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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.

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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 14 | Viewed by 5450
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)
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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 17 | Viewed by 2823
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)
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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 2873
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)
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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 38 | Viewed by 11063
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)
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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 9 | Viewed by 3409
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)
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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 16 | Viewed by 2713
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)
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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 39 | Viewed by 7733
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)
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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 17 | Viewed by 4650
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)
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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 16 | Viewed by 6033
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)
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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 20 | Viewed by 6651
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)
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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 18 | Viewed by 4147
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)
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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 17 | Viewed by 3849
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)
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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 26 | Viewed by 12649
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)
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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 18 | Viewed by 4282
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)
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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 16 | Viewed by 5671
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)
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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 44 | Viewed by 6547
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)
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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 70 | Viewed by 4783
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)
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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 26 | Viewed by 4970
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)
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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 36 | Viewed by 5045
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)
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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 3719
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)
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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 22 | Viewed by 5520
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)
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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 13 | Viewed by 4353
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)
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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 26 | Viewed by 3771
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)
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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 64 | Viewed by 10921
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)
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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 26 | Viewed by 3247
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)
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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 10 | Viewed by 4350
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)
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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 19 | Viewed by 4446
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)
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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 60 | Viewed by 13094
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)
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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 14 | Viewed by 4236
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)
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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 25 | Viewed by 3063
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)
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13 pages, 2784 KB  
Article
Application of the OECT-Based In Vivo Biosensor Bioristor in Fruit Tree Monitoring to Improve Agricultural Sustainability
by Filippo Vurro, Edoardo Marchetti, Manuele Bettelli, Luigi Manfrini, Adele Finco, Carlo Sportolaro, Nicola Coppedè, Nadia Palermo, Maria Grazia Tommasini, Andrea Zappettini and Michela Janni
Chemosensors 2023, 11(7), 374; https://doi.org/10.3390/chemosensors11070374 - 4 Jul 2023
Cited by 9 | Viewed by 4042
Abstract
Water scarcity is a major concern in agriculture worldwide. Fruit trees are severely affected by water deprivation in terms of growth, fruit yield, and quality. Plant monitoring combined with efficient irrigation is pivotal to achieve good quality standards and improve agricultural sustainability. This [...] Read more.
Water scarcity is a major concern in agriculture worldwide. Fruit trees are severely affected by water deprivation in terms of growth, fruit yield, and quality. Plant monitoring combined with efficient irrigation is pivotal to achieve good quality standards and improve agricultural sustainability. This study reports the use of in vivo sensing technology to monitor fruit tree species continuously, in real time and in vivo, through an Organic Electrochemical Transistor (OECT)-based biosensor called Bioristor. The sensor was applied to grapevines, apples, and kiwis, revealing its capability to trace the plant water status for the whole productive cycle. A correlation between the sensor response index (R) and environmental parameters such as air humidity and temperature were recorded for fruit species. The day/night oscillation of the ionic content in the transpiration stream varies during plant growth and fruit maturation and during severe drought stress. Bioristor promptly detected the occurrence of drought stress. The gate current (Igs) trend supports the reduction in the saturation of the system due to the lower water availability. The use of Bioristor-acquired indices can be used to improve precision irrigation techniques according to the real plant needs. Full article
(This article belongs to the Special Issue Recent Advances in Electrochemical Biosensors for Agricultural, Biological, and Environmental Applications)
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14 pages, 1657 KB  
Article
MoS2@Au as Label for Sensitive Sandwich-Type Immunoassay of Neuron-Specific Enolase
by Yingying Wang, Huixin Wang, Yaliang Bai, Guanhui Zhao, Nuo Zhang, Yong Zhang, Yaoguang Wang and Hong Chi
Chemosensors 2023, 11(6), 349; https://doi.org/10.3390/chemosensors11060349 - 19 Jun 2023
Cited by 21 | Viewed by 2919
Abstract
Neuron-specific enolase (NSE) has gained extensive attention as a reliable target for detecting small cell carcinoma of lungs. In this paper, an electrochemical immunoassay method based on molybdenum disulfide (MoS2) is proposed to detect NSE sensitively. By an in-situ growth method, [...] Read more.
Neuron-specific enolase (NSE) has gained extensive attention as a reliable target for detecting small cell carcinoma of lungs. In this paper, an electrochemical immunoassay method based on molybdenum disulfide (MoS2) is proposed to detect NSE sensitively. By an in-situ growth method, MoS2 and Au nanoclusters (Au NCs) were composited to form a MoS2@Au nanozyme, and then the secondary antibodies were modified. Primary antibodies were immobilized on amino-reduced graphene oxides to capture NSE. The flower-like MoS2 nanozyme provided abundant sites to load Au NCs and catalyze the decomposition of H2O2, which were beneficial to amplify an amperometric response as well as build up sensitivity. Under optimum conditions, the detection range of this strategy was 0.1 pg·mL−1–10 ng·mL−1 and the limit of detection was 0.05 pg·mL−1. This sensing strategy achieved the prospect of sensitively detecting NSE. Moreover, the prepared electrochemical immunosensor provides a theoretical basis and technical support for the detection of other disease markers. Full article
(This article belongs to the Special Issue Bionic Recognition and Biosensors: A Theme Issue in Honor of Professor Hong-Yuan Chen)
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13 pages, 2661 KB  
Article
Layer-by-Layer Films of Silsesquioxane and Nickel(II) Tetrasulphophthalocyanine as Glucose Oxidase Platform Immobilization: Amperometric Determination of Glucose in Kombucha Beverages
by João Paulo Winiarski, Douglas José de Melo, Edson Roberto Santana, Cleverson Siqueira Santos, Cliciane Guadalupe de Jesus, Sérgio Toshio Fujiwara, Karen Wohnrath and Christiana Andrade Pessôa
Chemosensors 2023, 11(6), 346; https://doi.org/10.3390/chemosensors11060346 - 14 Jun 2023
Cited by 15 | Viewed by 2417
Abstract
This paper describes the development of a novel glucose biosensor through the layer-by-layer technique (LbL). The self-assembled architectures were composed of a positive-charged silsesquioxane polyelectrolyte, 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl−), nickel (II) tetrassulphophthalocyanine (NiTsPc), and a conductive surface [...] Read more.
This paper describes the development of a novel glucose biosensor through the layer-by-layer technique (LbL). The self-assembled architectures were composed of a positive-charged silsesquioxane polyelectrolyte, 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl−), nickel (II) tetrassulphophthalocyanine (NiTsPc), and a conductive surface of FTO (fluor tin oxide). The construction of the biosensor was influenced by the isoelectric point (pI) of the glucose oxidase enzyme (GOx), which allowed electrostatic interaction between the outer layer of the silsesquioxane film and the enzyme. The architecture of modified electrode GOx/(SiPy+Cl−/NiTsPc)5.5/FTO was confirmed by UV-Vis, FTIR, and chronoamperometry techniques using different immobilization methods of GOx. Among the studied methods, a higher variation of current was observed for the modified electrode formed by mixed LbL films of SiPy+Cl− and NiTsPc and the enzyme immobilized by drop coating. The stability and reproducibility of the biosensor were verified when the last layer containing the enzyme was coated with 0.2% Nafion® polymer. Under these conditions, a linear response for glucose was obtained in the concentration range of 0.2 to 1.6 mmol L−1 (R2 = 0.991) with a limit of detection of 0.022 mmol L−1. The proposed biosensor was applied to quantify glucose in two different samples of kombucha juices with accuracy, allowing the glucose content of the healthy beverages to be estimated. Full article
(This article belongs to the Special Issue Advanced Nanomaterials-Based (Bio)sensors for Electrochemical Detection and Analysis)
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28 pages, 2119 KB  
Review
The Role of Nano-Sensors in Breath Analysis for Early and Non-Invasive Disease Diagnosis
by Nefeli Lagopati, Theodoros-Filippos Valamvanos, Vaia Proutsou, Konstantinos Karachalios, Natassa Pippa, Maria-Anna Gatou, Ioanna-Aglaia Vagena, Smaragda Cela, Evangelia A. Pavlatou, Maria Gazouli and Efstathios Efstathopoulos
Chemosensors 2023, 11(6), 317; https://doi.org/10.3390/chemosensors11060317 - 24 May 2023
Cited by 44 | Viewed by 9958
Abstract
Early-stage, precise disease diagnosis and treatment has been a crucial topic of scientific discussion since time immemorial. When these factors are combined with experience and scientific knowledge, they can benefit not only the patient, but also, by extension, the entire health system. The [...] Read more.
Early-stage, precise disease diagnosis and treatment has been a crucial topic of scientific discussion since time immemorial. When these factors are combined with experience and scientific knowledge, they can benefit not only the patient, but also, by extension, the entire health system. The development of rapidly growing novel technologies allows for accurate diagnosis and treatment of disease. Nanomedicine can contribute to exhaled breath analysis (EBA) for disease diagnosis, providing nanomaterials and improving sensing performance and detection sensitivity. Through EBA, gas-based nano-sensors might be applied for the detection of various essential diseases, since some of their metabolic products are detectable and measurable in the exhaled breath. The design and development of innovative nanomaterial-based sensor devices for the detection of specific biomarkers in breath samples has emerged as a promising research field for the non-invasive accurate diagnosis of several diseases. EBA would be an inexpensive and widely available commercial tool that could also be used as a disease self-test kit. Thus, it could guide patients to the proper specialty, bypassing those expensive tests, resulting, hence, in earlier diagnosis, treatment, and thus a better quality of life. In this review, some of the most prevalent types of sensors used in breath-sample analysis are presented in parallel with the common diseases that might be diagnosed through EBA, highlighting the impact of incorporating new technological achievements in the clinical routine. Full article
(This article belongs to the Section (Bio)chemical Sensing)
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16 pages, 5203 KB  
Article
Preparation of Reduced Graphene Oxide Sheets with Large Surface Area and Porous Structure for High-Sensitivity Humidity Sensor
by Seo Jin Kim, Hong Jun Park, Eun Seop Yoon and Bong Gill Choi
Chemosensors 2023, 11(5), 276; https://doi.org/10.3390/chemosensors11050276 - 4 May 2023
Cited by 25 | Viewed by 4473
Abstract
Humidity sensors provide environmental conditions suitable for several applications. However, they suffer from a limited reliable range originating from the low electrical conductivity and low water-sensitive sites of humidity-sensing materials. In this study, we developed high-sensitivity humidity sensors based on holey-reduced graphene oxide [...] Read more.
Humidity sensors provide environmental conditions suitable for several applications. However, they suffer from a limited reliable range originating from the low electrical conductivity and low water-sensitive sites of humidity-sensing materials. In this study, we developed high-sensitivity humidity sensors based on holey-reduced graphene oxide (HRGO) with a large surface area (274.5 m2/g) and an abundant pore structure. HRGO was prepared via the H2O2-etching-reaction-assisted hydrothermal processing of graphene oxide sheets. The resulting humidity sensor exhibited high sensitivity (−0.04317 log Z/%RH, R2 = 0.9717), a fast response time (<3 s), and long-term stability over 28 days. The impedance responses of the humidity sensor were almost similar between the mechanically standard and bent states. Furthermore, electrochemical impedance spectroscopy was performed to understand the humidity-sensing mechanism of the HRGO materials. Full article
(This article belongs to the Special Issue Recent Advances in Electrochemical Biosensors for Agricultural, Biological, and Environmental Applications)
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15 pages, 15419 KB  
Article
Perovskite-Structured NiTiO3 Modified NiO Gas Sensor for Xylene Detection
by Liyun Qin, Hongliang Gao and Fanli Meng
Chemosensors 2023, 11(5), 264; https://doi.org/10.3390/chemosensors11050264 - 29 Apr 2023
Cited by 27 | Viewed by 3093
Abstract
Xylene gas is highly toxic, can irritate the skin, and is also very harmful to the body. Therefore, it is necessary to prepare sensors that can accurately detect xylene. In this paper, NiTiO3 nanoparticles were synthesized by the hydrothermal method and used [...] Read more.
Xylene gas is highly toxic, can irritate the skin, and is also very harmful to the body. Therefore, it is necessary to prepare sensors that can accurately detect xylene. In this paper, NiTiO3 nanoparticles were synthesized by the hydrothermal method and used to modify NiO, and a NiTiO3-modified NiO (NiTiO3-NiO) nanosheet material was successfully prepared. Its microstructure and internal composition were observed and analyzed by various characterization methods. When detecting 100 ppm xylene gas at the optimum temperature, comparing the response level of the NiTiO3-NiO sensor with that of a pure nickel oxide sensor, the former was 20 times that of the latter, and the sensitivity was greatly improved. In a 100 ppm xylene gas environment, the response level of the sensor reached 21, the minimum detection limit was 1 ppm, and the recovery time was 135.75 s. NiTiO3 is a perovskite-structured material, with many active sites and good catalytic properties that promote redox reactions. Full article
(This article belongs to the Special Issue Application and Advance of Gas Sensors)
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17 pages, 5047 KB  
Article
MXene/NiO Composites for Chemiresistive-Type Room Temperature Formaldehyde Sensor
by Baoyu Huang, Xinwei Tong, Xiangpeng Zhang, Qiuxia Feng, Marina N. Rumyantseva, Jai Prakash and Xiaogan Li
Chemosensors 2023, 11(4), 258; https://doi.org/10.3390/chemosensors11040258 - 21 Apr 2023
Cited by 38 | Viewed by 5561
Abstract
In this work, MXene/NiO-composite-based formaldehyde (HCHO) sensing materials were successfully synthesized by an in situ precipitation method. The heterostructures between the MXene and NiO nanoparticles were verified by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The HCHO sensing [...] Read more.
In this work, MXene/NiO-composite-based formaldehyde (HCHO) sensing materials were successfully synthesized by an in situ precipitation method. The heterostructures between the MXene and NiO nanoparticles were verified by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The HCHO sensing performance of the MXene/NiO-based chemiresistive-type sensors was investigated. Compared to pure MXene and NiO materials, the sensing performance of the MXene/NiO-P2-based sensor to HCHO gas at room temperature was significantly enhanced by the formation of MXene/NiO heterojunctions. The response of the MXene/NiO-P2 sensor to 50 ppm HCHO gas was 8.8, which was much higher than that of the pure MXene and NiO. At room temperature, the detectable HCHO concentration of the MXene/NiO-P2-based sensor was 1 ppm, and the response and recovery time to 2 ppm HCHO was 279 s and 346 s, respectively. The MXene/NiO-P2 sensor also exhibited a good selectivity and a long-term stability to HCHO gas for 56 days. The in situ Fourier transform infrared (FTIR) spectra of the MXene/NiO-P2 sensor, when exposed to HCHO gas at different times, were investigated to verify the adsorption reaction products of HCHO molecules. Full article
(This article belongs to the Special Issue Low-Cost and High-Performance Gas Sensors: Materials, Design and Application)
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46 pages, 5210 KB  
Review
Electrochemical Sweat Sensors
by Emanuel Bilbao, Octavio Garate, Theo Rodríguez Campos, Mariano Roberti, Mijal Mass, Alex Lozano, Gloria Longinotti, Leandro Monsalve and Gabriel Ybarra
Chemosensors 2023, 11(4), 244; https://doi.org/10.3390/chemosensors11040244 - 14 Apr 2023
Cited by 33 | Viewed by 11966
Abstract
Sweat analysis by means of minimally invasive wearable sensors is considered a potentially disruptive method for assessing clinical parameters, with exciting applications in early medical diagnostics and high-performance sports. Electrochemical sensors and biosensors are especially attractive because of the possibility of the electronic [...] Read more.
Sweat analysis by means of minimally invasive wearable sensors is considered a potentially disruptive method for assessing clinical parameters, with exciting applications in early medical diagnostics and high-performance sports. Electrochemical sensors and biosensors are especially attractive because of the possibility of the electronic integration of wearable devices. In this article, we review several aspects regarding the potentialities and present limitations of electrochemical sweat (bio)sensors, including: the main target analytes and their relationships with clinical conditions; most usual electrochemical techniques of transduction used according to the nature of the target analytes; issues connected to the collection of representative sweat samples; aspects regarding the associated, miniaturized electronic instrumentation used for signal processing and communication; and signal processing by machine learning. Full article
(This article belongs to the Special Issue Electrochemical Detection: Analytical and Biological Challenges)
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20 pages, 4647 KB  
Article
Flexible Miniaturized Electrochemical Sensors Based on Multiwalled Carbon Nanotube-Chitosan Nanomaterial for Determination of Nitrite in Soil Solutions
by Ana-Maria Gurban, Lucian-Gabriel Zamfir, Petru Epure, Ioana-Raluca Șuică-Bunghez, Raluca Mădălina Senin, Maria-Luiza Jecu, Maria Lorena Jinga and Mihaela Doni
Chemosensors 2023, 11(4), 224; https://doi.org/10.3390/chemosensors11040224 - 5 Apr 2023
Cited by 28 | Viewed by 4298
Abstract
Flexible screen-printed electrodes (SPE) were modified in a simple manner with different composite nanomaterials based on carbon allotropes, polymers, and metallic nanoparticles, for amperometric detection of nitrites in soil. Multiwalled carbon nanotubes (MWCNT), chitosan (CS), silver nanoparticles (AgNPs), 1,8-diaminonaphthalene (1,8-DAN), and a sol-gel [...] Read more.
Flexible screen-printed electrodes (SPE) were modified in a simple manner with different composite nanomaterials based on carbon allotropes, polymers, and metallic nanoparticles, for amperometric detection of nitrites in soil. Multiwalled carbon nanotubes (MWCNT), chitosan (CS), silver nanoparticles (AgNPs), 1,8-diaminonaphthalene (1,8-DAN), and a sol-gel (SG) matrix were used for modification of the carbon paste working electrodes. Sensitive and selective detection of nitrite was achieved by using a MWCNT-CS-modified sensor, in acetate buffer at pH 5, at an applied potential of 0.58 V vs. Ag/AgCl. The MWCNT-CS-based sensor displayed a specific sensitivity of 204.4 mA·M−1·cm−2, with a detection limit of 2.3 µM (S/N = 3) in a linear range up to 1.7 mM, showing good stability, reproducibility, and selectivity towards other interfering species. A miniaturized portable system using the developed flexible electrochemical MWCNT-CS-based sensors was dedicated for the detection of nitrite in different samples of soil solutions extracted by using suction lysimeters. Full article
(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)
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12 pages, 3045 KB  
Communication
Ultra-Low Detection of Perfluorooctanoic Acid Using a Novel Plasmonic Sensing Approach Combined with Molecularly Imprinted Polymers
by Rosalba Pitruzzella, Francesco Arcadio, Chiara Perri, Domenico Del Prete, Giovanni Porto, Luigi Zeni and Nunzio Cennamo
Chemosensors 2023, 11(4), 211; https://doi.org/10.3390/chemosensors11040211 - 26 Mar 2023
Cited by 26 | Viewed by 6664
Abstract
In this work, a novel optical fiber sensor system for ultra-low perfluorooctanoic acid (PFOA) detection in aqueous solutions is proposed. It is based on the connection, in series, of two different plastic optical fiber (POF) platforms: the first is a chemical chip realized [...] Read more.
In this work, a novel optical fiber sensor system for ultra-low perfluorooctanoic acid (PFOA) detection in aqueous solutions is proposed. It is based on the connection, in series, of two different plastic optical fiber (POF) platforms: the first is a chemical chip realized by using a D-shaped POF with microholes filled with a specific molecularly imprinted polymer (MIP); the second is a typical surface plasmon resonance (SPR) sensor based on a D-shaped POF. In particular, the MIP-based chemical chip was used to launch the light inside the SPR–POF chip to change the SPR phenomenon by exploiting the PFOA–MIP interaction in the microholes. At first, experimental results were performed in water to demonstrate the applicability of the proposed sensing approach for measuring PFOA (or C8) in a concentration range of 1 ppt to 750 ppt, obtaining an ultra-low limit of detection (LOD) equal to about 0.81 ppt. Then, experimental results were carried out in simulated seawater to implement a complex matrix. The obtained results denoted a slight matrix effect, paving the way for the applicability of the proposed chemical sensing mechanism in several aqueous solutions. Full article
(This article belongs to the Section Optical Chemical Sensors)
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25 pages, 6186 KB  
Review
Electrospun Nanofibers as Chemosensors for Detecting Environmental Pollutants: A Review
by Yutong Du, Deng-Guang Yu and Tao Yi
Chemosensors 2023, 11(4), 208; https://doi.org/10.3390/chemosensors11040208 - 25 Mar 2023
Cited by 43 | Viewed by 7086
Abstract
Electrospun nanofibers have shown their advantages for applications in a wide variety of scientific fields thanks to their unique properties. Meanwhile, electrospinning is closely following the fast development of nano science and nanotechnology to move forward to smaller (pico-technology), more complicated nanostructures/nanodevices and [...] Read more.
Electrospun nanofibers have shown their advantages for applications in a wide variety of scientific fields thanks to their unique properties. Meanwhile, electrospinning is closely following the fast development of nano science and nanotechnology to move forward to smaller (pico-technology), more complicated nanostructures/nanodevices and more order (all kinds of nano arrays). Particularly, multiple-fluid electrospinning has the strong capability of creating nanostructures from a structural spinneret in a single-step and a straightforward “top-down” manner, holding great promise for creation on a large scale. This review is just to conclude the state-of-art studies on the related topics and also point out that the future directions of environmental detection require chemosensors, while the improvement of sensors requires new chemically synthesized functional substances, new nanostructured materials, application convenience, and functional integration or synergy. Based on the developments of electrospinning, more and more possibilities can be drawn out for detecting environmental pollutants with electrospun nanostructures as the strong support platform. Full article
(This article belongs to the Special Issue Chemical Sensors and Analytical Methods for Environmental Monitoring)
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24 pages, 2016 KB  
Article
Miniaturized NIR Spectrometers in a Nutshell: Shining Light over Sources of Variance
by Giulia Gorla, Paolo Taborelli, Hawbeer Jamal Ahmed, Cristina Alamprese, Silvia Grassi, Ricard Boqué, Jordi Riu and Barbara Giussani
Chemosensors 2023, 11(3), 182; https://doi.org/10.3390/chemosensors11030182 - 9 Mar 2023
Cited by 21 | Viewed by 5389
Abstract
The increasing portability and accessibility of miniaturized NIR spectrometers are promoting the spread of in-field and online applications. Alongside the successful outcomes, there are also several problems related to the acquisition strategies for each instrument and to experimental factors that can influence the [...] Read more.
The increasing portability and accessibility of miniaturized NIR spectrometers are promoting the spread of in-field and online applications. Alongside the successful outcomes, there are also several problems related to the acquisition strategies for each instrument and to experimental factors that can influence the collected signals. An insightful investigation of such factors is necessary and could lead to advancements in experimental set-up and data modelling. This work aimed to identify variation sources when using miniaturized NIR sensors and to propose a methodology to investigate such sources based on a multivariate method (ANOVA—Simultaneous Component Analysis) that considers the effects and interactions between them. Five different spectrometers were chosen for their different spectroscopic range and technical characteristics, and samples of worldwide interest were chosen as the case study. Comparing various portable sensors is interesting since results could significantly vary in the same application, justifying the idea that this kind of spectrometer is not to be treated as a general class of instruments. Full article
(This article belongs to the Section Analytical Methods, Instrumentation and Miniaturization)
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12 pages, 2169 KB  
Article
Aggregation-Induced Emission-Active Iridium(III) Complexes for Sensing Picric Acid in Water
by Ping He, Yan Chen, Xiao-Na Li, Ying-Ying Yan and Chun Liu
Chemosensors 2023, 11(3), 177; https://doi.org/10.3390/chemosensors11030177 - 6 Mar 2023
Cited by 20 | Viewed by 3396
Abstract
Herein, two new iridium(III) complexes, namely Ir2 and Ir3, with a phenyl or triphenylamine (TPA) moiety at the 4-position of the phenyl ring at 2-phenylbenzothiazole, have been synthesized, and their emission properties have been studied systematically compared with the non-substituted complex Ir1 [...] Read more.
Herein, two new iridium(III) complexes, namely Ir2 and Ir3, with a phenyl or triphenylamine (TPA) moiety at the 4-position of the phenyl ring at 2-phenylbenzothiazole, have been synthesized, and their emission properties have been studied systematically compared with the non-substituted complex Ir1. These three complexes exhibit aggregation-induced emission (AIE) in H2O/CH3CN. The TPA-substituted complex Ir3 shows the highest AIE activity. All complexes can be used as sensors to detect picric acid (PA) in water. The Stern–Volmer constant (KSV) of Ir3 for the detection of PA was determined to be 1.96 × 106 M−1, with a low limit of detection of 2.52 nM. Proton nuclear magnetic resonance spectra, high-resolution mass spectrometry analysis, and density function theory calculations confirm that the emission quenching mechanism of Ir3 is caused by photo-induced electron transfer. Furthermore, the efficient detection of PA in natural water proves that Ir1–Ir3 can be used as promising sensors in the natural environment. These results suggest that the AIE-active iridium(III) complexes can be used to detect PA under environment-friendly conditions. Full article
(This article belongs to the Special Issue 10th Anniversary of Chemosensors—Section 'Materials for Chemical Sensing')
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13 pages, 3752 KB  
Article
An Accessible Yarn-Based Sensor for In-Field Detection of Succinylcholine Poisoning
by Victor Ong, Nicholas R. Cortez, Ziru Xu, Farbod Amirghasemi, Mohamed K. Abd El-Rahman and Maral P. S. Mousavi
Chemosensors 2023, 11(3), 175; https://doi.org/10.3390/chemosensors11030175 - 4 Mar 2023
Cited by 8 | Viewed by 4824
Abstract
Succinylcholine (SUX) is a clinical anesthetic that induces temporary paralysis and is degraded by endogenous enzymes within the body. In high doses and without respiratory support, it results in rapid and untraceable death by asphyxiation. A potentiometric thread-based method was developed for the [...] Read more.
Succinylcholine (SUX) is a clinical anesthetic that induces temporary paralysis and is degraded by endogenous enzymes within the body. In high doses and without respiratory support, it results in rapid and untraceable death by asphyxiation. A potentiometric thread-based method was developed for the in-field and rapid detection of SUX for forensic use. We fabricated the first solid-contact SUX ion-selective electrodes from cotton yarn, a carbon black ink, and a polymeric ion-selective membrane. The electrodes could selectively measure SUX in a linear range of 1 mM to 4.3 μM in urine, with a Nernstian slope of 27.6 mV/decade. Our compact and portable yarn-based SUX sensors achieved 94.1% recovery at low concentrations, demonstrating feasibility in real-world applications. While other challenges remain, the development of a thread-based ion-selective electrode for SUX detection shows that it is possible to detect this poison in urine and paves the way for other low-cost, rapid forensic diagnostic devices. Full article
(This article belongs to the Special Issue Electrochemical Sensors and Their Applications: A Theme Issue in Honor of Professor Richard G. Compton)
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14 pages, 5608 KB  
Article
PEDOT:PSS/PEDOT Film Chemiresistive Sensors for Hydrogen Peroxide Vapor Detection under Ambient Conditions
by Xiaowen Xie, Nan Gao, Ling Zhu, Matthew Hunter, Shuai Chen and Ling Zang
Chemosensors 2023, 11(2), 124; https://doi.org/10.3390/chemosensors11020124 - 7 Feb 2023
Cited by 26 | Viewed by 5150
Abstract
Hydrogen peroxide (aqueous solution of H2O2) is one of the most used reagents i n medical sterilization, environmental disinfection, food storage, and other fields. However, hydrogen peroxide has the potential to cause serious harm to biological health and environmental [...] Read more.
Hydrogen peroxide (aqueous solution of H2O2) is one of the most used reagents i n medical sterilization, environmental disinfection, food storage, and other fields. However, hydrogen peroxide has the potential to cause serious harm to biological health and environmental safety. There are many methods (especially electrochemistry) for H2O2 detection in liquid phase systems, but a lack of methods for vapor detection. This is due to its colorless and tasteless nature, as well as the oxidative activity of the molecule and its coexistence with humidity. In this study, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), one of the most commercially successful and widely used conductive polymers, was employed to fabricate an all-organic chemiresistive sensor for simple, real-time, and on-site sensing of hydrogen peroxide vapor (HPV) at room temperature. In comparison with pristine PEDOT:PSS film, the PEDOT:PSS/PEDOT film was prepared by in situ electrochemical polymerization. Upon exposure to different concentrations of HPV, it was found that the hydrophobic and porous PEDOT layer could weaken the interference of humidity in HPV sensing, resulting in a more sensitive and accurate response. At 1.0 ppm HPV concentration, the resistance signal response was increased by nearly 89% compared with the pristine PEDOT:PSS film. This PEDOT-film-based chemiresistive sensor showcases the possibility for further development of nonenzymatic HPV monitoring technology. Full article
(This article belongs to the Special Issue 10th Anniversary of Chemosensors—Section 'Materials for Chemical Sensing')
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17 pages, 5695 KB  
Article
Pyrene-Based Fluorescent Probe for “Off-on-Off” Sequential Detection of Cu2+ and CN− with HeLa Cells Imaging
by Muthaiah Shellaiah, Parthiban Venkatesan, Natesan Thirumalaivasan, Shu-Pao Wu and Kien-Wen Sun
Chemosensors 2023, 11(2), 115; https://doi.org/10.3390/chemosensors11020115 - 4 Feb 2023
Cited by 59 | Viewed by 5212
Abstract
The novel pyrene-appended Schiff base probe L with aggregation-induced emissions (AIE) relevant to an increase in water fractions (0–90%) is synthesized and applied in sequentially detecting Cu2+ and CN−. The pyrene-based probe L firstly induces the excimer formation in the [...] Read more.
The novel pyrene-appended Schiff base probe L with aggregation-induced emissions (AIE) relevant to an increase in water fractions (0–90%) is synthesized and applied in sequentially detecting Cu2+ and CN−. The pyrene-based probe L firstly induces the excimer formation in the presence of Cu2+. However, the process can be reversed by sequentially adding CN−, which is demonstrated using the fluorescence “Off-On-Off” response in semi-aqueous media ethanol water (v/v = 7/3) under physiological pH (5 mM HEPES, pH 7.0). The Job’s plot, mass analysis, 1H NMR titrations, and density functional theory (DFT) interrogations confirm the 2:1 stoichiometry of excimer complex L–Cu2+-L*, preferential binding atoms, and CN− tuned complex reversibility. Based on the photoluminescence (PL) titration, the association constant of L to Cu2+ is determined as 4.95 × 106 M−1. From standard deviation and linear fittings, the detection limits (LODs) of Cu2+ and CN− are estimated as 219 nM and 580 nM, respectively. The practicality of Cu2+ and CN− detection is demonstrated using a TLC plate and a blended polymer membrane through which significant color changes under a UV lamp can be monitored. Moreover, utility of the designed probe L towards biological application with low toxicity is demonstrated by detecting Cu2+ and CN− inside HeLa cells. The responses of the probe to Cu(II) ions were also verified using living HeLa cells imaging. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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37 pages, 5976 KB  
Review
Screen-Printed Electrodes: Fabrication, Modification, and Biosensing Applications
by Giti Paimard, Ehsan Ghasali and Mireia Baeza
Chemosensors 2023, 11(2), 113; https://doi.org/10.3390/chemosensors11020113 - 3 Feb 2023
Cited by 195 | Viewed by 35781
Abstract
As electrochemical measuring instruments, screen-printed electrodes (SPEs) are constructed via a technology called thick film deposition onto plastic or ceramic substrates, allowing for simple, inexpensive, and rapid on-site analysis with high reproducibility, sensitivity, and accuracy. Numerous substances such as gold, silver, platinum, and [...] Read more.
As electrochemical measuring instruments, screen-printed electrodes (SPEs) are constructed via a technology called thick film deposition onto plastic or ceramic substrates, allowing for simple, inexpensive, and rapid on-site analysis with high reproducibility, sensitivity, and accuracy. Numerous substances such as gold, silver, platinum, and carbon are applied for electrode construction, enabling the analyst to design the best device based on its purpose to determine an analyte’s selectivity and sensitivity. Thus, in the current review, we report the latest results and analyses conducted over the past eight years (2015–2022) on the expansion of SPE electrochemical biosensors, including aptasensors, immunosensors, DNA sensors, and enzymatic biosensors. Such expansion has resulted in new possibilities for the identification, distinction, and quantification of biocompounds, drugs, enzymes, etc. Therefore, in this paper, we review the role of different nanomaterials in manufacturing on-screen electrode methods as well as strategies for the future stable diagnosis of biorecognition elements. Full article
(This article belongs to the Section (Bio)chemical Sensing)
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23 pages, 4368 KB  
Review
Engineering Rational SERS Nanotags for Parallel Detection of Multiple Cancer Circulating Biomarkers
by Zhipeng Zhang, Rui Guan, Junrong Li and Yao Sun
Chemosensors 2023, 11(2), 110; https://doi.org/10.3390/chemosensors11020110 - 3 Feb 2023
Cited by 25 | Viewed by 6650
Abstract
Precision cancer medicine necessitates a personalized treatment plan for each individual patient. Given cancer’s heterogeneity and dynamic nature, the plot of patient-specific signatures composed of multiple cancer circulating biomarkers is useful to reveal the complete tumor landscape for guiding precision medicine. As an [...] Read more.
Precision cancer medicine necessitates a personalized treatment plan for each individual patient. Given cancer’s heterogeneity and dynamic nature, the plot of patient-specific signatures composed of multiple cancer circulating biomarkers is useful to reveal the complete tumor landscape for guiding precision medicine. As an emerging new technology, surface-enhanced Raman scattering (SERS) shows the intrinsic advantage of performing multiplexed detection with the extremely narrow Raman spectral line widths. In this review, we first discuss the design principle of SERS nanotags to enable the detection of multiple circulating biomarkers, highlighting the important roles of plasmonic nanostructures and triple bond-modulated Raman reporters. Following this, we detail the use of isotropic and anisotropic nanostructures as SERS enhancement substrates for amplifying Raman signals in multi-biomarker detection. Furthermore, we present the triple bond-modulated molecules as Raman reporters in SERS nanotags to expand the multiplexing capability for biomarker measurements. Finally, we offer critical insights into the challenges and perspectives of SERS nanotags for cancer diagnosis, particularly from the aspect of future clinical transition. It is expected that this review can facilitate the design of more functional SERS nanotags with high sensitivity and multiplexing capability to assist early and accurate cancer screening. We also believe our review will be of interest in the fields of molecular imaging, biomedicine, and analytical chemistry. Full article
(This article belongs to the Collection Advances of Chemical and Biosensors in China)
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32 pages, 6494 KB  
Review
Fluorescence Modulation by Amines: Mechanistic Insights into Twisted Intramolecular Charge Transfer (TICT) and Beyond
by Cheng Chen and Chong Fang
Chemosensors 2023, 11(2), 87; https://doi.org/10.3390/chemosensors11020087 - 23 Jan 2023
Cited by 61 | Viewed by 9068
Abstract
Amine groups are common constituents of organic dyes and play important roles in tuning fluorescence properties. In particular, intensive research works have demonstrated the tendency and capabilities of amines in influencing chromophore brightness. Such properties have been explained by multiple mechanisms spanning from [...] Read more.
Amine groups are common constituents of organic dyes and play important roles in tuning fluorescence properties. In particular, intensive research works have demonstrated the tendency and capabilities of amines in influencing chromophore brightness. Such properties have been explained by multiple mechanisms spanning from twisted intramolecular charge transfer (TICT) to the energy gap law and beyond, which introduce additional nonradiative energy dissipation pathways. In this review, we aim to provide a focused overview of the mechanistic insights mainly for the TICT mechanism, accompanied by a few other less common or influential fluorescence quenching mechanisms in the amine-containing fluorescent molecules. Various aspects of current scientific findings including the rational design and synthesis of organic chromophores, theoretical calculations, steady-state and time-resolved electronic and vibrational spectroscopies are reviewed. These in-depth understandings of how the amine groups with diverse chemical structures at various atomic sites affect excited-state nonradiative decay pathways will facilitate the strategic and targeted development of fluorophores with desired emission properties as versatile chemosensors for broad applications. Full article
(This article belongs to the Special Issue Selected Papers from Optical Materials: Synthesis and Biological Applications Symposium (XXXVIII Biennial Meeting RSEQ))
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13 pages, 2061 KB  
Article
E-Nose Quality Evaluation of Extra Virgin Olive Oil Stored in Different Containers
by Elísabet Martín-Tornero, Juan Diego Barea-Ramos, Jesús Lozano, Isabel Durán-Merás and Daniel Martín-Vertedor
Chemosensors 2023, 11(2), 85; https://doi.org/10.3390/chemosensors11020085 - 21 Jan 2023
Cited by 21 | Viewed by 3989
Abstract
The degradation process of virgin olive oil (VOO) is related to storage time and the type of storage container used. The aim of this work is to explore the evolution of the VOO quality stored in different container types over a defined storage [...] Read more.
The degradation process of virgin olive oil (VOO) is related to storage time and the type of storage container used. The aim of this work is to explore the evolution of the VOO quality stored in different container types over a defined storage period in order to predict the organoleptic characteristics using a non-destructive technique such as the electronic-nose (E-nose). The “Picual” variety VOO was stored in different containers over a period of 21 months and monitored using sensory analysis, volatile compounds, and an E-nose. The panelists showed that oil stored in dark glass bottles and in green polyethylene bottles began to show defects after 12 and 15 weeks, respectively. However, oil stored in tin containers retained its quality throughout the 21 months studied. A total of 31 volatile compounds were identified, and the evolution of the volatile profile in the different containers during the storage period was studied. The E-nose data were able to classify oil quality by container using principal component analysis (PCA). Furthermore, the E-nose data combined with partial least squares (PLS) regression enabled the building of a predictive model to quantify sensory defect values (RCV2 = 0.92; RCV2 = 0.86), evidencing that this technique would be an appropriate screening tool to support a sensory panel. Full article
(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges)
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