Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
8.1
4.4
Journals
Chemosensors
Editor’s Choice
share announcement

Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

Order results
Result details
Results per page
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
29 pages, 8644 KB  
Review
Recent Advances in Resistive Gas Sensors: Fundamentals, Material and Device Design, and Intelligent Applications
by Peiqingfeng Wang, Shusheng Xu, Xuerong Shi, Jiaqing Zhu, Haichao Xiong and Huimin Wen
Chemosensors 2025, 13(7), 224; https://doi.org/10.3390/chemosensors13070224 - 21 Jun 2025
Cited by 45 | Viewed by 7741
Abstract
Resistive gas sensors have attracted significant attention due to their simple architecture, low cost, and ease of integration, with widespread applications in environmental monitoring, industrial safety, and healthcare diagnostics. This review provides a comprehensive overview of recent advances in resistive gas sensors, focusing [...] Read more.
Resistive gas sensors have attracted significant attention due to their simple architecture, low cost, and ease of integration, with widespread applications in environmental monitoring, industrial safety, and healthcare diagnostics. This review provides a comprehensive overview of recent advances in resistive gas sensors, focusing on their fundamental working mechanisms, sensing material design, device architecture optimization, and intelligent system integration. These sensors primarily operate based on changes in electrical resistance induced by interactions between gas molecules and sensing materials, including physical adsorption, charge transfer, and surface redox reactions. In terms of materials, metal oxide semiconductors, conductive polymers, carbon-based nanomaterials, and their composites have demonstrated enhanced sensitivity and selectivity through strategies such as doping, surface functionalization, and heterojunction engineering, while also enabling reduced operating temperatures. Device-level innovations—such as microheater integration, self-heated nanowires, and multi-sensor arrays—have further improved response speed and energy efficiency. Moreover, the incorporation of artificial intelligence (AI) and Internet of Things (IoT) technologies has significantly advanced signal processing, pattern recognition, and long-term operational stability. Machine learning (ML) algorithms have enabled intelligent design of novel sensing materials, optimized multi-gas identification, and enhanced data reliability in complex environments. These synergistic developments are driving resistive gas sensors toward low-power, highly integrated, and multifunctional platforms, particularly in emerging applications such as wearable electronics, breath diagnostics, and smart city infrastructure. This review concludes with a perspective on future research directions, emphasizing the importance of improving material stability, interference resistance, standardized fabrication, and intelligent system integration for large-scale practical deployment. Full article
(This article belongs to the Special Issue Recent Advances in Low-Cost Chemical Sensor Technologies for Environmental Monitoring Applications)
►▼ Show Figures

Figure 1

30 pages, 4171 KB  
Review
Two-Dimensional Materials for Biosensing: Emerging Bio-Converged Strategies for Wearable and Implantable Platforms
by Ki Ha Min, Koung Hee Kim and Seung Pil Pack
Chemosensors 2025, 13(6), 209; https://doi.org/10.3390/chemosensors13060209 - 8 Jun 2025
Cited by 16 | Viewed by 5693
Abstract
The development of functional biosensors is rapidly advancing in response to the growing demand for personalized and continuous healthcare monitoring. Two-dimensional (2D) nanostructured materials have attracted significant attention for next-generation biosensors due to their exceptional physicochemical properties, including a high surface-to-volume ratio, excellent [...] Read more.
The development of functional biosensors is rapidly advancing in response to the growing demand for personalized and continuous healthcare monitoring. Two-dimensional (2D) nanostructured materials have attracted significant attention for next-generation biosensors due to their exceptional physicochemical properties, including a high surface-to-volume ratio, excellent electrical conductivity, and mechanical flexibility. The integration of 2D materials with biological recognition elements offers synergistic improvements in sensitivity, stability, and overall sensor performance. These unique properties make 2D materials particularly well-suited for constructing wearable and implantable biosensors, which require conformal contact with soft tissues, mechanical adaptability to body movement, and reliable operation under physiological conditions. This review highlights recent advances in functionalized and composite 2D materials for wearable and implantable biosensing applications. We focus on key strategies in surface modification and hybrid nanostructure engineering aimed at optimizing performance in dynamic, body-integrated environments. Finally, we discuss current challenges and future directions for clinical translation, emphasizing the potential of 2D-material-based biosensors to drive progress in personalized and precision medicine. Full article
(This article belongs to the Special Issue Emerging 2D Materials for Sensing Applications)
►▼ Show Figures

Figure 1

35 pages, 9764 KB  
Review
Development of Gas Sensors and Their Applications in Health Safety, Medical Detection, and Diagnosis
by Jiayu Wang and Rui Wang
Chemosensors 2025, 13(5), 190; https://doi.org/10.3390/chemosensors13050190 - 20 May 2025
Cited by 34 | Viewed by 8442
Abstract
Gas sensors assume a crucial role in the medical domain, offering substantial support for disease diagnosis, treatment, medical environment management, and the operation of medical equipment by virtue of their distinctive gas detection capabilities. This paper presents an overview of the key research [...] Read more.
Gas sensors assume a crucial role in the medical domain, offering substantial support for disease diagnosis, treatment, medical environment management, and the operation of medical equipment by virtue of their distinctive gas detection capabilities. This paper presents an overview of the key research and development orientations for gas sensors, encompassing the exploration and optimization of novel sensitive materials, such as nanomaterials and metal oxides, to augment sensor sensitivity, selectivity, and stability. The innovation in sensor structural design, particularly the integration of micro-electromechanical systems (MEMS) technology to attain miniaturization and integration, is also addressed. The applications of gas sensors in health safety are expounded, covering the real-time monitoring of indoor air quality for harmful gases such as formaldehyde, as well as the detection of toxic gases in industrial environments to guarantee the safety of living and working spaces and prevent occupational health hazards. In the sphere of medical detection and diagnosis, this paper focuses on the detection of biomarkers in human exhaled breath by gas sensors, which facilitates the early diagnosis of diseases such as lung cancer. Additionally, the existing challenges and future development trends in this field are analyzed, with the aim of providing a comprehensive reference for the in-depth research and extensive application of gas sensors in the health, safety, and medical fields. Full article
(This article belongs to the Special Issue Electrochemical Sensing in Medical Diagnosis)
►▼ Show Figures

Figure 1

31 pages, 952 KB  
Review
Electronic Tongue Technology Applied to the Analysis of Grapes and Wines: A Comprehensive Review from Its Origins
by Celia Garcia-Hernandez, Cristina Garcia-Cabezon, Maria Luz Rodriguez-Mendez and Fernando Martin-Pedrosa
Chemosensors 2025, 13(5), 188; https://doi.org/10.3390/chemosensors13050188 - 17 May 2025
Cited by 16 | Viewed by 5778
Abstract
The electronic tongue (ET) and bioelectronic tongue (bioET) technologies have emerged as innovative and promising tools for the characterization and quality control of complex liquid matrices such as grape musts and wines. These multisensor systems, based on electrochemical detection and chemometric analysis, provide [...] Read more.
The electronic tongue (ET) and bioelectronic tongue (bioET) technologies have emerged as innovative and promising tools for the characterization and quality control of complex liquid matrices such as grape musts and wines. These multisensor systems, based on electrochemical detection and chemometric analysis, provide global and rapid information about taste-related attributes, antioxidant content, and other critical parameters, offering an alternative or complement to traditional analytical methods. This review explores the principles, development, and applications of ET and bioET in the wine industry, highlighting their capacity to assess grape ripeness, monitor fermentation, determine wine aging, detect adulterations, and support geographical and varietal authentication. Special attention is paid to advances in sensing materials—such as conducting polymers, metal nanoparticles, and enzymes—and the construction techniques of sensors and biosensors, which have improved ET performance. Finally, the potential of these technologies as cost-effective, portable, and on-site tools aligns with the demands of Industry 4.0 and next-generation smart agriculture and food production systems. Full article
(This article belongs to the Special Issue Applications of Electronic Nose (E-Nose) and Electronic Tongue (E-Tongue) in Food Quality)
►▼ Show Figures

Figure 1

33 pages, 4183 KB  
Review
Recent Advances on Fluorescent Sensors for Detection of Pathogenic Bacteria
by Xu Tang, Qi Qi, Binrong Li, Zhi Zhu, Jian Lu and Lei Liu
Chemosensors 2025, 13(5), 182; https://doi.org/10.3390/chemosensors13050182 - 13 May 2025
Cited by 11 | Viewed by 8087
Abstract
Pathogenic bacteria are one of the main causes of diseases and have become an important public health problem threatening human health and socio-economic development. Therefore, it is particularly important to develop an efficient and convenient detection method. Fluorescence detection has become a highly [...] Read more.
Pathogenic bacteria are one of the main causes of diseases and have become an important public health problem threatening human health and socio-economic development. Therefore, it is particularly important to develop an efficient and convenient detection method. Fluorescence detection has become a highly concerned analytical technology, which has gradually emerged in the aspect of pathogen detection, and is favored by researchers. In this review, we summarized a series of sensing strategies for pathogen detection based on fluorescence response signals in recent years, including single molecule fluorescent probes, biosensors, nanocomposite sensors and strategies for integrating different recognition elements with nanomaterials, along with the advantages and disadvantages of various design strategies. Based on the existing research reports, the existing problems and future research challenges of fluorescent sensor technology are proposed. Full article
(This article belongs to the Special Issue Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2025)
►▼ Show Figures

Figure 1

37 pages, 6833 KB  
Review
Recent Advances in Aggregation-Induced Emission (AIE) Fluorescent Sensors for Biomolecule Detection
by Kavya S. Keremane, M. Gururaj Acharya, Praveen Naik, Chandi C. Malakar, Kai Wang and Bed Poudel
Chemosensors 2025, 13(5), 174; https://doi.org/10.3390/chemosensors13050174 - 9 May 2025
Cited by 39 | Viewed by 7977
Abstract
Fluorescent sensors are indispensable tools in fields such as molecular biology, clinical diagnostics, biotechnology, and environmental monitoring, due to their high sensitivity, selectivity, biocompatibility, rapid response, and ease of use. However, conventional fluorophores often suffer from aggregation-caused quenching (ACQ), leading to diminished fluorescence [...] Read more.
Fluorescent sensors are indispensable tools in fields such as molecular biology, clinical diagnostics, biotechnology, and environmental monitoring, due to their high sensitivity, selectivity, biocompatibility, rapid response, and ease of use. However, conventional fluorophores often suffer from aggregation-caused quenching (ACQ), leading to diminished fluorescence in the aggregated state. The advent of aggregation-induced emission (AIE) luminogens, which exhibit enhanced fluorescence upon aggregation, offers a powerful solution to this limitation. Their unique photophysical properties have made AIE-based materials highly valuable for diverse applications, including biomedical imaging, optoelectronics, stimuli-responsive systems, drug delivery, and chemical sensing. Notably, AIE-based fluorescent probes are emerging as attractive alternatives to traditional analytical methods owing to their low cost, fast detection, and high selectivity. Over the past two decades, considerable progress has been made in the rational design and development of AIE-active small-molecule fluorescent probes for detecting a wide variety of analytes, such as biologically relevant molecules, drug compounds, volatile organic compounds (VOCs), explosives, and contaminants associated with forensic and food safety analysis. This review highlights recent advances in organic AIE-based fluorescent probes, beginning with the fundamentals of AIE and typical “turn-on” sensing mechanisms, and concluding with a discussion of current challenges and future opportunities in this rapidly evolving research area. Full article
(This article belongs to the Special Issue Advancements and Emerging Applications of Fluorescent Probes for Sensing and Imaging)
►▼ Show Figures

Figure 1

23 pages, 3229 KB  
Review
A Systematic Review of the Applications of Electronic Nose and Electronic Tongue in Food Quality Assessment and Safety
by Ramkumar Vanaraj, Bincy I.P, Gopiraman Mayakrishnan, Ick Soo Kim and Seong-Cheol Kim
Chemosensors 2025, 13(5), 161; https://doi.org/10.3390/chemosensors13050161 - 1 May 2025
Cited by 71 | Viewed by 18285
Abstract
Food quality assessment is a critical aspect of food production and safety, ensuring that products meet both regulatory and consumer standards. Traditional methods such as sensory evaluation, chromatography, and spectrophotometry are widely used but often suffer from limitations, including subjectivity, high costs, and [...] Read more.
Food quality assessment is a critical aspect of food production and safety, ensuring that products meet both regulatory and consumer standards. Traditional methods such as sensory evaluation, chromatography, and spectrophotometry are widely used but often suffer from limitations, including subjectivity, high costs, and time-consuming procedures. In recent years, the development of electronic nose (e-nose) and electronic tongue (e-tongue) technologies has provided rapid, objective, and reliable alternatives for food quality monitoring. These bio-inspired sensing systems mimic human olfactory and gustatory functions through sensor arrays and advanced data processing techniques, including artificial intelligence and pattern recognition algorithms. The e-nose is primarily used for detecting volatile organic compounds (VOCs) in food, making it effective for freshness evaluation, spoilage detection, aroma profiling, and adulteration identification. Meanwhile, the e-tongue analyzes liquid-phase components and is widely applied in taste assessment, beverage authentication, fermentation monitoring, and contaminant detection. Both technologies are extensively used in the quality control of dairy products, meat, seafood, fruits, beverages, and processed foods. Their ability to provide real-time, non-destructive, and high-throughput analysis makes them valuable tools in the food industry. This review explores the principles, advantages, and applications of e-nose and e-tongue systems in food quality assessment. Additionally, it discusses emerging trends, including IoT-based smart sensing, advances in nanotechnology, and AI-driven data analysis, which are expected to further enhance their efficiency and accuracy. With continuous innovation, these technologies are poised to revolutionize food safety and quality control, ensuring consumer satisfaction and compliance with global standards. Full article
(This article belongs to the Special Issue Applications of Electronic Nose (E-Nose) and Electronic Tongue (E-Tongue) in Food Quality)
►▼ Show Figures

Figure 1

20 pages, 3507 KB  
Review
Biosensors for Micro- and Nanoplastics Detection: A Review
by Maria Daoutakou and Spyridon Kintzios
Chemosensors 2025, 13(4), 143; https://doi.org/10.3390/chemosensors13040143 - 14 Apr 2025
Cited by 18 | Viewed by 9759
Abstract
Microplastics (MPs) and nanoplastics (NPs), which are widespread in many habitats as the byproducts of various industrial processes, pose considerable environmental and health hazards. However, current, conventional methods for detecting and characterizing them are considerably lacking in throughput, sensitivity, reliability, and field deployability. [...] Read more.
Microplastics (MPs) and nanoplastics (NPs), which are widespread in many habitats as the byproducts of various industrial processes, pose considerable environmental and health hazards. However, current, conventional methods for detecting and characterizing them are considerably lacking in throughput, sensitivity, reliability, and field deployability. In the current report, we review the state of the art in biosensor-based MP/NP detection, in particular, describing advances in optical and electrochemical approaches, along with the development of novel biorecognition elements and the application of bioinformatics tools. Full article
(This article belongs to the Special Issue Sensors for Food Testing, Environmental Analysis, and Medical Diagnostics)
►▼ Show Figures

Figure 1

61 pages, 8313 KB  
Review
Promising Solutions to Address the Non-Specific Adsorption in Biosensors Based on Coupled Electrochemical-Surface Plasmon Resonance Detection
by Alina Vasilescu, Szilveszter Gáspár, Mihaela Gheorghiu, Cristina Polonschii, Roberta Maria Banciu, Sorin David, Eugen Gheorghiu and Jean-Louis Marty
Chemosensors 2025, 13(3), 92; https://doi.org/10.3390/chemosensors13030092 - 5 Mar 2025
Cited by 37 | Viewed by 10084
Abstract
Nonspecific adsorption (NSA) impacts the performance of biosensors in complex samples. Coupled electrochemical–surface plasmon resonance biosensors (EC-SPR) offer interesting opportunities to evaluate NSA. This review details the main solutions to minimize fouling in electrochemical (EC), surface plasmon resonance (SPR) and EC-SPR biosensors. The [...] Read more.
Nonspecific adsorption (NSA) impacts the performance of biosensors in complex samples. Coupled electrochemical–surface plasmon resonance biosensors (EC-SPR) offer interesting opportunities to evaluate NSA. This review details the main solutions to minimize fouling in electrochemical (EC), surface plasmon resonance (SPR) and EC-SPR biosensors. The discussion was centered on blood, serum and milk as examples of complex matrices. Emphasis was placed on antifouling coatings, NSA evaluation protocols and universal functionalization strategies to obtain antifouling biosensors. In the last 5 years, various antifouling coatings were developed for EC biosensors, including new peptides, cross-linked protein films and hybrid materials. Due to the comparatively much more scarce literature, for SPR and EC-SPR biosensors the discussion was extended to the early 2010s. The analysis revealed a wide range of antifouling materials with tunable conductivity, thickness and functional groups that can be tested in the future with EC-SPR. The high-throughput screening of new materials, molecular simulations and machine learning-assisted evaluations will even further widen the range of antifouling materials available for biosensors. The minimization of NSA’s impact on the analytical signal is moreover facilitated by unique sensing mechanisms associated with the bioreceptor or the particularities of the detection method. It is hoped that this review will encourage research in the field of EC-SPR biosensors. Full article
(This article belongs to the Special Issue Sensors for Food Testing, Environmental Analysis, and Medical Diagnostics)
►▼ Show Figures

Figure 1

18 pages, 2477 KB  
Article
Electrochemical Detection of Dopamine with a Non-Enzymatic Sensor Based on Au@SiO2-APTES Composite
by Afef Dhaffouli, Pedro A. Salazar-Carballo, Soledad Carinelli, Michael Holzinger, Bruno V. M. Rodrigues and Houcine Barhoumi
Chemosensors 2025, 13(3), 87; https://doi.org/10.3390/chemosensors13030087 - 3 Mar 2025
Cited by 26 | Viewed by 4707
Abstract
A novel material composed of Au@SiO2-(3-Aminopropyl Triethoxysilane) (Au@SiO2-APTES) was successfully synthesised using the sol–gel method, and was used to modify glassy carbon electrodes. Its effectiveness as a molecular recognition element is evaluated in the design of an electrochemical sensor [...] Read more.
A novel material composed of Au@SiO2-(3-Aminopropyl Triethoxysilane) (Au@SiO2-APTES) was successfully synthesised using the sol–gel method, and was used to modify glassy carbon electrodes. Its effectiveness as a molecular recognition element is evaluated in the design of an electrochemical sensor for the precise detection of dopamine. The Au@SiO2-APTES composite was analysed using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Elemental analysis verified the presence of oxygen, silicon, and gold, with atomic percentages of around 77.19%, 21.12%, and 1.65%, respectively. The corresponding elemental mapping for Au@SiO2-APTES composite showed that the spatial distribution of all the elements was fairly homogeneous throughout the composite, indicating that the Au NPs are embedded in the silica structures. Traces of dopamine were detected by differential pulse voltammetry with a low limit of detection (S/N = 3) and quantification (S/N = 10) of 1.4 × 10−8 molL−1 and 4.7 × 10−8 molL−1, respectively. The Au@SiO2-APTES composite had two linear ranges: from 4.7 × 10−8 to 1 × 10−7 molL−1 and 1.25 × 10−7 to 8.75 × 10−7 molL−1. Moreover, the sensor showed outstanding selectivity even in the presence of various potential interfering species. It also demonstrated good reusability and signal recovery when tested in human urine and plasma samples spiked with different dopamine concentrations. The electrochemical sensor, constructed using this novel composite material, shows great promise in the selective and sensitive detection of dopamine in the biological matrix. These results underscore the sensor’s capability for practical application in analysing real-world samples. Full article
(This article belongs to the Special Issue Sensors for Food Testing, Environmental Analysis, and Medical Diagnostics)
►▼ Show Figures

Graphical abstract

9 pages, 2267 KB  
Perspective
Microneedle-Based Sensors for Wearable Diagnostics
by Hamdi Ben Halima, Boris Lakard and Nicole Jaffrezic-Renault
Chemosensors 2025, 13(2), 68; https://doi.org/10.3390/chemosensors13020068 - 15 Feb 2025
Cited by 9 | Viewed by 8502
Abstract
Microneedles (MNs) are miniature medical devices, presented as an array of micro-scale needles, each under 1 mm in height with sharp tips. MN technology is becoming a diagnostic platform associated with several qualities: no pain and no risk of infection, offering accuracy, comfort, [...] Read more.
Microneedles (MNs) are miniature medical devices, presented as an array of micro-scale needles, each under 1 mm in height with sharp tips. MN technology is becoming a diagnostic platform associated with several qualities: no pain and no risk of infection, offering accuracy, comfort, and usability. Monitoring biomarkers in interstitial fluid (ISF) in real time is crucial for tracking changes in metabolism and assisting in the early diagnosis of chronic illnesses. Some examples of MN sensors are summarized here: the real-time sensing of two metabolites (lactate and glucose or alcohol and glucose), the transdermal tracing of pH, Na+, K+, Ca2+, Li+, and Cl−, transdermal methotrexate (MTX) monitoring, the transdermal sensing of tyrosinase enzyme as a melanoma biomarker, the integration of CRISPR technology for nucleic acid analysis, and monitoring plant sap pH in the leaves of several plants. The challenges to be addressed to realize the transition to widespread One Health solutions are analyzed. Full article
(This article belongs to the Section Electrochemical Devices and Sensors)
►▼ Show Figures

Figure 1

23 pages, 7772 KB  
Review
Recent Advances in NIR-II Molecular Aggregates and Applications in the Biomedical Field
by Kun Wu, Ruowen Yang, Xuefang Song, Huangxian Ju and Ying Liu
Chemosensors 2025, 13(2), 67; https://doi.org/10.3390/chemosensors13020067 - 13 Feb 2025
Cited by 9 | Viewed by 4515
Abstract
Near-infrared (NIR) light is a promising tool for biomedical imaging and therapy, offering excellent tissue penetration, low scattering, and minimal biological fluorescence interference. An NIR-II optical range of 900–1880 nm with reduced background interference is particularly useful for disease diagnosis and treatment. Probes [...] Read more.
Near-infrared (NIR) light is a promising tool for biomedical imaging and therapy, offering excellent tissue penetration, low scattering, and minimal biological fluorescence interference. An NIR-II optical range of 900–1880 nm with reduced background interference is particularly useful for disease diagnosis and treatment. Probes based on organic molecules are gaining attention for their structural flexibility and stable performance. Organic molecular aggregates, such as J-aggregates, H-aggregates, and aggregation-induced emission (AIE)-aggregates, exhibit unique optical properties like tunable spectral shifts, improved photostability, and higher absorption and fluorescence quantum yields. This mini review briefly discusses the advancements in NIR-II optical imaging and therapy technologies, focusing on the classification, formation mechanisms, and applications of organic molecular aggregates in disease diagnosis and treatment, offering a theoretical foundation and practical guidance for future research. Full article
(This article belongs to the Special Issue Dedicated to Professor Huangxian Ju and Professor Xueji Zhang on the Occasion of Their 60th Birthday for Their Outstanding Contributions to the Field of Chemical/Bio Sensors)
►▼ Show Figures

Figure 1

20 pages, 7610 KB  
Article
Impact of ZnO Nanostructure Morphology on Electrochemical Sensing Performance for Lead Ion Detection in Real Water Samples
by Eriks Sledevskis, Marina Krasovska, Vjaceslavs Gerbreders, Irena Mihailova, Jans Keviss, Valdis Mizers and Andrejs Bulanovs
Chemosensors 2025, 13(2), 62; https://doi.org/10.3390/chemosensors13020062 - 9 Feb 2025
Cited by 14 | Viewed by 3290
Abstract
This study investigated the morphological dependence of ZnO nanostructures, specifically nanotube- and nanorod-based electrodes, on their electrochemical performance for the detection of lead ions (Pb2⁺) in aqueous solutions. The results demonstrate that ZnO nanotubes exhibit significantly enhanced sensitivity compared to nanorods [...] Read more.
This study investigated the morphological dependence of ZnO nanostructures, specifically nanotube- and nanorod-based electrodes, on their electrochemical performance for the detection of lead ions (Pb2⁺) in aqueous solutions. The results demonstrate that ZnO nanotubes exhibit significantly enhanced sensitivity compared to nanorods during CV measurements. During SWV measurements, the sensitivity (116.79 mA·mM−1) and a lower limit of detection of 0.0437 μM were determined. The hollow, high-aspect-ratio structure of nanotubes provides a larger active surface area and facilitates better ion accessibility, resulting in superior electron transfer efficiency and catalytic activity. These results underscore the critical role of morphology in optimizing ZnO-based sensors. Analysis of real water samples from various natural reservoirs revealed no detectable lead, while lead was identified exclusively in artificially prepared samples containing water exposed to lead hunting shot. Over a 30-day period, the sensor retained over 95% of its initial performance when stored under vacuum conditions, demonstrating minimal signal degradation. Under ambient conditions, stability loss was attributed to moisture adsorption on the porous nanostructure. The sensor also displayed outstanding reproducibility, with current response variations across multiple probes remaining within 4%. The cost-effective and simple fabrication process of ZnO nanostructures further highlights their potential for scalable production, environmental monitoring, and integration into portable sensing devices. Full article
(This article belongs to the Special Issue Electrochemical Sensors and Biosensors for Food, Environmental and Biomedical Analysis)
►▼ Show Figures

Figure 1

19 pages, 3520 KB  
Article
Electrochemical Detection of Diclofenac Using a Screen-Printed Electrode Modified with Graphene Oxide and Phenanthroline
by Ana-Raluca Măghinici, Alexandra-Virginia Bounegru and Constantin Apetrei
Chemosensors 2025, 13(2), 55; https://doi.org/10.3390/chemosensors13020055 - 7 Feb 2025
Cited by 15 | Viewed by 4010
Abstract
In recent years, interest in screen-printed electrodes (SPEs) has grown due to their wide range of applications. Diclofenac (DCF), a widely used non-steroidal anti-inflammatory drug, is a subject of interest in pharmaceutical research as well as environmental research, primarily due to its environmental [...] Read more.
In recent years, interest in screen-printed electrodes (SPEs) has grown due to their wide range of applications. Diclofenac (DCF), a widely used non-steroidal anti-inflammatory drug, is a subject of interest in pharmaceutical research as well as environmental research, primarily due to its environmental contamination and therapeutic applications. This study describes the development and characterization of an innovative screen-printed sensor based on graphene oxide (GO) and phenanthroline (PHEN) for the rapid and highly sensitive determination of diclofenac. The modified sensor was characterized by Fourier Transform Infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The electrochemical behavior of the screen-printed electrodes was assessed through cyclic voltammetry (CV) in phosphate buffer solution (PBS) and potassium ferrocyanide/potassium ferricyanide solution. The cyclic voltammograms of the electrodes modified with GO and PHEN revealed peaks in PBS related to redox processes of PHEN immobilized in the carbonaceous matrix. Additionally, the active surface area of the electrodes was found to be larger for the modified carbon screen-printed electrode with GO and PHEN, which also showed improved sensitivity to the detection of DCF. The limit of detection (1.53 nM) and the sensitivity of the novel sensor were promising, and these performance characteristics enabled the sensitive detection of DCF in different pharmaceutical products. The selectivity was confirmed to be appropriate based on recovery studies conducted with the pharmaceutical products, which produced values close to 100%. Full article
(This article belongs to the Special Issue Electrochemical Biosensors and Bioassays Based on Nanomaterials)
►▼ Show Figures

Figure 1

17 pages, 4649 KB  
Article
A Machine Learning Approach for Enhanced Glucose Prediction in Biosensors
by António Abreu, Daniela dos Santos Oliveira, Inês Vinagre, Dionisios Cavouras, Joaquim A. Alves, Ana I. Pereira, José Lima and Felismina T. C. Moreira
Chemosensors 2025, 13(2), 52; https://doi.org/10.3390/chemosensors13020052 - 4 Feb 2025
Cited by 8 | Viewed by 3958
Abstract
The detection of glucose is crucial for diagnosing diseases such as diabetes and enables timely medical intervention. In this study, a disposable enzymatic screen-printed electrode electrochemical biosensor enhanced with machine learning (ML) for quantifying glucose in serum is presented. The platinum working surface [...] Read more.
The detection of glucose is crucial for diagnosing diseases such as diabetes and enables timely medical intervention. In this study, a disposable enzymatic screen-printed electrode electrochemical biosensor enhanced with machine learning (ML) for quantifying glucose in serum is presented. The platinum working surface was modified by chemical adsorption with biographene (BGr) and glucose oxidase, and the enzyme was encapsulated in polydopamine (PDP) by electropolymerisation. Electrochemical characterisation and morphological analysis (scanning and transmission electron microscopy) confirmed the modifications. Calibration curves in Cormay serum (CS) and selectivity tests with chronoamperometry were used to evaluate the biosensor’s performance. Non-linear ML regression algorithms for modelling glucose concentration and calibration parameters were tested to find the best-fit model for accurate predictions. The biosensor with BGr and enzyme encapsulation showed excellent performance with a linear range of 0.75–40 mM, a correlation of 0.988, and a detection limit of 0.078 mM. Of the algorithms tested, the decision tree accurately predicted calibration parameters and achieved a coefficient of determination above 0.9 for most metrics. Multilayer perceptron models effectively predicted glucose concentration with a coefficient of determination of 0.828, demonstrating the synergy of biosensor technology and ML for reliable glucose detection. Full article
(This article belongs to the Special Issue Electrochemical Sensing in Medical Diagnosis)
►▼ Show Figures

Figure 1

21 pages, 5047 KB  
Article
Electrospun WO3/TiO2 Core–Shell Nanowires for Triethylamine Gas Sensing
by Wenhao Li, Bo Zhang, Xiangrui Dong, Qi Lu, Hao Shen, Yi Ni, Yuechen Liu and Haitao Song
Chemosensors 2025, 13(2), 45; https://doi.org/10.3390/chemosensors13020045 - 2 Feb 2025
Cited by 10 | Viewed by 2847
Abstract
In this work, WO3/TiO2 core–shell (C-S) nanowires (NWs) were successfully synthesized by the coaxial electrospinning method and subsequent high-temperature calcination treatment. After some microscopic structural characterizations, although the prepared WO3–TiO2 and TiO2–WO3 C-S NWs [...] Read more.
In this work, WO3/TiO2 core–shell (C-S) nanowires (NWs) were successfully synthesized by the coaxial electrospinning method and subsequent high-temperature calcination treatment. After some microscopic structural characterizations, although the prepared WO3–TiO2 and TiO2–WO3 C-S NWs displayed quite different surface morphologies, both of the shell coatings were uniform and their typical shell thicknesses were extremely close, with mean values of 22 and 20 nm, respectively. In gas sensing tests, WO3/TiO2 C-S NWs exhibited good selectivity towards triethylamine (TEA) without significant interfering gases. Compared with bare WO3 and TiO2 NWs, WO3/TiO2 C-S NWs showed better gas sensing performance. Specifically, the optimal operating temperature and response of TiO2–WO3 C-S NWs to 100 ppm TEA were 130 °C and 106, which were reduced by 70 °C and increased by 5.73 times compared to bare WO3, respectively. Obviously, the C-S nanostructures contributed to improving the gas sensing performance of materials towards TEA. Finally, some hypothetical sensing mechanisms were proposed, which were expected to have important reference significance for the design of target products applied to TEA sensing. Full article
(This article belongs to the Special Issue Recent Progress in Nano Material-Based Gas Sensors)
►▼ Show Figures

Figure 1

19 pages, 2712 KB  
Article
Implementing an Analytical Model to Elucidate the Impacts of Nanostructure Size and Topology of Morphologically Diverse Zinc Oxide on Gas Sensing
by Sanju Gupta and Haiyang Zou
Chemosensors 2025, 13(2), 38; https://doi.org/10.3390/chemosensors13020038 - 26 Jan 2025
Cited by 8 | Viewed by 4290
Abstract
The development of state-of-the-art gas sensors based on metal oxide semiconductors (MOS) to monitor hazardous and greenhouse gas (e.g., methane, CH4, and carbon dioxide, CO2) has been significantly advanced. Moreover, the morphological and topographical structures of MOSs have significantly [...] Read more.
The development of state-of-the-art gas sensors based on metal oxide semiconductors (MOS) to monitor hazardous and greenhouse gas (e.g., methane, CH4, and carbon dioxide, CO2) has been significantly advanced. Moreover, the morphological and topographical structures of MOSs have significantly influenced the gas sensors by means of surface catalytic activities. This work examines the impact of morphological and topological networked assembly of zinc oxide (ZnO) nanostructures, including microparticles and nanoparticles (0D), nanowires and nanorods (1D), nanodisks (2D), and hierarchical networks of tetrapods (3D). Gas sensors consisting of vertically aligned ZnO nanorods (ZnO–NR) and topologically interconnected tetrapods (T–ZnO) of varying diameter and arm thickness synthesized using aqueous phase deposition and flame transport method on interdigitated Pt electrodes are evaluated for methane detection. Smaller-diameter nanorods and tetrapod arms (nanowire-like), having higher surface-to-volume ratios with reasonable porosity, exhibit improved sensing behavior. Interestingly, when the nanorods’ diameter and interconnected tetrapod arm thickness were comparable to the width of the depletion layer, a significant increase in sensitivity (from 2 to 30) and reduction in response/recovery time (from 58 s to 5.9 s) resulted, ascribed to rapid desorption of analyte species. Additionally, nanoparticles surface-catalyzed with Pd (~50 nm) accelerated gas sensing and lowered operating temperature (from 200 °C to 50 °C) when combined with UV photoactivation. We modeled the experimental findings using a modified general formula for ZnO methane sensors derived from the catalytic chemical reaction between methane molecules and oxygen ions and considered the structural surface-to-volume ratios (S/V) and electronic depletion region width (Ld) applicable to other gas sensors (e.g., SnO2, TiO2, MoO3, and WO3). Finally, the effects of UV light excitation reducing detection temperature help to break through the bottleneck of ZnO-based materials as energy-saving chemiresistors and promote applications relevant to environmental and industrial harmful gas detection. Full article
(This article belongs to the Collection Recent Advances in Multifunctional Sensing Technology for Gas Analysis)
►▼ Show Figures

Figure 1

21 pages, 7403 KB  
Article
Low-Temperature, Highly Sensitive Ammonia Sensors Based on Nanostructured Copper Iodide Layers
by Sergey I. Petrushenko, Mateusz Fijalkowski, Kinga Adach, Denis Fedonenko, Yevhenii M. Shepotko, Sergei V. Dukarov, Volodymyr M. Sukhov, Alina L. Khrypunova and Natalja P. Klochko
Chemosensors 2025, 13(2), 29; https://doi.org/10.3390/chemosensors13020029 - 22 Jan 2025
Cited by 9 | Viewed by 2929
Abstract
Chemiresistive ammonia gas sensors with a low limit of detection of 0.15 ppm and moisture-independent characteristics based on p-type copper iodide (CuI) semiconductor films have been developed. CuI films were deposited on glass and polyethylene terephthalate (PET) substrates using a Successive Ionic [...] Read more.
Chemiresistive ammonia gas sensors with a low limit of detection of 0.15 ppm and moisture-independent characteristics based on p-type copper iodide (CuI) semiconductor films have been developed. CuI films were deposited on glass and polyethylene terephthalate (PET) substrates using a Successive Ionic Layer Adsorption and Reaction method to fabricate CuI/glass and CuI/PET gas sensors, respectively. They have a nanoscale morphology, an excess iodine and sulfur impurity content, a zinc blende γ-CuI crystal structure with a grain size of ~34 nm and an optical band gap of about 2.95 eV. The high selective sensitivity of both sensors to NH3 is explained by the formation of the [Cu(NH3)2]+ complex. At 5 °C, the responses to 3 ppm ammonia in air in terms of the relative resistance change were 24.5 for the CuI/glass gas sensor and 28 for the CuI/PET gas sensor, with short response times of 50 s to 210 s and recovery times of 10–70 s. The sensors have a fast response–recovery and their performance was well maintained after long-term stability testing for 45 days. After 1000 repeated bends of the flexible CuI/PET gas sensor in different directions, with bending angles up to 180° and curvature radii up to 0.25 cm, the response changes were only 3%. Full article
(This article belongs to the Special Issue Functional Nanomaterial-Based Gas Sensors and Humidity Sensors)
►▼ Show Figures

Figure 1

32 pages, 13426 KB  
Review
Non-Enzymatic Electrochemical Glucose Sensors Based on Metal Oxides and Sulfides: Recent Progress and Perspectives
by Haibing Zhu, Feng Shi, Maoying Peng, Ye Zhang, Sitian Long, Ruixin Liu, Juan Li and Zhanjun Yang
Chemosensors 2025, 13(1), 19; https://doi.org/10.3390/chemosensors13010019 - 16 Jan 2025
Cited by 33 | Viewed by 7951
Abstract
With the sudden advancement of glucose biosensors for monitoring blood glucose levels for the prevention and diagnosis of diabetes, non-enzymatic glucose sensors have aroused great interest owing to their sensitivity, stability, and economy. Recently, researchers have dedicated themselves to developing non-enzymatic electrochemical glucose [...] Read more.
With the sudden advancement of glucose biosensors for monitoring blood glucose levels for the prevention and diagnosis of diabetes, non-enzymatic glucose sensors have aroused great interest owing to their sensitivity, stability, and economy. Recently, researchers have dedicated themselves to developing non-enzymatic electrochemical glucose sensors for the rapid, convenient, and sensitive determination of glucose. However, it is desirable to explore economic and effective nanomaterials with a high non-enzymatic catalysis performance toward glucose to modify electrodes. Metal oxides (MOs) and metal sulfides (MSs) have attracted extensive interest among scholars owing to their excellent catalytic activity, good biocompatibility, low cost, simple synthesis process, and controllable morphology and structure. Nonetheless, the exploitation of MOs and MSs in non-enzymatic electrochemical glucose sensors still suffers from relatively low conductivity and biocompatibility. Therefore, it is of significance to integrate MOs and MSs with metal/carbon/conducive polymers to modify electrodes for compensating the aforementioned deficiency. This review introduces the recent developments in non-enzymatic electrochemical glucose sensors based on MOs and MSs, focusing on their preparation methods and how their structural composition influences sensing performance. Finally, this review discusses the prospects and challenges of non-enzymatic electrochemical glucose sensors. Full article
(This article belongs to the Special Issue Dedicated to Professor Huangxian Ju and Professor Xueji Zhang on the Occasion of Their 60th Birthday for Their Outstanding Contributions to the Field of Chemical/Bio Sensors)
►▼ Show Figures

Figure 1

35 pages, 4936 KB  
Review
Multi-Template Molecularly Imprinted Polymeric Electrochemical Biosensors
by Meltem Agar, Maisem Laabei, Hannah S. Leese and Pedro Estrela
Chemosensors 2025, 13(1), 11; https://doi.org/10.3390/chemosensors13010011 - 8 Jan 2025
Cited by 23 | Viewed by 7170
Abstract
Dual- or multi-template molecularly imprinted polymers have been an attractive research field for many years as they allow simultaneous detection of more than one target with high selectivity and sensitivity by creating template-specific recognition sites for multiple targets on the same functional monomer. [...] Read more.
Dual- or multi-template molecularly imprinted polymers have been an attractive research field for many years as they allow simultaneous detection of more than one target with high selectivity and sensitivity by creating template-specific recognition sites for multiple targets on the same functional monomer. Dual/multi-template molecular imprinting techniques have been applied to identify, extract, and detect many targets, from heavy metal ions to viruses, by different methods, such as high-performance liquid chromatography (HPLC), liquid chromatography–mass spectrometry (LC-MS), and piezoelectric, optical, and electrochemical methods. This article focuses on electrochemical sensors based on dual/multi-template molecularly imprinted polymers detecting a wide range of targets by electrochemical methods. Furthermore, this work highlights the use of these sensors for point-of-care applications, their commercialization and their integration with microfluidic systems. Full article
(This article belongs to the Special Issue Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2024)
►▼ Show Figures

Figure 1

9 pages, 1940 KB  
Communication
Electrochemical Detection of Microplastics in Water Using Ultramicroelectrodes
by Changhui Lee, Sangwon Han and Jun Hui Park
Chemosensors 2024, 12(12), 278; https://doi.org/10.3390/chemosensors12120278 - 23 Dec 2024
Cited by 17 | Viewed by 6069
Abstract
Herein, a method for detecting microplastics in water using single-entity electrochemistry is presented, with a focus on the interaction between microplastics in aqueous solution and the surface of an ultramicroelectrode (UME). Polystyrene and polypropylene, two commonly used plastics that were ground and dispersed [...] Read more.
Herein, a method for detecting microplastics in water using single-entity electrochemistry is presented, with a focus on the interaction between microplastics in aqueous solution and the surface of an ultramicroelectrode (UME). Polystyrene and polypropylene, two commonly used plastics that were ground and dispersed in aqueous solution, served as the detection target materials. The collisional contact of microplastics with the UME was transduced into a discernible signal. To detect microplastics in solution using an UME, redox species (e.g., ferrocyanide) were continuously oxidized at the electrode, and the resulting steady-state current was monitored. Collisional contact followed by adsorption of microplastics on the UME disturbed the diffusional flux of redox species, resulting in an immediate change in the steady-state current. Detection sensitivity was further enhanced by optimizing the electrolyte composition to induce a migration effect. COMSOL Multiphysics simulations were employed to analyze the magnitude of the current changes as a function of microplastic size. The size distribution obtained from the simulations closely matched measurements from dynamic light scattering (DLS). Full article
(This article belongs to the Section Electrochemical Devices and Sensors)
►▼ Show Figures

Figure 1

15 pages, 3476 KB  
Article
Flexible Humidity Sensor Based on Chemically Reduced Graphene Oxide
by Anna Maria Laera, Gennaro Cassano, Emiliano Burresi, Maria Lucia Protopapa and Michele Penza
Chemosensors 2024, 12(12), 245; https://doi.org/10.3390/chemosensors12120245 - 22 Nov 2024
Cited by 19 | Viewed by 3062
Abstract
The accurate measurement of moisture content in pure gases and in gas mixtures, such as air, has great relevance in many industrial processes. In the present study, graphene oxide reduced through a mild alkaline treatment was used as a humidity sensing material to [...] Read more.
The accurate measurement of moisture content in pure gases and in gas mixtures, such as air, has great relevance in many industrial processes. In the present study, graphene oxide reduced through a mild alkaline treatment was used as a humidity sensing material to fabricate a flexible chemiresistive device operating at room temperature. The active layer was deposited by solution casting on a substrate of bimatted polyester, previously coated with inkjet-printed interdigitated electrodes made of silver. Structural investigations were performed by means of X-ray diffraction, Raman spectroscopy, and FTIR spectroscopy, while the optical properties were investigated using UV-VIS absorption and photoluminescence excitation spectroscopy. With increasing relative hu-midity from 0 to 80%, the electrical resistance decreased from about 1.4 GΩ to 2.5 MΩ. The ex-traordinarily large range of resistance values highlights the ultrahigh humidity sensitivity of re-duced graphene oxide, which acquires a fair amount of electrical conductivity after physisorption of water molecules but results in a highly resistive material in dry air. The high sensitivity at room temperature, the response’s repeatability, the wide relative humidity range detected, and the fast response time are the main advantages of the proposed humidity sensor, while the presence of some hysteresis, mainly at low relative humidity, and the recovery time need further improve-ment. Finally, the sensing mechanisms are briefly discussed. Full article
(This article belongs to the Special Issue Functional Nanomaterial-Based Gas Sensors and Humidity Sensors)
►▼ Show Figures

Figure 1

12 pages, 2266 KB  
Article
A Nanodiamond-Based Electrochemical Sensor for the Determination of Paracetamol in Pharmaceutical Samples
by Déborah de Oliveira Lopes, Felipe Magalhães Marinho, Patricia Batista Deroco, Amanda Neumann, Jessica Rocha Camargo, Rafaela Cristina de Freitas, Lucas Ventosa Bertolim, Orlando Fatibello Filho, Bruno Campos Janegitz and Geiser Gabriel de Oliveira
Chemosensors 2024, 12(11), 243; https://doi.org/10.3390/chemosensors12110243 - 20 Nov 2024
Cited by 11 | Viewed by 3184
Abstract
This study presents an electrochemical sensor developed from a glassy carbon electrode modified with nanodiamond film (ND/GCE). This electrochemical response of the proposed sensor was improved, and it showed excellent analytical performance for the detection of paracetamol (PAR), which was attributed to the [...] Read more.
This study presents an electrochemical sensor developed from a glassy carbon electrode modified with nanodiamond film (ND/GCE). This electrochemical response of the proposed sensor was improved, and it showed excellent analytical performance for the detection of paracetamol (PAR), which was attributed to the high PAR charging capacity on the electrode surface and the excellent electrical conductivity of ND. Morphological and electrochemical characterizations of the sensor were performed via scanning electron microscopy (SEM) and cyclic voltammetry using a redox probe [Fe(CN)6]3−. The sensor was applied for the determination of PAR. Quantification was performed using square-wave voltammetry, and it showed a linear concentration range from 0.79 to 100 µmol L−1, with a limit of detection of 0.18 µmol L−1. The proposed sensor exhibited satisfactory repeatability and high sensitivity in the determination of the analyte of interest. The electrochemical sensor was also employed for the analysis of PAR in real samples, with recovery rates ranging between 96.4 and 98.7%. This sensor was successfully used for the determination of the drug in pharmaceutical samples. Full article
(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications, Volume II)
►▼ Show Figures

Graphical abstract

24 pages, 5048 KB  
Review
Humidity Sensing Using Polymers: A Critical Review of Current Technologies and Emerging Trends
by Jintian Qian, Ruiqin Tan, Mingxia Feng, Wenfeng Shen, Dawu Lv and Weijie Song
Chemosensors 2024, 12(11), 230; https://doi.org/10.3390/chemosensors12110230 - 2 Nov 2024
Cited by 59 | Viewed by 11956
Abstract
In the post-pandemic era, human demand for a healthy lifestyle and a smart society has surged, leading to vibrant growth in the field of flexible electronic sensor technology for health monitoring. Flexible polymer humidity sensors are not only capable of the real-time monitoring [...] Read more.
In the post-pandemic era, human demand for a healthy lifestyle and a smart society has surged, leading to vibrant growth in the field of flexible electronic sensor technology for health monitoring. Flexible polymer humidity sensors are not only capable of the real-time monitoring of human respiration and skin moisture information but also serve as a non-contact human–machine interaction method. In addition, the development of moist-electric generation technology is expected to break free from the traditional reliance of flexible electronic devices on power equipment, which is of significant importance for the miniaturization, reliability, and environmentally friendly development of flexible devices. Currently, flexible polymer humidity sensors are playing a significant role in the field of wearable electronic devices and thus have attracted considerable attention. This review begins by introducing the structural types and working principles of various humidity sensors, including the types of capacitive, impedance/resistive, frequency-based, fiber optic, and voltage-based sensors. It mainly focuses on the latest research advancements in flexible polymer humidity sensors, particularly in the modification of humidity-sensitive materials, sensor fabrication, and hygrosensitivity mechanisms. Studies on material composites including different types of polymers, polymers combined with porous nanostructured materials, polymers combined with metal oxides, and two-dimensional materials are reviewed, along with a comparative summary of the fabrication and performance mechanisms of related devices. This paper concludes with a discussion on the current challenges and opportunities faced by flexible polymer humidity sensors, providing new research perspectives for their future development. Full article
(This article belongs to the Special Issue Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2024)
►▼ Show Figures

Figure 1

11 pages, 488 KB  
Article
A Deep Learning Approach to Investigating Clandestine Laboratories Using a GC-QEPAS Sensor
by Giorgio Felizzato, Nicola Liberatore, Sandro Mengali, Roberto Viola, Vittorio Moriggia and Francesco Saverio Romolo
Chemosensors 2024, 12(8), 152; https://doi.org/10.3390/chemosensors12080152 - 5 Aug 2024
Cited by 11 | Viewed by 3812
Abstract
Illicit drug production in clandestine laboratories involves the use of large quantities of different chemicals that can be obtained for legitimate purposes. The identification of these chemicals, including reagents, catalyzers and solvents, is crucial for forensic investigations. From a legal point of view, [...] Read more.
Illicit drug production in clandestine laboratories involves the use of large quantities of different chemicals that can be obtained for legitimate purposes. The identification of these chemicals, including reagents, catalyzers and solvents, is crucial for forensic investigations. From a legal point of view, a drug precursor is a material that is specific and critical to the production of a finished chemical and that constitutes a significant portion of the final molecular structure of the drug. In this study, a gas chromatography quartz-enhanced photoacoustic spectroscopy (GC-QEPAS) sensor—in conjunction with a deep learning model—was evaluated for its effectiveness in the detection and identification of interesting compounds for the production of amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), phenylcyclohexyl piperidine (PCP), and cocaine. The GC-QEPAS sensor includes a gas sampler, a fast GC for separation, and a QEPAS detector, which excites molecules exiting the GC column using a quantum cascade laser to provide the infra-red (IR) spectrum. The on-site capability of the GC-QEPAS system offers significant advantages over the current instruments employed in this field, including rapid analysis, which is crucial in field operations. This allows law enforcement to quickly identify specimens of interest on site. The system’s performance was validated by taking into account the limit of detection, repeatability, and within-laboratory reproducibility. The results showed excellent repeatability and reproducibility for both the GC and QEPAS modules. The deep learning model, a multilayer perceptron neural network, was trained using IR spectra and retention times, achieving very high classification accuracy in the testing conditions. This study demonstrated the efficacy of the GC-QEPAS sensor combined with a deep learning model for the reliable identification of drug precursors, providing a robust tool for law enforcement during criminal investigations in clandestine laboratories. Full article
(This article belongs to the Special Issue Chemical Sensing and Analytical Methods for Forensic Applications)
►▼ Show Figures

Figure 1

16 pages, 1619 KB  
Article
Fast Monitoring of Quality and Adulteration of Blended Sunflower/Olive Oils Applying Near-Infrared Spectroscopy
by Magdalena Klinar, Maja Benković, Tamara Jurina, Ana Jurinjak Tušek, Davor Valinger, Sandra Maričić Tarandek, Anamaria Prskalo, Juraj Tonković and Jasenka Gajdoš Kljusurić
Chemosensors 2024, 12(8), 150; https://doi.org/10.3390/chemosensors12080150 - 2 Aug 2024
Cited by 18 | Viewed by 3127
Abstract
Food adulteration which is economically motivated (i.e., food fraud) is an incentive for the development and application of new and fast detection methods/instruments. An example of a fast method that is extremely environmentally friendly is near-infrared spectroscopy (NIRS). Therefore, the goal of this [...] Read more.
Food adulteration which is economically motivated (i.e., food fraud) is an incentive for the development and application of new and fast detection methods/instruments. An example of a fast method that is extremely environmentally friendly is near-infrared spectroscopy (NIRS). Therefore, the goal of this research was to examine the potential of its application in monitoring the adulteration of blended sunflower/olive oils and to compare two types of NIRS instruments, one of which is a portable micro-device, which could be used to assess the purity of olive oil anywhere and would be extremely useful to inspection services. Both NIR devices (benchtop and portable) enable absorbance monitoring in the wavelength range from 900 to 1700 nm. Extra virgin oils (EVOOs) and “ordinary” olive oils (OOs) from large and small producers were investigated, which were diluted with sunflower oil in proportions of 1–15%. However, with the appearance of different salad oils that have a defined share of EVOO stated on the label (usually 10%), the possibilities of the recognition and manipulation in these proportions were tested; therefore, EVOO was also added to sunflower oil in proportions of 1–15%. The composition of fatty acids, color parameters, and total dissolved substances and conductivity for pure and “adulterated” oils were monitored. Standard tools of multivariate analysis were applied, such as (i) analysis of main components for the qualitative classification of oil and (ii) partial regression using the least square method for quantitative prediction of the proportion of impurities and fatty acids. Qualitative models proved successful in classifying (100%) the investigated oils, regardless of whether the added thinner was olive or sunflower oil. Developed quantitative models relating measured parameters with the NIR scans, resulted in values of R2 ≥ 0.95 and was reliable (RPD > 8) for fatty acid composition prediction and for predicting the percentage of the added share of impurity oils, while color attributes were less successfully predicted with the portable NIR device (RPD in the range of 2–4.2). Although with the portable device, the prediction potentials remained at a qualitative level (e.g., color parameters), it is important to emphasize that both devices were tested not only with EVOO but also with OO and regardless of whether proportions of 1–15% sunflower oil were added to EVOO and OO or EVOO and OO in the same proportions to sunflower oil. Full article
(This article belongs to the Special Issue The Application of Surface-Enhanced Raman Spectroscopy (SERS) Platform)
►▼ Show Figures

Figure 1

25 pages, 3884 KB  
Review
Integrated Photonic Sensors for the Detection of Toxic Gasses—A Review
by Muhammad A. Butt and Ryszard Piramidowicz
Chemosensors 2024, 12(7), 143; https://doi.org/10.3390/chemosensors12070143 - 18 Jul 2024
Cited by 47 | Viewed by 8648
Abstract
Gas sensing is crucial for detecting hazardous gasses in industrial environments, ensuring safety and preventing accidents. Additionally, it plays a vital role in environmental monitoring and control, helping to mitigate pollution and protect public health. Integrated photonic gas sensors are important due to [...] Read more.
Gas sensing is crucial for detecting hazardous gasses in industrial environments, ensuring safety and preventing accidents. Additionally, it plays a vital role in environmental monitoring and control, helping to mitigate pollution and protect public health. Integrated photonic gas sensors are important due to their high sensitivity, rapid response time, and compact size, enabling precise recognition of gas concentrations in real-time. These sensors leverage photonic technologies, such as waveguides and resonators, to enhance performance over traditional gas sensors. Advancements in materials and fabrication techniques could further improve their efficiency, making them invaluable for environmental monitoring, industrial safety, and healthcare diagnostics. In this review, we delved into photonic gas sensors that operate based on the principles of evanescent field absorption (EFA) and wavelength interrogation methods. These advanced sensing mechanisms allow for highly sensitive and selective gas detection, leveraging the interplay of light with gas molecules to produce precise measurements. Full article
(This article belongs to the Special Issue Gas Sensors for Monitoring Environmental Changes, 2nd Edition)
►▼ Show Figures

Figure 1

15 pages, 4134 KB  
Article
Research on the Evaluation of Baijiu Flavor Quality Based on Intelligent Sensory Technology Combined with Machine Learning
by Aliya, Shi Liu, Danni Zhang, Yufa Cao, Jinyuan Sun, Shui Jiang and Yuan Liu
Chemosensors 2024, 12(7), 125; https://doi.org/10.3390/chemosensors12070125 - 3 Jul 2024
Cited by 26 | Viewed by 5083
Abstract
Baijiu, one of the world’s six major distilled spirits, has an extremely rich flavor profile, which increases the complexity of its flavor quality evaluation. This study employed an electronic nose (E-nose) and electronic tongue (E-tongue) to detect 42 types of strong-aroma Baijiu. Linear [...] Read more.
Baijiu, one of the world’s six major distilled spirits, has an extremely rich flavor profile, which increases the complexity of its flavor quality evaluation. This study employed an electronic nose (E-nose) and electronic tongue (E-tongue) to detect 42 types of strong-aroma Baijiu. Linear discriminant analysis (LDA) was performed based on the different production origins, alcohol content, and grades. Twelve trained Baijiu evaluators participated in the quantitative descriptive analysis (QDA) of the Baijiu samples. By integrating characteristic values from the intelligent sensory detection data and combining them with the human sensory evaluation results, machine learning was used to establish a multi-submodel-based flavor quality prediction model and classification model for Baijiu. The results showed that different Baijiu samples could be well distinguished, with a prediction model R2 of 0.9994 and classification model accuracy of 100%. This study provides support for the establishment of a flavor quality evaluation system for Baijiu. Full article
(This article belongs to the Special Issue Electrochemical Sensor Array for Food Detection and Human Perception)
►▼ Show Figures

Figure 1

32 pages, 3921 KB  
Review
Biosensors for Food Mycotoxin Determination: A Comparative and Critical Review
by Aurelia Magdalena Pisoschi, Florin Iordache, Loredana Stanca, Elena Mitranescu, Liliana Bader Stoica, Ovidiu Ionut Geicu, Liviu Bilteanu and Andreea Iren Serban
Chemosensors 2024, 12(6), 92; https://doi.org/10.3390/chemosensors12060092 - 30 May 2024
Cited by 20 | Viewed by 7062
Abstract
The need for performant analytical methodologies to assess mycotoxins is vital, given the negative health impact of these compounds. Biosensors are analytical devices that consist of a biological element for recognizing the analyte and a transducer, which translates the biorecognition event into a [...] Read more.
The need for performant analytical methodologies to assess mycotoxins is vital, given the negative health impact of these compounds. Biosensors are analytical devices that consist of a biological element for recognizing the analyte and a transducer, which translates the biorecognition event into a signal proportional to the analyte concentration. The biorecognition elements can be enzymes, antibodies, or DNA fragments. The modalities of detection can be optical, electrochemical, thermal, or mass-sensitive. These analytical tools represent viable alternatives to laborious, expensive traditional methods and are characterized by specificity given by the biorecognition element, sensitivity, fast response, portability, multi-modal detection, and the possibility of in situ application. The present paper focuses on a comprehensive view, enriched with a critical, comparative perspective on mycotoxin assay using biosensors. The use of different biorecognition elements and detection modes are discussed comparatively. Nanomaterials with optical and electrochemical features can be exploited in association with a variety of biorecognition elements. Analytical parameters are reviewed along with a broad range of applications. Full article
(This article belongs to the Special Issue Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2024)
►▼ Show Figures

Figure 1

18 pages, 3372 KB  
Review
The Developments on Lateral Flow Immunochromatographic Assay for Food Safety in Recent 10 Years: A Review
by Peng Wang, Jinyan Li, Lingling Guo, Jiaxun Li, Feng He, Haitao Zhang and Hai Chi
Chemosensors 2024, 12(6), 88; https://doi.org/10.3390/chemosensors12060088 - 24 May 2024
Cited by 29 | Viewed by 7673
Abstract
Food safety inspections are an essential aspect of food safety monitoring. Rapid, accurate, and low-cost food analysis can considerably increase the efficiency of food safety inspections. The lateral flow immunochromatographic assay (LFIA) technique has recently grown in popularity due to its ease of [...] Read more.
Food safety inspections are an essential aspect of food safety monitoring. Rapid, accurate, and low-cost food analysis can considerably increase the efficiency of food safety inspections. The lateral flow immunochromatographic assay (LFIA) technique has recently grown in popularity due to its ease of use and high efficiency. It is currently commonly utilized in food inspection. In this review, we briefly introduce the principle and classification of LFIA, critically discuss the recent application status of LFIA in food contaminantion detection, and finally propose that artificial intelligence and information technology will further advance the development of LFIA in the field of food safety monitoring. Full article
(This article belongs to the Special Issue Low-Cost Chemosensors for Applications in Environment, Health, Food, and Industry Process Control)
►▼ Show Figures

Figure 1

41 pages, 7651 KB  
Review
Conducting Polymers in Amperometric Sensors: A State of the Art over the Last 15 Years with a Focus on Polypyrrole-, Polythiophene-, and Poly(3,4-ethylenedioxythiophene)-Based Materials
by Maria I. Pilo, Gavino Sanna and Nadia Spano
Chemosensors 2024, 12(5), 81; https://doi.org/10.3390/chemosensors12050081 - 11 May 2024
Cited by 25 | Viewed by 4784
Abstract
Conducting polymers are used in a wide range of applications, especially in the design and development of electrochemical sensors. Their main advantage, in this context, is their ability to efficiently modify an electrode surface using the direct polymerization of a suitable monomer in [...] Read more.
Conducting polymers are used in a wide range of applications, especially in the design and development of electrochemical sensors. Their main advantage, in this context, is their ability to efficiently modify an electrode surface using the direct polymerization of a suitable monomer in an electrochemical cell, or by physical coating. Additionally, the conducting polymers can be mixed with further materials (metal nanoparticles, carbonaceous materials) to enhance conductivity and analytical features (linear range, limit of detection, sensitivity, and selectivity). Due to their characteristics, conducting polymer-based amperometric sensors are applied to the determination of different organic and inorganic analytes. A view of recent advances in this field focusing on pyrrole, thiophene, and 3,4-ethylenedioxythiophene as starting materials is reported. Full article
(This article belongs to the Special Issue Recent Advances in Electrode Materials for Electrochemical Sensing)
►▼ Show Figures

Figure 1

15 pages, 6985 KB  
Article
Study of the Gas Sensing Performance of Ni-Doped Perovskite-Structured LaFeO3 Nanospheres
by Fanli Meng, Zhenhua Yu, Renze Zhang, Hongliang Gao and Zhenyu Yuan
Chemosensors 2024, 12(4), 65; https://doi.org/10.3390/chemosensors12040065 - 16 Apr 2024
Cited by 21 | Viewed by 4619
Abstract
This study synthesizes Ni-doped perovskite-structured LaFeO3 composite materials via a one-step hydrothermal method, characterizes the morphology and structure of the materials, and tests their gas sensing performance. The test results show that compared to pure LaFeO3 material, the gas sensing performance [...] Read more.
This study synthesizes Ni-doped perovskite-structured LaFeO3 composite materials via a one-step hydrothermal method, characterizes the morphology and structure of the materials, and tests their gas sensing performance. The test results show that compared to pure LaFeO3 material, the gas sensing performance of Ni-doped LaFeO3 material is improved in all aspects. Specifically, LFO-Ni2% exhibits a response as high as 102 towards 100 ppm of triethylamine at 190 °C, along with better selectivity and stability. Furthermore, the gas sensing mechanism is investigated. On one hand, doping with an appropriate proportion of Ni can lead to the formation of more-complete and smaller-sized microsphere structures with pores. This is beneficial for the adsorption of oxygen from the air onto the material surface, as well as for the diffusion of the target gas to the surface of the material, thereby enhancing gas sensitivity performance. On the other hand, the doped Ni enters the interior of the LaFeO3 crystal, replacing some of the cations in LaFeO3, increasing the concentration of charge carriers in the material, and reducing the material’s resistance. The sample can adsorb more oxygen, promoting the reaction between adsorbed oxygen and the target gas, and thereby improving the gas sensitivity performance of the sample. Full article
(This article belongs to the Special Issue Functional Nanomaterial-Based Gas Sensors)
►▼ Show Figures

Figure 1

58 pages, 10512 KB  
Review
Electrochemical Sensors, Biosensors, and Optical Sensors for the Detection of Opioids and Their Analogs: Pharmaceutical, Clinical, and Forensic Applications
by Sayo O. Fakayode, Pamela Nicole Brady, Cidya Grant, Vivian Fernand Narcisse, Peter Rosado Flores, Catrena Higginbothan Lisse and David K. Bwambok
Chemosensors 2024, 12(4), 58; https://doi.org/10.3390/chemosensors12040058 - 8 Apr 2024
Cited by 34 | Viewed by 13775
Abstract
Pharmaceutical opioids are intravenously or orally administered analgesics. While they are effective in relieving chronic and acute pain, their narrow window of therapeutic use contributes to the high occurrence of abuse. The associated abuse of this family of drugs can be correlated to [...] Read more.
Pharmaceutical opioids are intravenously or orally administered analgesics. While they are effective in relieving chronic and acute pain, their narrow window of therapeutic use contributes to the high occurrence of abuse. The associated abuse of this family of drugs can be correlated to the increase in dependency, overdose, and death of users. The negative effects of opioids extend beyond the physical and psychological effects experienced by the user to their unregulated synthesis and sale, which contribute to socioeconomic challenges and are a biproduct of this global public health epidemic. From clinical to point-of-care applications, the detection and real-time monitoring of this family of drug is critical in the fight to decrease abuse and improve use in clinical settings. Chromatographic separations and chromatography–mass spectrometry are traditional methods of opioid analyses, but the high cost, long analysis time, and absence of portability highlight the need for the development of fast, in situ, point-of-care analysis, or of community drug monitoring services. This review highlights recent electrochemical and optical (FTIR, Raman, colorimetric, and fluorescent) advances and biosensors for pharmaceutical and illicit opioid analysis. Specifically, an emphasis is placed on the detection of opioids and their metabolites in biological samples and in vitro cellular assays for clinical diagnosis and forensic applications. The challenges and prospects of the role of electrochemical sensors, biosensors, and optical sensors for opioid analysis in promoting clinical diagnosis, forensic study, point-of-care, and community drug monitoring services to reduce harm are also provided. Full article
(This article belongs to the Special Issue Biological and Chemical Sensors Applied in Biopharmaceuticals)
►▼ Show Figures

Figure 1

17 pages, 5573 KB  
Article
Enhanced Gas Sensing Performance of CuO-ZnO Composite Nanostructures for Low-Concentration NO2 Detection
by Hakimeh Pakdel, Matteo Borsi, Massimo Ponzoni and Elisabetta Comini
Chemosensors 2024, 12(4), 54; https://doi.org/10.3390/chemosensors12040054 - 5 Apr 2024
Cited by 23 | Viewed by 5165
Abstract
The detection of nitrogen dioxide (NO2) is essential for safeguarding human health and addressing environmental sustainability. That is why, in the last decades, gas sensors have been developed to detect NO2 to overcome these hazards. This study explores the use [...] Read more.
The detection of nitrogen dioxide (NO2) is essential for safeguarding human health and addressing environmental sustainability. That is why, in the last decades, gas sensors have been developed to detect NO2 to overcome these hazards. This study explores the use of a novel CuO-ZnO composite synthesized through a polyol and sol–gel technique to enhance gas sensing performance. The CuO-ZnO composite offers the advantage of a synergic combination of its properties, leading to improved sensitivity, selectivity, and low detection limit. The innovative polyol technique employed in this research enables the controlled synthesis of hierarchical CuO and porous ZnO structures. The composite formation is achieved using the sol–gel method, resulting in CuO-ZnO composites with different ratios. The structural, morphological, and optical properties of the materials have been characterized using FESEM, X-ray diffraction, and UV-vis spectroscopy. Gas sensing experiments demonstrate enhanced performance, particularly in sensitivity and selectivity for NO2, even at low concentrations. The composites also exhibit improved baseline stability compared to pristine CuO and ZnO. This study explains the influence of humidity on gas sensing properties by examining interactions between water molecules and sensor surfaces. Notably, the developed CuO-ZnO composite displays excellent selectivity towards NO2, attributed to favorable bonding characteristics and acid-base properties. Overall, this research contributes to advancing gas sensor technology, providing a promising potential for sensitive and selective NO2 detection, thereby addressing critical needs for human health and environmental protection. Full article
(This article belongs to the Special Issue 10th Anniversary of Chemosensors—Recent Advances in Chemical Sensing Based on Nanomaterials)
►▼ Show Figures

Figure 1

17 pages, 4992 KB  
Article
Potentiometric Phosphate Ion Sensor Based on Electrochemically Modified All-Solid-State Copper Electrode for Phosphate Ions’ Detection in Real Water
by Yang He, Chenhua Han, Hao Du, Ying Ye and Chunhui Tao
Chemosensors 2024, 12(4), 53; https://doi.org/10.3390/chemosensors12040053 - 1 Apr 2024
Cited by 18 | Viewed by 6459
Abstract
The importance of phosphates has sparked researchers’ considerable interest in the electrochemical detection of phosphates within aqueous solutions in recent years. In this study, we present a novel all-solid-state phosphate ion-selective electrode (ISE) that integrates copper, copper nanoparticles, and copper phosphate. By modifying [...] Read more.
The importance of phosphates has sparked researchers’ considerable interest in the electrochemical detection of phosphates within aqueous solutions in recent years. In this study, we present a novel all-solid-state phosphate ion-selective electrode (ISE) that integrates copper, copper nanoparticles, and copper phosphate. By modifying the copper substrate of the electrode with a copper nanoparticle film and creating a lamellar copper phosphate film through electrochemical treatment, we significantly enhanced the electrode’s electron transfer efficiency. This microstructure with large specific surface area markedly improved the electrode’s responsiveness to the targeted ions by accelerating the achievement of chemical equilibrium on the electrode surface, thereby boosting its sensitivity and stability. The newly developed electrode was capable of detecting phosphate ions in solutions with a pH range from 6 to 11 and performed optimally in neutral solutions at pH 7, following Nernst principle, with a detection limit of 1 × 10−6 M. The electrode exhibited a short response time of less than 10 s with significant reproducibility, stability, longevity—maintaining functionality for more than two months. It also displayed good selectivity as the electrochemical equilibrium was not influenced by up to 1 mM of potential competing species like HCO3−, NO3−, Cl− and SO42−. We compared the detection results of current phosphate ion sensor and conventional determination methods for phosphate content in natural lake and aquaculture water samples, with a detection discrepancy of about 10% (RSD). Considering all feasible performance characteristics combined with its low cost, simple manufacture and portability, the sensor provides a new possibility for rapid, reliable, and long-term real-time in situ detection of phosphates. Full article
(This article belongs to the Special Issue Chemical Sensors and Analytical Methods for Environmental Monitoring)
►▼ Show Figures

Graphical abstract

10 pages, 3624 KB  
Communication
Pd-Decorated ZnO Hexagonal Microdiscs for NH3 Sensor
by Yi Li, Boyu Zhang, Juan Li, Zaihua Duan, Yajie Yang, Zhen Yuan, Yadong Jiang and Huiling Tai
Chemosensors 2024, 12(3), 43; https://doi.org/10.3390/chemosensors12030043 - 5 Mar 2024
Cited by 74 | Viewed by 5384
Abstract
The NH3 sensor is of great significance in preventing NH3 leakage and ensuring life safety. In this work, the Pd-decorated ZnO hexagonal microdiscs are synthesized using hydrothermal and annealing processes, and the gas sensor is fabricated based on Pd-decorated ZnO hexagonal [...] Read more.
The NH3 sensor is of great significance in preventing NH3 leakage and ensuring life safety. In this work, the Pd-decorated ZnO hexagonal microdiscs are synthesized using hydrothermal and annealing processes, and the gas sensor is fabricated based on Pd-decorated ZnO hexagonal microdiscs. The gas-sensing test results show that the Pd-ZnO gas sensor has a good response to NH3 gas. Specifically, it has a good linear response within 0.5–50 ppm NH3 at the optimal operating temperature of 230 °C. In addition, the Pd-ZnO gas sensor exhibits good repeatability, short response time (23.2 s) and good humidity resistance (10–90% relative humidity). This work provides a useful reference for developing an NH3 sensor. Full article
(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)
►▼ Show Figures

Figure 1

29 pages, 2720 KB  
Review
Metal Oxide-Based Sensors for Ecological Monitoring: Progress and Perspectives
by Mykhail Tereshkov, Tetiana Dontsova, Bilge Saruhan and Svitlana Krüger
Chemosensors 2024, 12(3), 42; https://doi.org/10.3390/chemosensors12030042 - 5 Mar 2024
Cited by 46 | Viewed by 7327
Abstract
This paper aims to provide a large coverage of recent developments regarding environmental monitoring using metal oxide-based sensors. Particular attention is given to the detection of gases such as H2, COx, SOx, NOx, and CH [...] Read more.
This paper aims to provide a large coverage of recent developments regarding environmental monitoring using metal oxide-based sensors. Particular attention is given to the detection of gases such as H2, COx, SOx, NOx, and CH4. The developments and analyses of the design of sensors and types of metal oxide sensing materials are emphasized. The sensing mechanisms and peculiarities of metal oxides used in chemoresistive sensors are provided. The main parameters that affect the sensitivity and selectivity of metal oxide sensors are indicated and their significance to the sensor signal is analyzed. Modern data processing algorithms, employed to optimize the measurement process and processing of the sensor signal, are considered. The existing sensor arrays/e-nose systems for environmental monitoring are summarized, and future prospects and challenges encountered with metal oxide-based sensor arrays are highlighted. Full article
(This article belongs to the Special Issue Innovative Nanomaterials-Based Chemosensor Devices for Air Quality Monitoring)
►▼ Show Figures

Figure 1

15 pages, 4097 KB  
Article
Selective Colorimetric Detection of Pb(II) Ions by Using Green Synthesized Gold Nanoparticles with Orange Peel Extract
by Marco Zannotti, Sara Piras, Lorenzo Remia, Diego Appignanesi and Rita Giovannetti
Chemosensors 2024, 12(3), 33; https://doi.org/10.3390/chemosensors12030033 - 24 Feb 2024
Cited by 27 | Viewed by 5570
Abstract
Gold nanoparticles (AuNPs) were prepared by using a green approach that employed orange (citrus sinensis) peel water extract (OPE) as a reducing agent. In this case, the organic compounds present in orange peel were able to reduce Au(III) to Au(0) and, at the [...] Read more.
Gold nanoparticles (AuNPs) were prepared by using a green approach that employed orange (citrus sinensis) peel water extract (OPE) as a reducing agent. In this case, the organic compounds present in orange peel were able to reduce Au(III) to Au(0) and, at the same time, to act as a capping agent, functionalizing the surface of the AuNPs, stabilizing them in a water solution. This “green” approach valorizes orange peel waste as a resourceful material and makes the synthetic process of AuNPs more environmentally sustainable, safe, and economically feasible than the traditional methods. The obtained gold nanoparticles (AuNPs@OPE) were characterized by FT–IR, DLS, SEM analysis, and UV–Vis spectroscopy; the latter showed a characteristic surface plasmon resonance (SPR) band at 530 nm, typical of spherical gold nanoparticles. The AuNPs@OPE were then tested as colorimetric sensors for heavy metals in water, showing an affinity and selectivity toward Pb2+. In fact, in the presence of Pb2+, the added cation favors the aggregation process, and, in this case, nanoparticles form clusters due to the interactions between Pb2+ and the carboxyl/hydroxyl groups on the surface of the AuNPs@OPE, increasing the size of the nanostructure. This process is accompanied by a change in color of the AuNPs@OPE from pink to violet, with a formation of a second, new SPR band, at a higher wavelength, relative to the aggregate formation. The colorimetric assay was tested at different times with the addition of Pb2+ ions showing different LOD values of 13.31 µM and 0.05 µM after 15 min and 90 min, respectively. The proposed colorimetric assay was also tested for analyzing Pb2+ in drinking water samples demonstrating the reliability to use AuNPs@OPE with real samples. Full article
(This article belongs to the Section Analytical Methods, Instrumentation and Miniaturization)
►▼ Show Figures

Figure 1

29 pages, 7041 KB  
Article
Combination of Machine Learning and RGB Sensors to Quantify and Classify Water Turbidity
by Lorena Parra, Ali Ahmad, Sandra Sendra, Jaime Lloret and Pascal Lorenz
Chemosensors 2024, 12(3), 34; https://doi.org/10.3390/chemosensors12030034 - 24 Feb 2024
Cited by 40 | Viewed by 5841
Abstract
Turbidity is one of the crucial parameters of water quality. Even though many commercial devices, low-cost sensors, and remote sensing data can efficiently quantify turbidity, they are not valid tools for the classification it. In this paper, we design, calibrate, and test a [...] Read more.
Turbidity is one of the crucial parameters of water quality. Even though many commercial devices, low-cost sensors, and remote sensing data can efficiently quantify turbidity, they are not valid tools for the classification it. In this paper, we design, calibrate, and test a novel optical low-cost sensor for turbidity quantification and classification. The sensor is based on an RGB light source and a light detector. The analyzed samples are characterized by turbidity values from 0.02 to 60 NTUs, and have four different sources. These samples were generated to represent natural turbidity sources and leaves in the marine areas close to agricultural lands. The data are gathered using 64 different combinations of light, generating complex matrix data. Machine learning models are compared to analyze this data, including training, validation, and test datasets. Moreover, different alternatives for data preprocessing and feature selection are assessed. Concerning the quantification of turbidity, the best results were obtained using averaged data and principal components analyses in conjunction with exponential gaussian process regression, achieving an R2 of 0.979. Regarding the classification of the turbidity, an accuracy of 91.23% is obtained with the fine K-Nearest-Neighbor classifier. The cases in which data were misclassified are characterized by turbidity values lower than 5 NTUs. The obtained results represent an improvement over the current solutions in terms of turbidity quantification and a completely novel approach to turbidity classification. Full article
(This article belongs to the Section Optical Chemical Sensors)
►▼ Show Figures

Figure 1

16 pages, 1570 KB  
Article
Easy-to-Use Chemiluminescent-Based Assay for a Rapid and Low-Cost Evaluation of the Antioxidant Activity of Cosmetic Products
by Seyedeh Rojin Shariati Pour, Donato Calabria, Augusto Nascetti, Domenico Caputo, Giampiero De Cesare, Massimo Guardigli, Martina Zangheri and Mara Mirasoli
Chemosensors 2024, 12(2), 25; https://doi.org/10.3390/chemosensors12020025 - 9 Feb 2024
Cited by 5 | Viewed by 4270
Abstract
New cosmetic formulations are continuously requested by the market and the ingredients are constantly evolving. Recently the use of antioxidants has gained success and, in this context, analytical methods able to quickly and easily assess the antioxidant activity of cosmetics would make it [...] Read more.
New cosmetic formulations are continuously requested by the market and the ingredients are constantly evolving. Recently the use of antioxidants has gained success and, in this context, analytical methods able to quickly and easily assess the antioxidant activity of cosmetics would make it possible to carry out analyses on new formulations even within the manufacturing process without the need for specialized laboratories and personnel, thus evaluating directly on-site the effectiveness and the shelf life of products. In this work, a chemiluminescent inhibition assay was developed for determining the total antioxidant activity in cosmetic products. The method was based on the luminol/enhancers/hydrogen peroxide/horseradish peroxidase chemiluminescent system, which generates light signals measurable through simple and compact instrumentation. The formation of the chemiluminescent signal is inhibited by the presence of antioxidant substances while it is restored once all the antioxidant molecules have been oxidized. The time of appearance of the light signal is related to the total antioxidant activity. The assay was carried out exploiting an integrated device comprising a microwell plate coupled with an array of amorphous silicon hydrogenated photosensors enclosed in a mini-dark box. The method was optimized in terms of concentrations and volumes of the required reagents and sample pre-treatment. A calibration curve was generated taking as a reference the antioxidant activity of ascorbic acid obtaining a detection limit of 10 µM. The developed method was applied to cosmetic products currently on the market as well as on spiked samples in order to evaluate the performance of the methods in terms of sensitivity, accuracy, and reproducibility. Full article
(This article belongs to the Special Issue Chemiluminescent and Bioluminescent Sensors)
►▼ Show Figures

Graphical abstract

18 pages, 6854 KB  
Review
A Review on Metal Oxide Semiconductor-Based Chemo-Resistive Ethylene Sensors for Agricultural Applications
by Kongcan Hu, Yahan Cai, Ziru Wang, Zhengwei Zhang, Jieyu Xian and Cheng Zhang
Chemosensors 2024, 12(1), 13; https://doi.org/10.3390/chemosensors12010013 - 12 Jan 2024
Cited by 26 | Viewed by 6174
Abstract
Ethylene, an important phytohormone, significantly influences plant growth and the ripeness of fruits and vegetables. During the transportation and storage of agricultural products, excessive ethylene can lead to economic losses due to rapid deterioration. Metal oxide semiconductor (MOS)-based chemo-resistive sensors are a promising [...] Read more.
Ethylene, an important phytohormone, significantly influences plant growth and the ripeness of fruits and vegetables. During the transportation and storage of agricultural products, excessive ethylene can lead to economic losses due to rapid deterioration. Metal oxide semiconductor (MOS)-based chemo-resistive sensors are a promising technology for the detection of ethylene due to their low cost, high sensitivity, portability, etc. This review comprehensively summarizes the materials, fabrications, agricultural applications, and sensing mechanisms of these sensors. Moreover, the current challenges are highlighted and the potential solutions are proposed. Full article
(This article belongs to the Special Issue Low-Cost Chemo/Bio-Sensors Based on Nanomaterials)
►▼ Show Figures

Figure 1

30 pages, 9014 KB  
Article
Prostate Cancer Detection in Colombian Patients through E-Senses Devices in Exhaled Breath and Urine Samples
by Cristhian Manuel Durán Acevedo, Jeniffer Katerine Carrillo Gómez, Carlos Alberto Cuastumal Vasquez and José Ramos
Chemosensors 2024, 12(1), 11; https://doi.org/10.3390/chemosensors12010011 - 5 Jan 2024
Cited by 14 | Viewed by 4891
Abstract
This work consists of a study to detect prostate cancer using E-senses devices based on electronic tongue and electronic nose systems. Therefore, two groups of confirmed prostate cancer and control patients were invited to participate through urine and exhaled breath samples, where the [...] Read more.
This work consists of a study to detect prostate cancer using E-senses devices based on electronic tongue and electronic nose systems. Therefore, two groups of confirmed prostate cancer and control patients were invited to participate through urine and exhaled breath samples, where the control patients group was categorized as Benign Prostatic Hyperplasia, Prostatitis, and Healthy patients. Afterward, the samples were subsequently classified using Pattern Recognition and machine learning methods, where the results were compared through clinical history, obtaining a 92.9% success rate in the PCa and control samples’ classification accuracy by using eTongue and a 100% success rate of classification using eNose. Full article
(This article belongs to the Special Issue Principles and Recent Advances in Electronic Nose and Electronic Tongue)
►▼ Show Figures

Figure 1

13 pages, 3139 KB  
Article
Nanorods Assembled Hierarchical Bi2S3 for Highly Sensitive Detection of Trace NO2 at Room Temperature
by Yongchao Yang, Chengli Liu, You Wang and Juanyuan Hao
Chemosensors 2024, 12(1), 8; https://doi.org/10.3390/chemosensors12010008 - 4 Jan 2024
Cited by 28 | Viewed by 4070
Abstract
The bismuth sulfide nanostructure has become a promising gas sensing material thanks to its exceptional intrinsic properties. However, pristine Bi2S3 as a room-temperature sensing material cannot achieve the highly sensitive detection of ppb-level NO2 gas. Herein, 1D nanorods with [...] Read more.
The bismuth sulfide nanostructure has become a promising gas sensing material thanks to its exceptional intrinsic properties. However, pristine Bi2S3 as a room-temperature sensing material cannot achieve the highly sensitive detection of ppb-level NO2 gas. Herein, 1D nanorods with self-assembled hierarchical Bi2S3 nanostructures were obtained via a simple hydrothermal process. The as-prepared hierarchical Bi2S3 nanostructures exhibited outstanding NO2 sensing behaviors, such as a high response value (Rg/Ra = 5.8) and a short response/recovery time (τ90 = 28/116 s) upon exposure to 1 ppm NO2. The limit of detection of hierarchical Bi2S3 was down to 50 ppb. Meanwhile, the sensor exhibited excellent selectivity and humidity tolerance. The improved NO2 sensing properties were associated with the self-assembled hierarchical nanostructures, which provided a rich sensing active surface and accelerated the diffusion and adsorption/desorption processes between NO2 molecules and Bi2S3 materials. Additionally, the sensing response of hierarchical Bi2S3 nanostructures is much higher at 100% N2 atmosphere, which is different from the chemisorption oxygen model. Full article
(This article belongs to the Special Issue Functional Nanomaterial-Based Gas Sensors)
►▼ Show Figures

Figure 1

29 pages, 3233 KB  
Review
Electrochemical vs. Optical Biosensors for Point-of-Care Applications: A Critical Review
by Seyedeh Rojin Shariati Pour, Donato Calabria, Afsaneh Emamiamin, Elisa Lazzarini, Andrea Pace, Massimo Guardigli, Martina Zangheri and Mara Mirasoli
Chemosensors 2023, 11(10), 546; https://doi.org/10.3390/chemosensors11100546 - 21 Oct 2023
Cited by 80 | Viewed by 11785
Abstract
Analytical chemistry applied to medical and diagnostic analysis has recently focused on the development of cost-effective biosensors able to monitor the health status or to assess the level of specific biomarkers that can be indicative of several diseases. The improvement of technologies relating [...] Read more.
Analytical chemistry applied to medical and diagnostic analysis has recently focused on the development of cost-effective biosensors able to monitor the health status or to assess the level of specific biomarkers that can be indicative of several diseases. The improvement of technologies relating to the possibility of the non-invasive sampling of biological fluids, as well as sensors for the detection of analytical signals and the computational capabilities of the systems routinely employed in everyday life (e.g., smartphones, computers, etc.), makes the complete integration of self-standing analytical devices more accessible. This review aims to discuss the biosensors that have been proposed in the last five years focusing on two principal detecting approaches, optical and electrochemical, which have been employed for quantifying different kinds of target analytes reaching detection limits below the clinical sample levels required. These detection principles applied to point-of-care (POC) devices have been extensively reported in literature, and even the limited examples found on the market are based on these strategies. This work will show the latest innovations considering the integration of optical and electrochemical detection with the most commonly reported analytical platforms for POC applications such as paper-based or wearable and implantable devices. Full article
(This article belongs to the Collection Electrochemical Biosensors for Medical Diagnosis)
►▼ Show Figures

Figure 1

15 pages, 6254 KB  
Article
Signal Amplification for Detection of Nilutamide in Three-Dimensional Electrochemical Sensor Using Copper Metal–Organic Framework Decorated Carbon Nanofibers
by Elaiyappillai Elanthamilan and Sea-Fue Wang
Chemosensors 2023, 11(10), 544; https://doi.org/10.3390/chemosensors11100544 - 20 Oct 2023
Cited by 28 | Viewed by 3491
Abstract
The extensive use of antibiotics has rapidly spread antibiotic resistance, which poses significant health risks to humans. Unfortunately, despite this pressing issue, there is still a lack of a reliable on-site detection method for the residues of antibiotics, such as nilutamide (Nlu). Consequently, [...] Read more.
The extensive use of antibiotics has rapidly spread antibiotic resistance, which poses significant health risks to humans. Unfortunately, despite this pressing issue, there is still a lack of a reliable on-site detection method for the residues of antibiotics, such as nilutamide (Nlu). Consequently, there is an urgent need to develop and perfect such a detection method to effectively monitor and control antibiotic residues. In this study, the hydrothermal development of copper-metal-organic framework (Cu-MOF) polyhedrons on the functionalized carbon nanofiber (f-CNF) matrix allowed for the detection of Nlu in biological liquids via a sensitive amperometry technique. Further electrochemical detection of Nlu took place with the cyclic voltammetry (CV) technique Cu-MOF/f-CNF. Analytical and spectroscopic approaches were used to confirm the successful synthesis of Cu-MOF/f-CNF. The prepared material was decorated on the surface of GCE and performed as an electrochemical Nlu sensor, with a broad linear range of 0.01 to 141.4 μM and 2 nM as a lower limit of detection. In addition, the composites had a large surface area and many dedicated sites, which improved electrocatalysis. In practical applications, Cu-MOF/f-CNF/GCE provides a novel strategy for improving electrochemical activity by measuring Nlu concentrations in biological samples. Full article
(This article belongs to the Special Issue Electrochemical Sensors and Their Applications: A Theme Issue in Honor of Professor Richard G. Compton)
►▼ Show Figures

Figure 1

16 pages, 6911 KB  
Article
Electro-Optical Nose for Indoor Air Quality Monitoring
by Víctor González, Félix Meléndez, Patricia Arroyo, Javier Godoy, Fernando Díaz, José Ignacio Suárez and Jesús Lozano
Chemosensors 2023, 11(10), 535; https://doi.org/10.3390/chemosensors11100535 - 11 Oct 2023
Cited by 11 | Viewed by 4591
Abstract
Nowadays, indoor air pollution is a major problem that affects human health. For that reason, measuring indoor air quality has an increasing interest. Electronic noses are low-cost instruments (compared with reference methods) capable of measuring air components and pollutants at different concentrations. In [...] Read more.
Nowadays, indoor air pollution is a major problem that affects human health. For that reason, measuring indoor air quality has an increasing interest. Electronic noses are low-cost instruments (compared with reference methods) capable of measuring air components and pollutants at different concentrations. In this paper, an electro-optical nose (electronic nose that includes optical sensors) with non-dispersive infrared sensors and metal oxide semiconductor sensors is used to measure gases that affect indoor air quality. To validate the developed prototype, different gas mixtures (CH4 and CO2) with variable concentrations and humidity values are generated to confirm the discrimination capabilities of the device. Principal Component Analysis (PCA) was used for dimensionality reduction purposes to show the measurements in a plot. Partial Least Squares Regression (PLS) was also performed to calculate the predictive capabilities of the device. PCA results using all the measurements from all the sensors obtained PC1 = 47% and PC2 = 10%; results are improved using only the relevant information of the sensors obtaining PC1 = 79% and PC2 = 9%. PLS results with CH4 using only MOX sensors received an RMSE = 118.8. When using NDIR and MOX sensors, RMSE is reduced to 19.868; this tendency is also observed in CO2 (RMSE = 116.35 with MOX and RMSE = 20.548 with MOX and NDIR). The results confirm that the designed electro-optical nose can detect different gas concentrations and discriminate between different mixtures of gases; also, a better correlation and dispersion is achieved. The addition of NDIR sensors gives better results in measuring specific gases, discrimination, and concentration prediction capabilities in comparison to electronic noses with metal oxide gas sensors. Full article
(This article belongs to the Collection Recent Advances in Multifunctional Sensing Technology for Gas Analysis)
►▼ Show Figures

Figure 1

12 pages, 2868 KB  
Communication
Detection of a Nerve Agent Simulant by a Fluorescent Sensor Array
by Rossella Santonocito, Mario Spina, Roberta Puglisi, Andrea Pappalardo, Nunzio Tuccitto and Giuseppe Trusso Sfrazzetto
Chemosensors 2023, 11(9), 503; https://doi.org/10.3390/chemosensors11090503 - 15 Sep 2023
Cited by 21 | Viewed by 4731
Abstract
Detection of nerve agents (NAs) gas in the environment through portable devices to protect people in case of emergencies still remains a challenge for scientists involved in this research field. Current detection strategies require the use of cumbersome, expensive equipment that is only [...] Read more.
Detection of nerve agents (NAs) gas in the environment through portable devices to protect people in case of emergencies still remains a challenge for scientists involved in this research field. Current detection strategies require the use of cumbersome, expensive equipment that is only accessible to specialized personnel. By contrast, emerging optical detection is one of the most promising strategies for the development of reliable, easy readout devices. However, the selectivity of the existing optical sensors needs to be improved. To overcome the lack of selectivity, the innovative strategy of the optical arrays is under evaluation due to the specific response, the ease of preparation, the portability of the equipment, and the possibility to use affordable detectors, such as smartphones, that are easily accessible to non-specialized operators. In this work, the first optical-based sensor array for the selective detection of gaseous dimethylmethylphosphonate (DMMP), a NAs simulant, is reported, employing a simple smartphone as a detector and obtaining remarkably efficient and selective detection. Full article
(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)
►▼ Show Figures

Graphical abstract

36 pages, 4557 KB  
Review
Smartphone-Based Portable Bio-Chemical Sensors: Exploring Recent Advancements
by The Huy Bui, Balamurugan Thangavel, Mirkomil Sharipov, Kuangcai Chen and Joong Ho Shin
Chemosensors 2023, 11(9), 468; https://doi.org/10.3390/chemosensors11090468 - 22 Aug 2023
Cited by 76 | Viewed by 13963
Abstract
Traditionally, analytical chemistry and diagnosis relied on wet laboratories and skilled professionals utilizing sophisticated instruments for sample handling and analysis. However, with the development of novel materials and sensing techniques, there has been a significant shift towards the use of standalone sensors, allowing [...] Read more.
Traditionally, analytical chemistry and diagnosis relied on wet laboratories and skilled professionals utilizing sophisticated instruments for sample handling and analysis. However, with the development of novel materials and sensing techniques, there has been a significant shift towards the use of standalone sensors, allowing tests to be conducted on-site or even in real time, leading to cost- and time-efficiency. With their widespread adoption globally, smartphones have emerged as an ideal platform for such sensors, boasting extensive sensor capabilities, advanced processing power, and communication functionalities. Smartphone-based assays make use of optical and electrochemical sensors, utilizing built-in cameras, ambient light sensors, and other features for optical sensing, while the micro-USB port, Bluetooth, and wireless connection facilitate data transmission and analog voltage application for electrochemical sensing. Previous overview papers have explored smartphone-based sensing in specific domains; this review provides a comprehensive examination of recent advancements in smartphone-based sensors, encompassing both optical and electrochemical sensing methods. The review provides the fundamental principles of these sensors and their implementation using smartphones, showcases recent applications, and presents innovative designs that take advantage of the inherent functionalities and sensor capabilities of smartphones. The review concludes by offering an outlook on the prospects of smartphone-based sensing and includes a reflective section emphasizing the potential impact of sensors in chemical and biological analyses. This comprehensive resource aims to provide information to researchers and practitioners interested in using smartphones for cutting-edge analytical methodologies. Full article
(This article belongs to the Special Issue Application and Advance of Optical Immunosensors)
►▼ Show Figures

Graphical abstract

15 pages, 2657 KB  
Article
Eco-Friendly, High-Performance Humidity Sensor Using Purple Sweet-Potato Peel for Multipurpose Applications
by Sheik Abdur Rahman, Shenawar Ali Khan, Shahzad Iqbal, Muhammad Muqeet Rehman and Woo Young Kim
Chemosensors 2023, 11(8), 457; https://doi.org/10.3390/chemosensors11080457 - 15 Aug 2023
Cited by 15 | Viewed by 4532
Abstract
Biomaterials offer great potential for enhancing the performance of humidity sensors, which play a critical role in controlling moisture levels across different applications. By utilizing environmentally friendly, sustainable, and cost-effective biomaterials, we can improve the manufacturing process of these sensors while reducing our [...] Read more.
Biomaterials offer great potential for enhancing the performance of humidity sensors, which play a critical role in controlling moisture levels across different applications. By utilizing environmentally friendly, sustainable, and cost-effective biomaterials, we can improve the manufacturing process of these sensors while reducing our environmental impact. In this study, we present a high-performance humidity sensor that utilizes purple sweet potato peel (PSPP) as both the substrate and sensing layer. The PSPP is chosen for its polar hydrophilic functional groups, as well as its environmentally friendly nature, sustainability, and cost-effectiveness. Remarkably, this humidity sensor does not require an external substrate. It exhibits a wide detection range of 0 to 85% relative humidity at various operating frequencies (100 Hz, 1 kHz, and 10 kHz) in ambient temperature, demonstrating its effectiveness in responding to different humidity levels. The sensor achieves a high sensitivity value of 183.23 pF/%RH and minimal hysteresis of only 5% at 10 kHz under ambient conditions. It also boasts rapid response and recovery times of 1 and 2 s, respectively, making it suitable for use in high-end electronic devices. Moreover, the sensor’s applications extend beyond environmental monitoring. It has proven effective in monitoring mouth and nasal breathing, indicating its potential for respiratory monitoring and noncontact proximity response. These findings suggest that sweet potato peel material holds great promise as a highly stable, non-toxic, biodegradable, cost-effective, and environmentally friendly option for various domains, including healthcare monitoring. Full article
(This article belongs to the Section Applied Chemical Sensors)
►▼ Show Figures

Figure 1

12 pages, 1754 KB  
Article
Exploiting the Advantages of Ag/ITO/Enzyme Trapped Gel Layers to Develop a Highly Sensitive and Selective Fiber Optic Plasmonic Urea Sensor
by Sonika Sharma and Satyendra K. Mishra
Chemosensors 2023, 11(8), 421; https://doi.org/10.3390/chemosensors11080421 - 26 Jul 2023
Cited by 27 | Viewed by 3279
Abstract
The fabrication and characterization of a surface plasmon resonance (SPR)-based urea biosensor, with thin silver (Ag), ITO (In2O3: SnO2), and enzyme-trapped gel over an unclad portion of plastic-clad silica fiber as a sensing element, is represented. The [...] Read more.
The fabrication and characterization of a surface plasmon resonance (SPR)-based urea biosensor, with thin silver (Ag), ITO (In2O3: SnO2), and enzyme-trapped gel over an unclad portion of plastic-clad silica fiber as a sensing element, is represented. The working principle is to identify changes in the refractive index of the enzyme (urease) entrapped gel layer following the interaction with the incoming analyte. This interaction causes swelling and shrinkage of the gel layer, which alters the effective refractive index of the sensing layer. The wavelength interrogation method is used, and the optimized sensor probe is characterized by urea samples having different pH values. Scanning electron microscopy confirmed the uniformity of the silver layer over the unclad core of the fiber. The sensor operates from 0 to 160 mM of urea concentrations to cover the physiological concentration range of blood urea normally present in the human body. The sensitivity and limit of detection (LOD) offered by the sensor are marked 0.59387 nm/mM near zero concentration of the urea sample and 0.56 mM, respectively, along with the provisions of high stability, remote sensing, and online monitoring of urea. The proposed sensor has proven to be one of a kind due to its fast response time. Full article
(This article belongs to the Special Issue Advanced Bio-Chemical Sensors Based on Plasmonic Nanostructures)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying article 1-50 on page 1 of 3.
Go to page     1 2 3 chevron_right
Back to TopTop