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

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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.

Chemosensors doi: 10.3390/chemosensors14020036

Authors: Dewi Murniati Deden Saprudin Irmanida Batubara Budi Riza Putra Utami Dyah Syafitri

This study aims to develop an electrochemical sensor based on a glassy carbon electrode (GCE) modified with Fe3O4 and graphene for the detection of myristicin as a characteristic compound in nutmeg plants. Electrode modification materials were prepared from a combination of graphene and magnetite, synthesized via a hydrothermal method, and further characterized using X-ray diffraction (XRD), scanning electron microscope–energy dispersive spectroscopy (SEM-EDS), and transmission electron microscopy (TEM). The two modifying materials were then optimized, and the optimum conditions were obtained at a w/w ratio of 1:2, which was applied to the GCE surface using the drop-casting technique. The electrochemical performance of the Fe3O4/graphene-modified electrode was evaluated under optimum experimental conditions using a Britton–Robinson buffer solution at pH 5. The scan-rate analysis of the electrode to evaluate its electrochemical performance showed an increase in surface area from 0.101 cm2 for the bare GCE to 0.534 cm2 for the GCE/Fe3O4–graphene. Electroanalytical performance was evaluated using differential pulse voltammetry (DPV), which showed a linear response over the concentration range of 1–100 µM, with a limit of detection of 0.19 µM and a limit of quantitation of 0.58 µM. The developed electrode was applied successfully to detect myristicin in nutmeg seed extract samples, and its calculated concentrations were not significantly different from those obtained with the GC-MS method. These results suggest that the developed sensor may have further potential as an alternative detection tool for characterizing electroactive compounds in nutmeg plants.

Chemosensors doi: 10.3390/chemosensors14020037

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

Multi-way analysis has become one of the most powerful and versatile chemometric approaches for dealing with the increasing complexity of data generated in modern analytical chemistry. Advances in instrumentation, the widespread use of hyphenated techniques, and the inherently multidimensional nature of many experimental designs require methods capable of preserving structural relationships within datasets. In this context, multi-way tools such as Tucker 3, PARAFAC, or other supervised variants provide rigorous and interpretable descriptions of variability across multiple modes (samples, variables, conditions), enabling the extraction of meaningful patterns, improved noise handling, and enhanced robustness, compared with traditional bilinear approaches. This review offers a critical overview of the most commonly applied multi-way algorithms and their practical use in fields such as environmental chemistry, food science, clinical diagnostics, industrial process monitoring, and pharmaceutical analysis. The essential steps of the workflow, from data acquisition and preprocessing to model selection and interpretation, are discussed, highlighting their impact on model reliability. A dedicated section summarizes the software environments available for performing multi-way analyses, guiding readers in selecting the most suitable tools for their needs. Overall, this review emphasizes how multi-way chemometrics is becoming increasingly crucial for converting complex, high-dimensional data into reliable and actionable chemical knowledge.

Chemosensors doi: 10.3390/chemosensors14020035

Authors: Diego Pardina Aizpitarte Eider Larrañaga Ugo Mayor Ainhoa Isla Jose Manuel Amigo Luis Bartolomé

The exceptional olfactory capabilities of trained detection dogs demonstrate high potential for identifying infectious diseases. However, safe and standardized canine training requires specific chemical targets rather than infectious biological samples. This study presents an analytical proof-of-concept combining untargeted metabolomics and machine learning (ML) to decode the specific odor profile of SARS-CoV-2 infection. Using headspace solid-phase microextraction gas chromatography coupled with time-of-flight mass spectrometry (HS-SPME-GC/MS-ToF), axillary sweat samples from 76 individuals (SARS-CoV-2 positive and negative) were analyzed. Data preprocessing and dimensionality reduction were performed to feed a Partial Least Squares-Discriminant Analysis (PLS-DA) model. The optimized model achieved an overall accuracy of 79%, with a specificity of 89% and sensitivity of 70% in external validation, identifying a specific panel of Volatile Organic Compounds (VOCs) as discriminant biomarkers. The optimized model achieved robust classification performance, effectively distinguishing infected individuals from healthy controls based solely on their volatilome. Six VOCs were found to be consistently presented in COVID-19-positive individuals. These compounds were proposed as candidate odor signatures for constructing artificial training aids to standardize and accelerate the training of detection dogs. This study establishes a framework where machine learning-driven metabolomic profiling directly informs biological sensor training, offering a novel synergy between ML and biological intelligence in disease detection. This study establishes a scalable computational framework to translate biological samples into chemical data, providing the scientific basis for designing safe, synthetic K9 training aids for future infectious disease outbreaks without the biosafety risks associated with handling live pathogens.

Chemosensors doi: 10.3390/chemosensors14020034

Authors: Catherine Kiefer Steffen Schwarz Nima Naderi Hadi Parastar Sascha Rohn Philipp Weller

The main characteristics of the large number of coffee species are differences in aroma and caffeine content. Labeled blends of Coffea arabica (C. arabica) and Coffea canephora (C. canephora) are common to broaden the flavor profile or enhance the stimulating effect of the beverage. New emerging species such as Coffea liberica (C. liberica) further increase the variability in blends. However, significant price differences between coffee species increase the risk of unlabeled blends and thus influence food quality and safety for consumers. In this study, a prototypic hyphenation of trapped headspace-gas chromatography-ion mobility spectrometry-quadrupole mass spectrometry (THS-GC-IMS-QMS) was used for the detection of characteristic compounds of C. arabica, C. canephora, and C. liberica in green and roasted coffee samples. For the discrimination of coffee species with IMS data, multivariate resolution with multivariate curve resolution–alternating least squares (MCR-ALS) prior to partial least squares–discriminant analysis (PLS-DA) was evaluated. With this approach, the classification accuracy, as well as sensitivity and specificity, of the PLS-DA model was significantly improved from an overall accuracy of 87% without prior feature selection to 92%. As MCR-ALS preserves the physical and chemical properties of the original data, characteristic features were determined for subsequent substance identification. The simultaneously generated QMS data allowed for partial annotation of the characteristic volatile organic compounds (VOC) of roasted coffee.

Chemosensors doi: 10.3390/chemosensors14020033

Authors: Yiming Qiao Mingna Yang Siyu Rao Cong Ji Xuemin Duan Xiaomei Yang Shuai Chen Ling Zang

Chemiresistive breath humidity sensors (CRBHSs) have emerged as a promising technology for non-invasive health monitoring, offering high sensitivity, a simple device architecture, strong miniaturization potential, and low power consumption. This review summarizes recent progress in CRBHSs from three core perspectives: sensing mechanisms, material systems, and device applications. First, we outline the fundamental sensing principles, emphasizing the Grotthuss proton-hopping mechanism and the resistance modulation associated with water adsorption/desorption. Next, we discuss structural engineering strategies for zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) sensing materials, highlighting how dimensional design can balance water uptake, charge transport, mechanical compliance, and wearability. Finally, we review representative applications ranging from healthcare diagnostics and respiratory monitoring to emotion- and behavior-related assessment. Overall, this review integrates the mechanism–material–application relationship to provide a cohesive understanding of CRBHSs; identifies key challenges such as environmental stability and anti-interference performance; and outlines future directions, including performance optimization, flexible/wearable integration, and intelligent sensor systems.

Chemosensors doi: 10.3390/chemosensors14020032

Authors: Milica Počuča-Nešić Katarina Vojisavljević Slavica Savić Ružić Zorica Marinković Stanojević Aleksandar Malešević Tian Tian Nan Ma Rong Qian Mao Huang Matejka Podlogar Goran Branković Zorica Branković

Pure SnO2 nanofibers were synthesized via an electrospinning method and subsequently calcined at 550 °C to investigate the structure–property relationship governing H2S gas sensing performance. X-Ray diffraction confirmed the formation of the crystalline rutile-type SnO2. FE-SEM and TEM methods revealed a hierarchically porous morphology with fiber diameters ranging from 70 to 160 nm. BET measurements indicated a high specific surface area of 75 m2/g, consistent with the observed porous architecture. Gas sensing measurements toward H2S revealed a pronounced response value of 25 at 200 °C with the response time of 23 s, both superior to those recorded for acetone, ethanol, and hydrogen. The enhanced sensitivity and dynamic response are attributed to the large surface area and interconnected porous network of the nanofibers, which provide the abundant active sites and facilitate efficient gas diffusion.

Chemosensors doi: 10.3390/chemosensors14020031

Authors: Xiaoyu He Wangcheng Lan Yuancai Lv Xiaojing Li Chen Tian

Monitoring trace nitrophenol pollutants in water has garnered considerable attention. A porous organic polymer-modified cellulose nanofiber membrane (COP-99@DCA) was fabricated via in situ growth of a porous organic polymer on an electrospun cellulose nanofiber membrane. The resulting brown COP-99@DCA composite possessed abundant functional groups, including C-F, C-O, and hydroxyl groups, and exhibited excellent thermal and chemical stability. Furthermore, when employed as a sorbent in dispersive solid-phase microextraction (d-SPME), COP-99@DCA efficiently enriched trace nitrophenols in water. Under optimal enrichment and desorption conditions, the enrichment efficiencies for five nitrophenol congeners ranged from 97.24% to 102.46%. Mechanistic investigations revealed that the efficient enrichment of trace nitrophenols by COP-99@DCA was primarily governed by hydrogen bonding, π-π stacking, and hydrophobic interactions. Coupled with solid-phase extraction (SPE) pre-treatment, high-performance liquid chromatography (HPLC) enabled the sensitive detection of trace nitrophenols. The established calibration curves exhibited favorable linearity, with low limits of quantitation (LOQs) ranging from 0.5 to 1 μg/L and low limits of detection (LODs) between 0.08 and 0.1 μg/L. Moreover, practical applications in real water samples confirmed the outstanding enrichment performance of COP-99@DCA. At spiked concentrations of 5 and 10 μg/L, the recovery rates were 85.35–113.55% and 92.17–110.46%, respectively. These results demonstrate the great potential of COP-99@DCA for practical water sample analysis. Collectively, these findings provide a novel strategy for the design of pre-treatment materials for the analysis of trace organic pollutants.

Chemosensors doi: 10.3390/chemosensors14020030

Authors: Francisca Rodríguez-Cabello Lyanne Rodríguez Fanny Guzmán Basilio Carrasco Sigrid Sanzana Andrés Trostchansky Iván Palomo Eduardo Fuentes

Natural bioactive peptides have emerged as pivotal candidates in modern science due to their multifaceted biological activities and versatile applications across biomedicine, biotechnology, and nutraceuticals. These molecules exhibit a broad pharmacological spectrum including antimicrobial, antiplatelet, antioxidant, antihypertensive, and antitumor properties, positioning them as potent therapeutic agents and essential functional food constituents. Compared to synthetic alternatives, their inherent structural diversity, biocompatibility, and biodegradability offer a superior safety profile by minimizing systemic toxicity and adverse effects. This review provides a comprehensive analysis of the primary natural reservoirs of these peptides, which encompass terrestrial flora and fauna as well as marine organisms and microorganisms, while elucidating their complex mechanisms of action and structure–function relationships. Furthermore, we evaluate contemporary methodologies for peptide identification and optimization, such as high-throughput proteomics, computational modeling, and strategic chemical modifications aimed at enhancing metabolic stability and bioavailability. Although bottlenecks in extraction, scalable production, and proteolytic susceptibility persist, recent breakthroughs in recombinant technology and rational design are facilitating their industrial translation. Finally, we discuss future perspectives focused on the synergy between artificial intelligence, nanotechnology, and sustainable circular economy strategies to maximize the therapeutic accessibility and functional efficacy of natural peptides.

Chemosensors doi: 10.3390/chemosensors14020029

Authors: Yi Lu Zhengyu Tao Xinyu Guo Tingqiang Li Wenwen Kong Fei Liu

Phytoremediation is an eco-friendly and in situ solution for remediating heavy metal-contaminated soils, yet practical application requires timely and accurate effectiveness evaluation. However, conventional chemical analysis of plant parts and soils is labor-intensive, time-consuming and limited for large-scale monitoring. This study proposed a rapid sensing framework integrating laser-induced breakdown spectroscopy (LIBS) with deep transfer learning and spectral indices to assess phytoremediation effectiveness of Sedum alfredii (a Cd/Zn co-hyperaccumulator). LIBS spectra were collected from plant tissues and diverse soil matrices. To overcome strong matrix effects, fine-tuned convolutional neural networks were developed for simultaneous multi-matrix quantification, achieving high-accuracy prediction for Cd and Zn (R2test > 0.99). These predicted concentrations enabled calculating conventional phytoremediation indicators like bioconcentration factor (BCF), translocation factor (TF), plant effective number (PEN), and removal efficiency (RE), yielding recovery rates near 100% for TF and PEN. Additionally, novel spectral indices (SIs)—directly derived from characteristic wavelength combinations—were constructed to bypass intermediate quantification. SIs significantly improved the direct evaluation of Zn removal and translocation. Finally, a decision-level fusion strategy combining concentration predictions and SIs enhanced Cd removal assessment accuracy. This study validates LIBS combined with intelligent algorithms as a rapid sensor tool for monitoring phytoremediation performance, facilitating sustainable environmental management.

Chemosensors doi: 10.3390/chemosensors14010028

Authors: Xiaomeng Zheng Qi Liu Qingjiang Pan Guo Zhang

Ethanolamine (EA) is a widely used yet toxic volatile organic compound (VOC). However, existing gas sensors for EA detection face persistent challenges in achieving exceptional sensitivity and low detection limits at room temperature (RT). In this study, a novel and high-performance EA sensor based on the MoO3/BiOI composite was prefabricated using hydrothermal and cyclic impregnation methods. The response value toward 100 ppm EA reached 861.3, which was 3.5-times higher compared to that of pure MoO3. In addition, the MoO3/BiOI composite exhibited a low detection limit (0.13 ppm), excellent selectivity, short response/recovery times, exceptional repeatability and long-term stability. The outstanding gas sensing performance of the MoO3/BiOI is attributed to the formation of a p-n heterojunction, synergistic effects between the two materials, abundant adsorbed oxygen species and superior charge transfer efficiency. The sensor developed in this work effectively addresses the long-standing challenges, demonstrating unprecedented practical application potential for EA gas detection. Simultaneously, this study provides a novel strategy, a new approach and a promising material for the subsequent development of advanced amine sensors.

Chemosensors doi: 10.3390/chemosensors14010027

Authors: Ivan Švancara Milan Sýs

This review examines the feasibility of electrochemical synthesis of poly-L-arginine (PArg) using repetitive cyclic voltammetry in neutral aqueous phosphate-buffered saline. Previous studies on electrochemical deposition of PArg onto different carbonaceous electrode materials are discussed with respect to the already reported mechanistic models. Some controversial interpretations are of interest, predominantly the formation of peptide bonds during the electropolymerisation of L-arginine. Several alternative anodic pathways are considered via the possibilities and limitations of ways of attaching L-arginine molecules to the electrode surface. Furthermore, the role of oxygen-containing surface groups is discussed, as this aspect has been largely overlooked in the context of L-arginine deposition, despite the O-terminating character of the electrode surface and its effect on the reactivity of the nucleophilic guanidine group in L-arginine. Also, the application of extremely high potentials around +2 V vs. Ag/AgCl/3 mol L−1 KCl is considered, as it can lead to the generation of reactive oxygen species that may interfere with or even govern the entire deposition process. Thus, the absence of such considerations may raise doubts about the peptide nature of the electrochemically assisted polymerisation of this basic amino acid. Finally, it seems that the identity of the electrochemically synthesised PArg does not correspond to that of this polymer prepared by conventional methods, such as solid-phase peptide synthesis, solution-phase synthesis, or N-carboxy-anhydride polymerisation, and therefore the whole process remains unproved.

Chemosensors doi: 10.3390/chemosensors14010026

Authors: Tasnim Ahmed Khan Mahmud Md Rejvi Kaysir Shazzad Rassel Dayan Ban

Diabetes is a developing global health concern that cannot be cured, necessitating frequent blood glucose monitoring and dietary management. Photoacoustic Spectroscopy (PAS) in the mid-infrared (MIR) region has recently emerged as a viable noninvasive blood glucose monitoring technique. However, MIR-PAS confronts significant challenges: (i) Water absorption, which reduces light penetration, and (ii) interference from other blood components. This paper systematically analyzes the background of photoacoustic signal generation and proposes a differential PAS (DPAS) in the MIR region for removing the background signals arising from water and other interfering components of blood, which improves the overall detection sensitivity. A detailed mathematical model with an explanation for choosing two suitable MIR quantum cascade lasers for this differential scheme is presented here. For single-wavelength PAS (SPAS), a detection sensitivity of 1.537 µPa mg−1 dL was obtained from the proposed model. Alternatively, 2.333 µPa mg−1 dL detection sensitivity was found by implementing the DPAS scheme, which is about 1.5 times higher than SPAS. Moreover, DPAS facilitates an additional parameter, a differential phase shift between two laser responses, that has an effective correlation with the glucose concentration variation. Thus, MIR-based DPAS could be an effective way of monitoring blood glucose levels noninvasively in the near future.

Chemosensors doi: 10.3390/chemosensors14010025

Authors: Zaihua Duan

Gas and humidity (water molecules) are important components of the environment and human respiration, which are closely related to human life and production [...]

Chemosensors doi: 10.3390/chemosensors14010024

Authors: Jianrui Zha Bo Sheng Wenjia Hu Jiake Chen Wengang Wu

Black crust and spalling are common deterioration phenomena affecting marble relics, yet their correlation remains inadequately understood. Hyperspectral imaging, reflectance spectroscopy, portable X-ray Fluorescence (p-XRF), infrared thermography, Scanning Electron Microscopy coupled with Energy-Dispersive Spectroscopy (SEM-EDS), and microbiological analysis was employed to connect these two types of deterioration on the Danbi stone carving of the Confucian Temple in Beijing. Spectral and thermal analyses reveal that black crust significantly reduces reflectance and increase solar absorption by 27%, resulting in thermal stress. p-XRF and SEM-EDS analyses indicated that black crust is enriched in Fe, Ti, Zn, Pb, As and clay minerals, while spalling areas display increase Ca, reflecting substrate exposure. Microscopy reveals microcracks at the layer–substrate interface. Microbiological analyses identify Cladosporium anthropophilum and Alternaria alternata as contributors to surface-darkening. These multi-scale datasets collectively demonstrate that alterations in surface chemistry and bio-mediated darkening promoting the formation of black crusts, which subsequently induce marble spalling due to solar absorption and thermal stress. These findings clarify the coupled physical–chemical–biological pathways through which black crust accelerates stone spalling.

Chemosensors doi: 10.3390/chemosensors14010023

Authors: Ahmed H. Naggar Atef Hemdan Ali Ebtsam K. Alenezy Tarek A. Seaf-Elnasr Salah Eid Tamer H. A. Hasanin Adel A. Abdelwahab Al-Sayed A. Bakr Abd El-Aziz Y. El-Sayed

Rapid, sensitive, and environmentally sustainable spectrophotometric methods for the determination of nitrite (NO2−) in environmental specimens are proposed. The presented procedures are grounded in the diazotization of sulphathiazole (STZ), followed by coupling with rhodanine (RDN) or 7-hydroxycoumarin (7-HC) in an alkaline medium, and the results were studied. This reaction gave an intense soluble red color at 504 nm and a pale red color at 525 nm for RDN and 7-HC, respectively. The conditions producing the maximum performance and other important analytical criteria in relation to the proposed procedures were investigated to enhance their sensitivity. Beer’s law was abided by for NO2− over the concentration ranges of 0.08–2.0 µg mL−1 and 0.04–2.4 µg mL−1 using RDN and 7-HC, respectively. The lower limit of detection (LLOD), lower limit of quantification (LLOQ), molar absorptivity (ε), and Sandell’s sensitivity were calculated as follows: 0.0303 µg mL−1, 0.0918 µg mL−1, 4.20 × 104 L mol−1 cm−1, and 1.63 × 10−6 µg cm−2 (in the case of RDN); and 0.0387 µg mL−1, 0.1172 µg mL−1, 6.90 × 104 L mol−1 cm−1, and 1.00 × 10−6 µg cm−2 (in case of 7-HC). Furthermore, the ecological implications were assessed using three green assessment methodologies: Analytical Eco-Scale (ESA), Analytical GREEnness metric (AGREE), and Green Analytical Procedure Index (GAPI). Thus, our proposed procedures are fully validated and implemented in order to carry out NO2− quantification in the selected ecological samples (water and soil samples).

Chemosensors doi: 10.3390/chemosensors14010022

Authors: Marjorie Montero-Jimenez Jael R. Neyra Recky Omar Azzaroni Juliana Scotto Waldemar A. Marmisollé

We present a methodology that enhances the analytical performance of organic electrochemical transistors (OECTs) by continuously cycling the devices through gate potential sweeps during sensing experiments. This continuous cycling methodology (CCM) enables real-time acquisition of full transfer curves, allowing simultaneous monitoring of multiple characteristic parameters. We show that the simultaneous temporal evolution of several OECT response parameters (threshold voltage (VTH), maximum transconductance (gmax), and maximum transconductance potential (VG,gmax)) provides highly sensitive descriptors for detecting pH changes and macromolecule adsorption on OECTs based on polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) (PEDOT) channels. Moreover, the method allows reconstruction of IDS–t (drain–source current vs. time) profiles at any selected gate potential, enabling the identification of optimal gate voltage (VG) values for maximizing sensitivity. This represents a substantial improvement over traditional measurements at fixed VG, which may suffer from reduced sensitivity and parasitic reactions associated with gate polarization. Moreover, the expanded set of parameters obtained with the CCM provides deeper insight into the physicochemical processes occurring at both gate and channel electrodes. We demonstrate its applicability in monitoring polyelectrolyte and enzyme adsorption, and detecting urea and glucose through enzyme-mediated reactions. Owing to its versatility and the richness of the information it provides, the CCM constitutes a significant advance for the development and optimization of OECT-based sensing platforms.

Chemosensors doi: 10.3390/chemosensors14010021

Authors: Chao-Sheng Chen Miao-Wei Lin Chin-Feng Wan

Highly accurate quantitative detection of heavy metals is crucial for preventing environmental pollution and safeguarding public health. To address the demand for sensitive and specific detection of Cu2+ ions, we have developed carbon dots using a simple hydrothermal process. The synthesized carbon dots are highly stable in aqueous media, environmentally friendly, and exhibit strong blue photoluminescence at 440 nm when excited at 352 nm, with a quantum yield of 5.73%. Additionally, the size distribution of the carbon dots ranges from 2.0 to 20 nm, and they feature excitation-dependent emission. They retain consistent optical properties across a wide pH range and under high ionic strength. The photoluminescent probes are selectively quenched by Cu2+ ions, with no interference observed from other metal cations such as Ag+, Ca2+, Cr3+, Fe2+, Fe3+, Hg2+, K+, Mg2+, Sn2+, Pb2+, Sr2+, and Zn2+. The emission of carbon dots exhibits a strong linear correlation with Cu2+ concentration in the range of 0–14 μM via a static quenching mechanism, with a detection limit (LOD) of 4.77 μM in water. The proposed carbon dot sensor is low cost and has been successfully tested for detecting Cu2+ ions in general water samples collected from rivers in Taiwan.

Chemosensors doi: 10.3390/chemosensors14010020

Authors: Xiaoyuan Dong Dapeng Li Aobei Chen Dezhi Zheng

Extreme environments such as low pressure, high temperature, and intense radiation pose severe challenges for humidity sensors, causing conventional hygroscopic materials to exhibit sluggish responses, drift, and instability. In response, recent research has adopted multi-level strategies involving material modification, structural engineering, and packaging optimization to enhance the adaptability of humidity-sensitive materials in extreme environments. This review examines humidity sensing from an environmental perspective, integrating sensing mechanisms, material classifications, and application scenarios. The performance, advantages, and limitations of six major categories of humidity-sensitive materials, including carbon-based, metal oxides, conductive and insulating polymers, two-dimensional (2D) materials, and composites, are systematically summarized under extreme conditions. Finally, emerging development trends are discussed, highlighting a shift from material-driven to system-driven approaches. Future progress will rely on multidisciplinary integration, including interface engineering, multiscale structural design, and intelligent algorithms, to achieve higher accuracy, stability, and durability in extreme-environment humidity sensing.

Chemosensors doi: 10.3390/chemosensors14010019

Authors: Yu Yang Danning Li Changchang Zheng Ling Zhang Xuwei Chen

Enzymatic electrochemical sensors are promising for real-time glucose monitoring due to their high sensitivity and continuous detection capability. In this work, a magnetic Fe3O4@MXene nanocomposite was synthesized hydrothermally. The introduction of Fe3O4 not only reduced MXene’s inherent negative surface charge, improving interaction with glucose oxidase (GOD), but also formed a porous structure that enhances enzyme immobilization via physical adsorption. Based on these properties, a Fe3O4@MXene/GOD/Nafion/GCE electrode was fabricated. The composite’s high specific surface area, excellent conductivity, and good biocompatibility significantly promoted the direct electron transfer (DET) of GOD. Meanwhile, the apparent electron transfer rate constant (ks) was calculated to be 9.57 s−1, representing a 1.26-fold enhancement over the MXene-based electrode (7.57 s−1) and confirming faster electron transfer kinetics. The sensor showed a bilinear glucose response in the ranges of 0.05–15 mM, with sensitivity of 120.47 μA·mM−1·cm−2 and a detection limit of 38 μM. It also exhibited excellent selectivity, reproducibility and stability. Satisfactory recovery rates were achieved in artificial serum samples while demonstrating comparable detection performance to commercial blood glucose meters.

Chemosensors doi: 10.3390/chemosensors14010018

Authors: Jiyeon Lee Sunghoon Park

This paper introduces a streamlined three-step synthesis method for crafting porous Fe2O3/ZnO nanofibers (NFs). Initially, Fe2O3 nanoparticles (NPs) were synthesized using the hydrothermal method. Subsequently, PVP NFs laden with Fe2O3 NPs and zinc salt were synthesized via an electrospinning method. Finally, porous Fe2O3/ZnO NFs were fabricated through calcination, resulting in an average diameter of approximately 100 nm. Gas-sensing experiments illuminate that the porous Fe2O3/ZnO NFs exhibit outstanding sensitivity, selectivity, and robust long-term stability. Although the response magnitude decreased under high relative humidity (RH) due to competitive adsorption, the sensor maintained distinct detectable responses towards NO2 vapor at an optimum temperature of 225 °C. Particularly noteworthy is the substantial enhancement in NO2 sensing properties observed in the Fe2O3/ZnO composite compared to pure ZnO NFs. This enhancement can be ascribed to the distinctive microstructure and heterojunction formed between Fe2O3 and ZnO.

Chemosensors doi: 10.3390/chemosensors14010017

Authors: Daniel D. S. de Sá João P. C. Trigueiro Luiz F. C. de Oliveira Hernane S. Barud Frank Alexis Roberto S. Nobuyasu Flávio B. Miguez Frederico B. De Sousa

Stimuli-responsive materials based on renewable biopolymers are highly attractive for developing sustainable chemical sensors. Here, two spiropyran derivatives (SP1 and SP2) were synthesized and covalently grafted onto cellulose, yielding the functional materials Cel-SP1 and Cel-SP2. Cellulose was selected as a biocompatible, biodegradable, and renewable support able to provide a stable, hydrogen-bond-rich microenvironment for chromic responses. Raman spectroscopy confirmed successful esterification, while SEM-EDS analyses revealed preserved cellulose morphology and the incorporation of nitrogen-rich spiropyran moieties. Both materials exhibited pronounced solvatochromic and pH-dependent behaviors in the solid state. Diffuse reflectance measurements revealed distinct bathochromic or hypsochromic shifts depending on solvent polarity and specific solute–matrix interactions, with DMF and DMSO producing the strongest responses. Under acidic vapors, both materials generated new absorption bands consistent with the formation of protonated merocyanine species, whereas basic vapors promoted partial or full reversion to the spiropyran form. Cel-SP1 and Cel-SP2 also displayed solvent- and pH-dependent luminescence, with Cel-SP2 showing a markedly higher sensitivity to protonation. Prototype solvent strips and acid/base vapor indicators demonstrated fast, naked-eye, reversible chromic transitions. These results highlight spiropyran-modified cellulose as an effective, renewable platform for dual solvent and acid/base vapor sensing.

Chemosensors doi: 10.3390/chemosensors14010016

Authors: Xu Lin Ruiqin Tan Wenfeng Shen Dawu Lv Weijie Song

Volatile organic compounds (VOCs) released from automotive interior materials and exchanged with external air seriously compromise cabin air quality and pose health risks to occupants. Electronic noses (E-noses) based on metal oxide semiconductor (MOS) micro-electro-mechanical system (MEMS) sensor arrays provide an efficient, real-time solution for in-vehicle gas monitoring. This review examines the use of SnO2-, ZnO-, and TiO2-based MEMS sensor arrays for this purpose. The sensing mechanisms, performance characteristics, and current limitations of these core materials are critically analyzed. Key MEMS fabrication techniques, including magnetron sputtering, chemical vapor deposition, and atomic layer deposition, are presented. Commonly employed pattern recognition algorithms—principal component analysis (PCA), support vector machines (SVM), and artificial neural networks (ANN)—are evaluated in terms of principle and effectiveness. Recent advances in low-power, portable E-nose systems for detecting formaldehyde, benzene, toluene, and other target analytes inside vehicles are highlighted. Future directions, including circuit–algorithm co-optimization, enhanced portability, and neuromorphic computing integration, are discussed. MOS MEMS E-noses effectively overcome the drawbacks of conventional analytical methods and are poised for widespread adoption in automotive air-quality management.

Chemosensors doi: 10.3390/chemosensors14010015

Authors: Marina Galić Ana Čikoš Leentje Persoons Dirk Daelemans Karolina Vrandečić Maja Karnaš Marijana Hranjec Robert Vianello

A novel series of benzoxazole-derived iminocoumarins was synthesized via a Knoevenagel condensation and fully characterized using NMR, UV–Vis spectroscopy, and computational methods. Their photophysical properties were systematically examined in solvents of varying polarity, revealing pronounced effects of both substituents and solvent environment on absorption maxima and intensity. Derivatives bearing electron-donating substituents on the coumarin core exhibited distinct and reversible pH-responsive spectral shifts, confirming their potential as optical pH probes. Experimental pKa values derived from absorption titrations showed excellent agreement with DFT-calculated data, validating the proposed protonation-deprotonation equilibria and associated electronic structure changes. Structure–property relationships revealed that electron-donating groups enhance intramolecular charge transfer, while electron-withdrawing substituents modulate spectral response and stability. In parallel, the compounds were evaluated for antiproliferative, antiviral, and antifungal activities in vitro. Strong electron-donating substituents were associated with potent but non-selective cytotoxicity, whereas derivatives bearing electron-withdrawing groups displayed moderate and more selective antiproliferative effects against leukemia cell lines. Antifungal screening revealed moderate inhibition of phytopathogenic fungi, particularly for compounds with electron-withdrawing or methoxy substituents. Overall, these findings demonstrate that benzoxazole iminocoumarins represent a promising class of multifunctional heterocycles with potential applications as optical pH sensors and scaffolds for bioactive compound development.

Chemosensors doi: 10.3390/chemosensors14010014

Authors: Fotoula Schoina Stamatina Xenou Angeliki Doukaki Symeon Makris Olga S. Papadopoulou Chrysoula Tassou George-John Nychas Nikos Chorianopoulos

This study evaluated the combined effect of the modified atmosphere packaging (MAP1: 60% CO2, 10% O2/30% N2 & MAP2: 40% CO2, 30% O2/30% N2), and active packaging of oregano essential oil (1% v/w) used as a natural preservative, on the quality and shelf-life extension of fresh sea bream fillets. The samples were stored at four different temperatures (0, 4, 8, and 12 °C), and a microbiological analysis, pH measurements, and sensory evaluations were performed. In parallel, spectral data were obtained using three different spectroscopic sensors (two MultiSpectral Imaging devices and an FT-IR one), and nine different machine-learning regression models were applied to predict the microbiological counts. Oregano essential oil positively affected preservation, reducing microbial growth by 0.5 to 2 log CFU/g, and extending the fillets’ shelf life by up to 48 h based on sensory evaluation. Regarding the sensors’ data, the examined nine models exhibited encouraging results for the rapid microbiological assessment, with the FT-IR data showing the best performance for evaluating the microbiological population. Among the tested algorithms, the least Angle Regression (lars) achieved the best performance for both the flesh and skin datasets, with RMSE values of 0.6075 and 0.5953, MAE of 0.3008 and 0.4567, R2 of 0.8858 and 0.7532, and accuracy of 87% and 91%, respectively. The Benchtop-MSI showed the best predictive performance for flesh (RMSE = 0.5926, MAE = 0.4876, R2 = 0.7338, and Accuracy = 92%), while the artificial neural network (nnet) performed best for skin (RMSE = 0.6761, MAE = 0.5247, R2 = 0.6560, and Accuracy = 84%). Regarding the Portable-MSI, the artificial neural network model gave the highest accuracy for flesh (RMSE = 0.5908, MAE = 0.4663, R2 = 0.5903, and Accuracy = 87%), whereas principal component regression was the most effective for skin (RMSE = 0.6600, MAE = 0.5413, R2 = 0.5534, and Accuracy = 83%).

Chemosensors doi: 10.3390/chemosensors14010013

Authors: Biswaranjan Paital Sk Abdul Rashid Prajnyani Dikshit Dipak Kumar Sahoo Tejasweta Bhuyan Ashutosh Panigrahi Tapaswini Subudhi Akshama Noorenazar Samarjeet Pradhan Barsha Sarangi Prasana Kumar Rath

Issues related to malnutrition are addressed primarily through the consumption of fish meat, as it is both affordable and accessible to economically weaker sections of the population. Therefore, challenges observed in the aquaculture and fishery sectors, such as the detection of environmental changes, disease outbreaks, hindered growth, and poor fish health management, need to be addressed to increase production. The employment of modern technologies, such as (bio)sensors, helps to enhance production in artisanal and large aquaculture systems, because these can timely detect challenges, including climate change factors, sea-level-rise-induced salinity load, changes in inland temperatures, ocean acidification, changes in precipitation patterns, ammonia toxicity, infectious diseases, and stress factors in aquatic systems. As a result, appropriate and timely measures can be taken at various stages of fish culture to address common problems. Using major scientific electronic databases, we comprehensively reviewed the topic of emerging needs, expanding applications, and recent technological advances in biosensors, with a particular focus on pisciculture. We highlight the biosensor technology used in the fisheries industry, which represents a pivotal step towards addressing its various aspects.

Chemosensors doi: 10.3390/chemosensors14010012

Authors: Azam Usefian Babukani Maziar Jafari Paul-Vahe Cicek Ricardo Izquierdo

A carbon nanotube (CNT)-integrated microfluidic electrochemical sensor was developed for sensitive nanoparticle detection using gold nanoparticles (AuNPs) as the model analyte. The device incorporated screen-printed polyethylene terephthalate (PET) electrodes, a polydimethylsiloxane (PDMS) microchannel, and a CNT membrane that simultaneously served as a filtration layer and working electrode. This configuration enhanced analyte trapping, increased the electroactive surface area, and accelerated electron transfer under convective flow. The CNT membrane was fabricated by vacuum filtration and torch-assisted bonding, ensuring strong adhesion without adhesives or plasma treatment. Electrochemical analysis showed that the filter-integrated CNT sensor exhibited an oxidation current of 63 µA compared to 11 µA for the non-filter sensor, representing a fifteen-fold sensitivity enhancement. The detection limit improved from 1.0 × 10−3 to 7.5 × 10−4 mol·L−1 with excellent reproducibility (RSD < 5%) and ∼90% accuracy. These findings validated the filtration-assisted accumulation mechanism and demonstrated the effectiveness of CNT-integrated microfluidic sensors for enhanced nanoparticle detection, while highlighting their potential for future adaptation to biosensing applications.

Chemosensors doi: 10.3390/chemosensors14010011

Authors: Arumugam Selva Sharma Nae Yoon Lee

Nanosurface energy transfer (NSET) has emerged as a pivotal mechanism in nanobiophotonics, facilitating the development of highly sensitive biosensors with extended dynamic ranges. Unlike conventional Förster resonance energy transfer, NSET exhibits an inverse fourth-power dependence on distance, enabling quantitative measurements over distances up to 40 nm. This review comprehensively explores the fundamental principles governing NSET, with particular emphasis on non-radiative coupling between fluorescent donors and metallic nanostructures such as gold nanoparticles. Additionally, the applications of these probes are surveyed across various bioanalytical domains, including nucleic acid assays, immunoassays, real-time intracellular monitoring, and various biomolecule detection. Additionally, the evolving integration of NSET, plasmonics, and nanophotonic architectures is discussed, focusing on emerging trends and the trajectory for developing next-generation, multiplexed, and point-of-care diagnostic platforms. Current challenges and prospective pathways for translating these advanced sensing systems into clinical and field-deployable solutions are also considered.

Chemosensors doi: 10.3390/chemosensors14010010

Authors: Rayssa Silva Correia Amanda Akemy Komorizono Julia Coelho Tagliaferro Natalia Candiani Simões Pessoa Valmor Roberto Mastelaro

rGO/ZnO composites have been widely studied for use as toxic gas sensors due to the synergistic effect between the materials and the reduction in sensor operating temperature promoted by rGO. However, few studies have employed rGO/ZnO sensors for ozone detection, as graphene materials are oxidized and/or degraded when exposed to ozone. This paper reports on a study of ZnO/rGO/ZnO-based sensors with different ZnO NP morphologies for ozone sensing. ZnO nanoparticles with needle-like and donut-like morphologies were synthesized by the precipitation method, and bare ZnO and ZnO/rGO/ZnO composite sensors were fabricated by layer-deposition of ZnO and/or rGO via drop-casting, forming a “sandwiched” structure that protects the rGO sheets. Bare ZnO and ZnO/rGO/ZnO composites were analyzed by varying the temperature from 200 to 300 °C. The ZnO/rGO/ZnO sensor provided a high 13.3 response (Rgas/Rair) and recovery times of 442 s and 253 s, respectively, for 50 ppb of O3, as well as high selectivity to ozone gas compared to CO, NH3, and NO2 gases. No oxidation or degradation of the sensor was observed during ozone detection measurements, indicating that the adopted manufacturing methodology was successful.

Chemosensors doi: 10.3390/chemosensors14010009

Authors: Huan-Qing Li Yun Li Ye-Tong Liu Si-Wei Deng Wei Wang Sheng-Yu Li Zhao-Yang Wang

Three Schiff base fluorescent probes 3a–3c with N-heterocyclic structure were designed and synthesized by using the reaction of 4-diethylaminosalicylaldehyde with different N-heterocyclic amines, such as 2-aminobenzimidazole, 2-aminobenzothiazole, and 2-amino-6-methylpyridine. Compound 3a exhibited excellent selectivity towards Hg2+, with a detection limit of 3.21 × 10−7 M and a response time of only 30 s. It could be used as a fluorescent probe for detecting Hg2+. Meanwhile, compounds 3b and 3c exhibited excellent selectivity towards Zn2+, with detection limits of 1.61 × 10−7 M and 2.03 × 10−7 M, respectively, and response times of only 30 s. They could serve as fluorescent probes for detecting Zn2+. Using probe 3a for Hg2+ as an example, the detecting mechanism was further elucidated through 1H NMR, ESI-MS testing, and DFT calculation analysis. For compound 3a, the coordination stoichiometry between compound 3a and Hg2+ was verified to be 1:1 through a Job’s plot. After coordination with Hg2+, the molecular rigidity of compound 3a was enhanced, which inhibited the non-radiative decay process and led to the closure of the excited-state intramolecular proton transfer (ESIPT) effect. At the same time, the fluorescence intensity was significantly increased through the chelation-enhanced fluorescence (CHEF) mechanism, which was confirmed by density functional theory (DFT) calculations. In addition, compounds 3a–3c were successfully applied in practical water samples and test strips for the detection of Hg2+/Zn2+.

Chemosensors doi: 10.3390/chemosensors14010008

Authors: Jingjing Gan Linlin Zhang Yue Wang Li Wang Shiwen Cheng Yunyun Luo Cheng Zheng Bilian Chen Shiyi Tian Cuifen Fang Yuezhong Mao

The processing of ginger-processed Pinellia ternata (Zhejiang) has long relied on empirical judgment, lacking objective and real-time monitoring methods. This study introduces an intelligent framework that combines a multi-frequency electronic tongue with chemometric modeling—including principal component analysis–discrimination index (PCA–DI) and wrapper-based support vector machine (SVM) classification—for dynamic process monitoring. Taste-response signals were systematically collected from key processing, water-leaching, and pickling stages. PCA–DI analysis demonstrated clear separability among seven key processing nodes (DI = 93.77%). Notably, samples from days 2 and 3 of water-leaching showed high similarity, suggesting an optimal soaking duration, while a marked transition on pickling day 6 indicated a critical transformation point. The wrapper–SVM models achieved high classification accuracies of 95.51% for key nodes, 100% for water-leaching, and 89.32% for pickling. These findings demonstrate that integrating electronic tongue sensing with machine learning effectively captures dynamic quality variations, offering a robust and objective strategy for the standardization and optimization of traditional medicine processing.

Chemosensors doi: 10.3390/chemosensors14010007

Authors: Masanori Ando Hideya Kawasaki Satoru Tamura Yasushi Shigeri

In the original publication [...]

Chemosensors doi: 10.3390/chemosensors14010006

Authors: Kandaswamy Theyagarajan Young-Joon Kim

The growing demand for advanced health-monitoring technologies has intensified the need for early diagnosis of incurable diseases and timely detection of life-threatening conditions. Among various detection modalities, electrochemical sensing has emerged as a particularly promising approach due to its simplicity, cost-effectiveness, high sensitivity, rapid response, ease of miniaturization, and compatibility with portable, wearable, and implantable platforms. The performance of electrochemical sensors is strongly governed by the morphology and physicochemical properties of electrode materials. In this context, MXenes, 2D transition-metal carbides, nitrides, and carbonitrides have attracted increasing attention for sensing applications owing to their high electrical conductivity, large surface area, hydrophilicity, and rich surface chemistry. However, their practical implementation is hindered by oxidation and environmental instability, while surface modification strategies, although improving stability, may compromise intrinsic electrochemical activity and biocompatibility. Notably, MXene-based hybrids consistently demonstrate enhanced sensing performance, underscoring their potential for flexible and wearable electrochemical devices. Despite rapid progress in this field, a comprehensive review addressing the significance of MXene hybrids, their structure–property–performance relationships, and their role in electrochemical detection remains limited. Therefore, this review summarizes recent advances in MXene-based hybrid materials for electrochemical sensing and biosensing of biologically relevant analytes, with an emphasis on design strategies, functional enhancements, and their prospects for next-generation health-monitoring technologies.

Chemosensors doi: 10.3390/chemosensors14010005

Authors: Fazia Mechai Ahmad Al Shboul Ahmad A. L. Ahmad Hossein Anabestani Mohsen Ketabi Natheer Alatawneh Ricardo Izquierdo

Efficient synthesis routes for zinc oxide nanoparticles (ZnO NPs) that are rapid and non-toxic and operate at room temperature (RT) are essential to expand accessibility, minimize environmental impact, and enable integration with temperature-sensitive substrates. In this work, ZnO NPs were synthesized by probe ultrasonication at RT for durations from 30 s to 10 min and benchmarked against our previously reported water bath sonication method. A 10-min probe treatment yielded highly uniform ZnO NPs with particle sizes of 60–550 nm and a specific surface area of up to 75 m2 g−1, compared to ~38 m2 g−1 for bath sonication. These features were largely preserved after calcination at 500 °C. When integrated into chemiresistive devices, the resulting ZnO (P(10))-based sensors exhibited pronounced selectivity toward styrene, showing reversible responses at low concentrations (10–50 ppm) and stronger signals at higher levels (up to 200 ppm, with resistance changes reaching 2930%). The sensors demonstrated stable operation across 10–90% relative humidity, and consistent performance from −20 °C to 180 °C. Flexibility tests confirmed reliable sensing after 100 bending cycles at 30°. Overall, RT-probe ultrasonication offers a rapid, scalable, and eco-friendly route to ZnO NPs with tunable properties, opening new opportunities for flexible gas sensing.

Chemosensors doi: 10.3390/chemosensors14010004

Authors: Cláudio M. R. Almeida Joana L. A. Miranda Manuela M. Moreira Júlia M. C. S. Magalhães Maria F. Barroso Luisa Durães

In this work, a potentiometric sensor for the detection of biogenic amines (BAs) in food samples was developed and characterised. The sensor employs a home-fabricated electrode incorporating a cucurbit[6]uril-modified polyvinyl chloride membrane as the sensing element. The working principle, system behaviour, and optimal operational conditions for BA monitoring were systematically investigated. The developed sensor demonstrated excellent analytical performance, showing a linear response in the concentration range of 3.0 × 10−5 to 1.0 × 10−2 mol L−1, with a low limit of detection of 2.4 × 10−5 mol L−1. Among the tested analytes, the sensor exhibited the highest sensitivity toward tyramine. These results highlight the potential of the proposed cucurbit[6]uril-based potentiometric sensor as an effective and reliable tool for monitoring BAs in complex food matrices, contributing to improved food safety, quality control, and spoilage prevention in the food industry, while also demonstrating its new application as a low-cost, easily constructed platform for rapid tyramine screening in food products.

Chemosensors doi: 10.3390/chemosensors14010003

Authors: Melody L. Candia Esteban Piccinini Omar Azzaroni Waldemar A. Marmisollé

Creatinine (Crn) is a clinically relevant biomarker commonly used for the diagnosis and monitoring of kidney disease. In this work, we report the fabrication of reduced-graphene-oxide-based field-effect transistors (rGO FETs) for Crn detection. These devices were functionalized using a layer-by-layer (LbL) assembly, in which polyethyleneimine (PEI) and creatinine deiminase (CD) were alternately deposited. This LbL strategy allows for the effective incorporation of CD without compromising its structural or functional integrity, while also taking advantage of the local pH changes caused by creatinine hydrolysis. It also benefits from the use of a polyelectrolyte that can amplify the enzymatic signal. Furthermore, it enables scalable and efficient fabrication. These transistors also address the challenges of point-of-care implementation in single-use cartridges. It is worth noting that the devices showed a linear relationship between the Dirac-point shift and the logarithm of the creatinine concentration in the 20–500 µM range in diluted simulated urine. The sensor response improved with increasing numbers of PEI/CD bilayers. Furthermore, the functionalized FETs demonstrated rapid detection dynamics and good long-term stability. Present results confirm the potential of these devices as practical biosensors for sample analysis under real-world conditions, making them ideal for implementation in practical settings.

Chemosensors doi: 10.3390/chemosensors14010002

Authors: Fatma Rejab Nour Elhouda Dardouri Nicole Jaffrezic-Renault Hamdi Ben Halima

This work presents the design of a novel electrochemical sensor for highly sensitive determination of LEV, utilizing a sensing platform based on a newly synthesized, high-purity manganese (III) porphyrin complex [5,10,15,20-tetrayltetrakis(2-methoxybenzene-4,1-diyl) tetraisonicotinateporphyrinato] manganese (III) porphyrin (MnTMIPP). The successful synthesis of the MnTMIPP complex was verified using ultraviolet–visible (UV–Vis) and infrared spectroscopy (IR). The sensing electrode was fabricated by depositing the synthesized material onto an indium tin oxide (ITO) electrode via a drop-coating method. Under optimized experimental conditions, the proposed sensor demonstrated a wide dynamic range, from 10−9 M to 10−3 M, with a low calculated detection limit of 4.82 × 10−10 M. Furthermore, the MnTMIPP/ITO electrode displayed interesting metrological performance: high selectivity, reproducibility, and stability. Successful application in spiked river water and saliva samples with satisfactory recovery rates confirms the sensor’s potential as a reliable and cost-effective platform for monitoring LEV in real-world environments.

Chemosensors doi: 10.3390/chemosensors14010001

Authors: Woosuck Shin Toshio Itoh Yoshitake Masuda Takehiro Kitawaki Makoto Sawano

Current gene-based PCR diagnostics involving reverse-transcription polymerase chain reaction (RT-PCR) require at least several hours, expensive tools, and complicated sample collection methods to obtain results. A test for detecting volatile organic compounds (VOCs) in exhaled breath is advantageous as a simple, non-invasive, and fast screening method. In this study, a VOC detection system of array sensors was applied for the classification of breath control and COVID-19 virus infection. The ability to classify VOCs in the breath with COVID-19 virus infection has been studied with two metal-oxide (MOX) gas sensor arrays, commercially available sensors, and in-house sensors. The dataset of gas response signals from the array-type semiconductive gas sensors of the VOC detection system was analyzed using machine learning; principal component analysis (PCA) was used as a dimensionality-reduction method, and random forest (RF) and a convolutional neural network (CNN) were used as classification methods for the VOC concentration patterns in each breath. For the RF model, the accuracy results for the classification by two gas sensor arrays was 0.917 and this was improved by CO2 calibration to 0.967, and the feature importance analysis revealed the importance of specific gas sensors. For the CNN, an input layer of a transformed gray-scale image with the shape of 12 data points × 8 sensors was used, and its accuracy reached 100% within a relatively small number of epochs, demonstrating a short training time, which is beneficial for breath detectors or e-nose devices.

Chemosensors doi: 10.3390/chemosensors13120434

Authors: Wenchen Li Weiying Lu

Chrysanthemum, a traditional medicinal and edible plant, possesses diverse health-promoting properties attributed to its rich profile of bioactive compounds. However, the intrinsic quality, influenced by the composition of fundamental components like starch and lignin, varies significantly across different cultivars and origins. This study establishes a comprehensive phytochemical profile of 12 representative Chinese chrysanthemum cultivars by systematically quantifying their starch and lignin contents. Furthermore, it develops and validates a novel, low-cost rapid detection method for starch utilizing smartphone-based colorimetry. The starch content, determined by a colorimetric anthrone-sulfuric acid assay, ranged from 2.68 to 18.69 g/100 g, while the lignin content, measured via the acetyl bromide digestion followed by UV spectrophotometry at 280 nm, varied from 4.21 to 13.63 g/100 g, revealing substantial inter-cultivar differences. For starch analysis, a low-cost, immediate, general-purpose, and high-throughput (LIGHt) smartphone-based colorimetry was implemented. Standard curves constructed from both absorbance and the LIGHt assay demonstrated excellent linearity (R2 > 0.99). The method’s performance was evaluated under different lighting conditions and across various smartphone models. The UV spectrophotometry condenses lignin quantification to a single 30-min digestion–reading cycle, bypassing the two-day Klason protocol and increases efficiency greatly. The work successfully provides a foundational component analysis and validates a portable, high-throughput framework for on-site quality control of plant-based products, demonstrating the strong potential of smartphone-based colorimetry for rapid starch detection and a complementary laboratory-scale lignin assay.

Chemosensors doi: 10.3390/chemosensors13120433

Authors: Nevena Radivojević Sanja Knežević Stefan Graovac Vladimir Rajić Tamara Terzić Nebojša Potkonjak Tamara Lazarević-Pašti Vedran Milanković

Mercury’s severe toxicity and persistence demand fast, low-cost, and sustainable detection. In this work, a Juglans regia ethanolic extract is introduced as an efficient biogenic reducing and stabilizing agent for the green synthesis of silver nanoparticles (AgNPs). This plant-mediated route enables environmentally friendly nanoparticle formation with suitable optical properties for sensing applications. To overcome the poor visual selectivity observed in the colloidal AgNPs suspension, the nanoparticles were immobilized onto filter paper to produce a solid-phase colorimetric sensor. The paper-based platform exhibited a highly selective response toward Hg2+, showing complete suppression of the yellow coloration exclusively in the presence of Hg2+, even when challenged with a 200-fold excess of potentially interfering ions. Quantitative colorimetric analysis revealed a broad linear detection range from 1 × 10−8 to 1 × 10−3 mol dm−3 and an excellent limit of detection of 1.065 × 10−8 mol dm−3, with visible color changes consistent with the calculated values. The sensor’s performance was further validated using real tap water samples, with recovery values ranging from 96% to 102%, confirming minimal matrix interference and reliable quantification. Altogether, this study demonstrates that Juglans regia-mediated AgNPs, integrated into a simple paper-based format, provide a fully green, low-cost, and portable platform for sensitive and selective on-site detection of Hg2+ in environmental waters.

Chemosensors doi: 10.3390/chemosensors13120432

Authors: Xinyang Cui Tingting Gu Kexin Ma Jiwu Zeng Hongqi Xia

Harmful substances in food and agricultural environments pose significant risks to human health, necessitating the development of sensitive detection technologies. Electrochemical sensors are ideal for rapid monitoring because of their low cost, high efficiency, and portability. Recently developed laser-induced graphene (LIG)-based electrochemical sensors have demonstrated exceptional potential owing to the unique structural properties and outstanding electrochemical performance of LIG. In this review, the key factors influencing the LIG material characteristics during fabrication are discussed. Then, LIG-based electrochemical sensors are systematically categorized as pristine LIG and nanomaterial-functionalized, biomaterial-modified, and polymer-functionalized electrochemical sensors, and their application in the detection of functional components, additives, and agrochemicals in food products, and the detection of environmental pollutants, is comprehensively analyzed. Finally, the current challenges and the directions for future development are discussed.

Chemosensors doi: 10.3390/chemosensors13120431

Authors: Jiaojiao Da Haixia Shi Vesna Antic Milica Balaban Bing Xie Li Gao

To enhance the sensitivity of graphene-DNA sensors for Hg2+ detection, a novel graphene nanoribbon-DNA sensor was fabricated using a template-assisted approach. Silicon nanowires served as templates to decorate the graphene device, followed by plasma etching to delineate graphene nanoribbons. After template removal, the resulting sensors based on silicon nanowire templates were successfully constructed. DNA sequences containing four guanine bases were conjugated with graphene sensors prepared using the templates. The carboxyl groups on the edges of the graphene nanoribbons were activated with EDC/NHS chemistry to facilitate covalent bonding with amino-modified DNA. The kinetic response and Hg2+ detection capability of the fabricated sensors were characterized using a semiconductor parameter analyzer. Results indicated that the silicon nanowire-templated graphene nanoribbon sensor exhibited high sensitivity, with a detection limit of 3.62 pM. This innovative approach further improved the sensitivity of graphene-DNA sensors for Hg2+ detection.