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Chemosensors, Volume 11, Issue 5 (May 2023) – 54 articles

Cover Story (view full-size image): Metal oxide materials (MOxMs) are highly useful materials due to their unique properties and excellent catalytic activity. Non-enzymatic sensors are becoming increasingly popular due to their versatility and superior performance for sensing applications. Glucose is an important target in the agro-food and pharmaceutical industries due to the growing prevalence of obesity and diabetes mellitus. Overall, this work highlights the potential of nanostructured MOxMs in electrochemical sensing applications, particularly for the development of highly sensitive and selective sensors. The use of reactive magnetron sputtering under oblique angle deposition (MS-OAD) configuration allows the creation of highly reactive and porous structures, improving the electrocatalytic and sensing properties of MOxMs-based non-enzymatic sensors. View this paper
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21 pages, 20950 KiB  
Article
Modeling and Simulation of a TFET-Based Label-Free Biosensor with Enhanced Sensitivity
by Sagarika Choudhury, Krishna Lal Baishnab, Koushik Guha, Zoran Jakšić, Olga Jakšić and Jacopo Iannacci
Chemosensors 2023, 11(5), 312; https://doi.org/10.3390/chemosensors11050312 - 22 May 2023
Cited by 5 | Viewed by 1878
Abstract
This study discusses the use of a triple material gate (TMG) junctionless tunnel field-effect transistor (JLTFET) as a biosensor to identify different protein molecules. Among the plethora of existing types of biosensors, FET/TFET-based devices are fully compatible with conventional integrated circuits. JLTFETs are [...] Read more.
This study discusses the use of a triple material gate (TMG) junctionless tunnel field-effect transistor (JLTFET) as a biosensor to identify different protein molecules. Among the plethora of existing types of biosensors, FET/TFET-based devices are fully compatible with conventional integrated circuits. JLTFETs are preferred over TFETs and JLFETs because of their ease of fabrication and superior biosensing performance. Biomolecules are trapped by cavities etched across the gates. An analytical mathematical model of a TMG asymmetrical hetero-dielectric JLTFET biosensor is derived here for the first time. The TCAD simulator is used to examine the performance of a dielectrically modulated label-free biosensor. The voltage and current sensitivity of the device and the effects of the cavity size, bioanalyte electric charge, fill factor, and location on the performance of the biosensor are also investigated. The relative current sensitivity of the biosensor is found to be about 1013. Besides showing an enhanced sensitivity compared with other FET- and TFET-based biosensors, the device proves itself convenient for low-power applications, thus opening up numerous directions for future research and applications. Full article
(This article belongs to the Special Issue State-of-the-Art (Bio)chemical Sensors—Celebrating 10th Anniversary)
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13 pages, 1737 KiB  
Article
Electrochemical Mercury Biosensor Based on Electrocatalytic Properties of Prussian Blue and Inhibition of Catalase
by Povilas Virbickas, Narvydas Dėnas and Aušra Valiūnienė
Chemosensors 2023, 11(5), 311; https://doi.org/10.3390/chemosensors11050311 - 22 May 2023
Cited by 1 | Viewed by 1033
Abstract
This paper presents a detailed study of a novel type of electrochemical mercury ion (Hg2+) biosensor developed by combining Prussian blue (PB) and catalase (Cat). The simultaneous PB-catalyzed reduction of hydrogen peroxide and the inhibition of catalase by Hg2+ ions [...] Read more.
This paper presents a detailed study of a novel type of electrochemical mercury ion (Hg2+) biosensor developed by combining Prussian blue (PB) and catalase (Cat). The simultaneous PB-catalyzed reduction of hydrogen peroxide and the inhibition of catalase by Hg2+ ions were used as the working principle of the biosensor. The biosensor described in this research was capable of detecting Hg2+ ions at relatively low potentials (+0.2 V vs. Ag|AgCl, KClsat) using chronoamperometry and a fast Fourier transform electrochemical impedance spectroscopy (FFT-EIS). Linear ranges of 0.07 mM–3 mM and 0.13 mM–0.80 mM of Hg2+ ions were obtained using amperometric and impedimetric techniques, respectively. In the course of this work, an amperometric study of the Hg2+ ion biosensor was also carried out on a real sample (tap water containing Hg2+ ions). Full article
(This article belongs to the Section Applied Chemical Sensors)
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10 pages, 1796 KiB  
Communication
Quantitative Structure-Activity Relationship of Fluorescent Probes and Their Intracellular Localizations
by Seong-Hyeon Park, Hong-Guen Lee, Xiao Liu, Sung Kwang Lee and Young-Tae Chang
Chemosensors 2023, 11(5), 310; https://doi.org/10.3390/chemosensors11050310 - 22 May 2023
Cited by 3 | Viewed by 1655
Abstract
The development of organelle-specific fluorescent probes has been impeded by the absence of a comprehensive understanding of the relationship between the physicochemical properties of fluorescent probes and their selectivity towards specific organelles. Although a few machine learning models have suggested several physicochemical parameters [...] Read more.
The development of organelle-specific fluorescent probes has been impeded by the absence of a comprehensive understanding of the relationship between the physicochemical properties of fluorescent probes and their selectivity towards specific organelles. Although a few machine learning models have suggested several physicochemical parameters that control the target organelle of the probes and have attempted to predict the target organelles, they have been challenged by low accuracy and a limited range of applicable organelles. Herein, we report a multi-organelle prediction QSAR model that is capable of predicting the destination of probes among nine categories, including cytosol, endoplasmic reticulum, Golgi body, lipid droplet, lysosome, mitochondria, nucleus, plasma membrane, and no entry. The model is trained using the Random Forest algorithm with a dataset of 350 organelle-specific fluorescent probes and 786 descriptors, and it is able to predict the target organelles of fluorescent probes with an accuracy of 75%. The MDI analysis of the model identifies 38 key parameters that have a significant impact on the organelle selectivity of the probes, including LogD, pKa, hydrophilic-lipophilic balance (HLB), and topological polar surface area (TPSA). This prediction model may be useful in developing new organelle-specific fluorescent probes by providing crucial variables that determine the destination of the probes. Full article
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11 pages, 2291 KiB  
Article
A Novel Nanoplatform Based on Biofunctionalized MNPs@UCNPs for Sensitive and Rapid Detection of Shigella
by Yaqi Song, Min Chen, Zhongyu Yan, Lu Han, Leiqing Pan and Kang Tu
Chemosensors 2023, 11(5), 309; https://doi.org/10.3390/chemosensors11050309 - 20 May 2023
Viewed by 1466
Abstract
Shigella, a typical and fatal foodborne pathogen with strong infectivity and survivability in foodstuff, demands a simple and sensitive detecting method. In this study, we reported a novel nanoplatform based on biofunctionalized magnetic nanoparticles (MNPs) modified upconversion nanoparticles (UCNPs) for rapid and [...] Read more.
Shigella, a typical and fatal foodborne pathogen with strong infectivity and survivability in foodstuff, demands a simple and sensitive detecting method. In this study, we reported a novel nanoplatform based on biofunctionalized magnetic nanoparticles (MNPs) modified upconversion nanoparticles (UCNPs) for rapid and specific determination of Shigella. Due to base pairing, Shigella aptamer-functionalized horseradish peroxidase (HRP) combined with complementary strand-modified MNPs@UCNPs. In the absence of Shigella, HRP associated with MNPs@UCNPs were magnetically separated, and colorless 3,3′,5,5′-tetramethylbenzidine (TMB) was oxidized into blue oxTMB. The overlap between oxTMB’s absorption peak and MNPs@UCNPs’ emission peak caused the fluorescence quenching at 545 nm. The MNPs@UCNPs fluorescence biosensor was achieved to detect Shigella in 1 h, with a limit of detection of 32 CFU/mL. This work showed a rapid and specific sensing platform and produced satisfactory chicken sample results. Full article
(This article belongs to the Section (Bio)chemical Sensing)
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15 pages, 3314 KiB  
Article
Organic Luminescent Sensor for Mercury(II) and Iron(III) Ions in Aqueous Solutions
by Sofian Kanan, Aysha Shabnam, Ahmed A. Mohamed and Imad A. Abu-Yousef
Chemosensors 2023, 11(5), 308; https://doi.org/10.3390/chemosensors11050308 - 20 May 2023
Cited by 4 | Viewed by 1164
Abstract
The substrate N1, N3, N5-tris(2-hydroxyphenyl)benzene-1,3,5-tricarboxamide (Sensor A) was prepared in the reaction of 1,3,5-benzenetricarboxylic acid (trimesic acid) and o-aminophenol in ethanol. The prepared organic sensor fulfills the chemiluminescent requirements including a luminophore, spacer, and [...] Read more.
The substrate N1, N3, N5-tris(2-hydroxyphenyl)benzene-1,3,5-tricarboxamide (Sensor A) was prepared in the reaction of 1,3,5-benzenetricarboxylic acid (trimesic acid) and o-aminophenol in ethanol. The prepared organic sensor fulfills the chemiluminescent requirements including a luminophore, spacer, and suitable binding receptor that distress the probe’s luminescent features, providing selective and sensitive detection of mercury and iron ions in aqueous solutions. The sensor selectively detects mercury and iron ions in a water matrix containing various metal ions, including sodium, calcium, magnesium, zinc, and nickel. Strong and immediate binding was observed between mercury ions and the substrate at pH 7.0 with a binding affinity toward Hg2+ 9-fold higher than that observed for iron sensor binding affinity, which makes the substrate a distinctive luminescence sensor for mercury detection at ambient conditions. The sensor shows a linear response toward Hg2+ in the concentration range from 50 ppb to 100 ppm (2.0 × 10−8 to 4.2 × 10−5 M) with a limit of detection of 2 ppb (1.0 × 10−8 M). Further, Sensor A provides linear detection for iron ions in the range from 10 ppb to 1000 ppm (1.5 × 10−8 to 1.5 × 10−3 M). The measured adsorption capacity of Sensor A toward mercury ions ranged from 1.25 to 1.97 mg/g, and the removal efficiency from water samples reached 98.8% at pH 7.0. The data demonstrate that Sensor A is an excellent probe for detecting and removing mercury ions from water bodies. Full article
(This article belongs to the Special Issue Advances in Nanocomposite Luminescent Sensors)
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11 pages, 3109 KiB  
Article
A Laser-Printed Surface-Enhanced Photoluminescence Sensor for the Sub-Nanomolar Optical Detection of Mercury in Water
by Yulia Borodaenko, Stanislav Gurbatov, Evgeny Modin, Aleksandr Chepak, Mikhail Tutov, Aleksandr Mironenko and Aleksandr Kuchmizhak
Chemosensors 2023, 11(5), 307; https://doi.org/10.3390/chemosensors11050307 - 20 May 2023
Viewed by 1253
Abstract
Here, we report a novel, easy-to-implement scalable single-step procedure for the fabrication of a solid-state surface-enhanced photoluminescence (SEPL) sensor via the direct femtosecond (fs) laser patterning of monocrystalline Si wafers placed under the layer of functionalizing solution simultaneously containing a metal salt precursor [...] Read more.
Here, we report a novel, easy-to-implement scalable single-step procedure for the fabrication of a solid-state surface-enhanced photoluminescence (SEPL) sensor via the direct femtosecond (fs) laser patterning of monocrystalline Si wafers placed under the layer of functionalizing solution simultaneously containing a metal salt precursor (AgNO3) and a photoluminescent probe (d114). Such laser processing creates periodically modulated micro- and nanostructures decorated with Ag nanoparticles on the Si surface, which effectively adsorbs and retains the photoluminescent sensor layer. The SEPL effect stimulated by the micro- and nanostructures formed on the Si surface localizing pump radiation within the near-surface layer and surface plasmons supported by the decorating Ag nanoparticles is responsible for the intense optical sensory response modulated by a small amount of analyte species. The produced SEPL sensor operating within a fluidic device was found to detect sub-nanomolar concentrations of Hg2+ in water which is two orders of magnitude lower compared to this molecular probe sensitivity in solution. The fabrication technique is upscalable, inexpensive, and flexible regarding the ability to the control surface nano-morphology, the amount and type of loading noble-metal nanoparticles, as well as the type of molecular probe. This opens up pathways for the on-demand development of various multi-functional chemosensing platforms with expanded functionality. Full article
(This article belongs to the Special Issue Advances in Nanocomposite Luminescent Sensors)
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14 pages, 3065 KiB  
Article
Additive Manufacturing Sensor for Stress Biomarker Detection
by Vinicius A. O. P. da Silva, Jéssica S. Stefano, Cristiane Kalinke, Juliano A. Bonacin and Bruno C. Janegitz
Chemosensors 2023, 11(5), 306; https://doi.org/10.3390/chemosensors11050306 - 20 May 2023
Cited by 2 | Viewed by 1400
Abstract
This work presents a new additive manufacturing electrochemical device with conductive graphene and polylactic acid (PLA) filament and its application for epinephrine sensing. A three-electrode configuration based on a screen-printed electrode architecture and an easy-to-connect connector was designed. The sensor surface was chemically [...] Read more.
This work presents a new additive manufacturing electrochemical device with conductive graphene and polylactic acid (PLA) filament and its application for epinephrine sensing. A three-electrode configuration based on a screen-printed electrode architecture and an easy-to-connect connector was designed. The sensor surface was chemically treated with dimethylformamide (DMF) to remove the insulating thermoplastic and expose the graphene binding groups. The scanning electron microscopy (SEM) results showed that the surface PLA was removed and the graphene nanofibers exposed, which corroborated the X-ray diffraction spectra (XRD). As a proof of concept, the G-PLA electrode was applied for the determination of epinephrine in human blood samples by square wave voltammetry with a linear range from 4.0 to 100 µmol L−1 and a limit of detection of 0.2 µmol L−1. Based on the results obtained and sensor application, 3D-printed G-PLA proved an excellent choice for epinephrine sensing purposes. Full article
(This article belongs to the Special Issue Novel Biosensors for Medical Diagnostics)
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16 pages, 4306 KiB  
Article
Rhodamine Derivative-Linked Silica-Coated Upconverting Nanophosphor (NaYF4: Yb3+/Er3+@SiO2-RBDA) for Ratiometric, Ultrasensitive Chemosensing of Pb2+ Ions
by Jitender Kumar and Indrajit Roy
Chemosensors 2023, 11(5), 305; https://doi.org/10.3390/chemosensors11050305 - 19 May 2023
Cited by 3 | Viewed by 1238
Abstract
Lead (Pb2+) ions are considered as one of the primary environmental pollutants and have a profound effect on human health. In this work, we have developed a hybrid organic–inorganic optical nanochemosensor for selective and ultrasensitive detection of Pb2+ ions based [...] Read more.
Lead (Pb2+) ions are considered as one of the primary environmental pollutants and have a profound effect on human health. In this work, we have developed a hybrid organic–inorganic optical nanochemosensor for selective and ultrasensitive detection of Pb2+ ions based on energy transfer (ET), involving a Pb2+ sensitive rhodamine-derived named (E)-4-(((3′,6′-bis(diethylamino)-3-oxospiro[isoindoline-1,9′-xanthen]-2-yl)imino)methyl)benzaldehyde represented as RBDA, covalently linked with silica coated upconverting nanophosphors (UCNPs). The UCNPs emit visible light after being excited by NIR light, activating the Pb2+ coordinated RBDA (fluorescent probe). When Pb2+ ions were added, a yellow emission band at about 588 nm formed in upconverting photoluminescence spectra, whereas the strength of green emission at about 542 nm reduced upon excitation of 980 nm laser, indicating the energy transfer from UCNP to RBDA-Pb2+ complex. The concentration of Pb2+ ions directly affects how well the probe reabsorbs the green emission of the nanophosphor, thus enabling the ratiometric chemosensing. With a detection limit of 20 nM in aqueous, the resulting ET-based nochemosensor can also preferentially detect Pb2+ despite the presence of other ions. Owing to the minimal autofluorescence and the great penetration depth of NIR light and special optical features of UCNPs, this is a promising approach for sensitive and in-depth detection of Pb2+ ions in a complex ecological and biological specimen. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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27 pages, 7745 KiB  
Review
Chemical Sensor Based on Piezoelectric/Triboelectric Nanogenerators: A Review of the Modular Design Strategy
by Zequan Zhao, Qiliang Zhu, Yin Lu, Yajun Mi, Xia Cao and Ning Wang
Chemosensors 2023, 11(5), 304; https://doi.org/10.3390/chemosensors11050304 - 19 May 2023
Cited by 7 | Viewed by 2414
Abstract
Piezoelectric and triboelectric nanogenerators (P-TENGs) have emerged as promising technologies for converting mechanical energy into electrical energy, with potential applications in self-powered wearable and environmental monitoring devices. Modular design in P-TENGs, characterized by the flexible assembly and customization of device components, enables the [...] Read more.
Piezoelectric and triboelectric nanogenerators (P-TENGs) have emerged as promising technologies for converting mechanical energy into electrical energy, with potential applications in self-powered wearable and environmental monitoring devices. Modular design in P-TENGs, characterized by the flexible assembly and customization of device components, enables the development of sustainable and versatile chemical sensors. In this review, we focus on the role of modularity in P-TENG-based chemical sensing, discussing how it enhances design flexibility, sensing versatility, scalability, and integration with other technologies. We explore the various strategies for functionalizing P-TENGs with specific recognition elements, facilitating selective and sensitive detection of target chemicals such as gases, biochemicals, or biomolecules. Furthermore, we examine the integration of modular P-TENGs with energy storage devices, signal conditioning circuits, and wireless communication modules, highlighting the potential for creating advanced, self-powered sensing systems. Finally, we address the challenges and future directions in the development of modular P-TENG-based chemical sensors (PCS and TCS), emphasizing the importance of improving selectivity, stability, and reproducibility for practical applications. Full article
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25 pages, 2071 KiB  
Review
Recent Progresses in Plasmonic Biosensors for Point-of-Care (POC) Devices: A Critical Review
by Caterina Serafinelli, Alessandro Fantoni, Elisabete C. B. A. Alegria and Manuela Vieira
Chemosensors 2023, 11(5), 303; https://doi.org/10.3390/chemosensors11050303 - 19 May 2023
Cited by 1 | Viewed by 1615
Abstract
The recent progresses in the research of plasmonic phenomena and materials paved the route toward the development of optical sensing platforms based on metal nanostructures with a great potential to be integrated into point-of-care (POC) devices for the next generation of sensing platforms, [...] Read more.
The recent progresses in the research of plasmonic phenomena and materials paved the route toward the development of optical sensing platforms based on metal nanostructures with a great potential to be integrated into point-of-care (POC) devices for the next generation of sensing platforms, thus enabling real-time, highly sensitive and accurate diagnostics. In this review, firstly, the optical properties of plasmonic metal nanoparticles will be illustrated, whereafter the engineering of POC platforms, such as microfluidics and readout systems, will be considered with another critical point which is surface functionalization. Attention will also be given to their potential in multiplexed analysis. Finally, the limitations for effective implementation in real diagnostics will be illustrated with a special emphasis on the latest trend in developing cutting-edge sensing systems. Full article
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14 pages, 3079 KiB  
Article
Highly Selective Arsenite Sensor Based on Gold Nanoparticles and Ionic Liquids
by Xuan Hao Lin, Mann Joe Wong and Sam Fong Yau Li
Chemosensors 2023, 11(5), 302; https://doi.org/10.3390/chemosensors11050302 - 19 May 2023
Viewed by 1259
Abstract
Here, we report a highly selective arsenite (As(III)) sensor based on gold nanoparticles (AuNPs) and ionic liquids (ILs). AuNPs were citrate-capped with negative charges on their surfaces, and could aggregate and precipitate once electrolytes were introduced to neutralize the negative charges. In this [...] Read more.
Here, we report a highly selective arsenite (As(III)) sensor based on gold nanoparticles (AuNPs) and ionic liquids (ILs). AuNPs were citrate-capped with negative charges on their surfaces, and could aggregate and precipitate once electrolytes were introduced to neutralize the negative charges. In this study, we discovered that organic ILs, behaving similarly to inorganic electrolytes such as NaCl, could induce the aggregation and precipitation of AuNPs much more efficiently than inorganic electrolytes. Since As(III) inhibited while ILs promoted the aggregation of AuNPs, we examined the interactions between AuNPs, As(III), and ILs and the possibility of using ILs and AuNPs as a sensing probe to detect arsenite and determine its concentration. Six different ILs were evaluated for this purpose in this study. Repeatability, interference, stability, selectivity, and sensitivity were investigated to evaluate the As(III) sensing probe. The limit of detection (LOD) of the sensor sBMP was as low as 0.18 ppb, ranked as the second lowest among the reported arsenite sensors. The sensing of arsenite was also demonstrated with real water samples and was cross-validated with ICP-OES. Full article
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13 pages, 5253 KiB  
Article
LIBS-MLIF Method: Stromatolite Phosphorite Determination
by Hongpeng Wang, Yingjian Xin, Peipei Fang, Jianjun Jia, Liang Zhang, Sicong Liu and Xiong Wan
Chemosensors 2023, 11(5), 301; https://doi.org/10.3390/chemosensors11050301 - 19 May 2023
Cited by 1 | Viewed by 1408
Abstract
The search for biominerals is one of the core targets in the deep space exploration mission. Stromatolite phosphorite is a typical biomineral that preserves early life on Earth. The enrichment of phosphate is closely related to microorganisms and their secretions. Laser-induced breakdown spectroscopy [...] Read more.
The search for biominerals is one of the core targets in the deep space exploration mission. Stromatolite phosphorite is a typical biomineral that preserves early life on Earth. The enrichment of phosphate is closely related to microorganisms and their secretions. Laser-induced breakdown spectroscopy (LIBS) has become an essential payload in deep space exploration with the ability to analyze chemical elements remotely, rapidly, and in situ. This paper aims to evaluate the rapid identification of biological and non-biological minerals through a remote LIBS payload. LIBS is used for element analysis and mineral classification determination, and molecular laser-induced fluorescence (MLIF) is used to detect halogenated element F to support the existence of fluorapatite. This paper analyzes the LIBS-MLIF spectral characteristics of stromatolites and preliminarily evaluates the feasibility of P element quantification. The results show that LIBS technology can recognize biological and non-biological signals. This discovery is significant because it is not limited to detecting and analyzing element composition. It can also realize the detection of molecular spectrum based on selective extraction of CaF molecule. Therefore, the LIBS payload still has the potential to search for biomineral under the condition of adjusting the detection strategy. Full article
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18 pages, 4725 KiB  
Review
Recent Advances for Imidacloprid Detection Based on Functional Nanomaterials
by Shu Chen, Yawen Wang, Xiuli Liu and Longhua Ding
Chemosensors 2023, 11(5), 300; https://doi.org/10.3390/chemosensors11050300 - 18 May 2023
Cited by 2 | Viewed by 1663
Abstract
Imidacloprid (IMI) has been applied in agricultural production to prevent pests. It is vital to detect IMI residues with high sensitivity for food safety. In general, nanomaterials have driven the development of highly sensitive sensing platforms owing to their unique physical and chemical [...] Read more.
Imidacloprid (IMI) has been applied in agricultural production to prevent pests. It is vital to detect IMI residues with high sensitivity for food safety. In general, nanomaterials have driven the development of highly sensitive sensing platforms owing to their unique physical and chemical properties. Nanomaterials play important roles in the construction of high-performance sensors, mainly through sample pretreatment and purification, recognition molecules immobilization, signal amplification, and providing catalytic active sites. This review addresses the advances in IMI sensors based on the combination of nanomaterials and various analytical techniques. The design principles and performance of different chromatographic, electrochemical, and fabricated optical sensors coupled with nanomaterials are discussed. Finally, the challenges and prospects of sensors based on nanomaterials for IMI analysis have also been incorporated. Full article
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26 pages, 2888 KiB  
Review
Conductive Molecularly Imprinted Polymers (cMIPs): Rising and Versatile Key Elements in Chemical Sensing
by Adriana Feldner, Julia Völkle, Peter Lieberzeit and Philipp Fruhmann
Chemosensors 2023, 11(5), 299; https://doi.org/10.3390/chemosensors11050299 - 18 May 2023
Cited by 1 | Viewed by 1917
Abstract
Molecularly imprinted polymers (MIPs) have proven useful as receptor materials in chemical sensing and have been reported for a wide range of applications. Based on their simplicity and stability compared to other receptor types, they bear huge application potential related to ongoing digitalization. [...] Read more.
Molecularly imprinted polymers (MIPs) have proven useful as receptor materials in chemical sensing and have been reported for a wide range of applications. Based on their simplicity and stability compared to other receptor types, they bear huge application potential related to ongoing digitalization. This is the case especially for conductive molecularly imprinted polymers (cMIPs), which allow easy connection to commercially available sensing platforms; thus, they do not require complex measuring setups. This review provides an overview of the different synthetic approaches toward cMIPs and the obtained limit of detections (LODs) with different transducing systems. In addition, it presents and discusses their use in different application areas to provide a detailed overview of the challenges and possibilities related to cMIP-based sensing systems. Full article
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20 pages, 1923 KiB  
Review
Methods and Analysis of Biological Contaminants in the Biomanufacturing Industry
by Mohammad Janghorban, Sara Kazemi, Rigel Tormon, Philippa Ngaju and Richa Pandey
Chemosensors 2023, 11(5), 298; https://doi.org/10.3390/chemosensors11050298 - 18 May 2023
Cited by 3 | Viewed by 3923
Abstract
The advent of bioprocessing has revolutionized the biomanufacturing industry, leading to the rise of biotherapeutics derived from biologic products such as chimeric antigen receptor (CAR) T-cells used for targeted cancer treatment and the Vero cell line for the production of viral vectors and [...] Read more.
The advent of bioprocessing has revolutionized the biomanufacturing industry, leading to the rise of biotherapeutics derived from biologic products such as chimeric antigen receptor (CAR) T-cells used for targeted cancer treatment and the Vero cell line for the production of viral vectors and vaccines. Despite these promising developments, most biologic products are characterized by fragile macromolecular structures that are heterogenous with a purity profile that varies with each batch making them susceptible to microorganism contamination. Regulatory oversight of biologic products is imperative to ensure adherence to good manufacturing practices and compliance with quality management systems. Current quality assurance protocols during production include monoclonality during cell line development, real-time monitoring of process parameters, flow cytometry for microbial monitoring, polymerase chain reaction, and immunoassay techniques to amplify DNA sequences related to bacterial or biological contaminants. FDA guidance recommends the implementation of process analytical technology within biomanufacturing production to measure critical quality parameters, which includes screening for potential biological contamination. Future advancements in bioprocess monitoring and control should capitalize on providing cheap, real-time, and sensitive detection. Biosensors, mass spectrometry, and polymerase chain reaction present robust, rapid, and real-time capabilities for multiplexed detection of contaminant analytes and have shown promise in meeting these needs. This review discusses the main biological contaminants of bioprocesses, European Union and FDA regulatory guidelines for monitoring and control within biologics production, existing methods and their limitations, and future advancements for biological contamination detection. Full article
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16 pages, 3309 KiB  
Article
Direct Electrochemical Analysis in Seawater: Evaluation of Chloride and Bromide Detection
by Yuqi Chen and Richard G. Compton
Chemosensors 2023, 11(5), 297; https://doi.org/10.3390/chemosensors11050297 - 18 May 2023
Cited by 2 | Viewed by 2007
Abstract
Chloride and bromide are two of the most abundant anions found in seawater, and knowledge of their concentrations is essential for environmental monitoring. However, the analysis of chloride and bromide in seawater is challenging due to the complex nature of the seawater matrix. [...] Read more.
Chloride and bromide are two of the most abundant anions found in seawater, and knowledge of their concentrations is essential for environmental monitoring. However, the analysis of chloride and bromide in seawater is challenging due to the complex nature of the seawater matrix. From an electrochemical perspective, we investigate the suitability of three types of electrode (Au, glassy carbon and Pt) for the analysis of Cl and/or Br in seawater. With the understanding of their electrochemical behaviours in artificial seawater (ASW), optimal voltammetric procedures for their detection are developed. The results show that the Au electrode is unsuitable for use as a Cl and/or Br sensor due to its dissolution and passivation in ASW. The use of glassy carbon resulted in poorly defined chloride and bromide signals. Finally, platinum was found to be a good candidate for chloride detection in artificial seawater using square wave voltammetry, and the results obtained in natural seawater via electrochemical measurement were in good agreement with those obtained via ion chromatography. Platinum electrodes are also recommended for bromide analysis. Full article
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12 pages, 6074 KiB  
Article
Engineering Band Structure of SnO2 Nanoparticles via Coupling with g-C3N4 Nanosheet for the Detection of Ethanolamine
by Jiuyu Li, Kerui Xie, Yating Wang, Ruihua Zhao, Yangyang Shang and Jianping Du
Chemosensors 2023, 11(5), 296; https://doi.org/10.3390/chemosensors11050296 - 16 May 2023
Cited by 4 | Viewed by 1181
Abstract
Volatile organoamines are important industrial raw materials and chemicals. Long-term exposure to amines could be harmful to human health and even cause serious pollution. In this study, SnO2 decorated g-C3N4 material was fabricated and used as a sensor material [...] Read more.
Volatile organoamines are important industrial raw materials and chemicals. Long-term exposure to amines could be harmful to human health and even cause serious pollution. In this study, SnO2 decorated g-C3N4 material was fabricated and used as a sensor material for the detection of ethanolamine (EA). The structures, morphology, surface chemical states, and band structure were characterized, and gas sensing was studied. The results showed that SnO2 nanoparticles were dispersed on g-C3N4, and band structure was dependent on g-C3N4 doping. Notably, the interface heterojunction was conducive to electron transferring and O2 molecule adsorption; the formed reactive oxygen species enhanced the reaction between oxygen and EA, thus leading to high sensitivity to EA. This composite exhibited a high response that was 2.6 times higher than that of pure SnO2, and the detection limit reached 294 ppb. A g-C3N4/SnO2-based sensor displayed a high selectivity to EA with a fast response time (1 s) and recovery time (20 s) at low operating temperatures. In particular, this sensor exhibited a linear relationship between the response and concentration, which is required for quantitative analysis. Full article
(This article belongs to the Special Issue Chemical Sensors for Volatile Organic Compound Detection)
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31 pages, 5935 KiB  
Review
From 1D to 2D to 3D: Electrospun Microstructures towards Wearable Sensing
by Jia-Han Zhang, Xidi Sun, Haitao Wang, Jiean Li, Xin Guo, Sheng Li, Yaqun Wang, Wen Cheng, Hao Qiu, Yi Shi and Lijia Pan
Chemosensors 2023, 11(5), 295; https://doi.org/10.3390/chemosensors11050295 - 16 May 2023
Cited by 5 | Viewed by 2235
Abstract
Wearable sensors open unprecedented opportunities for long-term health monitoring and human–machine interaction. Electrospinning is considered to be an ideal technology to produce functional structures for wearable sensors because of its unique merits to endow devices with highly designable functional microstructures, outstanding breathability, biocompatibility, [...] Read more.
Wearable sensors open unprecedented opportunities for long-term health monitoring and human–machine interaction. Electrospinning is considered to be an ideal technology to produce functional structures for wearable sensors because of its unique merits to endow devices with highly designable functional microstructures, outstanding breathability, biocompatibility, and comfort, as well as its low cost, simple process flow, and high productivity. Recent advances in wearable sensors with one-, two-, or three-dimensional (1D, 2D, or 3D) electrospun microstructures have promoted various applications in healthcare, action monitoring, and physiological information recognition. Particularly, the development of various novel electrospun microstructures different from conventional micro/nanofibrous structures further enhances the electrical, mechanical, thermal, and optical performances of wearable sensors and provides them with multiple detection functions and superior practicality. In this review, we discuss (i) the principle and typical apparatus of electrospinning, (ii) 1D, 2D, and 3D electrospun microstructures for wearable sensing and their construction strategies and physical properties, (iii) applications of microstructured electrospun wearable devices in sensing pressure, temperature, humidity, gas, biochemical molecules, and light, and (iv) challenges of future electrospun wearable sensors for physiological signal recognition, behavior monitoring, personal protection, and health diagnosis. Full article
(This article belongs to the Section Materials for Chemical Sensing)
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17 pages, 2784 KiB  
Article
Identification of Degradation Products of the New Anticancer Drug Substance ONC201 by Liquid Chromatography–High-Resolution Multistage Mass Spectrometry
by Maxime Annereau, Marina Vignes, Tahar Sif Eddine Bouchema, Lucas Denis, Audrey Solgadi, Victoire Vieillard, Muriel Paul, André Rieutord, Jacques Grill, Philippe-Henri Secretan and Bernard Do
Chemosensors 2023, 11(5), 294; https://doi.org/10.3390/chemosensors11050294 - 15 May 2023
Cited by 1 | Viewed by 2131
Abstract
ONC201 (dordaviprone) is a new drug substance used in a compassionate manner to treat patients with glioblastoma. Given the clinical context and the particularly promising preclinical results, we have been asked by the medical authorities to make a first treatment available throughout France [...] Read more.
ONC201 (dordaviprone) is a new drug substance used in a compassionate manner to treat patients with glioblastoma. Given the clinical context and the particularly promising preclinical results, we have been asked by the medical authorities to make a first treatment available throughout France as a hospital preparation to allow access to treatment and to conduct clinical trials. However, to control the quality and safety conditions inherent in this academic manufacturing process, while there is virtually no data available to date to understand the stability of ONC201, we had to determine the stability profile of ONC201, i.e., its sensitivity to different stressors and the types of impurities that could form during its degradation. We found that ONC201 was sensitive to oxidation in the presence of hydrogen peroxide or under light irradiation. Both conditions resulted in the formation of 20 degradation products detected and identified by liquid chromatography–high-resolution mass spectrometry. Their structural elucidation required an in-depth study of the fragmentation pattern of protonated ONC201, described for the first time. The product ions of the degradation products were compared to those of ONC201 protonated ion to assign the most plausible structures for all the detected degradation products. Of these degradation products, those that were rapidly produced, of high intensity and/or identified as potentially having a different toxicity profile to ONC201 by in silico studies, were selected to be monitored during batch release testing and stability studies. Full article
(This article belongs to the Collection Recent Trend in Chromatography for Pharmaceutical Analysis)
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24 pages, 8014 KiB  
Review
Architectures and Mechanisms of Perylene Diimide-Based Optical Chemosensors for pH Probing
by Shuai Chen, Meng Zhou, Ling Zhu, Xiaomei Yang and Ling Zang
Chemosensors 2023, 11(5), 293; https://doi.org/10.3390/chemosensors11050293 - 14 May 2023
Cited by 9 | Viewed by 1889
Abstract
The precise control and monitoring of pH values remain critical for many chemical, physiological and biological processes. Perylene diimide (PDI)-based molecules and materials exhibit excellent thermal, chemical and photochemical stability, unique UV-vis absorption and fluorescent emission properties, low cytotoxicity, as well as intrinsic [...] Read more.
The precise control and monitoring of pH values remain critical for many chemical, physiological and biological processes. Perylene diimide (PDI)-based molecules and materials exhibit excellent thermal, chemical and photochemical stability, unique UV-vis absorption and fluorescent emission properties, low cytotoxicity, as well as intrinsic electron-withdrawing (n-type semiconductor) nature and impressive molecular assembly capability. These features combined enable promising applications of PDIs in chemosensors via optical signal modulations (e.g., fluorescent or colorimetric). One of the typical applications lies in the probing of pH under various conditions, which in turn helps monitor the extracellular (environmental) and intracellular pH change and pH-relying molecular recognition of inorganic or organic ions, as well as biological species, and so on. In this review, we give a special overview of the recent progress in PDI-based optical chemosensors for pH probing in various aqueous and binary water–organic media. Specific emphasis will be given to the key design roles of sensing materials regarding the architectures and the corresponding sensing mechanisms for a sensitive and selective pH response. The molecular design of PDIs and structural optimization of their assemblies in order to be suitable for sensing various pH ranges as applied in diverse scenarios will be discussed in detail. Moreover, the future perspective will be discussed, focusing on the current key challenges of PDI-based chemosensors in pH monitoring and the potential approach of new research, which may help address the challenges. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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10 pages, 2215 KiB  
Communication
Screening the Specific Surface Area for Metal-Organic Frameworks by Cataluminescence
by Zenghe Li, Danning Pei, Rui Tian and Chao Lu
Chemosensors 2023, 11(5), 292; https://doi.org/10.3390/chemosensors11050292 - 14 May 2023
Cited by 3 | Viewed by 1818
Abstract
Metal-organic frameworks (MOFs) are famous for their large surface area, which is responsible for the dispersed active sites and decent behaviors in gas adsorption, storage, and catalytic reactions. However, it remains a great challenge to acquire a cost-effective and accurate evaluation on the [...] Read more.
Metal-organic frameworks (MOFs) are famous for their large surface area, which is responsible for the dispersed active sites and decent behaviors in gas adsorption, storage, and catalytic reactions. However, it remains a great challenge to acquire a cost-effective and accurate evaluation on the surface area for the MOFs. In this work, we have proposed cataluminescence (CTL) to evaluate the specific surface area for the MOFs, based on the adsorption–desorption and the catalytic reaction of ethanol. Aluminum-based MOFs with large-pore (lp), narrow-pore (np), and medium-pore (mp-130, mp-140, and mp-150 synthesized under 130, 140, and 150 °C) have been prepared. Distinguished CTL signals were acquired from ethanol in the presence of these MOFs: lp > mp-150 > mp-130 > mp-140 > np. Note that the CTL intensities were positively correlated with the specific surface areas of these MOFs acquired by the Brunauer–Emmett–Teller (BET) method. The distinct specific surface area of MOFs determined the capacity to accommodate and activate ethanol, leading to the varied CTL intensity signals. Therefore, the proposed CTL could be utilized for the rapid and accurate evaluation of the specific surface area for MOFs. It is believed that this CTL strategy showed great possibilities in the structural evaluation for various porous materials. Full article
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14 pages, 2685 KiB  
Article
Flexible Humidity Sensor Based on Au Nanoparticles/Organosilica-Containing Polyelectrolyte Composite
by Pi-Guey Su and Chih-Chang Hsu
Chemosensors 2023, 11(5), 291; https://doi.org/10.3390/chemosensors11050291 - 13 May 2023
Viewed by 1548
Abstract
A novel flexible humidity sensor incorporating gold nanoparticles (Au NPs) and a trifunctional organosilica compound has been developed through the integration of sol–gel processing, free radical polymerization, and self-assembly techniques. The trifunctional organosilica was initially synthesized by modifying (3-mercaptopropyl)trimethoxysilane (thiol-MPTMS) with 3-(trimethoxysilyl)propyl methacrylate [...] Read more.
A novel flexible humidity sensor incorporating gold nanoparticles (Au NPs) and a trifunctional organosilica compound has been developed through the integration of sol–gel processing, free radical polymerization, and self-assembly techniques. The trifunctional organosilica was initially synthesized by modifying (3-mercaptopropyl)trimethoxysilane (thiol-MPTMS) with 3-(trimethoxysilyl)propyl methacrylate (vinyl-TMSPMA). Subsequently, a hydrophilic polyelectrolyte, [3(methacryloylamino)propyl]trimethyl ammonium chloride (MAPTAC), was grafted onto the MPTMS-TMSPMA gel. The Au NPs were assembled onto the thiol groups present in the MPTMS-TMSPMA-MAPTAC gel network. The compositional and microstructural properties of the Au NPs/MPTMS-TMSPMA-MAPTAC composite film were investigated utilizing Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The presence of thiol groups and mesoporous silica skeletons ensured the stability of the humidity-sensing film on the substrate under highly humid conditions, while the hydrophilic groups functioned as humidity-sensitive sites. This innovative humidity sensor demonstrated high sensitivity, acceptable linearity, minimal hysteresis, and rapid response time across a broad range of working humidity levels. Based on the complex impedance spectra analysis, hydronium ions (H3O+) were determined to govern the conductance process of the flexible humidity sensor. Full article
(This article belongs to the Section Materials for Chemical Sensing)
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17 pages, 2008 KiB  
Review
Enzymeless Electrochemical Glucose Sensors Based on Metal–Organic Framework Materials: Current Developments and Progresses
by Chang Liu, Jian Zhou, Rongqiu Yan, Lina Wei and Chenghong Lei
Chemosensors 2023, 11(5), 290; https://doi.org/10.3390/chemosensors11050290 - 12 May 2023
Cited by 5 | Viewed by 1909
Abstract
Electrochemical glucose sensors play a crucial role in medicine, bioscience, food science, and agricultural science. Metal–organic frameworks possess exceptional properties, such as large specific surface area, high porosity, tunable pore structure, high catalytic activity, open metal active sites, and structural diversity. The catalytic [...] Read more.
Electrochemical glucose sensors play a crucial role in medicine, bioscience, food science, and agricultural science. Metal–organic frameworks possess exceptional properties, such as large specific surface area, high porosity, tunable pore structure, high catalytic activity, open metal active sites, and structural diversity. The catalytic activity of metal–organic frameworks enables electrocatalytic oxidation of glucose without the need for enzymes. Consequently, enzymeless electrochemical glucose sensors based on metal–organic framework materials have gained much attention and have been extensively studied for glucose detection. This mini-review provides an overview of the development and progress of enzymeless electrochemical glucose detection based on metal–organic framework material–modified electrodes, including doping materials, sensitivity, detection limit, and fast response capability. With the advancement of this technology, enzymeless electrochemical glucose sensors can continuously and stably detect glucose and can be utilized in various fields, such as wearable devices. Full article
(This article belongs to the Section Electrochemical Devices and Sensors)
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12 pages, 3442 KiB  
Article
Ppb-Level NO2 Sensor with High Selectivity Fabricated by Flower-like Au-Loaded In2O3
by Ji Zhang, Fangfang Zhang, Xu Li and Qingji Wang
Chemosensors 2023, 11(5), 289; https://doi.org/10.3390/chemosensors11050289 - 12 May 2023
Cited by 1 | Viewed by 1554
Abstract
With increasingly serious environmental problems caused by the improvement in people’s living standards, the number of cars has increased sharply in recent years, which directly leads to the continuous increase in the concentration of NO2 in the air. NO2 is a [...] Read more.
With increasingly serious environmental problems caused by the improvement in people’s living standards, the number of cars has increased sharply in recent years, which directly leads to the continuous increase in the concentration of NO2 in the air. NO2 is a common toxic and irritant gas, which is harmful to both the human body and the environment. Therefore, this research focuses on NO2 detection and is committed to developing high-performance, low detection limit NO2 sensors. In this study, flower-like Au-loaded In2O3 was successfully fabricated using the hydrothermal method and the wet impregnation method. The morphological features and chemical compositions of the as-prepared samples were characterized using SEM, TEM, XRD and XPS. A variety of sensors were fabricated and the gas-sensing properties of sensors were investigated. The results indicate that the sensor based on 0.5 mol% Au/In2O3 shows a response value of 1624 to 1 ppm NO2 at 100 °C, which is 14 times that based on pure In2O3. Meanwhile, the detection limit of the sensor based on 0.5 mol% Au/In2O3 for NO2 is 10 ppb, and the response value is 10.4. In addition, the sensor based on 0.5 mol% Au/In2O3 also has high selectivity to NO2 among CO, CO2, H2, CH4, NH3, SO2 and H2S. Finally, the sensitization mechanism of Au/In2O3 was discussed, and the reasons for improving the performance of the sensor were analyzed. The above results and analysis demonstrate that the gas-sensing attributes of the sensor based on 0.5 mol% Au/In2O3 to NO2 improved remarkably; at the same time, it has been proved that the composite material has extensive potential in practical applications. Full article
(This article belongs to the Special Issue Chemical Sensors for Volatile Organic Compound Detection)
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19 pages, 7122 KiB  
Article
Preparation of 2-Butanone Gas Sensor Based on Ag-Decorated In2O3 Nanocube with High Response and Low Detection Level
by Hua Zhang, Yinghao Guo, Hongliang Gao and Fanli Meng
Chemosensors 2023, 11(5), 288; https://doi.org/10.3390/chemosensors11050288 - 11 May 2023
Cited by 1 | Viewed by 1446
Abstract
In this work, 2-butanone-sensitive Ag-decorated In2O3 nanocomposites were successfully prepared using a facile one-step hydrothermal method to enhance the sensing performance of In2O3 nanocubes. The methods of scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission [...] Read more.
In this work, 2-butanone-sensitive Ag-decorated In2O3 nanocomposites were successfully prepared using a facile one-step hydrothermal method to enhance the sensing performance of In2O3 nanocubes. The methods of scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) analysis, and X-ray photoelectron spectroscopy (XPS) were used to observe the morphology, microstructure, crystalline phase, and the existing state of the elements in the produced nanomaterials, respectively. The gas sensing test results show that the prepared compounds could respond to 100 ppm of 2-butanone with a high response (242), fourfold that of the pure In2O3 material, at the optimum working temperature of 240 °C. Moreover, the Ag@In2O3-based sensor also showed excellent selectivity, good repeatability, and even long-term stability. In addition, noble metal surface modification not only decreased the optimum operating temperature (from 270 °C to 240 °C) but also decreased the lowest detection limit (from 5 ppm to 0.25 ppm). In the final section, the gas sensing mechanism of the Ag@In2O3-based sensor and the probable reason for 2-butanone’s enhanced sensing properties are both discussed. Full article
(This article belongs to the Special Issue Application and Advance of Gas Sensors)
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11 pages, 2320 KiB  
Article
Application of an Electronic Nose Technology for the Prediction of Chemical Process Contaminants in Roasted Almonds
by Marta Mesías, Juan Diego Barea-Ramos, Jesús Lozano, Francisco J. Morales and Daniel Martín-Vertedor
Chemosensors 2023, 11(5), 287; https://doi.org/10.3390/chemosensors11050287 - 11 May 2023
Cited by 3 | Viewed by 1337
Abstract
The purpose of this study was to investigate the use of an experimental electronic nose (E-nose) as a predictive tool for detecting the formation of chemical process contaminants in roasted almonds. Whole and ground almonds were subjected to different thermal treatments, and the [...] Read more.
The purpose of this study was to investigate the use of an experimental electronic nose (E-nose) as a predictive tool for detecting the formation of chemical process contaminants in roasted almonds. Whole and ground almonds were subjected to different thermal treatments, and the levels of acrylamide, hydroxymethylfurfural (HMF) and furfural were analysed. Subsequently, the aromas were detected by using the electronic device. Roasted almonds were classified as positive or negative sensory attributes by a tasting panel. Positive aromas were related to the intensity of the almond odour and the roasted aroma, whereas negative ones were linked to a burnt smell resulting from high-intensity thermal treatments. The electronic signals obtained by the E-nose were correlated with the content of acrylamide, HMF, and furfural (RCV2 > 0.83; RP2 > 0.76 in whole roasted almonds; RCV2  > 0.88; RP 2 > 0.95 in ground roasted almonds). This suggest that the E-nose can predict the presence of these contaminants in roasted almonds. In conclusion, the E-nose may be a useful device to evaluate the quality of roasted foods based on their sensory characteristics but also their safety in terms of the content of harmful compounds, making it a useful predictive chemometric tool for assessing the formation of contaminants during almond processing. Full article
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14 pages, 2240 KiB  
Article
A Highly Sensitive and Selective Near-Infrared Fluorescent Probe for Detecting Peroxynitrite in Living Cells and Drosophila Brains
by Wei Wang, Jian-Bin Deng, Long Jin and Bai-Ou Guan
Chemosensors 2023, 11(5), 286; https://doi.org/10.3390/chemosensors11050286 - 11 May 2023
Viewed by 1871
Abstract
Peroxynitrite (ONOO) is a highly reactive nitrogen species (RNS) that is closely associated with many physiological and pathological processes. In this study, we construct a near-infrared (NIR) fluorescent probe, NAF-BN, that utilizes benzyl boronic acid ester for fluorescence quenching of [...] Read more.
Peroxynitrite (ONOO) is a highly reactive nitrogen species (RNS) that is closely associated with many physiological and pathological processes. In this study, we construct a near-infrared (NIR) fluorescent probe, NAF-BN, that utilizes benzyl boronic acid ester for fluorescence quenching of naphthofluorescein cores. NAF-BN has been thoroughly evaluated for reliable imaging of exogenous ONOO in living cells. Further, NAF-BN can be applied effectively to visualize ONOO in Drosophila brains, confirming the hypothesis that neonicotinoid pesticides increase neurological damage and oxidative stress. The probe NAF-BN offers exciting potential to reveal the role of ONOO in various biological and medical fields. Full article
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12 pages, 3690 KiB  
Article
Effects of Oxygen Partial Pressure and Thermal Annealing on the Electrical Properties and High-Temperature Stability of Pt Thin-Film Resistors
by Yawen Pang, Nan Zhao, Yong Ruan, Limin Sun and Congchun Zhang
Chemosensors 2023, 11(5), 285; https://doi.org/10.3390/chemosensors11050285 - 10 May 2023
Cited by 2 | Viewed by 1588
Abstract
The effects of oxygen partial pressure and annealing temperature on the microstructure, electrical properties, and film adhesion of Pt thin-film resistors with PtxOy as the adhesion layer were investigated. Pt/PtxOy films were deposited on alumina substrates by [...] Read more.
The effects of oxygen partial pressure and annealing temperature on the microstructure, electrical properties, and film adhesion of Pt thin-film resistors with PtxOy as the adhesion layer were investigated. Pt/PtxOy films were deposited on alumina substrates by radio frequency sputtering and annealed in a muffle furnace at temperatures in the range of 800–1000 °C. The microstructure and chemical composition of Pt thin-film resistors were examined by optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. The experimental results show that annealing will lead to the formation of bubbles on the surface of the film, and the film prepared at 20% oxygen partial pressure has the least bubbles. The Pt thin-film resistors with a PtxOy adhesion layer sputtered with 10% oxygen partial pressure had the highest TCR (temperature coefficient of resistance) of 3434 ppm/°C, and the TCR increased with increasing annealing temperature. Repeated experiments show that Pt thin-film resistors have better stability at annealing temperatures of 800 °C and 900 °C. Comprehensively considering the TCR and stability, the optimal adhesion layer of Pt thin-film resistors was prepared at an oxygen partial pressure of 10% and an annealing temperature of 900 °C. Full article
(This article belongs to the Section Materials for Chemical Sensing)
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11 pages, 1967 KiB  
Article
Detection of Water Vapor by Chemiluminescence
by Toshihiro Shimada, Honami Nishimoto, Hikaru Hayakawa, Hisashi Ichikawa and Yoshifumi Nakacho
Chemosensors 2023, 11(5), 284; https://doi.org/10.3390/chemosensors11050284 - 9 May 2023
Viewed by 1667
Abstract
We examined the possibility of detecting water vapor by chemiluminescence using the reaction of popular “chemical light” (bis(2,4,5-trichlorophenyl-6-carbopentoxyphenyl)oxalate with H2O2). H2O2 is released from sodium percarbonate exposed to water molecules as in the oxygen bleach. The [...] Read more.
We examined the possibility of detecting water vapor by chemiluminescence using the reaction of popular “chemical light” (bis(2,4,5-trichlorophenyl-6-carbopentoxyphenyl)oxalate with H2O2). H2O2 is released from sodium percarbonate exposed to water molecules as in the oxygen bleach. The release of H2O2 by water vapor was confirmed by mass spectrometry in a vacuum. The chemiluminescence from the mixed reagents was observed when exposed to water vapor. This method opens the way to locally detect the faulty points of water barrier films and observe the real-time failure of the barrier films during bending tests of flexible packing materials. A molecular dynamics simulation was performed to study the diffusion of H2O2 molecules in polymers. Full article
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12 pages, 3124 KiB  
Article
3D-Printed Hydrodynamic Focusing Lab-on-a-Chip Device for Impedance Flow Particle Analysis
by Dayananda Desagani, Shani Kleiman, Teddy Zagardan and Hadar Ben-Yoav
Chemosensors 2023, 11(5), 283; https://doi.org/10.3390/chemosensors11050283 - 8 May 2023
Cited by 3 | Viewed by 1697
Abstract
Particles analysis, such as cell counting and differentiation, are widely used for the diagnosis and monitoring of several medical conditions, such as during inflammation. Three-dimensional-printed lab-on-a-chip (LOC) devices, which can utilize one of the cell counting methods, can bring this technology to remote [...] Read more.
Particles analysis, such as cell counting and differentiation, are widely used for the diagnosis and monitoring of several medical conditions, such as during inflammation. Three-dimensional-printed lab-on-a-chip (LOC) devices, which can utilize one of the cell counting methods, can bring this technology to remote locations through its cost-efficient advantages and easy handling. We present a three-dimensional-printed LOC device with integrated electrodes. To overcome the limited resolution of a 3D printer, we utilized a flow-focusing design. We modeled and simulated the mass transfer and flow dynamics in the LOC by incorporating a flow-focusing design and reached an optimal channel diameter of 0.5 mm, resulting in a flow-focusing distance of <60 µm. We also used electrochemical impedance spectroscopy to enable the dependence of the electrode–solution interface on the flow-focusing properties. Finally, we highlighted the proof-of-concept detection of microspheres (6 µm diameter), which model biological cells that flow in the channel, by recording the electrochemical impedance at 10 kHz, thus showing the potential of a future point-of-care (POC) device. Full article
(This article belongs to the Special Issue Electrochemical Impedance Spectroscopy (EIS): Biosensing Applications)
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