Chemosensors

25 pages, 6455 KiB

Open AccessArticle

Integrating Sensor Data, Laboratory Analysis, and Computer Vision in Machine Learning-Driven E-Nose Systems for Predicting Tomato Shelf Life

by Julia Marie Senge, Florian Kaltenecker and Christian Krupitzer

Chemosensors 2025, 13(7), 255; https://doi.org/10.3390/chemosensors13070255 (registering DOI) - 12 Jul 2025

Abstract

Assessing the quality of fresh produce is essential to ensure a safe and satisfactory product. Methods to monitor the quality of fresh produce exist; however, they are often expensive, time-consuming, and sometimes require the destruction of the sample. Electronic Nose (E-Nose) technology has [...] Read more.

Assessing the quality of fresh produce is essential to ensure a safe and satisfactory product. Methods to monitor the quality of fresh produce exist; however, they are often expensive, time-consuming, and sometimes require the destruction of the sample. Electronic Nose (E-Nose) technology has been established to track the ripeness, spoilage, and quality of fresh produce. Our study developed a freshness monitoring system for tomatoes, combining E-Nose technology with storage condition monitoring, color analysis, and weight-loss tracking. Different post-purchase scenarios were investigated, focusing on the influence of temperature and mechanical damage on shelf life. Support Vector Classifier (SVC) and k-Nearest Neighbor (kNN) were applied to classify storage scenarios and storage days, while Support Vector Regression (SVR) and kNN regression were used for predicting storage days. By using a data fusion approach with Linear Discriminant Analysis (LDA), the SVC achieved an accuracy of 72.91% in predicting storage days and an accuracy of 86.73% in distinguishing between storage scenarios. The kNN yielded the best regression results, with a Mean Absolute Error (MAE) of 0.841 days and a coefficient of determination of 0.867. The results highlight the method’s potential to predict storage scenarios and storage days, providing insight into the product’s remaining shelf life. Full article

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

16 pages, 3149 KiB

Open AccessArticle

Electrochemical Sensing of Dopamine Neurotransmitter by Deep Eutectic Solvent–Carbon Black–Crosslinked Chitosan Films: Charge Transfer Kinetic Studies and Biological Sample Analysis

by Alencastro Gabriel Ribeiro Lopes, Rafael Matias Silva, Orlando Fatibello-Filho and Tiago Almeida Silva

Chemosensors 2025, 13(7), 254; https://doi.org/10.3390/chemosensors13070254 (registering DOI) - 12 Jul 2025

Abstract

Dopamine (DA) is a neurotransmitter responsible for important functions in mammals’ bodies, including mood, movement and motivation. High or low dopamine levels are associated mainly with mental illnesses such as schizophrenia and depression. Therefore, contributing to the development of electrochemical devices to precisely [...] Read more.

Dopamine (DA) is a neurotransmitter responsible for important functions in mammals’ bodies, including mood, movement and motivation. High or low dopamine levels are associated mainly with mental illnesses such as schizophrenia and depression. Therefore, contributing to the development of electrochemical devices to precisely determine the DA levels in urine samples, a simple and low-cost sensor is proposed in this work. The proposed sensor design is based on crosslinked chitosan films combining carbon black (CB) and deep eutectic solvents (DESs), incorporated onto the surface of a glassy carbon electrode (GCE). Fourier Transform Infrared Spectroscopy (FT-IR) was applied to characterize the produced DESs and their precursors, while the films were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The sensor modified with CB and DES–ethaline (DES (ETHA)-CB/GCE) showed a significantly enhanced analytical signal for DA using differential pulse voltammetry under the optimized working conditions. Moreover, a better heterogeneous electron transfer rate constant (k⁰) was obtained, about 45 times higher than that of the bare GCE. The proposed sensor achieved a linear response range of 0.498 to 26.8 µmol L⁻¹ and limits of detection and quantification of 80.7 and 269 nmol L⁻¹, respectively. Moreover, the sensor was successfully applied in the quantification of DA in the synthetic urine samples, with recovery results close to 100%. Furthermore, the sensor presented good precision, as shown from the repeatability tests. The presented method to electrochemically detect DA has proven to be efficient and simple compared to the conventional methods commonly reported. Full article

(This article belongs to the Special Issue Electrochemical Sensing in Medical Diagnosis)

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72 pages, 910 KiB

Open AccessReview

Analytical Approaches Using GC-MS for the Detection of Pollutants in Wastewater Towards Environmental and Human Health Benefits: A Comprehensive Review

by Gonçalo Catarro, Rodrigo Pelixo, Mariana Feijó, Tiago Rosado, Sílvia Socorro, André R. T. S. Araújo and Eugenia Gallardo

Chemosensors 2025, 13(7), 253; https://doi.org/10.3390/chemosensors13070253 (registering DOI) - 12 Jul 2025

Abstract

The analysis of wastewater is essential in environmental chemistry, particularly for monitoring emerging contaminants and assessing ecological impacts. In this context, hyphenated chromatographic techniques are widely used, with liquid chromatography being one of the most common. However, gas chromatography coupled with mass spectrometry [...] Read more.

The analysis of wastewater is essential in environmental chemistry, particularly for monitoring emerging contaminants and assessing ecological impacts. In this context, hyphenated chromatographic techniques are widely used, with liquid chromatography being one of the most common. However, gas chromatography coupled with mass spectrometry (GC-MS) remains a valuable tool in this field due to its sensitivity, selectivity, and widespread availability in most laboratories. This review examines the application of validated methods for wastewater analysis using GC-MS (MS), highlighting its relevance in identifying micropollutants such as pharmaceuticals, drugs of abuse, pesticides, hormones, and industrial by-products. The validation of analytical methods is crucial to ensuring the reliability and reproducibility of data and the accurate monitoring of contaminants. Key parameters, including sample volume, recovery efficiency, and detection and quantification limits, are discussed, evaluating different approaches to optimising the identification of different classes of contaminants. Additionally, this study explores advances in sample preparation techniques, such as solid-phase microextraction (SPME), dispersive liquid–liquid microextraction (DLLME), and solid-phase extraction (SPE), which enhance efficiency and minimise interferences in the analysis. Finally, future perspectives are discussed, including the integration of emerging technologies such as high-resolution mass spectrometry, the miniaturisation of GC systems, and the development of faster and more sustainable analytical methods. Full article

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

15 pages, 2527 KiB

Open AccessArticle

A Disposable SWCNTs/AuNPs-Based Screen-Printed ISE at Different Temperatures to Monitor Ca²⁺ for Hypocalcemia Diagnosis

by Zhixue Yu, Hui Wang, Yue He, Ruipeng Chen, Xiangfang Tang and Benhai Xiong

Chemosensors 2025, 13(7), 252; https://doi.org/10.3390/chemosensors13070252 (registering DOI) - 12 Jul 2025

Abstract

In this paper, screen-printed ion-selective electrodes combined with single-walled carbon nanotubes (SWCNTs) and gold nanoparticles (AuNPs) were used to rapidly and accurately measure serum Ca²⁺ concentration. Due to the susceptibility of cows to hypocalcemia after delivery, this disease can affect the health [...] Read more.

In this paper, screen-printed ion-selective electrodes combined with single-walled carbon nanotubes (SWCNTs) and gold nanoparticles (AuNPs) were used to rapidly and accurately measure serum Ca²⁺ concentration. Due to the susceptibility of cows to hypocalcemia after delivery, this disease can affect the health of cows and reduce milk production. Therefore, the development of an economical and swift detection method holds paramount importance for facilitating early diagnosis and subsequent treatment. In this study, by combining the high electrical conductivity and large surface area of SWCNTs with the strong catalytic activity of AuNPs, a SWCNTs/AuNPs composite with high sensitivity and good stability was prepared, achieving efficient selective recognition and signal conversion of Ca²⁺. The experimental results indicate that the screen-printed electrode modified with SWCNTs/AuNPs exhibited excellent performance in the determination of Ca²⁺ concentration. Its linear response range is 10^−5.5–10⁻¹ M, covering the normal and pathological concentration range of Ca²⁺ in cow blood, and the detection limit is far below the clinical detection requirements. In addition, the electrode also has good anti-interference ability and fast response time (about 15 s), showing good performance in the range of 5–45 °C. In practical applications, the combination of the electrode and portable detection equipment can realize the field rapid determination of cow blood Ca²⁺ concentration. This method is easy to operate, cost-effective, and easy to promote, providing strong technical support for the health management of dairy farms. Full article

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

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18 pages, 7385 KiB

Open AccessArticle

An Electrochemical Sensor for the Simultaneous Detection of Pb²⁺ and Cd²⁺ in Contaminated Seawater Based on Intelligent Mobile Detection Devices

by Zizi Zhao, Wei Qu, Chengjun Qiu, Yuan Zhuang, Kaixuan Chen, Yi Qu, Huili Hao, Wenhao Wang, Haozheng Liu and Jiahua Su

Chemosensors 2025, 13(7), 251; https://doi.org/10.3390/chemosensors13070251 - 11 Jul 2025

Abstract

Excessive levels of Pb²⁺ and Cd²⁺ in seawater pose significant combined toxicity to marine organisms, resulting in harmful effects and further threatening human health through biomagnification in the food chain. Traditional methods for detecting marine Pb²⁺ and Cd²⁺ rely [...] Read more.

Excessive levels of Pb²⁺ and Cd²⁺ in seawater pose significant combined toxicity to marine organisms, resulting in harmful effects and further threatening human health through biomagnification in the food chain. Traditional methods for detecting marine Pb²⁺ and Cd²⁺ rely on laboratory analyses, which are hindered by limitations such as sample degradation during transport and complex operational procedures. In this study, we present an electrochemical sensor based on intelligent mobile detection devices. By combining G-COOH-MWCNTs/ZnO with differential pulse voltammetry, the sensor enables the efficient, simultaneous detection of Pb²⁺ and Cd²⁺ in seawater. The G-COOH-MWCNTs/ZnO composite film is prepared via drop-coating and is applied to a glassy carbon electrode. The film is characterized using cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy, while Pb²⁺ and Cd²⁺ are quantified using differential pulse voltammetry. Using a 0.1 mol/L sodium acetate buffer (pH 5.5), a deposition potential of −1.1 V, and an accumulation time of 300 s, a strong linear correlation was observed between the peak response currents of Pb²⁺ and Cd²⁺ and their concentrations in the range of 25–450 µg/L. The detection limits were 0.535 µg/L for Pb²⁺ and 0.354 µg/L for Cd²⁺. The sensor was applied for the analysis of seawater samples from Maowei Sea, achieving recovery rates for Pb²⁺ ranging from 97.7% to 103%, and for Cd²⁺ from 97% to 106.1%. These results demonstrate that the sensor exhibits high sensitivity and stability, offering a reliable solution for the on-site monitoring of heavy metal contamination in marine environments. Full article

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

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16 pages, 4139 KiB

Open AccessArticle

Engineering Hierarchical CuO/WO₃ Hollow Spheres with Flower-like Morphology for Ultra-Sensitive H₂S Detection at ppb Level

by Peishuo Wang and Xueli Yang

Chemosensors 2025, 13(7), 250; https://doi.org/10.3390/chemosensors13070250 - 11 Jul 2025

Abstract

Highly sensitive real-time detection of hydrogen sulfide (H₂S) is important for human health and environmental protection due to its highly toxic properties. The development of high-performance H₂S sensors remains challenging for poor selectivity, high limit detection and slow recovery [...] Read more.

Highly sensitive real-time detection of hydrogen sulfide (H₂S) is important for human health and environmental protection due to its highly toxic properties. The development of high-performance H₂S sensors remains challenging for poor selectivity, high limit detection and slow recovery from irreversible sulfidation. To solve these problems, we strategically prepared a layered structure of CuO-sensitized WO₃ flower-like hollow spheres with CuO as the sensitizing component. A 15 wt% CuO/WO₃ exhibits an ultra-high response (R_a/R_g = 571) to 10 ppm H₂S (131-times of pure WO₃), excellent selectivity (97-times higher than 100 ppm interference gas), and a low detection limit (100 ppb). Notably, its fast response (4 s) is accompanied by full recovery within 236 s. After 30 days of continuous testing, the response of 15 wt% CuO/WO₃ decreased slightly but maintained the initial response of 90.5%. The improved performance is attributed to (1) the p-n heterojunction formed between CuO and WO₃ optimizes the energy band structure and enriches the chemisorption sites for H₂S; (2) the reaction of H₂S with CuO generates highly conductive CuS, which significantly reduces the interfacial resistance; and (3) the hierarchical flowery hollow microsphere structure, heterojunction, and oxygen vacancy synergistically promote the desorption. This work provides a high-performance H₂S gas sensor that balances response, selectivity, and response/recovery kinetics. Full article

(This article belongs to the Special Issue Recent Progress in Nano Material-Based Gas Sensors)

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12 pages, 2279 KiB

Open AccessArticle

Electrostatic Self-Assembly of Heterostructured In₂O₃/Ti₃C₂T_x Nanocomposite for High-Selectivity NO₂ Gas Sensing at Room Temperature

by Yongjing Guo, Zhengxin Zhang, Hangshuo Feng, Qingfu Dai, Qiuni Zhao, Zaihua Duan, Shenghui Guo, Li Yang, Ming Hou and Yi Xia

Chemosensors 2025, 13(7), 249; https://doi.org/10.3390/chemosensors13070249 - 10 Jul 2025

Abstract

Owing to high electrical conductivity, layered structure, and abundant surface functional groups, transition metal carbides/nitrides (MXenes) have received enormous interest in the field of gas sensors at room temperature. In this work, we synthesize a heterostructured nanocomposite with indium oxide (In₂O [...] Read more.

Owing to high electrical conductivity, layered structure, and abundant surface functional groups, transition metal carbides/nitrides (MXenes) have received enormous interest in the field of gas sensors at room temperature. In this work, we synthesize a heterostructured nanocomposite with indium oxide (In₂O₃) decorated on titanium carbide (Ti₃C₂T_x) nanosheets by electrostatic self-assembly and develop it for high-selectivity NO₂ gas sensing at room temperature. Self-assembly formation of multiple heterojunctions in the In₂O₃/Ti₃C₂T_x composite provide abundant NO₂ gas adsorption sites and high electron transfer activity, which is conducive to improving the gas-sensing response of the In₂O₃/Ti₃C₂T_x gas sensor. Assisted by rich adsorption sites and hetero interface, the as-fabricated In₂O₃/Ti₃C₂T_x gas sensor exhibits the highest response to NO₂ among various interference gases. Meanwhile, a detection limit of 0.3 ppm, and response/recovery time (197.62/93.84 s) is displayed at room temperature. Finally, a NO₂ sensing mechanism of In₂O₃/Ti₃C₂T_x gas sensor is constructed based on PN heterojunction enhancement and molecular adsorption. This work not only expands the gas-sensing application of MXenes, but also demonstrates an avenue for the rational design and construction of NO₂-sensing materials. Full article

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

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16 pages, 2888 KiB

Open AccessArticle

Vitamin K Epoxide Reductase Complex (VKORC1) Electrochemical Genosensors: Towards the Identification of 1639 G>A Genetic Polymorphism

by Tiago Barbosa, Stephanie L. Morais, Renato Carvalho, Júlia M. C. S. Magalhães, Valentina F. Domingues, Cristina Delerue-Matos, Hygor Ferreira-Fernandes, Giovanny R. Pinto, Marlene Santos and Maria Fátima Barroso

Chemosensors 2025, 13(7), 248; https://doi.org/10.3390/chemosensors13070248 - 10 Jul 2025

Abstract

Anticoagulants, including warfarin, are often administered to patients who are exhibiting early symptoms of thromboembolic episodes or who have already experienced such episodes. However, warfarin has a limited therapeutic index and might cause bleeding and other clinical problems. Warfarin inhibits the vitamin K [...] Read more.

Anticoagulants, including warfarin, are often administered to patients who are exhibiting early symptoms of thromboembolic episodes or who have already experienced such episodes. However, warfarin has a limited therapeutic index and might cause bleeding and other clinical problems. Warfarin inhibits the vitamin K epoxide reductase complex subunit 1 (VKORC1), an enzyme essential for activating vitamin K, in the coagulation cascade. Genetic factors, such as polymorphisms, can change the natural function of VKORC1, causing variations in the medication reaction among individuals. Hence, before prescribing warfarin, the patient’s genetic profile should also be considered. In this study, an electrochemical genosensor capable of detecting the VKORC1 1639 G>A polymorphism was designed and optimized. This analytical approach detects the electric current obtained during the hybridization reaction between two 52 base pair complementary oligonucleotide sequences. Investigating public bioinformatic platforms, two DNA sequences with the A and G single-nucleotide variants were selected and designed. The experimental protocol of the genosensor implied the formation of a bilayer composed of a thiolate DNA and an alkanethiol immobilized onto gold electrodes, as well as the formation of a DNA duplex using a sandwich-format hybridization reaction through a fluorescein labelled DNA signalling probe and the enzymatic amplification of the electrochemical signal, detected by chronoamperometry. A detection limit of 20 pM and a linear range of 0.05–1.00 nM was obtained. A clear differentiation between A/A, G/A and G/G genotypes in biological samples was successfully identified by his novel device. Full article

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

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14 pages, 2431 KiB

Open AccessArticle

Reduced Graphene Oxide/β-Cyclodextrin Nanocomposite for the Electrochemical Detection of Nitrofurantoin

by Al Amin, Gajapaneni Venkata Prasad, Venkatachalam Vinothkumar, Seung Joo Jang, Da Eun Oh and Tae Hyun Kim

Chemosensors 2025, 13(7), 247; https://doi.org/10.3390/chemosensors13070247 - 10 Jul 2025

Viewed by 28

Abstract

In this work, a glassy carbon electrode (GCE) modified with reduced graphene oxide and β-cyclodextrin (rGO/β-CD) nanocomposite was developed for the electrochemical detection of nitrofurantoin (NFT). The structural and morphological characteristics of the synthesized nanocomposite were determined using scanning electron microscopy (SEM), Raman [...] Read more.

In this work, a glassy carbon electrode (GCE) modified with reduced graphene oxide and β-cyclodextrin (rGO/β-CD) nanocomposite was developed for the electrochemical detection of nitrofurantoin (NFT). The structural and morphological characteristics of the synthesized nanocomposite were determined using scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Moreover, the electrochemical behavior of the modified electrodes was thoroughly examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), with the rGO/β-CD-modified glassy carbon electrode (GCE) demonstrating superior electron transfer capability. Key experimental parameters, including scan rate, material loading, and solution pH, were systematically optimized. After optimizing the experimental conditions, the modified sensor showed excellent electrocatalytic performance and selectivity toward NFT, achieving a broad linear detection range from 0.5 to 120 μM, a low limit of detection (LOD) of 0.048 μM, and a high sensitivity of 12.1 µA µM^–1 cm^–2 using differential pulse voltammetry (DPV). Furthermore, the fabricated electrode exhibited good anti-interference ability, stability, precision, and real-time applicability for NFT detection in a wastewater sample. These results highlight the potential of the rGO/β-CD nanocomposite as a high-performance platform for electrochemical sensing applications. Full article

(This article belongs to the Special Issue Sensors for Food Testing, Environmental Analysis, and Medical Diagnostics)

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24 pages, 1871 KiB

Open AccessArticle

Data Analyses and Chemometric Modeling for Rapid Quality Assessment of Enriched Honey

by Jasenka Gajdoš Kljusurić, Vesna Knights, Berat Durmishi, Smajl Rizani, Vezirka Jankuloska, Valentina Velkovski, Ana Jurinjak Tušek, Maja Benković, Davor Valinger and Tamara Jurina

Chemosensors 2025, 13(7), 246; https://doi.org/10.3390/chemosensors13070246 - 9 Jul 2025

Viewed by 69

Abstract

The quality and authenticity of honey are of crucial importance for food safety and consumer confidence. Given the increasing interest in enriched honey and potential fraud, rapid and non-destructive analytical methods for quality assessment, such as Near-Infrared Spectroscopy (NIRS), are needed. Therefore, the [...] Read more.

The quality and authenticity of honey are of crucial importance for food safety and consumer confidence. Given the increasing interest in enriched honey and potential fraud, rapid and non-destructive analytical methods for quality assessment, such as Near-Infrared Spectroscopy (NIRS), are needed. Therefore, the aim of this work was to investigate the applicability of NIR spectroscopy coupled with chemometric methods to assess the quality change in honey from three different countries, after addition of five different aromatic plants (lavender, rosemary, oregano, sage, and white pine oil) in three different concentrations (0.5%, 0.8% and 1%). Measurements of basic physicochemical properties, color, antioxidant activity, and NIR spectra were performed for all samples (pure honey and honey with added aromatic plants). Chemometric models, such as Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression, were applied to analyze spectral data, correlate spectra with physicochemical properties, color and antioxidant activity measurements, and develop classification and prediction models. Spectral changes in the NIR region, as expected, showed the ability to distinguish samples depending on the type and concentration of added aromatic plants. Chemometric models enabled efficient discrimination between pure and enriched honey samples, as well as assessment of the influence of different additives on antioxidant activity and color. The results highlight the potential of NIRS as a rapid, non-destructive and environmentally friendly method for quality monitoring and detection of specific additives in honey, offering technical support for quality control and food safety regulation. Full article

(This article belongs to the Special Issue Chemometrics for Food, Environmental and Biological Analysis)

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16 pages, 3764 KiB

Open AccessArticle

Luminescence of Carbon Dots Induced by MeV Protons

by Mariapompea Cutroneo, Vladimir Havranek, Vaclav Holy, Petr Malinsky, Petr Slepicka, Selena Cutroneo and Lorenzo Torrisi

Chemosensors 2025, 13(7), 245; https://doi.org/10.3390/chemosensors13070245 - 9 Jul 2025

Viewed by 126

Abstract

In this study, we describe the preparation of carbon dots (CDs) from natural charcoal by laser ablation in a liquid. A continuum wave (CW) laser diode operating at a wavelength of 450 nm, hitting a solid carbon target placed into a biocompatible liquid, [...] Read more.

In this study, we describe the preparation of carbon dots (CDs) from natural charcoal by laser ablation in a liquid. A continuum wave (CW) laser diode operating at a wavelength of 450 nm, hitting a solid carbon target placed into a biocompatible liquid, constituted of a phosphate-buffered saline (PBS) solution and distilled water, was used for the generation of the CDs suspension. Exploring the practical applications of carbon dots, it was observed that the luminescence of the produced CDs can be used as bioimaging in living organisms, environmental monitoring, chemical analysis, targeted drug delivery, disease diagnosis, therapy, and others. The CDs’ luminescence can be induced by UV irradiation and, as demonstrated in this study, by energetic MeV proton beams. The fluorescence was revealed mainly at 480 nm when UV illuminated the CDs, and also in the region at 514–642 nm when the CDs were irradiated by energetic proton ions. Atomic force microscopy (AFM) of the CD films revealed their spherical shape with a size of about 10 nm. The significance of the manuscript lies in the use of CDs produced by laser ablation exhibiting luminescence under irradiation of an energetic proton beam. Full article

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

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40 pages, 12228 KiB

Open AccessArticle

Design and Synthesis of Arylboronic Acid Chemosensors for the Fluorescent-Thin Layer Chromatography (f-TLC) Detection of Mycolactone

by Gideon Atinga Akolgo, Benjamin M. Partridge, Timothy D. Craggs, Kingsley Bampoe Asiedu and Richard Kwamla Amewu

Chemosensors 2025, 13(7), 244; https://doi.org/10.3390/chemosensors13070244 - 9 Jul 2025

Viewed by 244

Abstract

Fluorescent chemosensors are increasingly becoming relevant in recognition chemistry due to their sensitivity, selectivity, fast response time, real-time detection capability, and low cost. Boronic acids have been reported for the recognition of mycolactone, the cytotoxin responsible for tissue damage in Buruli ulcer disease. [...] Read more.

Fluorescent chemosensors are increasingly becoming relevant in recognition chemistry due to their sensitivity, selectivity, fast response time, real-time detection capability, and low cost. Boronic acids have been reported for the recognition of mycolactone, the cytotoxin responsible for tissue damage in Buruli ulcer disease. A library of fluorescent arylboronic acid chemosensors with various signaling moieties with certain beneficial photophysical characteristics (i.e., aminoacridine, aminoquinoline, azo, BODIPY, coumarin, fluorescein, and rhodamine variants) and a recognition moiety (i.e., boronic acid unit) were rationally designed and synthesised using combinatorial approaches, purified, and fully characterised using a set of complementary spectrometric and spectroscopic techniques such as NMR, LC-MS, FT-IR, and X-ray crystallography. In addition, a complete set of basic photophysical quantities such as absorption maxima (λ_abs^max), emission maxima (λ_em^max), Stokes shift (∆λ), molar extinction coefficient (ε), fluorescence quantum yield (Φ_F), and brightness were determined using UV-vis absorption and fluorescence emission spectroscopy techniques. The synthesised arylboronic acid chemosensors were investigated as chemosensors for mycolactone detection using the fluorescent-thin layer chromatography (f-TLC) method. Compound 7 (with a coumarin core) emerged the best (λ_abs^max = 456 nm, λ_em^max = 590 nm, ∆λ = 134 nm, ε = 52816 M⁻¹cm⁻¹, Φ_F = 0.78, and brightness = 41,197 M⁻¹cm⁻¹). Full article

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

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27 pages, 690 KiB

Open AccessReview

Phthalocyanine-Modified Electrodes Used in the Electroanalysis of Monoamine Neurotransmitters

by Anton Alexandru Ciucu, Mihaela Buleandră, Dana Elena Popa and Dragoș Cristian Ștefănescu

Chemosensors 2025, 13(7), 243; https://doi.org/10.3390/chemosensors13070243 - 7 Jul 2025

Viewed by 285

Abstract

Metallo-phthalocyanines (MPcs) are versatile materials with applications in electroanalysis because of their superior catalytic properties. This review presents the electrochemical methods based on MPc-modified electrodes and reports some of their remarkable properties and applications in the electroanalysis of monoamine neurotransmitters and biomolecules that [...] Read more.

Metallo-phthalocyanines (MPcs) are versatile materials with applications in electroanalysis because of their superior catalytic properties. This review presents the electrochemical methods based on MPc-modified electrodes and reports some of their remarkable properties and applications in the electroanalysis of monoamine neurotransmitters and biomolecules that play a crucial role in vital functions of the human body. The development of electrocatalytic chemically modified electrodes is based on their ability to provide a selective and rapid response toward a specific analyte in complex media without the need for sample pretreatment. The explanation of several phenomena occurring at the MPc-modified electrode surface (e.g., MPc-mediated electrocatalysis), the advantages of promoting different electron transfer reactions, and the detection mechanism are also presented. The types of MPcs and different materials, such as carbon nanotubes and graphene, used as substrates for modified working electrodes are discussed. Modifying the properties of MPcs through various interactions, or combining MPcs with carbonaceous materials, creates a synergistic effect. Such hybrid materials present both extraordinary catalytic and increased conductivity properties. We conducted a compilation study based on recent works to demonstrate the efficacy of the developed sensors and methods in sensing monoamine neurotransmitters. We emphasize the analyte type, optimized experimental parameters, working range, limits of detection and quantification, and application to real samples. MPc–carbon hybrids have led to the development of sensors with superior sensitivity and improved selectivity, enabling the detection of analytes at lower concentrations. We highlight the main advantages and drawbacks of the discussed methods. This review summarizes recent progress in the development and application of metallo-phthalocyanine-modified electrodes in the electroanalysis of monoamine neurotransmitters. Some possible future trends are highlighted. Full article

(This article belongs to the Special Issue New Electrodes Materials for Electroanalytical Applications)

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23 pages, 3823 KiB

Open AccessReview

Electrochemical Strategies for MicroRNA Quantification Leveraging Amplification and Nanomaterials: A Review

by Alexander Hunt and Gymama Slaughter

Chemosensors 2025, 13(7), 242; https://doi.org/10.3390/chemosensors13070242 - 6 Jul 2025

Viewed by 265

Abstract

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression and have emerged as critical biomarkers in various diseases, including cancer. Their stability in bodily fluids and role as oncogenes or tumor suppressors make them attractive targets for non-invasive diagnostics. However, conventional detection [...] Read more.

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression and have emerged as critical biomarkers in various diseases, including cancer. Their stability in bodily fluids and role as oncogenes or tumor suppressors make them attractive targets for non-invasive diagnostics. However, conventional detection methods, such as Northern blotting, RT-PCR, and microarrays, are limited by low sensitivity, lengthy protocols, and limited specificity. Electrochemical biosensors offer a promising alternative, providing high sensitivity, rapid response times, portability, and cost-effectiveness. These biosensors translate miRNA hybridization events into quantifiable electrochemical signals, often leveraging redox-active labels, mediators, or intercalators. Recent advancements in nanomaterials and signal amplification strategies have further enhanced detection capabilities, enabling sensitive, label-free miRNA quantification. This review provides a comprehensive overview of the recent advances in electrochemical biosensing of miRNAs, emphasizing innovative redox-based detection strategies, probe immobilization techniques, and hybridization modalities. The critical challenges and future perspectives in advancing electrochemical miRNA biosensors toward clinical translation and point-of-care diagnostics are discussed. Full article

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

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32 pages, 7710 KiB

Open AccessReview

Illuminating Pollutants: The Role of Carbon Dots in Environmental Sensing

by Naveen Thanjavur and Young-Joon Kim

Chemosensors 2025, 13(7), 241; https://doi.org/10.3390/chemosensors13070241 - 6 Jul 2025

Viewed by 346

Abstract

The pursuit of cleaner environments and healthier ecosystems has driven the development of innovative strategies for detecting and mitigating toxic pollutants. Among emerging nanomaterials, carbon dots (CDs) have gained prominence due to their low toxicity, excellent biocompatibility, high fluorescence efficiency, and environmental sustainability. [...] Read more.

The pursuit of cleaner environments and healthier ecosystems has driven the development of innovative strategies for detecting and mitigating toxic pollutants. Among emerging nanomaterials, carbon dots (CDs) have gained prominence due to their low toxicity, excellent biocompatibility, high fluorescence efficiency, and environmental sustainability. This review critically analyzes the transformative role of CDs in environmental sensing and remediation. Highlighting their versatile applications, including bioimaging, photocatalysis, and sensitive biochemical sensing, we examine how CDs support the next generation of pollutant detection and degradation technologies, such as contaminant adsorption, membrane filtration, and photocatalytic breakdown. Furthermore, we discuss advances in sensor architectures integrating CDs and outline pathways for their expanded use in environmental monitoring. By mapping the intersection of nanotechnology, environmental science, and sensor innovation, this review anticipates future developments that could redefine pollution control through the strategic deployment of carbon dots. Full article

(This article belongs to the Special Issue Sensors for Food Testing, Environmental Analysis, and Medical Diagnostics)

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11 pages, 403 KiB

Open AccessArticle

Modeling the Frequency–Amplitude Characteristics of a Tunable SAW Oscillator

by Ionut Nicolae and Cristian Viespe

Chemosensors 2025, 13(7), 240; https://doi.org/10.3390/chemosensors13070240 - 6 Jul 2025

Viewed by 182

Abstract

The resonant frequency of an SAW oscillator can be modulated by varying the signal amplitude, due to non-linear acoustic interactions within the chemoselective layer. In this study, we developed an explicit model to describe the amplitude–frequency behavior of a tunable SAW oscillator. A [...] Read more.

The resonant frequency of an SAW oscillator can be modulated by varying the signal amplitude, due to non-linear acoustic interactions within the chemoselective layer. In this study, we developed an explicit model to describe the amplitude–frequency behavior of a tunable SAW oscillator. A polymeric layer of variable thickness was deposited in a circular area (radius 1.1 mm) at the center of the piezoactive surface. Increasing the oscillator loop attenuation resulted in a continuous increase in the resonant frequency by up to 1.8 MHz. The layer was modeled as a succession of non-interacting sub-layers of varying thicknesses. As a result, the function model consists of a superposition of terms, each corresponding to a layer region of distinct length and thickness. The maximum difference between the experimental data and function model (also known as residual of the fit) was below 1% (13.02 kHz) of the resonant frequency variation, thus supporting the validity of our approach. While our model proved successful, the results suggest that some interactions are unaccounted for, as evidenced by the periodicity of the residuals of fit and unrealistically large variation in acoustic wave velocity. Full article

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

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13 pages, 2602 KiB

Open AccessArticle

Hollow Mesoporous ZnO/ZnCo₂O₄ Based on Ostwald Ripening for H₂S Detection

by Hongtao Wang, Yang Liu, Yuanchao Xie, Jianan Ma, Dan Han and Shengbo Sang

Chemosensors 2025, 13(7), 239; https://doi.org/10.3390/chemosensors13070239 - 5 Jul 2025

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Abstract

Mesoporous ZnO/ZnCo₂O₄ nanocomposites with excellent gas-sensing performance were synthesized using the Ostwald ripening method. The as-prepared ZnO/ZnCo₂O₄ comprised aggregated monodisperse nanoparticles, and the nanoparticle size grew with increasing thermal treatment temperature. Increasing the calcination temperature did not [...] Read more.

Mesoporous ZnO/ZnCo₂O₄ nanocomposites with excellent gas-sensing performance were synthesized using the Ostwald ripening method. The as-prepared ZnO/ZnCo₂O₄ comprised aggregated monodisperse nanoparticles, and the nanoparticle size grew with increasing thermal treatment temperature. Increasing the calcination temperature did not significantly change the overall size of the ZnO/ZnCo₂O₄ nanocomposites, but the pore size and specific surface area were noticeably affected. The gas-sensing results showed that ZnO/ZnCo₂O₄ composites calcined at 500 °C exhibited the highest response to H₂S at 200 °C, with a detection limit of 500 ppb. The ZnO/ZnCo₂O₄ composites also exhibited remarkable selectivity, response/recovery speed, and stability. Their excellent gas-sensing performance might be attributed to their porous structure, large specific surface area, and the heterogeneous interface between ZnO and ZnCo₂O₄. This work not only represents a new example of the Ostwald ripening-based formation of inorganic hollow structures in a template-free aqueous solution but also provides a novel and efficient sensing material for the detection of H₂S gas. Full article

(This article belongs to the Special Issue Recent Progress in Nano Material-Based Gas Sensors)

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11 pages, 417 KiB

Open AccessArticle

Investigating Consumer Preferences for Novel Grape Varieties Through Hedonic Sensory Analysis and Non-Destructive Near-Infrared Spectroscopy

by Teodora Basile, Lucia Rosaria Forleo and Rocco Perniola

Chemosensors 2025, 13(7), 238; https://doi.org/10.3390/chemosensors13070238 - 3 Jul 2025

Viewed by 218

Abstract

While resistance or tolerance is a highly sought-after trait in new grape varieties, producing such grapes does not guarantee acceptance in the market. The objective of this study was to explore consumers’ appreciation of a novel tolerant table grape variety by integrating chemical, [...] Read more.

While resistance or tolerance is a highly sought-after trait in new grape varieties, producing such grapes does not guarantee acceptance in the market. The objective of this study was to explore consumers’ appreciation of a novel tolerant table grape variety by integrating chemical, textural, and sensory analyses with near-infrared (NIR) spectroscopy. To achieve this, we developed multivariate prediction models using artificial neural networks (ANNs) that were applied to the spectra of samples subjected to sensory analysis, allowing us to predict their composition. This approach offers a non-destructive way to conduct sensory analysis, as a single NIR spectrum can assess consumer appreciation and identify the chemical and physical characteristics of each berry. For the grape variety tested, we observed a significant favorable consensus among consumers. Therefore, instead of identifying differences, we focused on determining the optimal maturity ranges that enhance consumer appreciation for this variety. Our findings represent a step toward non-destructive sensory analysis; however, further research is still needed to refine this approach. Full article

(This article belongs to the Special Issue Novel Analytical Approaches for Food Analysis with a Focus on Chemosensors)

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20 pages, 3156 KiB

Open AccessArticle

Quantitative and Qualitative Evaluation of Microplastic Contamination of Shrimp Using Visible Near-Infrared Multispectral Imaging Technology Combined with Supervised Self-Organizing Map

by Sureerat Makmuang and Abderrahmane Aït-Kaddour

Chemosensors 2025, 13(7), 237; https://doi.org/10.3390/chemosensors13070237 - 2 Jul 2025

Viewed by 197

Abstract

Microplastic (MP) contamination is a growing environmental concern with significant impacts on ecosystems, the economy, and potentially human health. However, accurately detecting and characterizing MPs in biological samples remains a challenge due to the complexity of biological matrices and analytical limitations. This study [...] Read more.

Microplastic (MP) contamination is a growing environmental concern with significant impacts on ecosystems, the economy, and potentially human health. However, accurately detecting and characterizing MPs in biological samples remains a challenge due to the complexity of biological matrices and analytical limitations. This study presents a novel, non-destructive visible near-infrared multispectral imaging (Vis-NIR-MSI) method combined with a supervised self-organizing map (SOM) to enable rapid qualitative and quantitative analysis of MPs in seafood. We specifically aimed to identify and differentiate four types of microplastics, namely PET, PE, PP, and PS, in the range 1–4 mm, present on the surface of minced shrimp and shrimp shell. For quantification, MPs were incorporated into minced shrimp surface at concentrations ranging from 0.04% to 1% w/w. The modified model achieved a high coefficient of determination (R² > 0.99) for PE and PP quantification. Unlike conventional techniques, this approach eliminates the need for pre-sorting or chemical processing, offering a cost-effective and efficient solution for large-scale monitoring of MPs in seafood, with potential applications in food safety and environmental protection. Full article

(This article belongs to the Special Issue Novel Analytical Approaches for Food Analysis with a Focus on Chemosensors)

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19 pages, 3235 KiB

Open AccessArticle

Electrochemical Detection of Bisphenol S Based on Molecularly Imprinted Polymers Grafted on Functionalized Multiwalled Carbon Nanotubes: A Facile Sensor Fabrication Approach

by Christopher Mwanza, Lin Zhao, Qing Zhang and Shou-Nian Ding

Chemosensors 2025, 13(7), 236; https://doi.org/10.3390/chemosensors13070236 - 30 Jun 2025

Viewed by 241

Abstract

Bisphenol S (BPS), a key ingredient in polycarbonate plastics and epoxy resins, is a known endocrine-disrupting compound that poses significant risks to human health and the environment. As such, the development of rapid and reliable analytical techniques for its detection is essential. In [...] Read more.

Bisphenol S (BPS), a key ingredient in polycarbonate plastics and epoxy resins, is a known endocrine-disrupting compound that poses significant risks to human health and the environment. As such, the development of rapid and reliable analytical techniques for its detection is essential. In this work, we present a newly engineered electrochemical sensor designed for the sensitive and selective detection of BPS using a straightforward and effective fabrication approach. The sensor was constructed by grafting molecularly imprinted polymers (MIPs) onto vinyl-functionalized multiwalled carbon nanotubes (f-MWCNTs). Ethylene glycol dimethacrylate and acrylamide were used as the cross-linker and functional monomer, respectively, in the synthesis of the MIP layer. The resulting MIP@f-MWCNT nanocomposite was characterized using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The MIP@f-MWCNT material was then combined with chitosan, a biocompatible binder, to fabricate the final MIP@f-MWCNT/chitosan-modified glassy carbon electrode (GCE). Electrochemical evaluation showed a broad linear detection range from 1 to 60 µM (R² = 0.992), with a sensitivity of 0.108 µA/µM and a detection limit of 2.00 µM. The sensor retained 96.0% of its response after four weeks and exhibited high selectivity against structural analogues. In spiked plastic extract samples, recoveries ranged from 95.6% to 105.0%. This robust, cost-effective, and scalable sensing platform holds strong potential for environmental monitoring, food safety applications, and real-time electrochemical detection of endocrine-disrupting compounds like BPS. Full article

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

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14 pages, 1587 KiB

Open AccessArticle

Electrochemical Disposable Printed Aptasensor for Sensitive Ciprofloxacin Monitoring in Milk Samples

by Daniela Nunes da Silva, Thaís Cristina de Oliveira Cândido and Arnaldo César Pereira

Chemosensors 2025, 13(7), 235; https://doi.org/10.3390/chemosensors13070235 - 28 Jun 2025

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Abstract

An electrochemical aptasensor was developed for the rapid and sensitive detection of ciprofloxacin (CPX) in milk samples. The device was fabricated on a polyethylene terephthalate (PET) substrate using a screen-printing technique with carbon-based conductive ink. Gold nanoparticles (AuNPs) were incorporated to enhance aptamer [...] Read more.

An electrochemical aptasensor was developed for the rapid and sensitive detection of ciprofloxacin (CPX) in milk samples. The device was fabricated on a polyethylene terephthalate (PET) substrate using a screen-printing technique with carbon-based conductive ink. Gold nanoparticles (AuNPs) were incorporated to enhance aptamer immobilization and facilitate electron transfer at the electrode surface. The sensor’s analytical performance was optimized by adjusting key parameters, including AuNP volume, DNA aptamer concentration, and incubation times for both the aptamer and the blocking agent (6-mercapto-1-hexanol, MCH). Differential pulse voltammetry (DPV) measurements demonstrated a linear response ranging from 10 to 50 nmol L⁻¹ and a low detection limit of 3.0 nmol L⁻¹. When applied to real milk samples, the method achieved high recovery rates (101.4–106.7%) with a relative standard deviation below 3.1%, confirming its robustness. This disposable and cost-effective aptasensor represents a promising tool for food safety monitoring, with potential for adaptation to detect other pharmaceutical residues in dairy products. Full article

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

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15 pages, 3183 KiB

Open AccessArticle

Platinum-Functionalized Hierarchically Structured Flower-like Nickel Ferrite Sheets for High-Performance Acetone Sensing

by Ziwen Yang, Zhen Sun, Yuhao Su, Caixuan Sun, Peishuo Wang, Shaobin Yang, Xueli Yang and Guofeng Pan

Chemosensors 2025, 13(7), 234; https://doi.org/10.3390/chemosensors13070234 - 26 Jun 2025

Viewed by 404

Abstract

Acetone detection is crucial for non-invasive health monitoring and environmental safety, so there is an urgent demand to develop high-performance gas sensors. Here, platinum (Pt)-functionalized layered flower-like nickel ferrite (NiFe₂O₄) sheets were efficiently fabricated via facile hydrothermal synthesis and [...] Read more.

Acetone detection is crucial for non-invasive health monitoring and environmental safety, so there is an urgent demand to develop high-performance gas sensors. Here, platinum (Pt)-functionalized layered flower-like nickel ferrite (NiFe₂O₄) sheets were efficiently fabricated via facile hydrothermal synthesis and wet chemical reduction processes. When the Ni/Fe molar ratio is 1:1, the sensing material forms a Ni/NiO/NiFe₂O₄ composite, with performance further optimized by tuning Pt loading. At 1.5% Pt mass fraction, the sensor shows a high acetone response (R_g/R_a = 58.33 at 100 ppm), a 100 ppb detection limit, fast response/recovery times (7/245 s at 100 ppm), and excellent selectivity. The enhancement in performance originates from the synergistic effect of the structure and Pt loading: the layered flower-like morphology facilitates gas diffusion and charge transport, while Pt nanoparticles serve as active sites to lower the activation energy of acetone redox reactions. This work presents a novel strategy for designing high-performance volatile organic compound (VOC) sensors by combining hierarchical nanostructured transition metal ferrites with noble metal modifications. Full article

(This article belongs to the Special Issue Recent Progress in Nano Material-Based Gas Sensors)

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15 pages, 2854 KiB

Open AccessArticle

Development of a Hydrogen-Sensing Antenna Operating in the Microwave Region for Applications in Safety-Critical Systems

by Antonio Jefferson Mangueira Sales, Stephen Rathinaraj Benjamin, João Paulo Costa do Nascimento, Felipe Felix do Carmo, Juscelino Chaves Sales, Roterdan Fernandes Abreu, Francisco Enilton Alves Nogueira, Paulo Maria de Oliveira Silva, Marcelo Antonio Santos da Silva, José Adauto da Cruz, Enio Pontes de Deus and Antonio Sergio Bezerra Sombra

Chemosensors 2025, 13(7), 233; https://doi.org/10.3390/chemosensors13070233 - 25 Jun 2025

Viewed by 458

Abstract

Hydrogen is gaining prominence as a clean energy vector, yet its extreme flammability demands robust detection solutions for industrial safety. In this study, we present the development and experimental validation of a microwave hydrogen gas sensor based on a patch-type microstrip antenna with [...] Read more.

Hydrogen is gaining prominence as a clean energy vector, yet its extreme flammability demands robust detection solutions for industrial safety. In this study, we present the development and experimental validation of a microwave hydrogen gas sensor based on a patch-type microstrip antenna with a silver sensing element. The device operates at 5.99 GHz and was tested under controlled environmental conditions (humidity: 20 ± 0.4%, temperature: 27 ± 0.2 °C). Hydrogen exposure induces measurable shifts in the antenna’s resonant frequency due to dielectric modulation of the silver layer. The sensor exhibited a linear sensitivity of 3 kHz/ppm in the 310–600 ppm concentration range, with a residual standard deviation of 31.1 kHz and a calculated limit of detection (LOD) of approximately 31 ppm. The reflection coefficient remained below −10 dB throughout, confirming that the antenna maintains functional RF performance during sensing. These results demonstrate the sensor’s dual functionality for gas detection and communication, offering a compact and scalable platform for hydrogen safety monitoring. Full article

(This article belongs to the Special Issue Novel Materials for Gas Sensing)

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16 pages, 2416 KiB

Open AccessArticle

Predicting the Color of Archaeological Littorina obtusata/fabalis Shells Using Raman Spectroscopy and Clustering Algorithms

by Andrea Perez-Asensio, María Gabriela Fernández-Manteca, David Cuenca-Solana, Igor Gutiérrez-Zugasti, Asier García-Escárzaga, Jesús Mirapeix, José Miguel López-Higuera, Luis Rodríguez-Cobo and Adolfo Cobo

Chemosensors 2025, 13(7), 232; https://doi.org/10.3390/chemosensors13070232 - 25 Jun 2025

Viewed by 369

Abstract

Archaeological mollusk shells, such as those of Littorina obtusata/fabalis, hold valuable information about past human behavior and cultural practices. However, the original coloration of these shells, crucial for understanding their symbolic significance, is often lost due to taphonomic processes. Raman spectroscopy is [...] Read more.

Archaeological mollusk shells, such as those of Littorina obtusata/fabalis, hold valuable information about past human behavior and cultural practices. However, the original coloration of these shells, crucial for understanding their symbolic significance, is often lost due to taphonomic processes. Raman spectroscopy is a powerful technique for non-destructive analysis of archaeological samples, enabling the identification of pigments and mineralogical components. In this study, we present a methodology to predict, using Raman spectroscopy and k-means clustering, the original coloration of archaeological L. obtusata/fabalis shells which have lost their original coloration. Raman spectra were acquired from both modern shells, exhibiting a range of natural colors, and archaeological shell samples from La Chora cave (Cantabria, northern Spain). Spectral data were preprocessed to remove noise and baseline effects, and k-means clustering was applied to group the spectra based on their inherent spectral similarities. By comparing the spectral signatures of the archaeological samples with those of the modern shells within the generated clusters, we inferred the likely original coloration of the archaeological specimens. This approach provides a quantitative framework for predicting archaeological shell colors. Full article

(This article belongs to the Section Optical Chemical Sensors)

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18 pages, 4853 KiB

Open AccessArticle

Origin Identification of Table Salt Using Flame Atomic Absorption and Portable Near-Infrared Spectrometries

by Larissa Rodrigues Zanela Lima, Luana Dalagrana dos Santos, Isabella Taglieri, David Cabral, Letícia Estevinho, Fábio Luiz Melquiades, Luís Guimarães Dias and Evandro Bona

Chemosensors 2025, 13(7), 231; https://doi.org/10.3390/chemosensors13070231 - 24 Jun 2025

Viewed by 370

Abstract

The mineral composition of table salt can be indicative of its origin. This work evaluated the possibility of identifying the origin of salt from four countries: Brazil, Spain, France, and Portugal. Eight metals were quantified through flame atomic absorption/emission spectroscopy (FAAS). The possibility [...] Read more.

The mineral composition of table salt can be indicative of its origin. This work evaluated the possibility of identifying the origin of salt from four countries: Brazil, Spain, France, and Portugal. Eight metals were quantified through flame atomic absorption/emission spectroscopy (FAAS). The possibility of using portable near-infrared spectroscopy (NIR) as a faster and lower-cost alternative for identifying salt provenance was also evaluated. The content of Ca, Mg, Fe, Mn, and Cu was identified as possible markers to differentiate the salt origin. One-class classifiers using FAAS data and DD-SIMCA could discriminate the salt origin with few misclassifications. For NIR spectroscopy, it was possible to highlight the importance of controlling the humidity and granulometry before the spectra acquisition. After drying and milling the samples, it was possible to discriminate between samples based on the interaction between the water of hydration and the presence of the cations in the sample. The Mg, Mn, and Cu are important in identifying the origin of salt using NIR spectra. The DD-SIMCA model using NIR spectra could classify the origin with the same performance as observed in FAAS. However, it is important to emphasize that NIR spectroscopy requires less sample preparation, is faster, and has low-cost instrumentation. Full article

(This article belongs to the Special Issue Chemometrics Tools Used in Chemical Detection and Analysis)

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51 pages, 5828 KiB

Open AccessReview

A Comprehensive Review of Advanced Sensor Technologies for Fire Detection with a Focus on Gasistor-Based Sensors

by Mohsin Ali, Ibtisam Ahmad, Ik Geun, Syed Ameer Hamza, Umar Ijaz, Yuseong Jang, Jahoon Koo, Young-Gab Kim and Hee-Dong Kim

Chemosensors 2025, 13(7), 230; https://doi.org/10.3390/chemosensors13070230 - 23 Jun 2025

Viewed by 768

Abstract

Early fire detection plays a crucial role in minimizing harm to human life, buildings, and the environment. Traditional fire detection systems struggle with detection in dynamic or complex situations due to slow response and false alarms. Conventional systems are based on smoke, heat, [...] Read more.

Early fire detection plays a crucial role in minimizing harm to human life, buildings, and the environment. Traditional fire detection systems struggle with detection in dynamic or complex situations due to slow response and false alarms. Conventional systems are based on smoke, heat, and gas sensors, which often trigger alarms when a fire is in full swing. In order to overcome this, a promising approach is the development of memristor-based gas sensors, known as gasistors, which offer a lightweight design, fast response/recovery, and efficient miniaturization. Recent studies on gasistor-based sensors have demonstrated ultrafast response times as low as 1–2 s, with detection limits reaching sub-ppm levels for gases such as CO, NH₃, and NO₂. Enhanced designs incorporating memristive switching and 2D materials have achieved a sensitivity exceeding 90% and stable operation across a wide temperature range (room temperature to 250 °C). This review highlights key factors in early fire detection, focusing on advanced sensors and their integration with IoT for faster, and more reliable alerts. Here, we introduce gasistor technology, which shows high sensitivity to fire-related gases and operates through conduction filament (CF) mechanisms, enabling its low power consumption, compact size, and rapid recovery. When integrated with machine learning and artificial intelligence, this technology offers a promising direction for future advancements in next-generation early fire detection systems. Full article

(This article belongs to the Special Issue Recent Progress in Nano Material-Based Gas Sensors)

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21 pages, 6541 KiB

Open AccessArticle

A Sensitive Epinephrine Sensor Based on Photochemically Synthesized Gold Nanoparticles

by Eyup Metin, Gonul S. Batibay, Meral Aydin and Nergis Arsu

Chemosensors 2025, 13(7), 229; https://doi.org/10.3390/chemosensors13070229 - 23 Jun 2025

Viewed by 381

Abstract

In this study, gold nanoparticles (AuNPs) and AuNPs-graphene oxide (AuNPs@GO) nanostructures were synthesized in aqueous media using an in-situ photochemical method with bis-acyl phosphine oxide (BAPO) photoinitiator as a photoreducing agent in the presence of HAuCl₄. The parameters for synthesis were [...] Read more.

In this study, gold nanoparticles (AuNPs) and AuNPs-graphene oxide (AuNPs@GO) nanostructures were synthesized in aqueous media using an in-situ photochemical method with bis-acyl phosphine oxide (BAPO) photoinitiator as a photoreducing agent in the presence of HAuCl₄. The parameters for synthesis were arranged to obtain stable and reproducible dispersions with desirable chemical and optical properties. Both AuNPs and AuNPs@GO were employed as sensing platforms for the detection of epinephrine in two concentration ranges: micromolar (µM) and nanomolar (nM). Field emission scanning electron microscopy (FE-SEM), Dynamic Light Scattering (DLS), UV-Vis absorption, fluorescence emission, and Fourier Transform Infrared (FT-IR) spectroscopy techniques were used to investigate the morphological, optical, and chemical properties of the nanostructures as well as their sensing ability towards epinephrine. Fluorescence spectroscopy played a crucial role in demonstrating the high sensitivity and effectiveness of these systems, especially in the low concentration (nM) range, confirming their strong potential as fluorescence-based sensors. By constructing calibration curves on best linear subranges, limit of detection (LOD) and limit of quantification (LOQ) were calculated with two different approaches, SE_intercept and S_y/x. Among all the investigated nanostructures, AuNPs@GO exhibited the highest sensitivity towards epinephrine. The efficiency and reproducibility of the in-situ photochemical AuNPs synthesis approach highlight its applicability in small-molecule detection and particularly in analytical and bio-sensing applications. Full article

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

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16 pages, 5477 KiB

Open AccessArticle

Enhanced Triethylamine-Sensing Characteristics of SnS₂/LaFeO₃ Composite

by Hong Wu, Xiaobing Wang, Yuxiang Chen and Xiaofeng Wang

Chemosensors 2025, 13(7), 228; https://doi.org/10.3390/chemosensors13070228 - 23 Jun 2025

Viewed by 338

Abstract

Triethylamine (TEA), a volatile organic compound (VOC), has important applications in industrial production. However, TEA has an irritating odor and potential toxicity, making it necessary to develop sensitive TEA gas sensors with high efficiency. This study focused on preparing LaFeO₃ nanoparticles modified [...] Read more.

Triethylamine (TEA), a volatile organic compound (VOC), has important applications in industrial production. However, TEA has an irritating odor and potential toxicity, making it necessary to develop sensitive TEA gas sensors with high efficiency. This study focused on preparing LaFeO₃ nanoparticles modified by SnS₂ nanosheets (SnS₂/LaFeO₃ composite) using a hydrothermal method together with sol–gel technique. According to the comparison results of the gas-sensing performance between pure LaFeO₃ and SnS₂/LaFeO₃ composite with varying composition ratios, 5% SnS₂/LaFeO₃ sensor had a sensitivity for TEA that was 3.2 times higher than pure LaFeO₃ sensor. The optimized sensor operates at 140 °C and demonstrates strong stability, selectivity, and long-term durability. Detailed analyses revealed that the SnS₂ nanosheets enhanced oxygen vacancy (O_V) content and carrier mobility through heterojunction formation with LaFeO₃. This study provides insights into improving gas-sensing performance via p-n heterostructure design and proposes a novel LaFeO₃-based material for TEA detection. Full article

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

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27 pages, 5575 KiB

Open AccessReview

Modeling of Chemiresistive Gas Sensors: From Microscopic Reception and Transduction Processes to Macroscopic Sensing Behaviors

by Zhiqiao Gao, Menglei Mao, Jiuwu Ma, Jincheng Han, Hengzhen Feng, Wenzhong Lou, Yixin Wang and Teng Ma

Chemosensors 2025, 13(7), 227; https://doi.org/10.3390/chemosensors13070227 - 22 Jun 2025

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Abstract

Chemiresistive gas sensors have gained significant attention and have been widely applied in various fields. However, the gap between experimental observations and fundamental sensing mechanisms hinders systematic optimization. Despite the critical role of modeling in explaining atomic-scale interactions and offering predictive insights beyond [...] Read more.

Chemiresistive gas sensors have gained significant attention and have been widely applied in various fields. However, the gap between experimental observations and fundamental sensing mechanisms hinders systematic optimization. Despite the critical role of modeling in explaining atomic-scale interactions and offering predictive insights beyond experiments, existing reviews on chemiresistive gas sensors remain predominantly experimental-centric, with a limited systematic exploration of the modeling approaches. Herein, we present a comprehensive overview of the modeling approaches for chemiresistive gas sensors, focusing on two critical processes: the reception and transduction stages. For the reception process, density functional theory (DFT), molecular dynamics (MD), ab initio molecular dynamics (AIMD), and Monte Carlo (MC) methods were analyzed. DFT quantifies atomic-scale charge transfer, and orbital hybridization, MD/AIMD captures dynamic adsorption kinetics, and MC simulates equilibrium/non-equilibrium behaviors based on statistical mechanics principles. For the transduction process, band-bending-based theoretical models and power-law models elucidate the resistance modulation mechanisms, although their generalizability remains limited. Notably, the finite element method (FEM) has emerged as a powerful tool for full-process modeling by integrating gas diffusion, adsorption, and electronic responses into a unified framework. Future directions highlight the use of multiscale models to bridge microscopic interactions with macroscopic behaviors and the integration of machine learning, accelerating the iterative design of next-generation sensors with superior performance. Full article

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

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19 pages, 3123 KiB

Open AccessArticle

Giant Chemo-Resistive Response of POSS Nano-Spacers in PS- and PMMA-Based Quantum Resistive Vapour Sensors (vQRS) Used for Cancer Biomarker Analysis

by Abhishek Sachan, Mickaël Castro, Veena Choudhary and Jean-François Feller

Chemosensors 2025, 13(7), 226; https://doi.org/10.3390/chemosensors13070226 - 21 Jun 2025

Viewed by 425

Abstract

The detection of volatile organic compound (VOC) biomarkers from the volatolome for the anticipated diagnosis of severe diseases such as cancers is made difficult due to the presence of high quantities of H₂O in the collected samples. It has been shown [...] Read more.

The detection of volatile organic compound (VOC) biomarkers from the volatolome for the anticipated diagnosis of severe diseases such as cancers is made difficult due to the presence of high quantities of H₂O in the collected samples. It has been shown that water molecules tend to compete or combine themselves with analytes, which requires either their removal or the development of more sensitive and discriminant sensors. In this later prospect, a positive effect of poly(hedral oligomeric silsesquioxanes) (POSS) is sought out to enhance the sensitivity of carbon nanotube-based quantum resistive vapour sensors (vQRS). POSS, once copolymerized with methyl methacrylate or styrene, can be used as nano-spacers amplifying the disconnection of the nano-junctions due to swelling of the polymer upon the diffusion of VOC. The amplitude of this phenomenon, which is at the origin of the chemo-resistive behaviour of vQRS, was compared with that of homologue transducers made of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA)-coated carbon nanotube (CNT) random networks. The presence of POSS in PS-based sensors has enhanced their sensitivity by 213 times for toluene, by 268 times for acetone, by 4 times for ethanol, and by 187 times for cyclohexane. Similarly, the presence of POSS in PMMA chains increases the sensitivity of sensors to cyclohexane by 10 times, to ethanol by 45 times, to toluene by 244 times, and to acetone and butanone by 4 times. All transducers were made by spray layer by layer (sLbL) to obtain a hierarchically structured conducting architecture. The transducers’ surface was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to observe the CNT coating and dispersion level in the matrix. All sensors were tested with twenty-one VOC part of lung and skin cancer biomarkers by using a dynamic vapour analysis (DVA). The vQRS based on POSS copolymers demonstrated much larger chemo-resistive responses (A_R) than the sensors based only on pure polymers and were found to be very selective towards cyclohexane and hexene-1. The PMMA-co-POSS/CNT sensor was able to detect down to 12 ppm of VOC with a very high signal-to-noise ratio (SNR) and to discriminate six VOC among them all with a PCA (principal component analysis) projection. Full article

(This article belongs to the Collection Recent Advances in Multifunctional Sensing Technology for Gas Analysis)

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