilizer, PO43− is an essential component to regulate the in situ synthesis of CdS QDs. The fluorescence intensity following the addition of different concentrations of PO43− was monitored for quantification. Under optimum conditions, the fluorescence intensity shows a linear relationship with concentrations ranging from 3.0 to 300 µM, and a detection limit of 2.9 µM. This assay was successfully employed to assess PO43− in tap water and wastewater. Compared with traditional methods, which require pre-synthesizing QDs and tethering them with recognition elements to achieve sample detection, the proposed method is simpler and quicker. It takes less than 5 min to complete PO43− detection.

Chemosensors doi: 10.3390/chemosensors14020040

Authors: Wei Wang Peiting Zhao Chenjie Wang Aixuan Xu Wei Ma Gan Wang Zehua Han Yishan Lu Jin Yan Ran Peng

Efficient detection of heavy metal ions in complex marine environments is essential to the safety of marine organisms and human beings. This study developed a novel screen-printed-electrode (SPE) electrochemical sensor for rapid on-site determination of typical heavy metal ions such as Cu2+, Pb2+, Cd2+, and Hg2+ in seawater. The sensor employs a three-electrode system, with the working electrode modified with a composite of metal–organic framework-derived carbon (MOF-C) and multiwalled carbon nanotubes (MWCNTs), thereby significantly enhancing detection sensitivity and selectivity. By optimizing square-wave anodic stripping voltammetry (SWASV) parameters, detection limits of 0.83, 0.40, 1.05, and 0.30 μM for the detection of Cu2+, Pb2+, Cd2+, and Hg2+ ions were achieved. In mixed-ion detection, excellent peak separation and strong resistance to interferences were demonstrated. Experimental results demonstrate that the sensor exhibits good linear response, excellent interference resistance, and high practicality, providing a new approach for rapid on-site determination of heavy metal pollution in marine environments.

Chemosensors doi: 10.3390/chemosensors14020039

Authors: Fabiola Zanette Rossella Svigelj Rosanna Toniolo

In this study, we present a new approach for detecting carbon dioxide based on the voltammetric behavior of selected pH indicators in a deep eutectic solvent (DES). The sensing strategy exploits the electrochemical oxidation potentials of acid–base indicators, in contrast to their conventional use in spectrophotometric analyses. For this purpose, a screen-printed carbon electrode (SPCE) coated with a thin film of DES containing an acid–base indicator was employed. This approach takes advantage of the unique properties of DESs, which make them safe and appealing electrolytes for gas sensing applications. It also exploits the behavior of acid–base indicators, which can exist in protonated or deprotonated forms with distinct oxidation potentials; the electron-rich basic form oxidizes at a lower potential than its protonated counterpart. Phenol Red (PR), Bromocresol Purple (BCP), and Bromothymol Blue (BTB) were investigated, and their voltammetric behavior was studied in different pH buffers as well as in reline DES. The pH dependence of their oxidation potential was used as the analytical parameter, varying in response to the concentration of acidic species in the gas phase. The proposed strategy was evaluated by performing CO2 measurements, achieving limits of detection (LOD) and quantification (LOQ) of 2083 and 6875 ppm, respectively. The same approach was then applied to monitor food freshness via CO2 detection, with results comparing favorably to nondispersive infrared (NDIR) methods for carbon dioxide analysis.

Chemosensors doi: 10.3390/chemosensors14020038

Authors: Roberto María-Hormigos Olga Monago-Maraña Agustin G. Crevillen

Aberrant glycosylation is linked to several diseases, making glycoproteins and their glycoforms promising biomarkers. Traditional methods like mass spectrometry offer high sensitivity but are costly, time-consuming, and unsuitable for point-of-care testing. Electrochemical biosensors emerge as an attractive alternative due to their simplicity, affordability, portability, and rapid response. This review focuses on electrochemical strategies developed to assess the glycosylation level of a specific glycoprotein or biological structure rather than merely glycoprotein or cell concentration, as in previous reviews. Approaches include the use of aptamers, boronic acid derivatives, antibodies, and lectins, often combined with nanomaterials for enhanced sensitivity. Applications span the diagnosis/prognosis of several illnesses such as diabetes, congenital disorders of glycosylation, cancer, and neurodegenerative diseases. Innovative designs incorporate microfluidic and paper-based platforms for faster, low-cost analysis, while strategies using dual-signal acquisition or competitive assays improve accuracy. Despite promising sensitivity and selectivity, most sensors require multi-step protocols and lack of validation in clinical samples. Future research should focus on simplifying procedures, integrating microfluidics, and exploring novel capture or detection probes such as metal complexes or metal–organic frameworks. Overall, electrochemical sensors hold significant potential for point-of-care testing, enabling rapid and precise evaluation of glycosylation status, which could drive cell-based biomarker discovery and disease diagnostics.