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Chemosensors
Volume 10
Issue 12
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Chemosensors, Volume 10, Issue 12 (December 2022) – 50 articles

Cover Story (view full-size image): Nitrogen dioxide (NO2) is the most toxic and prevalent form of air pollutant of the NOx family; thus, the detection of this gas is significant in preventing environmental and human health problems. A new porous material obtained via the modification of a robust metal-organic framework (MOF), UiO-66(Hf), with a very small amount of meso-tetrakis(4-carboxyphenyl) N-methylpyrrolidine-fused chlorin (TCPC)—TCPC@MOF—revealed notable potential for NO2 sensing. The modified MOF-based material brings together the chemical stability of UiO-66(Hf) and the photophysical properties of the pyrrolidine-fused chlorin. Interestingly, this also represents a rare example of a chlorin derivative utilized for gas-sensing applications through emission changes. View this paper
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15 pages, 1018 KiB  
Article
Enhancing the Performance of Two Different Commercial CO2 Indicators Using Digital Colourimetric Analysis, DCA
by Lauren McDonnell, Dilidaer Yusufu, Christopher O’Rourke and Andrew Mills
Chemosensors 2022, 10(12), 544; https://doi.org/10.3390/chemosensors10120544 - 19 Dec 2022
Cited by 3 | Viewed by 2693
Abstract
Two different, commercial colourimetric CO2 indicators are made in the lab, namely one based on an indicator in solution for monitoring the level of dissolved CO2 in an aquarium, i.e., a drop check indicator, and another based on an ink, for [...] Read more.
Two different, commercial colourimetric CO2 indicators are made in the lab, namely one based on an indicator in solution for monitoring the level of dissolved CO2 in an aquarium, i.e., a drop check indicator, and another based on an ink, for monitoring the level of CO2 in breath (capnography), i.e., a correct tracheal placement indicator. The selected commercial indicators are limited currently in terms of the analytical information they provide (qualitative) as they are normally assessed by eye. Thus, in each case, for both the lab-made and commercial indicators, colour photography coupled with digital image analysis, i.e., digital colour analysis (DCA), is used to convert the colour data from the indicator into a quantitative measure of CO2 and so markedly improve the quality of the analytical information provided by original indicator. This is the first time either indicator has been studied as a quantitative analytical system. The CO2 sensitivity of each of the lab-made indicators is found to match well that of its commercial counterpart. A simple program is provided to help non-experts and experts alike to apply DCA in this way. The potential of DCA to enhance the performance of other commercial indicators is discussed briefly. Full article
(This article belongs to the Section Optical Chemical Sensors)
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11 pages, 2573 KiB  
Article
Silver-Coated Gold Nanorods as Optical Probes for the Sensitive Detection of Ascorbic Acid in Tablets
by Shuai Wen, Min Huang, Ru Cheng, Jie Gao and Jian Wang
Chemosensors 2022, 10(12), 543; https://doi.org/10.3390/chemosensors10120543 - 18 Dec 2022
Cited by 2 | Viewed by 1977
Abstract
Ascorbic acid (AA) has been widely used to improve human health since it was first found, such as resisting scurvy, enhancing immunity, and preventing arteriosclerosis. Moreover, it plays a very important role in the anti-oxidation process in the human body. Therefore, it is [...] Read more.
Ascorbic acid (AA) has been widely used to improve human health since it was first found, such as resisting scurvy, enhancing immunity, and preventing arteriosclerosis. Moreover, it plays a very important role in the anti-oxidation process in the human body. Therefore, it is of great significance to develop sensitive and accurate detection methods. In this work, silver-coated gold nanorods (Au@Ag NRs) acted as the optical probe, which could be etched with hydroxyl radicals (·OH) from the Fenton reaction between H2O2 and Fe2+, leading to the blue shift of longitudinal localized surface plasmon resonance absorption. However, as a free radical scavenger, AA was able to inhibit the Fenton reaction, resulting in a red shift of plasmon resonance absorption. Based on the change in longitudinal plasma resonance absorption of silver-coated gold nanorods, a linear relationship between the maximum longitudinal absorption wavelength and the concentration of AA was established in the range of 2.5–17.5 μM with a limit of detection (LOD) of 0.48 μM and a limit of quantitation (LOQ) of 1.61 μM, which was feasible to detect AA in tablets. Full article
(This article belongs to the Special Issue Application of Luminescent Materials for Sensing)
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8 pages, 1765 KiB  
Communication
Comparison of Colorimetric and Fluorometric Chemosensors for Protein Concentration Determination and Approaches for Estimation of Their Limits of Detection
by Anastasiya A. Mamaeva, Vladimir I. Martynov, Sergey M. Deyev and Alexey A. Pakhomov
Chemosensors 2022, 10(12), 542; https://doi.org/10.3390/chemosensors10120542 - 17 Dec 2022
Cited by 3 | Viewed by 2125
Abstract
Here, we present a direct comparison of different dyes and assays for the determination of protein concentrations. We compared the classical Bradford assay with two modern assays based on the fluorogenic dyes QuDye and ProteOrange and showed that the Bradford reagent achieved excellent [...] Read more.
Here, we present a direct comparison of different dyes and assays for the determination of protein concentrations. We compared the classical Bradford assay with two modern assays based on the fluorogenic dyes QuDye and ProteOrange and showed that the Bradford reagent achieved excellent results in the determination of protein concentrations as compared with more modern rivals. We also showed that standard approaches for determining the limit of detection (LoD) and limit of quantification (LoQ) may not work correctly with the tested dyes. We proposed a new approach that extends the standard algorithm for LoD and LoQ determination. This approach works well with both classical colorimetric and fluorogenic dyes, as well as with nontrivial fluorescent probes. Full article
(This article belongs to the Special Issue Advanced Techniques for the Analysis of Protein and RNA)
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17 pages, 4148 KiB  
Article
Multiparametric Guided-Mode Resonance Biosensor Monitoring Bulk and Surface-Film Variations
by Joseph A. Buchanan-Vega and Robert Magnusson
Chemosensors 2022, 10(12), 541; https://doi.org/10.3390/chemosensors10120541 - 17 Dec 2022
Cited by 1 | Viewed by 2097
Abstract
A guided-mode resonance (GMR) sensor with multiple resonant modes is used to measure the collection of biomolecules on the sensor surface and the index of refraction of the sensor environment (bulk). The number of sensor variables that can be monitored (biolayer index of [...] Read more.
A guided-mode resonance (GMR) sensor with multiple resonant modes is used to measure the collection of biomolecules on the sensor surface and the index of refraction of the sensor environment (bulk). The number of sensor variables that can be monitored (biolayer index of refraction, biolayer thickness, and bulk, or background, index of refraction) is determined by the number of supported resonant modes that are sensitive to changes in these variable values. The sensor we use has a grating and homogeneous layer, both of which are made of silicon nitride (Si3N4), on a quartz substrate. In this work, we simulate the sensor reflection response as a biolayer grows on the sensor surface at thicknesses from 0 to 20 nm and biolayer indices of refraction from 1.334 to 1.43 RIU; simultaneously, we vary the bulk index of refraction from 1.334 to 1.43 RIU. In the specified span of sensor variable values, the resonance wavelength shifts for 2023 permutations of the biolayer index of refraction, biolayer thickness, and bulk index of refraction are calculated and accurately inverted. Inversion is the process of taking resonant wavelength shifts, for resonant modes of a sensor, as input, and finding a quantitative variation of sensor variables as output. Analysis of the spectral data is performed programmatically with MATLAB. Using experimentally measured resonant wavelength shifts, changes in the values of biolayer index of refraction, biolayer thickness, and bulk index of refraction are determined. In a model experiment, we deposit Concanavalin A (Con A) on our sensor and subsequently deposit yeast, which preferentially bonds to Con A. A unique contribution of our work is that biolayer index and biolayer thickness are simultaneously determined. Full article
(This article belongs to the Collection Optical Chemosensors and Biosensors)
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13 pages, 2353 KiB  
Article
Virtual Filter Membranes in a Microfluidic System for Sorting and Separating Size-Based Micro Polystyrene Beads by Illumination Intensity Design in Optically Induced Dielectrophoresis (ODEP)
by Chia-Ming Yang, Ai-Yun Wu, Jian-Cyun Yu, Po-Yu Chu, Chia-Hsun Hsieh and Min-Hsien Wu
Chemosensors 2022, 10(12), 540; https://doi.org/10.3390/chemosensors10120540 - 16 Dec 2022
Cited by 3 | Viewed by 2052
Abstract
In biomedical diagnosis, the efficient separation and purification of specific targets from clinical samples is the desired first step. Herein, the concept of virtual filter membranes based on optically-induced dielectrophoresis (ODEP) manipulation in a microfluidic channel is proposed as a light screening membrane [...] Read more.
In biomedical diagnosis, the efficient separation and purification of specific targets from clinical samples is the desired first step. Herein, the concept of virtual filter membranes based on optically-induced dielectrophoresis (ODEP) manipulation in a microfluidic channel is proposed as a light screening membrane for the separation of polystyrene (PS) microparticles with three different diameters of 15.8, 10.8 and 5.8 µm. The ODEP manipulation velocity of three types of PS microparticles reacted with the color brightness setting was investigated to determine the light intensity to induce an ODEP force higher than the drag force of fluid speed. The color brightness of the light bar in three areas of the light screening membrane was selected as 60%, 70% and 100% to isolate PS microparticles with diameters of 15.8, 10.8 and 5.8 µm, respectively. With a double light bar and a flow rate of 3 µL/min, the recovery rate and isolation purity was improved by 95.1~100% and 94.4~98.6% from the mixture of three types of PS microparticles within 2 min, respectively. This proposed light screening membrane could be a candidate for the separation of small-volume and rare biomedical samples, including circulating tumor cells (CTCs) and bacteria in the blood. Full article
(This article belongs to the Section Electrochemical Devices and Sensors)
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13 pages, 2183 KiB  
Article
Nanoporous Ag-Decorated Ag7O8NO3 Micro-Pyramids for Sensitive Surface-Enhanced Raman Scattering Detection
by Linfan Guo, Haibin Tang, Xiujuan Wang, Yupeng Yuan and Chuhong Zhu
Chemosensors 2022, 10(12), 539; https://doi.org/10.3390/chemosensors10120539 - 16 Dec 2022
Cited by 7 | Viewed by 2001
Abstract
Porous noble metal nanomaterials can be employed to construct sensitive surface-enhanced Raman scattering (SERS) substrates, because the plasmonic nanopores and nanogaps of the porous materials can provide a larger number of hotspots, and can also serve as containers of analyte molecules. However, the [...] Read more.
Porous noble metal nanomaterials can be employed to construct sensitive surface-enhanced Raman scattering (SERS) substrates, because the plasmonic nanopores and nanogaps of the porous materials can provide a larger number of hotspots, and can also serve as containers of analyte molecules. However, the fabrication processes of nanoporous noble metal are generally complicated. Here, a facile method is presented to prepare nanoporous Ag nanoparticles-decorated Ag7O8NO3 micro-pyramids, which are fabricated through the chemical reduction of the electrodeposited Ag7O8NO3 micro-pyramids using NaBH4. The Ag7O8NO3 micro-pyramids are fabricated by electrodeposition by using a simple aqueous solution of AgNO3 as electrolyte. Then, porous Ag-decorated Ag7O8NO3 micro-pyramids are achieved by the chemical reduction of the surface of the electrodeposited Ag7O8NO3 micro-pyramids with NaBH4. The high-density nanopores and nanogaps of the fabricated nanoporous Ag can provide plenty of hot spots for Raman enhancement. Additionally, the nanopores have an effective capacity to trap and enrich analytes. Using rhodamine 6G (R6G) as a probe molecule, the SERS performance of the fabricated SERS substrate has been investigated. It is found that a limit of detection (LOD) ~1.0 × 10−15 M can be achieved for R6G. Then, the SERS substrates are employed to detect dye molecule (crystal violet) and pesticide (thiram), and their LODs are calculated down to 9.6 × 10−13 M and 1.3 × 10−15 M, respectively. The enhancement factor of the fabricated SERS substrate is estimated to be as high as 5.6 × 108. Therefore, the nanoporous Ag-decorated Ag7O8NO3 micro-pyramids have shown promising application in the sensitive SERS detection of organic molecules. Full article
(This article belongs to the Special Issue Nanocomposites for SERS Sensing)
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40 pages, 75040 KiB  
Review
Review on Anti-Aggregation-Enabled Colorimetric Sensing Applications of Gold and Silver Nanoparticles
by Muthaiah Shellaiah and Kien-Wen Sun
Chemosensors 2022, 10(12), 536; https://doi.org/10.3390/chemosensors10120536 - 16 Dec 2022
Cited by 16 | Viewed by 3421
Abstract
Gold- and silver nanoparticles (Au NPs and Ag NPs)-based colorimetric detection of specific analytes has attracted intense research interest and is still in great demand. The majority of Au NPs- and Ag NPs-based sensory reports have revealed that, during the analyte recognition, dispersed [...] Read more.
Gold- and silver nanoparticles (Au NPs and Ag NPs)-based colorimetric detection of specific analytes has attracted intense research interest and is still in great demand. The majority of Au NPs- and Ag NPs-based sensory reports have revealed that, during the analyte recognition, dispersed NPs typically aggregated and displayed color changes from wine-red to blue/purple and yellow to orange/brown, respectively. On the other hand, only a few reports demonstrated that the aggregated Au NPs and Ag NPs underwent anti-aggregation in the presence of certain analytes, which displayed reversed color changes from blue/purple to wine-red and orange/brown to yellow, correspondingly. There are some examples of anti-aggregation phenomena mentioned in a vast number of studies on Au NPs- and Ag NPs-based colorimetric sensors via NP aggregation. However, a review targeting the anti-aggregation-enabled Au NPs- and Ag NPs-based colorimetric sensing of diverse analytes is not yet available. In this review, anti-aggregation-facilitated Au NPs- and Ag NPs-based colorimetric detection of metal ions, anions, bio-analytes, pesticides, and herbicides is delivered with detailed underlying mechanisms. Moreover, the probe design, sensory requirement, merits, limitations, and future scope of anti-aggregation-enabled Au NPs- and Ag NPs-based colorimetric sensors are discussed. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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21 pages, 1363 KiB  
Article
Kullback–Leibler Importance Estimation Procedure to Improve Gas Quantification in an Electronic Nose
by Daniel Alejandro Piracoca Gordillo, Maria Camila Cardenas Castellanos, David Nicolás Torres Barrera, Jaime Alberto Escobar Gomez, Juan Felipe Nieto Sanchez and Jersson X. Leon-Medina
Chemosensors 2022, 10(12), 538; https://doi.org/10.3390/chemosensors10120538 - 15 Dec 2022
Viewed by 2280
Abstract
An electronic nose sensor array can classify and quantify different types of gases; however, the sensor can alter its measurement capability over time. The main problem presented during the measurements of the sensors is related to the variation of the data acquired for [...] Read more.
An electronic nose sensor array can classify and quantify different types of gases; however, the sensor can alter its measurement capability over time. The main problem presented during the measurements of the sensors is related to the variation of the data acquired for long periods due to changes in the chemosensory response, thus affecting the correct functioning of the implemented measuring system. This research presents an approach to improve gas quantification through the implementation of machine learning regression techniques in an array of nose-type electronic sensors. The implemented methodology uses a domain adaptation approach with the Kullback–Leibler importance estimation procedure (KLIEP) to improve the performance of the gas quantification electronic nose array. This approach is validated using a three-year dataset measured by a 16-electronic-nose-sensor array. The R2 regression error obtained for each of the gases fits the resulting dataset’s measured values with good precision. Full article
(This article belongs to the Special Issue Chemosensors in Biological Challenges)
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11 pages, 6316 KiB  
Article
Fabric Phase Sorptive Extraction Combined with HPLC-UV for the Quantitation of Amphotericin B in Human Urine
by Evmorfia Asimakopoulou, Natalia Manousi, Nikoleta Anaxagorou, Abuzar Kabir, Kenneth G. Furton and Constantinos K. Zacharis
Chemosensors 2022, 10(12), 537; https://doi.org/10.3390/chemosensors10120537 - 15 Dec 2022
Cited by 2 | Viewed by 2371
Abstract
Herein, a fabric phase sorptive extraction-based scheme was reported for the determination of amphotericin B in human urine. The developed method allowed the direct extraction of the analyte from the biological matrix with improved selectivity, repeatability and recovery. Due to the membrane’s engineered [...] Read more.
Herein, a fabric phase sorptive extraction-based scheme was reported for the determination of amphotericin B in human urine. The developed method allowed the direct extraction of the analyte from the biological matrix with improved selectivity, repeatability and recovery. Due to the membrane’s engineered affinity towards the analyte, extraction equilibrium was achieved in 30 min. Moreover, no additional sample pretreatment was required due to the high permeability of the FPSE membrane and the small volume of eluting solvent required for quantitative back-extraction of the analytes. The hydrophobic sol–gel polydimethylphenylsiloxane (sol–gel PDMDPheS) coated membrane provided the optimum extraction performance. Important parameters that affect the extraction efficiency (such as sample volume, extraction time, membrane size, stirring rate, ion strength, elution solvent and time) were thoroughly investigated. The analyte was separated from the internal standard (nimesulide) and endogenous compounds of the human urine using a gradient elution program. The proposed assay was linear within the range of 0.10–10.0 μg mL−1 while the relative standard deviation of the repeatability (sr) and within-laboratory reproducibility (sR) were less than 12.7% in all cases. The method exhibited good accuracy which varied between 88.1 to 110.3%. The developed method was successfully applied for the monitoring of amphotericin B concentration in human urine. Full article
(This article belongs to the Collection Recent Trend in Chromatography for Pharmaceutical Analysis)
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12 pages, 4369 KiB  
Article
A Surface-Scattering-Based Composite Optical Waveguide Sensor for Aerosol Deposition Detection
by Min Zhao, Hongyi Tang, Ziwei Liu, Zhaoyang Tong and Zhimei Qi
Chemosensors 2022, 10(12), 535; https://doi.org/10.3390/chemosensors10120535 - 15 Dec 2022
Viewed by 1664
Abstract
Aerosol is a suspension of fine chemical or biological particles in the air, and it is harmful, easily causing air pollution, respiratory diseases, infrastructure corrosion, and poor visibility. Therefore, the development of advanced optical sensors for real-time detection of aerosol deposition is of [...] Read more.
Aerosol is a suspension of fine chemical or biological particles in the air, and it is harmful, easily causing air pollution, respiratory diseases, infrastructure corrosion, and poor visibility. Therefore, the development of advanced optical sensors for real-time detection of aerosol deposition is of great significance. In this work, a prism-coupled composite optical waveguide (COWG) sensor for aerosol deposition detection based on surface scattering is proposed and demonstrated theoretically and experimentally. The COWG consists of a single-mode slab glass waveguide locally covered with a tapered thin film of high-index metal oxide. The tapered film can greatly enhance the evanescent field through the adiabatic transition of the fundamental transverse electric (TE0) mode between the uncovered and film-covered regions, thereby enabling the COWG to serve as a simple yet highly sensitive evanescent-wave scattering sensor for sensitive detection of aerosol deposition. The COWG with a tapered layer of Ta2O5 was prepared by masked sputtering, aerosol salt particle deposition on the COWG was successfully detected, and the influence of surface water droplets on the COWG sensor performance was analyzed. The experimental results indicate that the sensitivity of the COWG is 30 times higher than that of the bare glass waveguide. Full article
(This article belongs to the Collection Optical Chemosensors and Biosensors)
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13 pages, 4037 KiB  
Article
Engineering SERS Properties of Silicon Nanotrees at the Nanoscale
by Hrvoje Gebavi, Petra Pál, István Csarnovics, Vlatko Gašparić and Mile Ivanda
Chemosensors 2022, 10(12), 534; https://doi.org/10.3390/chemosensors10120534 - 15 Dec 2022
Cited by 1 | Viewed by 1883
Abstract
Large specific surface area nanostructures are desirable in a wide range of sensing applications due to their longer light-trapping path and increased absorption. Engineering of the specific nanotree structure which possesses a high branch density turned out to be challenging from the experimental [...] Read more.
Large specific surface area nanostructures are desirable in a wide range of sensing applications due to their longer light-trapping path and increased absorption. Engineering of the specific nanotree structure which possesses a high branch density turned out to be challenging from the experimental point of view, and certainly not adequately explored. This paper shows how to design substrates with a silicon nanotree structure for surface-enhanced Raman spectroscopy (SERS) applications. Silicon nanotrees were synthesized by a Ag-Au nanocluster-catalyzed low-pressure chemical vapor deposition method (LPCVD). By the presented approaches, it is possible to manipulate branches’ number, length and thickness. The synthesized nanostructures are flexible after immersion in water which improves SERS performance. The amount of sputtered metal played a key role in preserving the flexibility of the nanotree structure. The obtained substrates with highly fractal nanostructure were tested on 4-mercaptophenylboronic acid (MPBA) to match the optimal SERS parameters. The silicon nanotrees fabrication, and particularly obtained SERS substrates plated with Ag and Au nanoparticles, demonstrated good features and a promising approach for further sensor development. Full article
(This article belongs to the Special Issue Recent Developments in Platforms for SERS Applications)
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14 pages, 5289 KiB  
Article
Preparation and Photoluminescent Properties of Tb3+-Doped Lu2W3O12 and Lu2Mo3O12 Green Phosphors
by Nihui Huang, Guojun Lu, Bihai Bai, Zijun Chen, Min Zhang, Yuechan Li, Chunyan Cao and An Xie
Chemosensors 2022, 10(12), 533; https://doi.org/10.3390/chemosensors10120533 - 14 Dec 2022
Cited by 7 | Viewed by 1696
Abstract
Tungstate and molybdate phosphors have received great attention for their excellent photoluminescent properties and thermal stabilities. In the article, Tb3+-activated tungstate and molybdate green phosphors were prepared by a solid-state reaction method at different caline temperatures and were compared and studied. [...] Read more.
Tungstate and molybdate phosphors have received great attention for their excellent photoluminescent properties and thermal stabilities. In the article, Tb3+-activated tungstate and molybdate green phosphors were prepared by a solid-state reaction method at different caline temperatures and were compared and studied. The crystal structures and the morphologies of samples were characterized by X-ray diffraction (XRD) patterns and field emission scanning electron microscopy (FE-SEM) images. The energy-dispersive spectra (EDS) proved the compositions of the prepared samples. The photoluminescence (PL) spectra showed that the PL excitation spectra of Tb3+-doped Lu2W3O12 and Lu2Mo3O12 green phosphors consisted of a broad and strong charge transfer band (CTB) and 4f–5d transitions of Tb3+ in the ultraviolet (UV) wavelength range and some narrowed excitation peaks from the 4f–4f transition of Tb3+ in the near ultraviolet (NUV) wavelength region. The PL emission spectra of the phosphors exhibited the characteristic green emissions owing to the 5D4→7F5 transition of Tb3+ located at about 547 nm. The values of energy gap Eg were calculated based on the diffuse reflection spectra (DRS). The measuring temperature-dependent PL spectra illustrated the thermal stabilities of phosphors. The Tb3+-doped Lu2Mo3O12 phosphor presented normal thermal quenching phenomena and the values of the thermal activation energy Ea were calculated based on the measuring temperature dependent PL emission spectra. The Tb3+-doped Lu2W3O12 phosphor exhibited abnormal thermal enhancing CTB excitation intensity at about 170 °C. Furthermore, the PL decay curves suggested that the lifetime corresponding to the 5D4 level of Tb3+ in the Lu2W3O12 host lattice was longer than that in the Lu2Mo3O12 host lattice. Compared the Tb3+-doped Lu2Mo3O12 phosphor, the Tb3+-doped Lu2W3O12 phosphor has shown potential as an application in temperature sensors. Full article
(This article belongs to the Special Issue Advances in Fluorescence Sensing)
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14 pages, 2465 KiB  
Article
Pithecellobium dulce Leaf-Derived Carbon Dots for 4-Nitrophenol and Cr(VI) Detection
by Simei Darinel Torres Landa, Inderbir Kaur and Vivechana Agarwal
Chemosensors 2022, 10(12), 532; https://doi.org/10.3390/chemosensors10120532 - 13 Dec 2022
Cited by 9 | Viewed by 2208
Abstract
Luminescent carbon dots (CDs) synthesized from Pithecellobium dulce (P. Dulce) leaves, in a simple, single-step carbonization procedure, were used as optical nanosensors. TEM revealed the crystalline nature of the CDs with the average dimension of 20 nm with a quantum yield of 24%. [...] Read more.
Luminescent carbon dots (CDs) synthesized from Pithecellobium dulce (P. Dulce) leaves, in a simple, single-step carbonization procedure, were used as optical nanosensors. TEM revealed the crystalline nature of the CDs with the average dimension of 20 nm with a quantum yield of 24%. In addition to carbon, the X-ray photoelectron spectroscopy shows the presence of oxygen and nitrogen. The FTIR spectra and Zeta potential were used for additional characterization of the nanoprobes. Among the contaminants and heavy metals, the proposed nanoprobes were found to be selective towards 4-nitrophenol (4-NP) and Cr(VI), respectively. The emission response of CDs towards 4-NP solution not only reveals the high sensitivity of the CDs (Limit of detection (LOD) of 14 nM) but also demonstrates a color change (light to dark yellow) that is attributed to spontaneous deprotonation detectable with the naked eye. The selectivity of CDs towards Cr(VI) (LOD 0.9 nM) was also tested in the presence of other metals. The quenching mechanism has been attributed to the inner filter effect for both analytes. The observed low detection limits in river and tap water opens up the possible applicability of the proposed nanoprobes as optical sensors in environmental pollution monitoring. Full article
(This article belongs to the Section Optical Chemical Sensors)
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17 pages, 1110 KiB  
Article
Target and Suspect Analysis with High-Resolution Mass Spectrometry for the Exhaustive Monitoring of PCBs and Pesticides in Posidonia oceanica Meadows and Sediments
by Marina Astudillo-Pascual, Pedro A. Aguilera, Antonia Garrido Frenich and Irene Domínguez
Chemosensors 2022, 10(12), 531; https://doi.org/10.3390/chemosensors10120531 - 12 Dec 2022
Cited by 2 | Viewed by 1911
Abstract
This study enables the simultaneous monitoring of persistent organics pollutants (POPs) in the relevant marine seagrass Posidonia oceanica (L.) Delile (P. oceanica), without causing damage and preserving their ecological integrity and their key ecosystem services, and in marine sediments. Two classes [...] Read more.
This study enables the simultaneous monitoring of persistent organics pollutants (POPs) in the relevant marine seagrass Posidonia oceanica (L.) Delile (P. oceanica), without causing damage and preserving their ecological integrity and their key ecosystem services, and in marine sediments. Two classes of POPs that suppose a current threat to the environmental health status are investigated: polychlorinated biphenyls (PCBs) and pesticides. Comparisons between tissues and sediment compartmentation are studied for the first time. For these purposes, the sediments, P. oceanica leaves and, as a novelty, rhizomes, were studied. Samples were analyzed by gas chromatography coupled with high-resolution mass spectrometry (GC-Q-Orbitrap MS) for a comprehensive study. Eco-friendly methods were developed and validated for the determination of 38 POPs, 25 PCBs and 13 priority pesticides. The results showed that, when detected, regulated contaminants were localized mainly in the long-lived rhizomes, and 7 PCBs (the most abundant being PCB 44) and 4 priority pesticides (trifluralin, chlorpyrifos, isodrin and o,p’-DDT) were seen. Additionally, a retrospective analysis (suspect screening) was conducted, exhibiting up to 13 current-use pesticide residues in leaves and rhizomes alike. The results suggest that P. oceanica might be acting as a sink to contaminants in coastal areas and that rhizomes, due to their longer lifespan, reflect past and legacy contamination. Full article
(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges)
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22 pages, 2543 KiB  
Review
Mass Spectrometry as an Analytical Tool for Detection of Microplastics in the Environment
by Sechul Chun, Manikandan Muthu and Judy Gopal
Chemosensors 2022, 10(12), 530; https://doi.org/10.3390/chemosensors10120530 - 12 Dec 2022
Cited by 7 | Viewed by 4636
Abstract
Plastic particles smaller than 5 mm accumulate in aqueous, terrestrial, and atmospheric environments and their discovery has been a serious concern when it comes to eco-toxicology and human health risk assessment. In the following review, the potential of mass spectrometry (MS) for the [...] Read more.
Plastic particles smaller than 5 mm accumulate in aqueous, terrestrial, and atmospheric environments and their discovery has been a serious concern when it comes to eco-toxicology and human health risk assessment. In the following review, the potential of mass spectrometry (MS) for the detection of microplastic (MP) pollutants has been elaborately reviewed. The use of various mass spectrometric techniques ranging from gas chromatography–mass spectrometry (GC-MS), liquid chromatographic mass spectrometric (LC-MS) to matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), including their variants, have been reviewed. The lapses in the detection system have been addressed and future recommendations proposed. The challenges facing microplastics and their detection have been discussed and future directions, including mitigation methods, have been presented. Full article
(This article belongs to the Special Issue Chemical Sensors and Biosensors for Biomedical and Environmental Application: Recent Advances and Future Perspectives)
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15 pages, 3012 KiB  
Article
Accurate Traceability of Stable C, H, O, N Isotope Ratios and Multi-Element Analysis Combined with Chemometrics for Chrysanthemi Flos ‘Hangbaiju’ from Different Origins
by Xiuyun Bai, Hengye Chen, Wanjun Long, Wei Lan, Siyu Wang, Guanghua Lei, Yuting Guan, Jian Yang and Haiyan Fu
Chemosensors 2022, 10(12), 529; https://doi.org/10.3390/chemosensors10120529 - 12 Dec 2022
Cited by 3 | Viewed by 2137
Abstract
Chrysanthemi Flos ‘Hangbaiju’ (HBJ) is a common Chinese medicinal material with the same origin as the medicinal and edible cognate plant in China, whose quality is seriously affected by the place of origin. In this study, four stable isotope ratios (δ15N, [...] Read more.
Chrysanthemi Flos ‘Hangbaiju’ (HBJ) is a common Chinese medicinal material with the same origin as the medicinal and edible cognate plant in China, whose quality is seriously affected by the place of origin. In this study, four stable isotope ratios (δ15N, δ2H, δ13C, and δ18O) and 44 elements were detected and analyzed in 191 HBJ flower samples from six locations in China to trace the origin of HBJ. An ANOVA analysis of δ15N, δ2H, δ13C, and δ18O values, as well as milti-elements, showed that there were significant differences among the six places of origin. Partial least squares discriminant analysis (PLSDA) and one-class partial least squares discriminant analysis (OPLS-DA) models were established to trace the origin of HBJ from these six locations. The results showed that the classification effect of the PLSDA model is poor; however, the established OPLS-DA model can distinguish between products of national geographic origin (Tongxiang City, Zhejiang Province, China) and samples from other origins, among which Ni, Mo, δ13C, Cu, and Ce elements (VIP > 1) contribute the most to this classification. Therefore, this study provides a new method for tracing the origins of HBJ, which is of great significance for the protection of origin labeling of products. Full article
(This article belongs to the Special Issue Chemometrics for Analytical Chemistry)
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16 pages, 5503 KiB  
Article
SERS-TLC Device for Simultaneous Determination of Sulfamethoxazole and Trimethoprim in Milk
by Frederico Luis Felipe Soares, Benedito Roberto de Alvarenga Junior and Renato Lajarim Carneiro
Chemosensors 2022, 10(12), 528; https://doi.org/10.3390/chemosensors10120528 - 12 Dec 2022
Cited by 4 | Viewed by 1728
Abstract
The aim of this work is to develop a device based on thin-layer chromatography coupled with surface-enhanced Raman spectroscopy (TLC-SERS) to analyze sulfamethoxazole (SMX) and trimethoprim (TMP) in commercial milk samples using chemometric tools. Samples were eluted in TLC plates, and a central [...] Read more.
The aim of this work is to develop a device based on thin-layer chromatography coupled with surface-enhanced Raman spectroscopy (TLC-SERS) to analyze sulfamethoxazole (SMX) and trimethoprim (TMP) in commercial milk samples using chemometric tools. Samples were eluted in TLC plates, and a central composite design (CCD) of two factors was performed to optimize the gold nanoparticle dispersion on TLC plates for SERS, aiming at the detection of both drugs at concentrations close to their maximum residual limits (MRLs). Following the optimization, hyperspectral images from the SERS were captured of the TLC plates. Multivariate curve resolution (MCR-ALS) and independent component analysis (ICA) chemometric techniques were used to extract the signals of the analytes. All the samples presented recovery values of 81–128% for TMP. The quantification of SMX was not possible due to SERS suppression by an interferent. However, it was possible to detect SMX at a concentration of two times the MRL (8.0 × 10−7 mol·L−1). The results demonstrate that the TLC-SERS device is a potential tool for the quantification of TMP and the detection of SMX in milk. Full article
(This article belongs to the Section Imaging for (Bio)chemical Sensing)
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19 pages, 5129 KiB  
Article
Microstructure and Photoluminescence of ZrTiO4:Eu3+ Phosphors: Host-Sensitized Energy Transfer and Optical Thermometry
by Anheng Gu, Guo-Hui Pan, Huajun Wu, Liangliang Zhang, Ligong Zhang, Hao Wu and Jiahua Zhang
Chemosensors 2022, 10(12), 527; https://doi.org/10.3390/chemosensors10120527 - 12 Dec 2022
Cited by 5 | Viewed by 2260
Abstract
Orthorhombic ZrTiO4 is an attractive dielectric material; its optical properties are, however, less known. In this paper, we reported on the microstructure and luminescence studies of pristine ZrTiO4 and Eu3+-doped ZrTiO4 phosphors. The results indicated that two types [...] Read more.
Orthorhombic ZrTiO4 is an attractive dielectric material; its optical properties are, however, less known. In this paper, we reported on the microstructure and luminescence studies of pristine ZrTiO4 and Eu3+-doped ZrTiO4 phosphors. The results indicated that two types of TiO6 octahedra, the isolated/ localized and coupled/delocalized, coexisted in host matrix. Eu3+ doping could induce oxygen vacancy defect states located below the bottom of the conduction band. Pristine ZrTiO4 showed bright yellow luminescence via STEs recombination at defects sites at low temperatures, but significant thermal quenching occurred due to STEs migration to quenching centers at elevated temperatures. Effective host sensitized energy transfer to Eu3+ was observed in ZrTiO4:Eu3+ phosphors and yielded the red characteristic emissions of Eu3+. Anomalous STEs luminescence enhancement and spectral blue-shift in the excitation spectra with higher Eu3 + concentration appeared and were explained by considering three factors: competitive absorption between electron transitions from the top of the valence band to the defect states and host conduction band, Eu3+ doping driving the production of more isolated TiO6 octahedra, and energy back-transfer from Eu3+ activators to other titanate groups. On the basis of the dual-emitting combination strategy involving host STEs and Eu3+ luminescence, ZrTiO4:Eu3+ phosphors were demonstrated to be ratiometric self-referencing optical thermometric materials, with a working range of 153–313 K and a maxima of relative sensitivity to ~1.1% K−1 at 243 K. Full article
(This article belongs to the Special Issue Advances in Fluorescence Sensing)
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12 pages, 4498 KiB  
Article
Study on the Detection Characteristics and Response Mechanism of SnS2-Based Sensors for SO2 and SOF2
by Chengjun Li, Mengyang He, Shuangshuang Tian, Jiawei Yuan, Jincong Wang and Yi Li
Chemosensors 2022, 10(12), 526; https://doi.org/10.3390/chemosensors10120526 - 11 Dec 2022
Cited by 5 | Viewed by 1421
Abstract
Based on the wide application of sulfur hexafluoride (SF6) gas in the power industry, the analysis and detection of its decomposition components have become important technical means for state detection and fault evaluation of gas-insulated equipment. The gas-sensitive characteristics and adsorption [...] Read more.
Based on the wide application of sulfur hexafluoride (SF6) gas in the power industry, the analysis and detection of its decomposition components have become important technical means for state detection and fault evaluation of gas-insulated equipment. The gas-sensitive characteristics and adsorption mechanism of the SnS2 sensor for SO2 and SOF2 gases were investigated using SO2 and SOF2, the main SF6 decomposition components, as the target detection gases. SnS2 gas-sensitive materials and components were prepared, and the temperature response, concentration response, response recovery and stability of the SnS2 sensor for the two SF6 decomposition components were tested based on the gas-sensitive test platform. The results demonstrate that the sensor had the best working performance at 200 °C, with obvious response and ideal recovery for both target gases and good stability in a certain time. Based on the first principle, the SnS2 surface structure model and the target gas adsorption model were established, and the adsorption mechanism was analyzed in terms of frontier molecular orbital theory to verify the correctness of the gas-sensitive test results. The gas-sensitive test analysis and simulation calculation can provide data basis and theoretical support for the study of SF6 decomposition components detected by gas sensors. Full article
(This article belongs to the Special Issue Application and Advance of Gas Sensors)
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13 pages, 5477 KiB  
Article
Room-Temperature NO2 Gas Sensors Based on Granulated Carbon Nanofiber Material
by Alexander G. Bannov, Nikita I. Lapekin, Pavel B. Kurmashov, Arina V. Ukhina and Anton Manakhov
Chemosensors 2022, 10(12), 525; https://doi.org/10.3390/chemosensors10120525 - 10 Dec 2022
Cited by 6 | Viewed by 2224
Abstract
Room-temperature gas sensors based on granulated carbon nanofiber material were investigated for the detection of NO2. The granulated material consisting of intertwined carbon nanofibers was synthesized by the decomposition of CH4 over the Ni/Al2O3 catalyst in a [...] Read more.
Room-temperature gas sensors based on granulated carbon nanofiber material were investigated for the detection of NO2. The granulated material consisting of intertwined carbon nanofibers was synthesized by the decomposition of CH4 over the Ni/Al2O3 catalyst in a vibro-fluidized bed reactor. Carbon material was investigated using transmission electron microscopy, Raman spectroscopy, low-temperature nitrogen adsorption, and X-ray photoelectron spectroscopy. Investigation of the gas sensors towards NO2 at room temperature (25 ± 2 °C) was carried out in a dynamic flow-through setup in the range from 1 to 500 ppm. A comparison of the sensitivity gas sensor to NH3 and CH4 was also given. The sensor based on non-treated carbon nanofiber material showed the response ΔR/R0 of 5.1 % to 10 ppm of NO2. It was found that the sensor response to NO2 decreased when increasing the relative humidity. The effect of the relative humidity was more pronounced for low concentrations of nitrogen dioxide and decreases with a further increase in them. Full article
(This article belongs to the Special Issue Advances in Chemosensors Technologies for Monitoring and Diagnostics)
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12 pages, 4044 KiB  
Article
Phosphoric Acid Induced Controllable Nanoparticle Aggregation for Ultrasensitive SERS Detection of Malondialdehyde in a Microfluidic Chip
by Yu Lu, Siying Wan, Xin Ruan, Huijun Liang, Jingting Su, Zhuyuan Wang and Li Zhu
Chemosensors 2022, 10(12), 524; https://doi.org/10.3390/chemosensors10120524 - 9 Dec 2022
Cited by 4 | Viewed by 2695
Abstract
Malondialdehyde (MDA), one of the most important products of lipid peroxidation, has been widely accepted as a biomarker to indicate food rancidity as well as the progress of some human diseases. However, ready detection of MDA with ultra-high sensitivity remains a challenge. In [...] Read more.
Malondialdehyde (MDA), one of the most important products of lipid peroxidation, has been widely accepted as a biomarker to indicate food rancidity as well as the progress of some human diseases. However, ready detection of MDA with ultra-high sensitivity remains a challenge. In this work, a microfluidic surface-enhanced Raman scattering (SERS) sensing chip based on phosphoric acid induced nanoparticles aggregation was proposed for ultrasensitive MDA detection. The sensing chip was composed of an ultrafast microfluidic mixer, which efficiently transferred analytes to hot spots via the mixer assisted hot spots occupying (MAHSO) SERS strategy. Phosphoric acid, a reagent used in MDA detection, played the role of aggregator to induce aggregation of silver nanoparticles (Ag NPs); meanwhile, as fast as a few milliseconds mixing time effectively prevented over-aggregation of Ag NPs. Therefore, this process generated a uniform and dense SERS substrate with analyte molecules located in hot spots. As a result, the MDA SERS sensing chip possessed a limit of detection (LOD) lower than 3.3 × 10−11 M, high spot-to-spot uniformity with a relative standard deviation (RSD) of 9.0% and an excellent batch-to-batch reproducibility with a RSD of 3.9%. This method also demonstrated excellent specificity and reliability in real sample detection with recoveries of 90.4–109.8% in spiked tests. Full article
(This article belongs to the Special Issue Nanocomposites for SERS Sensing)
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14 pages, 3494 KiB  
Article
Potentiometric Surfactant Sensor for Anionic Surfactants Based on 1,3-dioctadecyl-1H-imidazol-3-ium tetraphenylborate
by Nikola Sakač, Dubravka Madunić-Čačić, Dean Marković, Lucija Hok, Robert Vianello, Valerije Vrček, Bojan Šarkanj, Bojan Đurin, Bartolomeo Della Ventura, Raffaele Velotta and Marija Jozanović
Chemosensors 2022, 10(12), 523; https://doi.org/10.3390/chemosensors10120523 - 8 Dec 2022
Cited by 3 | Viewed by 1734
Abstract
As anionic surfactants are used as cleaning agents, they pose an environmental and health threat. A novel potentiometric sensor for anionic surfactants based on the 1,3-dioctadecyl-1H-imidazol-3-ium tetraphenylborate (DODI–TPB) ionophore is presented. The newly developed approach for DODI–TPB synthesis is faster and [...] Read more.
As anionic surfactants are used as cleaning agents, they pose an environmental and health threat. A novel potentiometric sensor for anionic surfactants based on the 1,3-dioctadecyl-1H-imidazol-3-ium tetraphenylborate (DODI–TPB) ionophore is presented. The newly developed approach for DODI–TPB synthesis is faster and simpler than the currently used strategies and follows the green chemistry principles. The DODI–TPB ionophore was characterized by computational and instrumental techniques (NMR, LC–MS, FTIR, elemental analysis) and used to produce a PVC-based DODI–TPB sensor. The sensor showed linear response to dodecylbenzenesulfonate and dodecyl sulfate in concentration ranges of 6.3 × 10−7–3.2 × 10−4 M and 5.9 × 10−7–4.1 × 10−3 M, for DBS and SDS, respectively. The sensor exhibits a Nernstian slope (59.3 mV/decade and 58.3 mV/decade for DBS and SDS, respectively) and low detection limits (7.1 × 10−7 M and 6.8 × 10−7 M for DBS and SDS, respectively). The DODI–TPB sensor was successfully tested on real samples of commercial detergents and the results are in agreement with the referent methods. A computational analysis underlined the importance of long alkyl chains in DODI+ and their C–H∙∙∙π interactions with TPB− for the ionophore formation in solution, thereby providing guidelines for the future design of efficient potentiometric sensors. Full article
(This article belongs to the Special Issue Recent Developments in Electrochemical Sensing)
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13 pages, 3791 KiB  
Article
In Situ Growth of Dopamine on QCM for Humidity Detection
by Pengjia Qi, Ziwei Xu and Tong Zhang
Chemosensors 2022, 10(12), 522; https://doi.org/10.3390/chemosensors10120522 - 8 Dec 2022
Cited by 4 | Viewed by 1592
Abstract
Polydopamine (PDA) films were successfully prepared on quartz crystal microbalance (QCM) by in-situ growth method, and the obtained QCM sensor was used for humidity detection. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to study the chemical composition and [...] Read more.
Polydopamine (PDA) films were successfully prepared on quartz crystal microbalance (QCM) by in-situ growth method, and the obtained QCM sensor was used for humidity detection. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to study the chemical composition and microstructure of the in-situ grown PDA sensitive films. The experimental results showed that the PDA-QCM humidity sensor with 2 h polymerization growth times (2-PDA-QCM) owned high sensitivity (20.77 Hz/% RH), good selectivity, short response/recovery time (5 s/11 s) and acceptable long-term stability. In addition, the energy loss of the sensors fabricated under different conditions was investigated by impedance analysis. Based on all the test results, it is concluded that the combination of in-situ growth method and QCM can produce a room temperature humidity sensor with excellent performance. Full article
(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)
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15 pages, 2220 KiB  
Article
Droplet-Based Microfluidic Platform for High Spatiotemporal Resolved Single-Cell Signaling Profiling
by Yingnan Sun, Qingqing Tian, Yongshu Liu, Kunming Xing, Yuyan Li, Yumin Liu and Shusheng Zhang
Chemosensors 2022, 10(12), 521; https://doi.org/10.3390/chemosensors10120521 - 8 Dec 2022
Cited by 1 | Viewed by 1768
Abstract
A small indentation embedded in a microchannel creates a surface energy well (SEW) for a confined droplet due to surface energy release. Inspired by this, we developed a SEW-based microfluidic platform to realize high spatiotemporal-resolved signal profiling at the single-cell level applying droplet [...] Read more.
A small indentation embedded in a microchannel creates a surface energy well (SEW) for a confined droplet due to surface energy release. Inspired by this, we developed a SEW-based microfluidic platform to realize high spatiotemporal-resolved signal profiling at the single-cell level applying droplet stimulus on a single chip. The method allows for controlled droplet replacement within only 3 s with almost 100% exchange efficiency, reliable single-cell patterning of adherent cells and successive treatment of adherent cells with reagent droplets. Furthermore, the PDGFR/Akt pathway served as a model system for evaluating the performance of the SEW-based method in determining the effects of ligand stimulation duration (3 s to 3 min) on receptor phosphorylation. The novel strategy offers a general platform for probing the temporal dynamics of single cells, as well for monitoring rapid chemical reactions in various applications. 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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14 pages, 3177 KiB  
Article
SERS Sensor for Human Glycated Albumin Direct Assay Based on Machine Learning Methods
by Ekaterina A. Slipchenko, Irina A. Boginskaya, Robert R. Safiullin, Ilya A. Ryzhikov, Marina V. Sedova, Konstantin N. Afanasev, Natalia L. Nechaeva, Ilya N. Kurochkin, Alexander M. Merzlikin and Andrey N. Lagarkov
Chemosensors 2022, 10(12), 520; https://doi.org/10.3390/chemosensors10120520 - 7 Dec 2022
Cited by 6 | Viewed by 2226
Abstract
In this study, a non-labeled sensor system for direct determining human glycated albumin levels for medical application is proposed. Using machine learning methods applied to surface-enhanced Raman scattering (SERS) spectra of human glycated albumin and serum human albumin enabled the avoidance of complex [...] Read more.
In this study, a non-labeled sensor system for direct determining human glycated albumin levels for medical application is proposed. Using machine learning methods applied to surface-enhanced Raman scattering (SERS) spectra of human glycated albumin and serum human albumin enabled the avoidance of complex sample preparation. By implementing linear discriminant analysis and regularized linear regression, classification and regression problems were solved based on the spectra obtained as a result of the experiment. The results show that, coupled with data augmentation and a special cross-validation procedure, the methods we employed yield better results in the corresponding tasks in comparison with popular random forest methods and the support vector method. The results show that SERS, in combination with machine learning methods, can be a powerful and effective tool for the simple and direct assay of protein mixtures. Full article
(This article belongs to the Special Issue SERS: Analytical and Biological Challenges)
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16 pages, 6824 KiB  
Article
Porphyrin-Based Metal–Organic Frameworks for Efficient Electrochemiluminescent Chiral Recognition of Tyrosine Enantiomers
by Wen-Rong Cai, Wen-Kai Zhu, Bao-Zhu Yang, Da-Tong Wu, Jun-Yao Li, Zheng-Zhi Yin and Yong Kong
Chemosensors 2022, 10(12), 519; https://doi.org/10.3390/chemosensors10120519 - 7 Dec 2022
Cited by 3 | Viewed by 1877
Abstract
Science the biological activities of chiral enantiomers are often different or even opposite, their chiral recognition is of great significance. A new assembly structure named TCPP-Zn-(S)-BINOL was obtained based on the interaction between chiral binaphthol (BINOL) and the porphyrin-based MOF structure formed by [...] Read more.
Science the biological activities of chiral enantiomers are often different or even opposite, their chiral recognition is of great significance. A new assembly structure named TCPP-Zn-(S)-BINOL was obtained based on the interaction between chiral binaphthol (BINOL) and the porphyrin-based MOF structure formed by Meso-Tetra(4-carboxyphenyl)porphine (TCPP) and Zn2+, and a new chiral sensor was designed relying on TCPP-Zn-(S)-BINOL. The chiral platform was designed by using binaphthol as a chiral recognizer and the porphyrin MOF as an emitter, which can recognize tyrosine (Tyr) enantiomers via the electrochemiluminescence (ECL) method. According to density functional theory (DFT), TCPP-Zn-(S)-BINOL has a different affinity with L/D-Tyr due to the different strength of the hydrogen bond between chiral ligand BINOL and the tyrosine (Tyr) enantiomer. It will be more suitable for combination with L-Tyr, and the presence of L-Tyr will increase the ECL intensity of the modified electrode via the catalytic reduction of co-reactant reagents, achieving the purpose of the chiral recognition of Tyr enantiomers. These findings show that TCPP-Zn-(S)-BINOL can be used as an advanced ECL chiral recognition platform for biomedical applications. Full article
(This article belongs to the Special Issue Innovative Analytical Methods in Pharmaceutical and Biomedical Analysis)
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13 pages, 3672 KiB  
Article
New Quantum-Dot-Based Fluorescent Immunosensor for Cancer Biomarker Detection
by Mariana P. Sousa, Ana Margarida L. Piloto, Ana Cláudia Pereira, Fernando C. Schmitt, Ruben Fernandes and Felismina T. C. Moreira
Chemosensors 2022, 10(12), 518; https://doi.org/10.3390/chemosensors10120518 - 7 Dec 2022
Cited by 6 | Viewed by 2620
Abstract
Cancer antigen 15-3 (CA 15-3) is a biomarker for breast cancer used to monitor response to treatments and disease recurrence. The present work demonstrates the preparation and application of a fluorescent biosensor for ultrasensitive detection of the cancer antigen CA 15-3 protein tumor [...] Read more.
Cancer antigen 15-3 (CA 15-3) is a biomarker for breast cancer used to monitor response to treatments and disease recurrence. The present work demonstrates the preparation and application of a fluorescent biosensor for ultrasensitive detection of the cancer antigen CA 15-3 protein tumor marker using mercaptopropionic-acid-functionalized cadmium telluride (CdTe@MPA) quantum dots (QDs) conjugated with CA 15-3 antibodies. First, the QDs were synthesized by the hydrothermal route, resulting in spherical nanoparticles up to 3.50 nm in diameter. Subsequently, the QD conjugates were characterized by Fourier transform infrared spectroscopy (FTIR), UV absorption, and fluorescence. The interaction between the conjugates and the protein was studied by fluorescence spectroscopy in buffer and in 10-fold diluted commercial human serum. Calibration in spiked serum samples gave a detection limit of 0.027 U/mL, 1000-fold lower than the clinical limit for CA 15-3 (25 U/mL to 30 U/mL), indicating that this is an ultrasensitive technique. In addition, a rapid response was obtained within 10 min. The biosensor was selective in the presence of the interfering serum proteins BSA, CEA, and CA-125, with a maximum interference of 2% for BSA. The percent recovery was close to 100% with maximum relative standard deviation (RSD%) values of 1.56. Overall, the developed CA 15-3 biosensor provides a simple and sensitive method for ultrasensitive monitoring of breast cancer, as well as the ability to detect other molecules of interest in human serum matrices. Full article
(This article belongs to the Special Issue Advances in Fluorescence Sensing)
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14 pages, 2047 KiB  
Article
Voltammetric Detection of Irbesartan by Molecularly Imprinted Polymer (MIP)-Modified Screen-Printed Electrodes
by Camilla Zanoni, Riccardo Rovida, Lisa Rita Magnaghi, Raffaela Biesuz and Giancarla Alberti
Chemosensors 2022, 10(12), 517; https://doi.org/10.3390/chemosensors10120517 - 6 Dec 2022
Cited by 8 | Viewed by 1740
Abstract
Irbesartan is a drug used to treat hypertension and high blood pressure. Recent studies associated sartans with several forms of cancer, making removing this class of substances from the environment a high priority. The EU has categorized drugs as emerging pollutants, and they [...] Read more.
Irbesartan is a drug used to treat hypertension and high blood pressure. Recent studies associated sartans with several forms of cancer, making removing this class of substances from the environment a high priority. The EU has categorized drugs as emerging pollutants, and they can be more potent than other substances because they were designed to operate at low concentrations. Thus, effective and sensitive methods of determining Irbesartan selectively and accurately in environmental samples are necessary. MIPs have already been used to remove pollutants from complex matrixes, so they were also chosen for this work. In particular, a polyacrylate-based MIP was used to functionalize the graphite working electrode of screen-printed cells (SPCs), aiming to develop a voltammetric method for Irbesartan sensing. The MIP composition and the experimental conditions for the electrochemical determination were optimized through a Design of Experiments (DoE) approach. The whole analysis was replicated with different SPCs obtaining similar results, which highlight the good reproducibility potential. MIP-based electrodes were also applied to determine Irbesartan in fortified tap water samples, obtaining high recovery percentages. Given the good results, the electrochemical method based on MIP-modified screen-printed electrodes is promising for quantifying Irbesartan at a trace level. Full article
(This article belongs to the Special Issue Innovative Analytical Methods in Pharmaceutical and Biomedical Analysis)
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38 pages, 4757 KiB  
Review
Recent Progress in the Core-Shell Nanostructures of the NiMoO4-Based Composite Materials for Supercapacitor Applications: A Comprehensive Review
by Kandasamy Sasikumar and Heongkyu Ju
Chemosensors 2022, 10(12), 516; https://doi.org/10.3390/chemosensors10120516 - 6 Dec 2022
Cited by 7 | Viewed by 2797
Abstract
Supercapacitors have emerged as one of the promising energy storage systems owing to their rapid charge/discharge capability, long-term cycling stability, and high power density. The application of core-shell nanostructures for supercapacitors is one of the effective strategies to achieve a high specific surface [...] Read more.
Supercapacitors have emerged as one of the promising energy storage systems owing to their rapid charge/discharge capability, long-term cycling stability, and high power density. The application of core-shell nanostructures for supercapacitors is one of the effective strategies to achieve a high specific surface area for abundant reaction sites and good electrical conductivity for fast charge transfer, hence improving the performance of supercapacitors. Particularly, the use of NiMoO4 for the core-shell structure has drawn great attention due to its outstanding advantages, such as its natural abundance, low material cost, superior electrochemical performance, and wide electrochemical potential window in cyclic voltammetry. In this context, this review comprehensively covers the recent progress of the core-shell nanostructures based on the NiMoO4-composite materials, which find applications in supercapacitors. The composite materials that incorporate metal oxides such as NiMoO4, metal hydroxides, metal chalcogenides, carbon materials, and conductive polymers are discussed in detail for such core-shell nanostructures with the aim of understanding how the adopted materials and the relevant morphology govern the electrochemical features for supercapacitors. Finally, the existing challenges in current technologies for supercapacitors are discussed, while possible future directions in developing the NiMoO4-composite-based core-shell nanostructures are proposed for high-performance supercapacitors. Full article
(This article belongs to the Special Issue Novel Materials for Sensing, Imaging and Energy Conversion/Storage)
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20 pages, 4582 KiB  
Article
Tetrafluorosubstituted Metal Phthalocyanines: Study of the Effect of the Position of Fluorine Substituents on the Chemiresistive Sensor Response to Ammonia
by Darya Klyamer, Dmitry Bonegardt, Pavel Krasnov, Alexander Sukhikh, Pavel Popovetskiy and Tamara Basova
Chemosensors 2022, 10(12), 515; https://doi.org/10.3390/chemosensors10120515 - 4 Dec 2022
Cited by 9 | Viewed by 1790
Abstract
A comparative analysis of the chemiresistive sensor response of thin films of a series of tetrasubstituted phthalocyanines of various metals with F-substituent in peripheral (MPcF4-p, M = Cu, Co, Zn, Pb, VO) and non-peripheral (MPcF4-np) positions in macroring to [...] Read more.
A comparative analysis of the chemiresistive sensor response of thin films of a series of tetrasubstituted phthalocyanines of various metals with F-substituent in peripheral (MPcF4-p, M = Cu, Co, Zn, Pb, VO) and non-peripheral (MPcF4-np) positions in macroring to low concentrations of ammonia (1–50 ppm) was carried out. It was found that MPcF4-p films exhibit a higher sensor response than MPcF4-np ones. A CoPcF4-p film demonstrated a calculated LOD of 0.01 ppm with a recovery time of 215 s, while a VOPcF4-p film had LOD of 0.04 ppm and the recovery time of 270 s. The selectivity test showed that CO2, ethanol, acetone, benzene, and formaldehyde did not interfere with the determination of ammonia, while H2S at a concentration of more than 10 ppm could act as an interfering gas. It was shown that, as a result of quantum-chemical calculations, the observed regularities are best described by the interaction of NH3 with phthalocyanines through the formation of hydrogen bonds between NH3 and side atoms of the macroring. In the case of MPcF4-p, the NH3 molecule approaches the macrocycle more closely and binds more strongly than in the case of MPcF4-np. The stronger binding leads to a stronger effect of the ammonia molecule on the electronic structure of phthalocyanine and, as a consequence, on the chemiresistive sensor response of the films to ammonia. Full article
(This article belongs to the Special Issue Gas Sensors for Monitoring Environmental Changes)
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