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Chemosensors, Volume 11, Issue 4 (April 2023) – 55 articles

Cover Story (view full-size image): A 2D Sb-modified screen-printed carbon nanofibers electrode (2D Sbexf-SPCNFE) was developed to improve the stripping voltammetric determination of Cd(II) and Pb(II), heavy metals responsible for water pollution. The analytical performance of 2D Sbexf-SPCNFE was much better than those achieved by 2D Sbexf-SPCE and the respective bare electrodes (SPCNFE and SPCE). Compared to other reported sensors based on the use of antimony and carbon nanomaterials, the analytical parameters exhibited by 2D Sbexf-SPCNFE were also generally superior. The excellent performance proved by 2D Sbexf-SPCNFE can be associated with a synergistic effect between both merged nanomaterials, i.e., the high surface-to-volume ratio and the high charge carrier mobility provided by 2D Sbexf, and the high electrical conductivity and the large surface area of CNF. View this paper
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17 pages, 5047 KiB  
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 11 | Viewed by 2889
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
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17 pages, 6425 KiB  
Article
Advances in a Microwave Sensor-Type Interdigital Capacitor with a Hexagonal Complementary Split-Ring Resonator for Glucose Level Measurement
by Supakorn Harnsoongnoen and Benjaporn Buranrat
Chemosensors 2023, 11(4), 257; https://doi.org/10.3390/chemosensors11040257 - 20 Apr 2023
Cited by 6 | Viewed by 2044
Abstract
This study involved the creation and assessment of a microwave sensor to measure glucose levels in aqueous solutions without invasiveness. The sensor design utilized a planar interdigital capacitor (IDC) loaded with a hexagonal complementary split-ring resonator (HCSRR). The HCSRR was chosen for its [...] Read more.
This study involved the creation and assessment of a microwave sensor to measure glucose levels in aqueous solutions without invasiveness. The sensor design utilized a planar interdigital capacitor (IDC) loaded with a hexagonal complementary split-ring resonator (HCSRR). The HCSRR was chosen for its ability to generate a highly intense electric field that is capable of detecting variations in the dielectric characteristics of the specimen. A chamber tube was used to fill glucose solutions at the sensor’s sensitive area, and changes in the device’s resonance frequency (Fr) and reflection coefficient (S11) were used to measure glucose levels. Fitting formulas were developed to analyze the data, and laboratory tests showed that the sensor could accurately measure glucose levels within a range of 0–150 mg/dL. At a concentration of 37.5 mg/dL, the sensitivity based on S11 and Fr reached maximum values of 10.023 dB per mg/dL and 1.73 MHz per mg/dL, respectively. This implies that the sensor put forward has the possibility of being utilized in medical settings for the monitoring of glucose levels. Full article
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22 pages, 5106 KiB  
Review
Tesla Valve Microfluidics: The Rise of Forgotten Technology
by Agnes Purwidyantri and Briliant Adhi Prabowo
Chemosensors 2023, 11(4), 256; https://doi.org/10.3390/chemosensors11040256 - 20 Apr 2023
Cited by 5 | Viewed by 8190
Abstract
The Tesla valve (TV), a valvular conduit invented by Nicola Tesla over a century ago, has recently acquired significant attention and application in various fields because of the growing interest in microfluidics and nanofluidics. The unique architecture of TV characterized by an asymmetrical [...] Read more.
The Tesla valve (TV), a valvular conduit invented by Nicola Tesla over a century ago, has recently acquired significant attention and application in various fields because of the growing interest in microfluidics and nanofluidics. The unique architecture of TV characterized by an asymmetrical design and an arc-shaped channel has long been an intriguing yet underrated design for building a passive component in a microfluidic system. While previously regarded as a technology without significant use, TV structures have been implemented in thermal manipulation fluidics, micromixers and micropumps, benefitting the advancement of urgently demanding technology in various areas, such as in biomedical diagnostics through wearable electronics and medical instruments, lab on a chip, chemosensors and in application toward sustainable technology manifested in fuel cell devices. This article presents the first comprehensive review of TV structures in the literature, which has seen significant growth in the last two years. The review discusses typical TV structures, including single-stage TV (STV), multistage TV (MSTV), and TV derivatives (TVD), along with their characteristics and potential applications. The designs of these structures vary based on their intended applications, but all are constructed based on the fundamental principle of the TV structure. Finally, future trends and potential applications of TV structures are summarized and discussed. This topical review provides a valuable reference for students, early-career scientists, and practitioners in fluidic devices, particularly those interested in using TV structures as passive components. Full article
(This article belongs to the Section Analytical Methods, Instrumentation and Miniaturization)
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21 pages, 1060 KiB  
Review
LFA: The Mysterious Paper-Based Biosensor: A Futuristic Overview
by Saumitra Singh, Mohd. Rahil Hasan, Akshay Jain, Roberto Pilloton and Jagriti Narang
Chemosensors 2023, 11(4), 255; https://doi.org/10.3390/chemosensors11040255 - 19 Apr 2023
Cited by 5 | Viewed by 3815
Abstract
Lateral flow assay (LFA) is emerging as one of the most popular paper-based biosensors in the field of the diagnostic industry. LFA fills all the gaps between diagnosis and treatment as it provides beneficial qualities to users such as quick response, Point-of-care appeal, [...] Read more.
Lateral flow assay (LFA) is emerging as one of the most popular paper-based biosensors in the field of the diagnostic industry. LFA fills all the gaps between diagnosis and treatment as it provides beneficial qualities to users such as quick response, Point-of-care appeal, early detection, low cost, and effective and sensitive detections of various infectious diseases. These benefits increase LFA’s dependability for disease management because rapid and accurate disease diagnosis is a prerequisite for effective medication. Only 2% of overall healthcare expenditures, according to Roche Molecular Diagnostics, are spent on in vitro diagnostics, even though 60% of treatment choices are based on this data. To make LFA more innovative, futuristic plans have been outlined in many reports. Thus, this review reports on very knowledgeable literature discussing LFA and its development along with recent futuristic plans for LFA-based biosensors that cover all the novel features of the improvement of LFA. LFA might therefore pose a very significant economic success and have a significant influence on medical diagnosis. Full article
(This article belongs to the Collection Electrochemical Biosensors for Medical Diagnosis)
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18 pages, 11190 KiB  
Article
Disposable Sensor with Copper-Loaded Carbon Nanospheres for the Simultaneous Determination of Dopamine and Melatonin
by Sivaguru Jayaraman, Thenmozhi Rajarathinam and Seung-Cheol Chang
Chemosensors 2023, 11(4), 254; https://doi.org/10.3390/chemosensors11040254 - 19 Apr 2023
Cited by 3 | Viewed by 1422
Abstract
A novel electrochemical sensor based on Cu-loaded carbon nanospheres (Cu–CNSs) was designed and fabricated. Initially, the CNSs were synthesized using a natural or inexpensive carbon source (dark brown sugar), and Cu was loaded to enhance the electrocatalytic properties of the material. Subsequently, the [...] Read more.
A novel electrochemical sensor based on Cu-loaded carbon nanospheres (Cu–CNSs) was designed and fabricated. Initially, the CNSs were synthesized using a natural or inexpensive carbon source (dark brown sugar), and Cu was loaded to enhance the electrocatalytic properties of the material. Subsequently, the synthesized Cu–CNSs were modified onto a screen-printed carbon electrode (SPCE), termed Cu–CNS/SPCE, to simultaneously detect the biomarkers dopamine (DA) and melatonin (MT) through differential pulse voltammetry. The surface characterization of the Cu–CNSs confirmed the formation of carbon spheres and Cu nanoparticles covering the spheres. Electrochemical studies showed that the Cu–CNS/SPCE had a high selectivity and sensitivity toward DA and MT, with a significant peak separation of 0.502 V. The two linear ranges of DA were 0.125–20 μM and 20–100 μM and the linear range of MT was 1.0–100 μM, with corresponding detection limits of 0.34 μM and 0.33 μM (S/N = 3), respectively. The quantification limits for DA and MT were 2.19 and 1.09 μM (S/N = 10), respectively. The sensor performance is attributed to the high conductivity and large, electrochemically active surface area of the Cu–CNS. In human serum samples, the Cu–CNS/SPCE exhibited good selectivity and satisfactory reproducibility for the simultaneous determination of DA and MT. Full article
(This article belongs to the Special Issue Advanced Electrochemical Sensors or Biosensors Based on Nanomaterial)
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15 pages, 2199 KiB  
Article
Precise Integration of Polymeric Sensing Functional Materials within 3D Printed Microfluidic Devices
by Jaione Etxebarria-Elezgarai, Maite Garcia-Hernando, Lourdes Basabe-Desmonts and Fernando Benito-Lopez
Chemosensors 2023, 11(4), 253; https://doi.org/10.3390/chemosensors11040253 - 19 Apr 2023
Cited by 1 | Viewed by 1515
Abstract
This work presents a new architecture concept for microfluidic devices, which combines the conventional 3D printing fabrication process with the stable and precise integration of polymeric functional materials in small footprints within the microchannels in well-defined locations. The approach solves the assembly errors [...] Read more.
This work presents a new architecture concept for microfluidic devices, which combines the conventional 3D printing fabrication process with the stable and precise integration of polymeric functional materials in small footprints within the microchannels in well-defined locations. The approach solves the assembly errors that normally occur during the integration of functional and/or sensing materials in hybrid microfluidic devices. The method was demonstrated by embedding four pH-sensitive ionogel microstructures along the main microfluidic channel of a complex 3D printed microfluidic device. The results showed that this microfluidic architecture, comprising the internal integration of sensing microstructures of diverse chemical compositions, highly enhanced the adhesion force between the microstructures and the 3D printed microfluidic device that contains them. In addition, the performance of this novel 3D printed pH sensor device was investigated using image analysis of the pH colour variations obtained from photos taken with a conventional camera. The device presented accurate and repetitive pH responses in the 2 to 12 pH range without showing any type of device deterioration or lack of performance over time. Full article
(This article belongs to the Special Issue Chemosensors in Biological Challenges)
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13 pages, 2433 KiB  
Article
Quantum Dots-Sensitized High Electron Mobility Transistor (HEMT) for Sensitive NO2 Detection
by Zhixiang Hu, Licheng Zhou, Long Li, Binzhou Ying, Yunong Zhao, Peng Wang, Huayao Li, Yang Zhang and Huan Liu
Chemosensors 2023, 11(4), 252; https://doi.org/10.3390/chemosensors11040252 - 18 Apr 2023
Cited by 2 | Viewed by 1629
Abstract
Colloidal quantum dots (CQDs) are gaining increasing attention for gas sensing applications due to their large surface area and abundant active sites. However, traditional resistor-type gas sensors using CQDs to realize molecule recognition and signal transduction at the same time are associated with [...] Read more.
Colloidal quantum dots (CQDs) are gaining increasing attention for gas sensing applications due to their large surface area and abundant active sites. However, traditional resistor-type gas sensors using CQDs to realize molecule recognition and signal transduction at the same time are associated with the trade-off between sensitivity and conductivity. This limitation has restricted their range of practical applications. In this study, we propose and demonstrate a monolithically integrated field-effect transistor (FET) gas sensor. This novel FET-type gas sensor utilizes the capacitance coupling effect of the CQD sensing film based on a floating gate, and the quantum capacitance plays a role in the capacitance response of the CQD sensing film. By effectively separating the gate sensing film from the two-dimensional electron gas (2DEG) conduction channel, the lead sulfide (PbS) CQD gate-sensitized FET gas sensor offers high sensitivity, a high signal-to-noise ratio, and a wide range, with a real-time response of sub-ppb NO2. This work highlights the potential of quantum dot-sensitized FET gas sensors as a practical solution for integrated gas sensor chip applications using CQDs. Full article
(This article belongs to the Special Issue Chemical Sensors Based on Low-Dimensional Semiconductors)
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26 pages, 5964 KiB  
Review
Metal Oxide Semiconductor Gas Sensors for Lung Cancer Diagnosis
by Guangyao Li, Xitong Zhu, Junlong Liu, Shuyang Li and Xiaolong Liu
Chemosensors 2023, 11(4), 251; https://doi.org/10.3390/chemosensors11040251 - 17 Apr 2023
Cited by 13 | Viewed by 3419
Abstract
Lung cancer is the most prevalent severe illness in both sexes and all ages and the leading cause of cancer-related deaths globally. Late-stage diagnosis is the primary cause of its high mortality rate. Therefore, the management of lung cancer needs early-stage screening. Breath [...] Read more.
Lung cancer is the most prevalent severe illness in both sexes and all ages and the leading cause of cancer-related deaths globally. Late-stage diagnosis is the primary cause of its high mortality rate. Therefore, the management of lung cancer needs early-stage screening. Breath analysis is a non-invasive, low-cost, and user-friendly approach to diagnosing lung cancer. Among the various types of breath sensors, MOS gas sensors are preferred due to their high gas responses, fast response times, robustness, and lower price. This review focuses on the critical role of MOS gas sensors in detecting VOCs in lung cancer patients’ exhaled breath. It introduces the basic working mechanism of MOS gas-sensitive materials, summarizes some high-performance MOS materials suitable for detecting potential lung cancer biomarkers and provides performance enhancement strategies. The review also briefly introduces the sensor array and its pattern recognition algorithm. Finally, we discuss the challenges in developing MOS gas sensors for lung cancer screening and present the prospect of using the e-nose for large-scale early lung cancer screening. Full article
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12 pages, 11540 KiB  
Article
Enhancing the Potentiometric H2 Sensing of Pr0.1Ce0.9O2−δ Using Fe2O3 Surface Modification
by Liang Wang and Jianxin Yi
Chemosensors 2023, 11(4), 250; https://doi.org/10.3390/chemosensors11040250 - 17 Apr 2023
Cited by 1 | Viewed by 1291
Abstract
Monitoring the concentration of hydrogen is very important as it is a flammable and explosive gas. Non-Nernstian potentiometric hydrogen sensors hold promising potentials for the sensitive detection of hydrogen. This paper reports the improved H2-sensing performance of a mixed oxide ion-electron [...] Read more.
Monitoring the concentration of hydrogen is very important as it is a flammable and explosive gas. Non-Nernstian potentiometric hydrogen sensors hold promising potentials for the sensitive detection of hydrogen. This paper reports the improved H2-sensing performance of a mixed oxide ion-electron conducting (MIEC) Pr0.1Ce0.9O2−δ (PCO) electrode using Fe2O3 surface modification. The Fe2O3-modified PCO exhibited a high response of −184.29 mV to 1000 ppm H2 at 450 °C. The response values exhibited a linear or logarithmic dependence on the H2 concentration for below or above 20 ppm, respectively. A sensitivity of −74.9 mV/decade in the concentration range of 20–1000 ppm was achieved, and the theoretical limit of detection was calculated to be 343 ppb. Moreover, a power-law relationship between the response time and the concentration value was also found. Electrochemical impedance analyses revealed that the excellent H2-sensing performance may be attributed to the large ratio of the electrochemical activity of the hydrogen oxidation reaction (HOR) over the oxygen exchange reaction (OER). In addition, the distribution of relaxation time (DRT) results reveal that the enhanced electrochemical kinetics caused by H2 presence in air is mainly related to acceleration of the electrode surface processes. Full article
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13 pages, 5546 KiB  
Communication
Pyranine Immobilized on Aminopropyl-Modified Mesoporous Silica Film for Paraquat Detection
by Sudarat Sombatsri, Krittanun Deekamwong, Pongtanawat Khemthong and Sanchai Prayoonpokarach
Chemosensors 2023, 11(4), 249; https://doi.org/10.3390/chemosensors11040249 - 17 Apr 2023
Viewed by 1721
Abstract
An optical sensor based on pyranine immobilized on aminopropyl-modified mesoporous silica films was developed for paraquat detection in aqueous solutions. An electrochemically assisted self-assembly method was used to deposit mesoporous silica film on fluorine-doped tin oxide glass. The obtained films were modified with [...] Read more.
An optical sensor based on pyranine immobilized on aminopropyl-modified mesoporous silica films was developed for paraquat detection in aqueous solutions. An electrochemically assisted self-assembly method was used to deposit mesoporous silica film on fluorine-doped tin oxide glass. The obtained films were modified with various concentrations of 3-aminopropyl triethoxysilane (APTES) before the immobilization of pyranine. Cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and fluorescence spectroscopy were used to characterize the films. Pyranine-immobilized films gave an emission at 506 nm with an excitation at 450 nm. The fluorescence signal was quenched in the presence of paraquat. The films modified with 3% APTES provided the optimum response to paraquat. The developed films had a linear response to paraquat in the concentration range of 1 to 10 ppm at the optimum conditions, with a detection limit of 0.80 ppm. The developed method was used to quantify paraquat in sugarcane peel and tap water samples with satisfactory results. Full article
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15 pages, 2209 KiB  
Article
The Human Nose as a Chemical Sensor in the Perception of Coffee Aroma: Individual Variability
by Roberto Crnjar, Paolo Solari and Giorgia Sollai
Chemosensors 2023, 11(4), 248; https://doi.org/10.3390/chemosensors11040248 - 17 Apr 2023
Cited by 2 | Viewed by 1666
Abstract
The flavor of foods and beverages is generally composed of a mixture of volatile compounds, however not all the molecules that form an aroma are sensorially relevant. The odor-active compounds present in a mixture are different for each subject, both in quantitative and [...] Read more.
The flavor of foods and beverages is generally composed of a mixture of volatile compounds, however not all the molecules that form an aroma are sensorially relevant. The odor-active compounds present in a mixture are different for each subject, both in quantitative and qualitative terms. This means that the ability of the human nose to act as a chemical sensor varies among individuals. In this study, we used the headspace of roasted coffee beans as a complex olfactory stimulus and, by means of the coupled Gas Chromatography-Olfactometry (GC-O) technique, the single components of coffee flavor were separated. Each subject, previously classified for his/her olfactory status (normosmic, hyposmic or anosmic) by means of the Sniffin’ Sticks battery (composed of Threshold, Discrimination and Identification subtests), had to identify and evaluate each smelled molecule. The results show that the individual ability to detect individual compounds during the GC-O experiments and the odor intensity reported during the sniffing of pen #10 (the pen of the identification test) containing coffee aroma were related to TDI olfactory status (based on the score obtained from the sum composed of Threshold, Discrimination and Identification scores). We also found that the number of total molecules and of molecules smelling of coffee is linearly related to the TDI olfactory score. Finally, the odor intensity reported when sniffing pen #10 containing coffee aroma is positively correlated with the number of molecules detected and the average intensity reported. In conclusion, our findings show that the human perception of both individual compounds and complex odors is strongly conditioned by the olfactory function of subjects. Full article
(This article belongs to the Special Issue Gas Sensors for Monitoring Environmental Changes)
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16 pages, 6425 KiB  
Article
Sensitive and Reversible Ammonia Gas Sensor Based on Single-Walled Carbon Nanotubes
by Abniel Machín, María Cotto, José Duconge, Carmen Morant, Florian I. Petrescu and Francisco Márquez
Chemosensors 2023, 11(4), 247; https://doi.org/10.3390/chemosensors11040247 - 16 Apr 2023
Cited by 4 | Viewed by 1932
Abstract
The present study reports on the fabrication and performance of ammonia sensors based on single-walled carbon nanotubes (SWCNTs) coated with gold nanoparticles (AuNPs). The AuNPs were incorporated onto the SWCNTs using two different methods: sputtering and chemical deposition. The sensors were exposed to [...] Read more.
The present study reports on the fabrication and performance of ammonia sensors based on single-walled carbon nanotubes (SWCNTs) coated with gold nanoparticles (AuNPs). The AuNPs were incorporated onto the SWCNTs using two different methods: sputtering and chemical deposition. The sensors were exposed to controlled concentrations of ammonia at two temperatures, namely, 25 °C and 140 °C, and their response was monitored through successive cycles of ammonia exposure (0.5 ppm and 1.0 ppm) and nitrogen purging. The results demonstrate that the sputtering-based deposition of the AuNPs on SWCNTs led to the best sensor performance, characterized by a rapid increase in resistance values (tresp = 12 s) upon exposure to ammonia and an efficient recovery at 140 °C (trec = 52 s). By contrast, the sensor with chemically impregnated AuNPs exhibited a slower response time (tresp = 25 s) and the same recovery time (trec = 52 s). Additionally, a novel device was developed that combined MoS2-AuNPs (sputtering)-SWCNTs. This sensor was obtained by impregnating nanosheets of MoS2 onto AuNPs (sputtering)-SWCNTs showing improved sensor performance compared to the devices with only AuNPs. In this case, the sensor exhibited a better behavior with a faster recovery of resistance values, even at room temperature. Overall, the study provides valuable insights into the fabrication and optimization of SWCNT-based ammonia sensors for various applications, particularly in detecting and quantifying small amounts of ammonia (concentrations below 1 ppm). Full article
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13 pages, 4189 KiB  
Article
Sensitive Evanescence-Field Waveguide Interferometer for Aqueous Nitro-Explosive Sensing
by Wen Wang, Guowei Deng, Zhanwei Hu, Kaixin Chen and Jieyun Wu
Chemosensors 2023, 11(4), 246; https://doi.org/10.3390/chemosensors11040246 - 15 Apr 2023
Cited by 3 | Viewed by 1450
Abstract
The development of novel chemical nitro-explosive sensors with high sensitivity, low cost and a compact size is essential for homeland security, environmental protection and addressing military challenges. Polymeric optical waveguides based on refractive index sensing are widely used in biochemical detection due to [...] Read more.
The development of novel chemical nitro-explosive sensors with high sensitivity, low cost and a compact size is essential for homeland security, environmental protection and addressing military challenges. Polymeric optical waveguides based on refractive index sensing are widely used in biochemical detection due to their advantages of large-scale integration, low cost, high sensitivity and anti-electromagnetic interference. In this study, we designed and fabricated a polymer waveguide Mach–Zehnder interferometer (MZI) sensor to detect 2,4-dinitrotoluene (DNT) in water. One phase shifter of the MZI waveguide was functionalized by coating a thin cladding layer of polycarbonate with dipolar chromophores and used as the sensing arm; the other arm was coated with passive epoxy resin cladding and used as the reference arm. The phase difference between the two arms of the MZI was modulated using the refractive index (RI) change in the polycarbonate cladding when dipolar chromophores interacted with electro-deficient DNT. The theoretical sensitivity of the designed MZI can reach up to 24,696 nm/RIU. When used for explosive detection, our fabricated sensor had a maximum wavelength shift of 4.465 nm and good linear relation, with an R2 of 0.96 between the wavelength shift and a concentration ranging from 3.5 × 10−5 to 6.3 × 10−4 mol/L. The sensitivity of our device was 6821.6 nm/(mol/L). The design of an unbalanced MZI sensor, together with the sensing material, provides a new approach to using low-cost, compact and highly sensitive devices for in-field explosive detection. Full article
(This article belongs to the Collection Advances of Chemical and Biosensors in China)
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15 pages, 1233 KiB  
Article
A Novel Highly Sensitive Chemiluminescence Enzyme Immunoassay with Signal Enhancement Using Horseradish Peroxidase-Luminol-Hydrogen Peroxide Reaction for the Quantitation of Monoclonal Antibodies Used for Cancer Immunotherapy
by Ibrahim A. Darwish, Nourah Z. Alzoman and Nehal N. Khalil
Chemosensors 2023, 11(4), 245; https://doi.org/10.3390/chemosensors11040245 - 14 Apr 2023
Cited by 2 | Viewed by 2459
Abstract
The development and validation of a novel enhanced chemiluminescence enzyme immunoassay (CLEIA) with excellent sensitivity for the quantification of monoclonal antibodies (mAbs) used for immunotherapy of cancer are described in this paper for the first time. The 96-microwell plates were used for the [...] Read more.
The development and validation of a novel enhanced chemiluminescence enzyme immunoassay (CLEIA) with excellent sensitivity for the quantification of monoclonal antibodies (mAbs) used for immunotherapy of cancer are described in this paper for the first time. The 96-microwell plates were used for the assay procedures, which involved the non-competitive binding reaction to a specific antigen. The immune complex of the antigen-mAb formed on the internal surface of the plate wells was quantified by a novel chemiluminescence (CL)-producing horseradish peroxidase (HRP) reaction. The reaction employed 4-(imidazol-1-yl)phenol (IMP) as a highly potent signal enhancer for the HRP-luminol–hydrogen peroxide (H2O2) CL reaction. The proposed CLEIA was developed for bevacizumab (BEV), as a representative example for mAbs. The CLEIA was validated in accordance with the immunoassay validation for bioanalysis standards, and all of the validation criteria were met. The assay’s limit of detection (LOD) and limit of quantitation (LOQ) were 9.3 and 28.2 pg mL−1, respectively, with a working dynamic range of 10–400 pg mL−1. The assay enables the accurate and precise quantitation of mAbs in human plasma samples without any interference from endogenous substances and/or plasma matrix. The novel CLEIA was compared in terms of dynamic range and sensitivity with other pre-validated enzyme-linked immunosorbent assay (ELISA) using HRP/colorimetric substrate as a detection system and the observed differences were explained. The CLEIA protocol’s ease of use, high throughput, and simplicity allows to analyze numerous samples in clinical settings. The proposed CLEIA has a significant benefit in the assessment of mAbs in clinical settings for the evaluation of their pharmacokinetics, pharmacodynamics, therapeutic drug monitoring, and refining their safety profiles, opening a new era for a better understanding of pharmacodynamics at the cellular level. Full article
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46 pages, 5210 KiB  
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 9 | Viewed by 3836
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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16 pages, 5594 KiB  
Article
Functionalized Three–Dimensional Graphene Containing Chitosan and Bovine Serum Albumin for Recognizing Chiral Drug Intermediates
by Sha Li, Wenyan Yao, Licheng Xie and Yan Jiang
Chemosensors 2023, 11(4), 243; https://doi.org/10.3390/chemosensors11040243 - 14 Apr 2023
Viewed by 1347
Abstract
Chiral enantiomer recognition has important research significance in the field of analytical chemistry research. At present, most prepared chiral sensors are used for recognizing amino acids, while they are rarely used in the identification of drug intermediates. This work found that combining CS [...] Read more.
Chiral enantiomer recognition has important research significance in the field of analytical chemistry research. At present, most prepared chiral sensors are used for recognizing amino acids, while they are rarely used in the identification of drug intermediates. This work found that combining CS and reduced graphene oxide can enhance conductivity, increasing the recognition effect by connecting CS with BSA. Based on the above preparation, a new type of chiral sensor (3D–rGO–CS–BSA) was synthesized for the identification of drug intermediates, including the 1–Boc–3–hydroxypyrrolidine enantiomer. An obvious difference was achieved (IR/IS = 2.82) in the oxidation peak currents between the two enantiomers. The detection limits of the R–enantiomer and S–enantiomer were 4.85 nM and 11.76 nM, respectively. The proposed electrochemical sensing platform also has better potential for detecting the percentage content of mixed chiral enantiomer drugs. Full article
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14 pages, 3917 KiB  
Article
In-Situ Formation of NiFe-MOF on Nickel Foam as a Self-Supporting Electrode for Flexible Electrochemical Sensing and Energy Conversion
by Shuting Weng, Qi An, Yanchao Xu, Yang Jiao and Jianrong Chen
Chemosensors 2023, 11(4), 242; https://doi.org/10.3390/chemosensors11040242 - 13 Apr 2023
Cited by 2 | Viewed by 2450
Abstract
Ni- and Fe-based metal-organic frameworks (NiFe-MOFs) have abundant valence states and have the potential to be used as bifunctional electrode materials. However, unannealed NiFe-MOFs are still not widely used in electrode materials, including electrochemical sensing, supercapacitors, and overall water splitting. In addition, the [...] Read more.
Ni- and Fe-based metal-organic frameworks (NiFe-MOFs) have abundant valence states and have the potential to be used as bifunctional electrode materials. However, unannealed NiFe-MOFs are still not widely used in electrode materials, including electrochemical sensing, supercapacitors, and overall water splitting. In addition, the direct growth of active material on a conductive carrier has been developed as a binder-free strategy for electrode preparation. This strategy avoids the use of insulating binders and additional electrode treatments, simplifies the preparation process of the NiFe-MOFs, and improves the conductivity and mechanical stability of the electrode. Therefore, in this study, we employed a simple solvothermal method combined with an in situ growth technique to directly grow NiFe-MOF-X (X = 4, 8, 12) nanomaterials of different sizes and morphologies on nickel foam at low reaction temperatures and different reaction times. The NiFe-MOF-8 electrode exhibited high capacitive properties, with an area-specific capacitance of 5964 mF cm−2 at 2 mA cm−2 and excellent durability. On the other hand, NiFe-MOF-12 exhibited strong catalytic activity in electrocatalytic tests performed in a 1 M KOH aqueous solution, demonstrating hydrogen evolution reaction (η10 = 150 mV) and oxygen evolution reaction (η50 = 362 mV) activities. The electrochemical sensing tests demonstrated a good response to BPA. Overall, our results suggest that the direct growth of NiFe-MOFs on nickel foam using a simple solvothermal method combined with an in situ growth technique is a promising strategy. Full article
(This article belongs to the Special Issue Recent Advances in Electrode Materials for Electrochemical Sensing)
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26 pages, 16498 KiB  
Review
Recent Advances in Small Molecular Fluorescence Probes for Fatty Liver Diseases
by Bo Liu, Honghui Yin, Yaxiong Li, Guojiang Mao, Sheng Yang and Kai Zhang
Chemosensors 2023, 11(4), 241; https://doi.org/10.3390/chemosensors11040241 - 12 Apr 2023
Cited by 3 | Viewed by 2165
Abstract
Fatty liver diseases are a spectrum of liver disorders consisting of the benign fatty liver, which could eventually lead to cirrhosis or even hepatocellular cancer (HCC) without timely treatment. Therefore, early diagnosis is crucial for fatty liver diseases. Liver biopsy is regarded as [...] Read more.
Fatty liver diseases are a spectrum of liver disorders consisting of the benign fatty liver, which could eventually lead to cirrhosis or even hepatocellular cancer (HCC) without timely treatment. Therefore, early diagnosis is crucial for fatty liver diseases. Liver biopsy is regarded as the gold standard in the diagnosis of fatty liver diseases. However, it is not recommended for routine use due to its invasiveness and complicated operation. Thus, it is urgent to diagnose fatty liver diseases with non-invasive and precise methods. In this regard, fluorescence imaging technology has attracted intensive attention and become a robust non-invasive method for fatty liver visualization, and a series of fluorescent probes are being intensively designed to track the biomarkers in fatty liver. In this brief review, the small molecular fluorescent probes employed in fatty liver are summarized, mainly focusing on the last four years. Moreover, current opportunities and challenges in the development of fluorescent probes for fatty liver will be highlighted. Full article
(This article belongs to the Special Issue Fluorescent Probe and Biosensing)
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11 pages, 2776 KiB  
Communication
Ag-ZnS Embedded Polymeric Receptors for the Recognition of Human Serum Albumin
by Amara Nasrullah, Muhammad Zahid, Asghar Ali, Mirza Nadeem Ahmad, Adnan Mujahid, Tajamal Hussain, Usman Latif, Muhammad Imran Din and Adeel Afzal
Chemosensors 2023, 11(4), 240; https://doi.org/10.3390/chemosensors11040240 - 12 Apr 2023
Viewed by 1938
Abstract
The detection of human serum albumin (HSA) is of significant clinical importance in disease diagnoses. In this work, polymer-based synthetic receptors are designed by incorporating Ag-ZnS microspheres in molecularly imprinted poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MIPs) for the gravimetric detection of HSA. Among different [...] Read more.
The detection of human serum albumin (HSA) is of significant clinical importance in disease diagnoses. In this work, polymer-based synthetic receptors are designed by incorporating Ag-ZnS microspheres in molecularly imprinted poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MIPs) for the gravimetric detection of HSA. Among different compositions of Ag-ZnS@MIPs, MIPs having methacrylic acid and ethylene glycol dimethacrylate volume ratio of 3:2 exhibit enhanced HSA sensitivity in the concentration range of 5–200 ng/mL. A remarkably low threshold limit of detection (LOD = 0.364 ng/mL) is achieved with quartz crystal microbalance (QCM) based gravimetric sensors. Furthermore, the Ag-ZnS@MIPs/QCM sensors show high selectivity for HSA compared to other proteins, e.g., bovine serum albumin (BSA), glycoprotein, ribonuclease, and lysozyme. Hence, the gravimetric quantification of HSA realizes a highly sensitive, selective, and label-free detection mechanism with a limit of quantification down to 1.1 ng/mL. Full article
(This article belongs to the Section Nanostructures for Chemical Sensing)
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15 pages, 6567 KiB  
Article
Combinatorial Material Strategy: Parallel Synthesis and High-Throughput Screening of WO3 Nanoplates Decorated with Noble Metals for VOCs Sensor
by Yanjia Ma, Ming Hou, Li Yang, Jiyun Gao, Guozhu Zhang, Ronghui Guo and Shenghui Guo
Chemosensors 2023, 11(4), 239; https://doi.org/10.3390/chemosensors11040239 - 11 Apr 2023
Cited by 1 | Viewed by 1254
Abstract
In this study, we report on the rapid preparation of WO3 nanoplates decorated with noble metals and evaluate their gas-sensing performance using a high-throughput screening technique. The incorporation of Pd significantly enhanced the gas-sensing properties, and, among all of the samples tested, [...] Read more.
In this study, we report on the rapid preparation of WO3 nanoplates decorated with noble metals and evaluate their gas-sensing performance using a high-throughput screening technique. The incorporation of Pd significantly enhanced the gas-sensing properties, and, among all of the samples tested, the WO3 nanoplate containing 0.3 mol% Pd exhibited the highest response to 100 ppm xylene at 250 °C (Ra/Rg = 131.2), which was almost 56 times greater than that of the pure WO3 sample. Additionally, this sample demonstrated rapid response and recovery times (τresponse = 3.9 s and τrecovery = 189.2 s, respectively). The nanoplate samples were also classified and screened using cluster analysis, and the selected samples were optimized for use in a sensor array. By applying principal component analysis and Fisher discriminant analysis, four typical gases were identified and a potential sensitization mechanism was elucidated. Full article
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13 pages, 1883 KiB  
Article
Low-Cost, High-Sensitivity Paper-Based Bacteria Impedance Sensor Based on Vertical Flow Assay
by Yifan Long, Zhehong Ai, Longhan Zhang, Han Zhang, Jing Jiang and Gang Logan Liu
Chemosensors 2023, 11(4), 238; https://doi.org/10.3390/chemosensors11040238 - 11 Apr 2023
Viewed by 1566
Abstract
This study proposes a low-cost, portable paper-fluidic vertical flow assay bacterium counter with high accuracy. We designed sensors with low fabrication costs based on e-beam evaporation and three-dimensional printing based on the impedance measurement principle. Interdigitated (IDT) electrodes were coated on the filter [...] Read more.
This study proposes a low-cost, portable paper-fluidic vertical flow assay bacterium counter with high accuracy. We designed sensors with low fabrication costs based on e-beam evaporation and three-dimensional printing based on the impedance measurement principle. Interdigitated (IDT) electrodes were coated on the filter membrane by e-beam evaporation with a shadow mask. We could print wafer-scale frames with low melting temperature three-dimensional-printing materials for confining liquid bacterial samples within the IDT sensing region. This novel fabrication technique significantly reduced the chip’s cost to less than 1% of that of silicon-based chips. Two equivalent circuit models were proposed for different concentration ranges to analyze the principle of paper-based impedance bacterial sensors. We proposed an improved model based on the Randles model for low concentrations by considering the leaky double-layer capacitor effect and spherical diffusion from the nano-structural electrodes of the gold-coated filter membrane. The phenomenon in which charge transfer resistance, Rct, declines at high concentration ranges was found and explained by the pearl chain effect. The pearl effect could cause a false-negative at high concentrations. We modeled the pearl chain effect as an R and C, connected parallel to the low-concentration model. When users properly applied both models for analyses, this sensor could quantitatively measure cell concentrations from 400 to 400 M per milliliter with superior linearity. Full article
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15 pages, 2092 KiB  
Article
Trypsin-Based Chemoenzymatic Assay for Detection of Pollutants and Safety Assessment of Food Additives
by Elena N. Esimbekova, Irina G. Torgashina, Elena V. Nemtseva, Anna A. Antashkevich, Polina Yu. Sasova and Valentina A. Kratasyuk
Chemosensors 2023, 11(4), 237; https://doi.org/10.3390/chemosensors11040237 - 10 Apr 2023
Cited by 3 | Viewed by 1621
Abstract
Chemoenzymatic assay systems are widely used to detect toxicants in various samples, including food and environment specimens. These methods are based on the ability of various types of toxicant to specifically inhibit/activate the functions of individual enzymes or enzyme systems. The present study [...] Read more.
Chemoenzymatic assay systems are widely used to detect toxicants in various samples, including food and environment specimens. These methods are based on the ability of various types of toxicant to specifically inhibit/activate the functions of individual enzymes or enzyme systems. The present study examines the possibility of using the proteolytic enzyme trypsin as a specific marker to detect protease inhibitors in different samples. The study shows that trypsin activity is not affected by various heavy metals, pesticides, or quinones at levels considerably greater than their maximum allowable concentrations (MACs) in water bodies. At the same time, the IC50 value for the food preservative potassium sorbate (E202) is 15 mg/L, which is substantially lower than its acceptable daily intake (ADI). The quenching of trypsin fluorescence in the presence of potassium sorbate suggests that inhibition could occur due to the binding of the preservative to the enzyme in the region adjacent to the active center. The trypsin was immobilized in starch gel to ensure its stability in the enzyme inhibition based assay. Single-use reagents were prepared as dry starch disks that could be stored over long periods. Their sensitivity to copper (II) chloride, potassium sorbate, and chromium (III) chloride was similar to the sensitivity of the free trypsin. Full article
(This article belongs to the Special Issue Advanced Techniques for the Analysis of Protein and RNA)
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13 pages, 3353 KiB  
Article
A Method of Ultra-Low Power Consumption Implementation for MEMS Gas Sensors
by Yu Bing, Fuyun Zhang, Jiatong Han, Tingting Zhou, Haixia Mei and Tong Zhang
Chemosensors 2023, 11(4), 236; https://doi.org/10.3390/chemosensors11040236 - 10 Apr 2023
Cited by 4 | Viewed by 1972
Abstract
In recent years, there has been a growing need for the development of low-power gas sensors. This paper proposes pulse heating and a corresponding measurement strategy using a Pulse Width Modulation (PWM) signal to realize the ultra-low power consumption for metal oxide semiconductor [...] Read more.
In recent years, there has been a growing need for the development of low-power gas sensors. This paper proposes pulse heating and a corresponding measurement strategy using a Pulse Width Modulation (PWM) signal to realize the ultra-low power consumption for metal oxide semiconductor (MOS) gas sensors. A Micro-Hot-Plate (MHP) substrate was chosen to investigate the temperature and power characteristics of the MHP under different applied heating methods. The temperature of this given substrate could respond to the applied voltage within 0.1 s, proving the prac ticability of a pulse heating strategy. In addition, Pd-doped SnO2 was synthesized as the sensing material in the implementation of an ultra-low power gas sensor. The sensing performance and power consumption under different conditions were compared in the detection of reducing gases such as ethanol (C2H5OH) and formaldehyde (HCHO). Additionally, the results revealed that the sensor could work under PWM excitation while reducing the operating power to less than 1mW. The features shown in the measurements provide the feasibility for MOS gas sensors’ application in wearable and portable devices. Full article
(This article belongs to the Special Issue Chemical Sensors Based on Low-Dimensional Semiconductors)
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14 pages, 3410 KiB  
Article
Three Generations of Surface Nanocomposites Based on Hexagonally Ordered Gold Nanoparticle Layers and Their Application for Surface-Enhanced Raman Spectroscopy
by Shireen Zangana, Tomáš Lednický and Attila Bonyár
Chemosensors 2023, 11(4), 235; https://doi.org/10.3390/chemosensors11040235 - 10 Apr 2023
Cited by 5 | Viewed by 1972
Abstract
The fabrication technology of surface nanocomposites based on hexagonally ordered gold nanoparticle (AuNP) layers (quasi-arrays) and their possible application as surface-enhanced Raman spectroscopy (SERS) substrates are presented in this paper. The nanoparticle layers are prepared using a nanotextured template formed by porous anodic [...] Read more.
The fabrication technology of surface nanocomposites based on hexagonally ordered gold nanoparticle (AuNP) layers (quasi-arrays) and their possible application as surface-enhanced Raman spectroscopy (SERS) substrates are presented in this paper. The nanoparticle layers are prepared using a nanotextured template formed by porous anodic alumina (PAA) and combined with gold thin-film deposition and subsequent solid-state dewetting. Three types of hexagonal arrangements were prepared with different D/D0 values (where D is the interparticle gap, and D0 is the diameter of the ellipsoidal particles) on a large surface area (~cm2 range), namely, 0.65 ± 0.12, 0.33 ± 0.10 and 0.21 ± 0.09. The transfer of the particle arrangements to transparent substrates was optimized through three generations, and the advantages and disadvantages of each transfer technology are discussed in detail. Such densely packed nanoparticle arrangements with high hot-spot density and tunable interparticle gaps are very beneficial for SERS applications, as demonstrated with two practical examples. The substrate-based enhancement factor of the nanocomposites was determined experimentally using a DNA monolayer and was found to be between 4 × 104 and 2 × 106 for the different particle arrangements. We also determined the sensing characteristics of a small dye molecule, rhodamine 6G (R6G). By optimizing the experimental conditions (e.g., optimizing the laser power and the refractive index of the measurement medium with an ethylene-glycol/water mixture), concentrations as low as 10−16 M could be detected at 633 nm excitation. Full article
(This article belongs to the Special Issue Nanocomposites for SERS Sensing)
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13 pages, 1990 KiB  
Article
An Impedimetric Biosensing Strategy Based on BicyclicPeptides as Bioreceptors for Monitoring h-uPA Cancer Biomarkers
by Giulia Moro, Leonardo Ferrari, Alessandro Angelini and Federico Polo
Chemosensors 2023, 11(4), 234; https://doi.org/10.3390/chemosensors11040234 - 9 Apr 2023
Cited by 2 | Viewed by 2255
Abstract
In the era of liquid biopsies, the reliable and cost-effective detection and screening of cancer biomarkers has become of fundamental importance, thus paving the way for the advancement of research in the field of point-of-care testing and the development of new methodologies and [...] Read more.
In the era of liquid biopsies, the reliable and cost-effective detection and screening of cancer biomarkers has become of fundamental importance, thus paving the way for the advancement of research in the field of point-of-care testing and the development of new methodologies and technologies. Indeed, the latter ones can help designing advanced diagnostic tools that can offer portability, ease of use with affordable production and operating costs. In this respect, impedance-based biosensing platforms might represent an attractive alternative. In this work, we describe a proof-of-concept study aimed at designing portable impedimetric biosensors for the monitoring of human urokinase-type plasminogen activator (h-uPA) cancer biomarker by employing small synthetic receptors. Aberrant levels of h-uPA were correlated with different types of cancers. Herein, we report the use of two bicyclic peptides (P2 and P3) which have been engineered to bind h-uPA with high affinity and exquisite specificity. The synthetic receptors were immobilized via biotin-streptavidin chemistry on the surface of commercial screen-printed electrodes. The impedimetric changes in the electrode/solution interface upon incubation of spiked h-uPA samples in the presence of a redox probe were followed via electrochemical impedance spectroscopy. The P3-based impedimetric assay showed the best outcomes in terms of dynamic range and linearity (0.01–1 μg mL−1) and sensitivity (LOD = 9 ng mL−1). To fully assess the performances of P3 over P2, and to compare the label-free architecture vs. labelled architecture, a voltammetric assay was also developed. Full article
(This article belongs to the Special Issue Electrochemical Impedance Spectroscopy (EIS): Biosensing Applications)
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30 pages, 9176 KiB  
Review
Recent Advances in the Application of Nanozymes in Amperometric Sensors: A Review
by Liu Tong, Lina Wu, Enben Su, Yan Li and Ning Gu
Chemosensors 2023, 11(4), 233; https://doi.org/10.3390/chemosensors11040233 - 9 Apr 2023
Cited by 2 | Viewed by 2839
Abstract
Amperometric sensors evaluate current changes that occur as a result of redox reactions under constant applied potential. These changes in current intensity are stoichiometrically related to the concentration of analytes. Owing to their unique features, such as fast reaction velocity, high specificity, abundant [...] Read more.
Amperometric sensors evaluate current changes that occur as a result of redox reactions under constant applied potential. These changes in current intensity are stoichiometrically related to the concentration of analytes. Owing to their unique features, such as fast reaction velocity, high specificity, abundant existence in nature, and feasibility to be immobilized, enzymes are widely used by researchers to improve the performance of amperometric sensors. Unfortunately, natural enzymes have intrinsic disadvantages due to their protein structures. To overcome these proteinic drawbacks, scientists have developed nanozymes, which are nanomaterials with enzymatic properties. As the result of significant advances in materiology and analytical science, great progress has been achieved in the development of nanozyme-based amperometric sensors with outstanding performance. To highlight achievements made in recent years, we first summarize the development directions of nanozyme-based amperometric sensors. Then, H2O2 sensors, glucose sensors, sensors combining natural enzymes with nanozymes, and sensors targeting untraditional specific targets will be introduced in detail. Finally, the current challenges regarding the nanozymes utilized in amperometric sensors are discussed and future research directions in this area are suggested. Full article
(This article belongs to the Section Electrochemical Devices and Sensors)
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14 pages, 2774 KiB  
Article
Rapid Fabrication of Homogeneous Submicron Silver Particles via a Microfluidic Chip and Use as a SERS Detection Substrate
by Junjie Chen, Suyang Li, Fuqi Yao, Wanbing Xu, Yunfeng Li, Qiang Chen and Pei Liang
Chemosensors 2023, 11(4), 232; https://doi.org/10.3390/chemosensors11040232 - 7 Apr 2023
Cited by 5 | Viewed by 1627
Abstract
Silver particles have been widely used in SERS detection as an enhancement substrate. The large-scale synthesis of Ag particles with controllable size and shape is still a challenge. We demonstrate a high-throughput method for the preparation of monodisperse submicron silver particles using S-shaped [...] Read more.
Silver particles have been widely used in SERS detection as an enhancement substrate. The large-scale synthesis of Ag particles with controllable size and shape is still a challenge. We demonstrate a high-throughput method for the preparation of monodisperse submicron silver particles using S-shaped microfluidic chips. Submicron silver particles were prepared by a simplified reduction method. By adjusting the concentration of the reducing agent ascorbic acid and the stabilizer PVP, the particle size and morphology could be controlled, obtaining a size distribution of 1–1.2 μm for flower-like silver particles and a size distribution of 0.5–0.7 μm for quasi-spherical silver particles. This microfluidic system can be used to fabricate submicron silver particles on a large scale, continuously and stably, with a production efficiency of around 1.73 mg/min. The synthesized submicron silver particles could realize ultra-sensitive SERS detection, and the lowest concentration of rhodamine 6G (R6G) that could be detected was 10−9 M. Full article
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12 pages, 2332 KiB  
Article
Fully Printed Organic Phototransistor Array with High Photoresponse and Low Power
by Yuan Tan, Xinwei Zhang, Rui Pan, Wei Deng, Jialin Shi, Tianxing Lu, Junye Zhang, Jiansheng Jie and Xiujuan Zhang
Chemosensors 2023, 11(4), 231; https://doi.org/10.3390/chemosensors11040231 - 7 Apr 2023
Viewed by 2538
Abstract
Organic phototransistors (OPTs) as optical chemical sensors have progressed excitingly in recent years, mainly due to the development of new materials, new device structures, and device interfacial engineering. Exploiting the maximum potential of low-cost and high-throughput fabrication of organic electronics and optoelectronics requires [...] Read more.
Organic phototransistors (OPTs) as optical chemical sensors have progressed excitingly in recent years, mainly due to the development of new materials, new device structures, and device interfacial engineering. Exploiting the maximum potential of low-cost and high-throughput fabrication of organic electronics and optoelectronics requires devices that can be manufactured in a fully printed way that also have a low operation voltage. In this work, we demonstrate a fully printed fabrication process that enables the realization of a high-yield (~90%) and low-voltage OPT array. By solution printing of a high-quality organic crystalline thin film on the pre-printed electrodes, we create a van der Waals contact between the metal and organic semiconductor, resulting in a small subthreshold swing of 445 mV dec−1 with a signal amplification efficiency over 5.58 S A−1. Our OPTs thus exhibit both a low operation voltage of −1 V and a high photosensitivity over 5.7 × 105, making these devices suitable for a range of applications requiring low power consumption. We further demonstrate the capability of the low-voltage OPT array for imaging and show high imaging contrasts. These results indicate that our fabrication process may provide an entry into integrated and low-power organic optoelectronic circuits fabricated by scalable and cost-effective methods for real-world applications. Full article
(This article belongs to the Special Issue Field-Effect Transistor-Based Sensors)
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13 pages, 1735 KiB  
Article
Automatic Analysis of Isothermal Amplification via Impedance Time-Constant-Domain Spectroscopy: A SARS-CoV-2 Case Study
by Roberto G. Ramírez-Chavarría, Elizabeth Castillo-Villanueva, Bryan E. Alvarez-Serna, Julián Carrillo-Reyes, Lizeth Torres, Rosa María Ramírez-Zamora, Germán Buitrón and Luis Alvarez-Icaza
Chemosensors 2023, 11(4), 230; https://doi.org/10.3390/chemosensors11040230 - 7 Apr 2023
Cited by 4 | Viewed by 1537
Abstract
The development of sensitive and affordable testing devices for infectious diseases is essential to preserve public health, especially in pandemic scenarios. In this work, we have developed an attractive analytical method to monitor products of genetic amplification, particularly the loop-mediated isothermal amplification reaction [...] Read more.
The development of sensitive and affordable testing devices for infectious diseases is essential to preserve public health, especially in pandemic scenarios. In this work, we have developed an attractive analytical method to monitor products of genetic amplification, particularly the loop-mediated isothermal amplification reaction (RT-LAMP). The method is based on electrochemical impedance measurements and the distribution of relaxation times model, to provide the so-called time-constant-domain spectroscopy (TCDS). The proposed method is tested for the SARS-CoV-2 genome, since it has been of worldwide interest due to the COVID-19 pandemic. Particularly, once the method is calibrated, its performance is demonstrated using real wastewater samples. Moreover, we propose a simple classification algorithm based on TCDS data to discriminate among positive and negative samples. Results show how a TCDS-based method provides an alternative mechanism for label-free and automated assays, exhibiting robustness and specificity for genetic detection. Full article
(This article belongs to the Special Issue Electrochemical Detection: Analytical and Biological Challenges)
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16 pages, 3437 KiB  
Article
Efficient Monitoring of Microbial Communities and Chemical Characteristics in Incineration Leachate with Electronic Nose and Data Mining Techniques
by Zhongyuan Zhang, Qiaomei Zhou, Shanshan Qiu, Jie Zhou and Jingang Huang
Chemosensors 2023, 11(4), 229; https://doi.org/10.3390/chemosensors11040229 - 7 Apr 2023
Cited by 3 | Viewed by 1643
Abstract
Incineration leachate is a hazardous liquid waste that requires careful management due to its high levels of organic and inorganic pollutants, and it can have serious environmental and health implications if not properly treated and monitored. This study applied a novel electronic nose [...] Read more.
Incineration leachate is a hazardous liquid waste that requires careful management due to its high levels of organic and inorganic pollutants, and it can have serious environmental and health implications if not properly treated and monitored. This study applied a novel electronic nose to monitor the microbial communities and chemical characteristics of incineration leachate. The e-nose data were aggregated using principal component analysis (PCA) and T-distributed stochastic neighbor embedding (TSNE). Random forest (RF) and gradient-boosted decision tree (GBDT) algorithms were employed to establish relationships between the e-nose signals and the chemical characteristics (such as pH, chemical oxygen demand, and ammonia nitrogen) and microbial communities (including Proteobacteria, Firmicutes, and Bacteroidetes) of the incineration leachate. The PCA-GBDT models performed well in recognizing leachate samples, achieving 100% accuracy for the training set and 98.92% accuracy for the testing data without overfitting. The GBDT models based on the original data performed exceptionally well in predicting changes in chemical parameters, with R2 values exceeding 0.99 for the training set and 0.86 for the testing set. The PCA-GBDT models also demonstrated superior performance in predicting microbial community composition, achieving R2 values above 0.99 and MSE values below 0.0003 for the training set and R2 values exceeding 0.86 and MSE values below 0.015 for the testing set. This research provides an efficient monitoring method for the effective enforcement and implementation of monitoring programs by utilizing e-noses combined with data mining to provide more valuable insights compared with traditional instrumental measurements. Full article
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