Subjects -> CHEMISTRY (Total: 928 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (661 journals)
    - CRYSTALLOGRAPHY (23 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
    - ORGANIC CHEMISTRY (47 journals)
    - PHYSICAL CHEMISTRY (65 journals)

CHEMISTRY (661 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accounts of Materials Research     Hybrid Journal   (Followers: 11)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 33)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 18)
ACS Catalysis     Hybrid Journal   (Followers: 61)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 26)
ACS Combinatorial Science     Hybrid Journal   (Followers: 14)
ACS Environmental Au     Open Access   (Followers: 11)
ACS Macro Letters     Hybrid Journal   (Followers: 29)
ACS Materials Letters     Open Access   (Followers: 10)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 45)
ACS Nano     Hybrid Journal   (Followers: 235)
ACS Photonics     Hybrid Journal   (Followers: 16)
ACS Symposium Series     Full-text available via subscription   (Followers: 5)
ACS Synthetic Biology     Hybrid Journal   (Followers: 39)
Acta Chemica Malaysia     Open Access   (Followers: 2)
Acta Chimica Slovaca     Open Access   (Followers: 4)
Acta Chimica Slovenica     Open Access   (Followers: 4)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 10)
Acta Scientifica Naturalis     Open Access   (Followers: 4)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 10)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 12)
Adsorption Science & Technology     Open Access   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 14)
Advanced Functional Materials     Hybrid Journal   (Followers: 78)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 4)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 3)
Advanced Science Focus     Free   (Followers: 8)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 141)
Advances in Chemical Science     Open Access   (Followers: 52)
Advances in Chemistry     Open Access   (Followers: 40)
Advances in Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Environmental Chemistry     Open Access   (Followers: 15)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 35)
Advances in Nanoparticles     Open Access   (Followers: 17)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Polymer Science     Hybrid Journal   (Followers: 50)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Sample Preparation     Open Access   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 18)
Aerosol Science and Engineering     Hybrid Journal   (Followers: 2)
African Journal of Chemical Education     Open Access   (Followers: 7)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Aggregate     Open Access   (Followers: 2)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 2)
Alchemy : Jurnal Penelitian Kimia     Open Access  
Alfarama Journal of Basic & Applied Sciences     Open Access   (Followers: 12)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 45)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 21)
American Journal of Chemistry     Open Access   (Followers: 37)
American Journal of Plant Physiology     Open Access   (Followers: 9)
Analyst     Hybrid Journal   (Followers: 35)
Analytical Science Advances     Open Access   (Followers: 1)
Angewandte Chemie     Hybrid Journal   (Followers: 173)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 285)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 6)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 5)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 14)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 20)
Applied Surface Science     Hybrid Journal   (Followers: 31)
Arabian Journal of Chemistry     Open Access   (Followers: 4)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 2)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 2)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 8)
Autophagy     Hybrid Journal   (Followers: 8)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Hybrid Journal   (Followers: 257)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 5)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 24)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 3)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 86)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 61)
Bioorganic Chemistry     Hybrid Journal   (Followers: 7)
Biopolymers     Hybrid Journal   (Followers: 15)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 3)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 25)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 5)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 1)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 11)
Canadian Mineralogist     Full-text available via subscription   (Followers: 5)
Carbohydrate Polymer Technologies and Applications     Open Access   (Followers: 1)
Carbohydrate Polymers     Hybrid Journal   (Followers: 11)
Carbohydrate Research     Hybrid Journal   (Followers: 23)
Carbon     Hybrid Journal   (Followers: 64)
Carbon Capture Science & Technology     Open Access   (Followers: 1)
Carbon Trends     Open Access   (Followers: 6)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 10)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 12)
Cell Reports Physical Science     Open Access   (Followers: 1)
Cellulose     Hybrid Journal   (Followers: 8)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
Chem     Hybrid Journal   (Followers: 8)
Chem Catalysis     Hybrid Journal   (Followers: 2)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 22)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Hybrid Journal   (Followers: 85)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Physics Impact     Full-text available via subscription   (Followers: 1)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 228)
Chemical Science     Open Access   (Followers: 45)
Chemical Science International Journal     Open Access  
Chemical Technology     Open Access   (Followers: 75)
Chemical Thermodynamics and Thermal Analysis     Open Access   (Followers: 4)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 39)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 18)
ChemInform     Hybrid Journal   (Followers: 5)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Industry     Full-text available via subscription   (Followers: 6)
Chemistry - A European Journal     Hybrid Journal   (Followers: 154)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 22)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 7)
Chemistry Education Review     Open Access   (Followers: 2)
Chemistry in Education     Open Access   (Followers: 5)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 5)
Chemistry of Materials     Hybrid Journal   (Followers: 195)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Hybrid Journal   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal   (Followers: 1)
Chemistry–Methods     Open Access   (Followers: 4)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 13)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPhysMater     Full-text available via subscription  
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access  
ChemSystemsChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal   (Followers: 1)
CHIMIA International Journal for Chemistry     Open Access   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 9)
Chromatographia     Hybrid Journal   (Followers: 21)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 4)
Ciencia     Open Access  
Clay Minerals     Hybrid Journal   (Followers: 9)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 7)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 9)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 2)
Combustion Science and Technology     Hybrid Journal   (Followers: 26)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Communications Chemistry     Open Access   (Followers: 2)
Communications Materials     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 7)

        1 2 3 4 | Last

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Number of Followers: 1  

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ISSN (Online) 2227-9040
Published by MDPI Homepage  [258 journals]
  • Chemosensors, Vol. 11, Pages 468: Smartphone-Based Portable Bio-Chemical
           Sensors: Exploring Recent Advancements

    • Authors: The Huy Bui, Balamurugan Thangavel, Mirkomil Sharipov, Kuangcai Chen, Joong Ho Shin
      First page: 468
      Abstract: Traditionally, analytical chemistry and diagnosis relied on wet laboratories and skilled professionals utilizing sophisticated instruments for sample handling and analysis. However, with the development of novel materials and sensing techniques, there has been a significant shift towards the use of standalone sensors, allowing tests to be conducted on-site or even in real time, leading to cost- and time-efficiency. With their widespread adoption globally, smartphones have emerged as an ideal platform for such sensors, boasting extensive sensor capabilities, advanced processing power, and communication functionalities. Smartphone-based assays make use of optical and electrochemical sensors, utilizing built-in cameras, ambient light sensors, and other features for optical sensing, while the micro-USB port, Bluetooth, and wireless connection facilitate data transmission and analog voltage application for electrochemical sensing. Previous overview papers have explored smartphone-based sensing in specific domains; this review provides a comprehensive examination of recent advancements in smartphone-based sensors, encompassing both optical and electrochemical sensing methods. The review provides the fundamental principles of these sensors and their implementation using smartphones, showcases recent applications, and presents innovative designs that take advantage of the inherent functionalities and sensor capabilities of smartphones. The review concludes by offering an outlook on the prospects of smartphone-based sensing and includes a reflective section emphasizing the potential impact of sensors in chemical and biological analyses. This comprehensive resource aims to provide information to researchers and practitioners interested in using smartphones for cutting-edge analytical methodologies.
      Citation: Chemosensors
      PubDate: 2023-08-22
      DOI: 10.3390/chemosensors11090468
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 469: Sensing of Digestive
           Enzymes—Diagnosis and Monitoring of Pancreatitis

    • Authors: Jiaju Yin, Tianrui Cui, Yi Yang, Tian-Ling Ren
      First page: 469
      Abstract: This paper is a comprehensive review of the techniques for the detection of pancreatic enzymes, which are common biochemical indicators of pancreatitis, including amylase, trypsin, chymotrypsin, elastase, and lipase. Pancreatitis is a disease with self-digestion due to the abnormal activation of digestive enzymes in the pancreas. Hospitalization is often required due to the lack of convenient therapeutic agents. The main recent results are reported in this review, especially the techniques that enable portability and Point-of-Care testing (POCT). This is because timely diagnosis at the early stage and avoiding recurrence after recovery are the keys to treatment. It is also important to reduce the rate of misdiagnosis and to avoid overtreatment. Various detection methods are discussed, with particular attention given to the implementation of chemical sensing and probe design. The new sensing technology for digestive enzymes makes it possible to perform early screening for pancreatitis in remote areas or in one’s own home.
      Citation: Chemosensors
      PubDate: 2023-08-22
      DOI: 10.3390/chemosensors11090469
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 470: Recent Advances in Wearable Sensors for
           the Monitoring of Sweat: A Comprehensive Tendency Summary

    • Authors: Zhe Xing, Jianan Hui, Bo Lin, Zhenhua Wu, Hongju Mao
      First page: 470
      Abstract: Sweat, as a biofluid that is easy to extract and contains a variety of biomarkers, can provide various types of physiological information for health monitoring. In recent years, research on wearable sensors for sweat sensing has been emerging continuously. Wearable sweat sensing will probably become an alternative method to traditional chemical analysis. This is due to its advantages of portability, non-invasiveness, comfort, and continuous monitoring. Since the inception of this research field, wearable sweat sensors have achieved significant development in terms of materials, structures, systems, and application directions. Research interests are gradually evolving from single biomarker detection to the pursuit of multi-channel, multi-modal system-level architecture. The analysis of physiological signals has also developed from single signal characterization to omics analysis using multiple physiological information sources. Based on the changes mentioned above, this paper mainly introduces the latest researches of wearable sweat sensors from the aspects of strategy, architecture, material, system, data processing, etc., and tries to summarize the trends of sweat sensors. Finally, this paper analyzes the challenges faced by the sensing platform and possible methods for optimization.
      Citation: Chemosensors
      PubDate: 2023-08-23
      DOI: 10.3390/chemosensors11090470
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 471: A Green Voltammetric Determination of
           Molnupiravir Using a Disposable Screen-Printed Reduced Graphene Oxide
           Electrode: Application for Pharmaceutical Dosage and Biological Fluid

    • Authors: Abdelrahman Nabil, Hassan A. M. Hendawy, Randa Abdel-Salam, Rasha M. Ahmed, Ahmed Shawky, Samy Emara, Noha Ibrahim
      First page: 471
      Abstract: A new green-validated and highly sensitive electrochemical method for the determination of molnupiravir (MOV) has been developed using cyclic voltammetry. The proposed analytical platform involves the use of a disposable laboratory-made screen-printed reduced graphene oxide 2.5% modified electrode (rGO-SPCE 2.5%) for the first time to measure MOV with high specificity. The surface morphology of the sensor was investigated by using a scanning electron microscope armed with an energy-dispersive X-ray probe. The fabricated sensor attained improved sensitivity when sodium dodecyl sulfate (SDS) surfactant (3 µM) was added to the supporting electrolyte solution of 0.04 M Britton–Robinson buffer at pH 2. The electrochemical activity of rGO-SPCE was examined in comparison with two different working electrodes in order to demonstrate that it was the most competitive sensor for MOV monitoring. The method was validated using differential pulse voltammetry according to ICH guidelines, resulting in good precision, accuracy, specificity, and robustness over a concentration range of 0.152–18.272 µM, with a detection limit of 0.048 µM. The stability investigation demonstrated that rGO-SPCE 2.5% can provide high-stability behavior towards the analyte throughout a six-week period under refrigeration. The fabricated rGO-SPCE 2.5% was successfully employed for the measurement of MOV in pharmaceutical capsules and human biofluids without the interference of endogenous matrix components as well as the commonly used excipient.
      Citation: Chemosensors
      PubDate: 2023-08-23
      DOI: 10.3390/chemosensors11090471
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 472: Fusion Recalibration Method for
           Addressing Multiplicative and Additive Effects and Peak Shifts in
           Analytical Chemistry

    • Authors: Dapeng Jiang, Yizhuo Zhang, Yilin Ge, Keqi Wang
      First page: 472
      Abstract: Analytical chemistry relies on the qualitative and quantitative analysis of multivariate data obtained from various measurement techniques. However, artifacts such as missing data, noise, multiplicative and additive effects, and peak shifts can adversely affect the accuracy of chemical measurements. To ensure the validity and accuracy of results, it is crucial to preprocess the data and correct for these artifacts. This paper proposes a fusion recalibration algorithm, called Spectral Offset Recalibration (SOR), that combines the Extended Multiplicative Signal Correction (EMSC) and Correlation-Optimized Warping (COW) algorithms to address both multiplicative and additive effects and peak shifts. The algorithm incorporates prior spectroscopic knowledge to down-weight or disregard spectral regions with strong absorption or significant distortion caused by peak alignment algorithms. Experimental validation on wood NIR datasets and simulated datasets demonstrates the effectiveness of the proposed method. The fusion recalibration approach offers a comprehensive solution for accurate analyses and predictions in analytical chemistry by mitigating the impact of artifacts.
      Citation: Chemosensors
      PubDate: 2023-08-23
      DOI: 10.3390/chemosensors11090472
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 473: Review of the Status and Prospects of
           Fiber Optic Hydrogen Sensing Technology

    • Authors: Changyu Shen, Zihan Xie, Zhenlin Huang, Sasa Yan, Wenbo Sui, Jun Zhou, Zhaokun Wang, Wei Han, Xianglong Zeng
      First page: 473
      Abstract: With the unprecedented development of green and renewable energy sources, the proportion of clean hydrogen (H2) applications grows rapidly. Since H2 has physicochemical properties of being highly permeable and combustible, high-performance H2 sensors to detect and monitor hydrogen concentration are essential. This review discusses a variety of fiber-optic-based H2 sensor technologies since the year 1984, including: interferometer technology, fiber grating technology, surface plasma resonance (SPR) technology, micro lens technology, evanescent field technology, integrated optical waveguide technology, direct transmission/reflection detection technology, etc. These technologies have been evolving from simply pursuing high sensitivity and low detection limits (LDL) to focusing on multiple performance parameters to match various application demands, such as: high temperature resistance, fast response speed, fast recovery speed, large concentration range, low cross sensitivity, excellent long-term stability, etc. On the basis of palladium (Pd)-sensitive material, alloy metals, catalysts, or nanoparticles are proposed to improve the performance of fiber-optic-based H2 sensors, including gold (Au), silver (Ag), platinum (Pt), zinc oxide (ZnO), titanium oxide (TiO2), tungsten oxide (WO3), Mg70Ti30, polydimethylsiloxane (PDMS), graphene oxide (GO), etc. Various microstructure processes of the side and end of optical fiber H2 sensors are also discussed in this review.
      Citation: Chemosensors
      PubDate: 2023-08-23
      DOI: 10.3390/chemosensors11090473
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 474: Synthesis of Photoluminescent Carbon
           Dots Using Hibiscus Tea Waste and Heteroatom Doping for Multi-Metal Ion
           Sensing: Applications in Cell imaging and Environmental Samples

    • Authors: Sonaimuthu Mohandoss, Naushad Ahmad, Kuppu Sakthi Velu, Mohammad Rizwan Khan, Subramanian Palanisamy, SangGuan You, Yong Rok Lee
      First page: 474
      Abstract: Novel photoluminescent carbon dots (CDs) were synthesized through a facile hydrothermal method using Hibiscus tea extract as a natural carbon source and boric acid as a boron source. The optical and physicochemical properties of the as-synthesized nitrogen- and boron-doped CDs (NB-CDs) were characterized using UV–Visible (UV–Vis), photoluminescence (PL) spectroscopy, Fourier-transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The as-synthesized NB-CDs showed spherical morphology of approximately 6.2 ± 0.5 nm with quantum yield (9.2%), high aqueous solubility, strong photo-stability, and excitation-dependent PL behavior. The obtained NB-CDs exhibited high stability over a wide pH range and high ionic strength. Additionally, NB-CDs exhibited PL enhancement response with excellent sensitivity toward multi-metal ions, including Ag+, Cd2+, and Cr3+ ions, with very low detection limits of 44.5, 164.4, and 54.6 nM, respectively, with a wide concentration range of 0–10 μM. Upon testing the cytotoxicity of the NB-CDs at a concentration of 20 μg/mL for 24 h, we found no obvious inhibition of cell viability. Therefore, the proposed sensor method can be successfully applied to detect Ag+, Cd2+, and Cr3+ ions in cell imaging as well as in real water environmental samples.
      Citation: Chemosensors
      PubDate: 2023-08-24
      DOI: 10.3390/chemosensors11090474
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 475: A 3D-Printed Electrochemical
           Immunosensor Employing Cd/Se ZnS QDs as Labels for the Rapid and
           Ultrasensitive Detection of Salmonella typhimurium in Poultry Samples

    • Authors: Michailia Angelopoulou, Dimitra Kourti, Maria Mertiri, Panagiota Petrou, Sotirios Kakabakos, Christos Kokkinos
      First page: 475
      Abstract: Salmonella is one of the leading causes of foodborne illnesses worldwide, with poultry products being a major source of contamination. Thus, the detection of salmonella in commercial poultry products is crucial to minimize the effects on public health. Electrochemical sensors are promising tools for bacteria detection due to their sensitivity, simplicity, and potential for on-site analysis. In this work, a three-dimensional (3D) printed electrochemical immunosensor for the determination of Salmonella typhimurium in fresh chicken through a sandwich immunoassay employing biotinylated anti-S. typhimurium antibody followed by streptavidin labeled with Cd/Se ZnS quantum dots (QDs) is presented. The device features three carbon-black polylactic acid electrodes and a holder, and the quantification of S. typhimurium is performed by anodic stripping voltametric (ASV) determination of the Cd(II) released after acidic dissolution of the QDs. To enhance sensitivity, an electroplated bismuth film was deposited on the working electrode, achieving a detection limit of 5 cfu/mL in a total assay time of 25 min, whereas 5 h of sample pre-enrichment was required for the detection of 1 cfu/25 mL of chicken rinse and chicken broth. The method is accurate, with %recovery values ranging from 93.3 to 113% in fresh chicken samples, and repeatable with intra- and inter- assay coefficient of variations <2 and 5%, respectively, indicating the suitability of the proposed immunosensor for the detection of S. typhimurium at the point-of-need.
      Citation: Chemosensors
      PubDate: 2023-08-26
      DOI: 10.3390/chemosensors11090475
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 476: High-Performance MEMS Oxygen Sensors
           Based on Au/TiO2 Films

    • Authors: Mingzhi Jiao, Xiaohu Zhao, Xinjian He, Gang Wang, Wei Zhang, Qian Rong, DucHoa Nguyen
      First page: 476
      Abstract: High-performance microelectromechanical system (MEMS) oxygen sensors were realized by successful preparation of Au nanofilms over TiO2 thin films through successive sputtering on commercial MEMS microhotplates. Oxygen sensing performance of 3 and 6 nm thick Au over TiO2 thin films were compared with that of pure TiO2 thin films. It was shown that 6 nm thick Au over TiO2 thin films have the best sensitivity toward oxygen. The prepared TiO2 thin films were characterized using SEM, EDS, XPS, and a gas testing instrument. The results show that Au decoration has little influence on the surface morphologies of TiO2 thin films. However, Au decoration has a strong influence on the surface properties of the composite films. The favorable performance of 6 nm Au-doped TiO2 thin films is attributed to factors such as catalytical performance, height of Schottky contact, and number of oxygen vacancies. This work makes contributions to low power consumption and high-performance oxygen sensors for Internet of Things applications.
      Citation: Chemosensors
      PubDate: 2023-08-28
      DOI: 10.3390/chemosensors11090476
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 477: Design of Functional Ti3C2Tx MXene for
           Gas Sensors and Energy Harvesting: A Review

    • Authors: Qui Thanh Hoai Ta, Deepika Thakur, Jin-Seo Noh
      First page: 477
      Abstract: Two-dimensional (2D) inorganic compounds, MXenes, are the most promising candidate for chemical sensors and environmental remediation. Since the first synthesis of Ti3C2Tx MXene from the Ti3AlC2 MAX phase in 2011, 2D materials have been attracting significant attention from a wide range of scientific communities because of their unique physicochemical properties. The attractive properties of MXenes motivated us to explore the new wave of front-end research and applications. Over the past 12 years, there have been more than 10,000 theoretical and experimental studies on MXenes. All these publications have primarily focused on Ti3C2Tx MXene because of its fascinating material properties and tunability towards target applications. To provide readers with a fundamental understanding of this emerging 2D material, this review discusses the recent trends in the design of Ti3C2Tx MXene for gas sensors and energy harvesting applications. For the most updated information, this review focuses on important findings and applications reported in the last decade.
      Citation: Chemosensors
      PubDate: 2023-09-01
      DOI: 10.3390/chemosensors11090477
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 478: Recent Progress of Electrochemical
           Sensors in Food Analysis

    • Authors: Zhaoxia Shi, Ling Xia, Gongke Li
      First page: 478
      Abstract: Electrochemical sensors have the advantages of being sensitive, stable, selective, simple, fast, and cost-efficient, and they have attracted much attention in food analysis. Electrode modification materials are very important for the performance of electrochemical sensors. This review summarizes the type of electrode modification material (metal nanoparticles/metal oxides, conductive polymers, carbon materials, and the metal-organic framework and its composite materials) and the application progress of electrochemical sensors in food analysis, mainly including the detection of food additives, pesticide residues, veterinary drugs residue, heavy metals, and mycotoxins in food in the recent ten years. Moreover, the application of electrochemical sensors is prospected.
      Citation: Chemosensors
      PubDate: 2023-09-01
      DOI: 10.3390/chemosensors11090478
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 479: Utilising Portable Laser-Induced
           Breakdown Spectroscopy for Quantitative Inorganic Water Testing

    • Authors: Nils Schlatter, Bernd G. Lottermoser, Simon Illgner, Stefanie Schmidt
      First page: 479
      Abstract: At present, the majority of water testing is carried out in the laboratory, and portable field methods for the quantification of elements in natural waters remain to be established. In contrast, portable instruments like portable X-ray fluorescence (pXRF) analysis and portable laser-induced breakdown spectroscopy (pLIBS) have become routine analytical methods for the quantification of elements in solids. This study aims to show that pLIBS can also be used for chemical compositional measurements of natural waters. Bottled mineral waters were selected as sample materials. A surface-enhanced liquid-to-solid conversion technique was used to improve the detection limits and circumvent the physical limitations in liquid analysis. The results show that low to medium mineralised waters can be analysed quantitatively for their ions using the documented method. For more highly concentrated samples, typically above an electrical conductivity (EC) of 1000 µS/cm, further adjustment is required in the form of self-absorption correction. However, water with a conductivity up to this limit can be analysed for the main cations (Li+, Na+, Mg2+, K+, Ca2+, and Sr2+) as well as the main anions (SO42− and Cl−) using the documented method. This study demonstrates that there is significant potential for developing field-based pLIBS as a tool for quantitative water analysis.
      Citation: Chemosensors
      PubDate: 2023-09-01
      DOI: 10.3390/chemosensors11090479
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 480: Electrochemical Etching-Assisted
           Fabrication of Quantum Tunneling Sensing Probes with Controlled Nanogap

    • Authors: Bangrui Shao, Qiuxiang He, Tao Jiang, Biaofeng Zeng, Cuifang Kuang, Xu Liu, Longhua Tang
      First page: 480
      Abstract: Quantum tunneling electrical probes, consisting of a pair of nanoelectrodes with a gap width of less than 5 nm, can be used as a robust electrical sensing platform for the detection of various nanoscale objects. To achieve this, stable and gap-width-controllable electrodes are essential. Although various methods, including lithography and electrochemical strategies, have been proposed for the fabrication of tunneling electrodes, the ability to precisely control the gap width and ensure reproducibility is still lacking. Here, we report a feedback-controlled electrochemical etching approach to fabricate the tunneling electrodes with a controlled nanogap. The connected nanoelectrodes, derived from a dual-barrel nanopipette, were subjected to a controlled electrochemical etching process from a short-circuited state to a tunneling gap. The resulting tunneling electrodes exhibited solvent-response current–voltage electrical behavior, which was well fitted with the Simons model, indicating the formation of tunneling electrodes. Overall, a success rate of more than 60% could be achieved to obtain the tunneling gaps. Furthermore, to verify the function of tunneling electrodes, we used the etched-tunneling electrodes for free-diffusing protein detection, showing the potential of etched-tunneling electrodes as single-molecule sensors.
      Citation: Chemosensors
      PubDate: 2023-09-01
      DOI: 10.3390/chemosensors11090480
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 481: Recent Advances in Functionalization
           Strategies for Biosensor Interfaces, Especially the Emerging
           Electro-Click: A Review

    • Authors: Feiyu Wang, Yiwen Xie, Weijie Zhu, Tianxiang Wei
      First page: 481
      Abstract: The functionalization of biosensor interfaces constitutes a crucial aspect of biosensing systems, as it directly governs key characteristics, including sensitivity, selectivity, accuracy, and rapidity. Among the diverse range of functionalization strategies available for biosensor interfaces, the click reaction has emerged as an exceptionally straightforward and stable approach for modifying electrodes and sensing films. Notably, the electro-click reaction enables the reagent-free functionalization of the biosensing interface, offering significant advantages, such as high speed, selectivity, and minimal pollution. Consequently, this strategy has garnered substantial attention and is widely regarded as a promising avenue for enhancing biosensor interface functionalization. Within this comprehensive review, we commence by presenting the latest advancements in functionalized biosensor interfaces, organizing the regulatory strategies into distinct categories based on the mediators employed, ranging from nanomaterials to biomolecules. Subsequently, we provide a comprehensive summary with an emphasis on recently developed electro-click strategies for functionalizing electrochemical and optical biosensor interfaces, covering both principles and applications. It is our anticipation that gaining a profound understanding of the principles and applications underlying electro-click strategies for biosensor interface functionalization will facilitate the design of highly selective and sensitive biosensor systems for diverse domains, such as clinical, pharmaceutical, environmental, and food analyses.
      Citation: Chemosensors
      PubDate: 2023-09-01
      DOI: 10.3390/chemosensors11090481
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 482: Novel Electrochemical Sensor Based on
           MnO2 Nanowire Modified Carbon Paper Electrode for Sensitive Determination
           of Tetrabromobisphenol A

    • Authors: Chunmao Zhu, Qi Wu, Fanshu Yuan, Jie Liu, Dongtian Wang, Qianli Zhang
      First page: 482
      Abstract: In this paper, a MnO2 nanowire (MnO2-NW) modified carbon paper electrode (CP) was developed as a novel electrochemical sensor for the sensitive determination of tetrabromobisphenol A (TBBPA). The MnO2 nanowire was prepared by a hydrothermal synthesis method, and the morphology and structure of MnO2 were characterized using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical performance of TBBPA on MnO2-NW/CP was investigated by cyclic voltammetry, and the result confirmed that MnO2-NW/CP exhibited excellent sensitivity for the determination of TBBPA due to the high specific surface area and good electrical conductivity of the nanowire-like MnO2. Moreover, the important electrochemical factors such as pH value, incubation time and modified material proportion were systematically studied to improve the determination sensitivity. The interferences from similar structure compounds on TBBPA have also been investigated. Under the optimal conditions, MnO2-NW/CP displayed a linear range of 70~500 nM for TBBPA with a detection limit of 3.1 nM. This was superior to some electrochemical methods in reference. The work presents a novel and simple method for the determination of TBBPA.
      Citation: Chemosensors
      PubDate: 2023-09-01
      DOI: 10.3390/chemosensors11090482
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 483: Recent Progress in Multifunctional Gas
           Sensors Based on 2D Materials

    • Authors: Zhifang Liu, Zirui Qiao, Chen-Yuan Li, Yilin Sun
      First page: 483
      Abstract: The detection of specific gas components under various working conditions while at the same time realizing other functions with the same devices has emerged through great efforts due to these devices’ superior energy-saving and high-efficiency properties. Although so-called multifunctional gas sensors have been fabricated with various novel materials, two-dimensional (2D) materials with unique physical and chemical properties used in multifunctional gas sensors have not yet been well studied. In this review, we summarize up-to-date multifunctional gas sensors based on different 2D materials, including graphene and its derivatives, transition metal dichalcogenides (TMDs), MXenes, etc. The progress of machine learning and artificial intelligence used in emerging powerful sensors is introduced. Their sensing abilities and mechanisms are discussed, and further smart devices equipped with IoT platforms and 5G communication are expected for future electronic use.
      Citation: Chemosensors
      PubDate: 2023-09-01
      DOI: 10.3390/chemosensors11090483
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 484: Colorimetric Detection and Killing of
           Bacteria by Enzyme-Instructed Self-Aggregation of Peptide-Modified Gold

    • Authors: Dan Yin, Xiao Li, Xin Wang, Jin-Zhou Liu, Wen-Zhi She, Jiahui Liu, Jian Ling, Rong Sheng Li, Qiue Cao
      First page: 484
      Abstract: Bacterial infections seriously threaten human safety. Therefore, it is very important to develop a method for bacterial detection and treatment with rapid response, high sensitivity, and simple operation. A peptide CF4KYP (C, cysteine; F4, phenylalanine tetrapeptide; K, lysine; YP, phosphorylated tyrosine) functionalized gold nanoparticle (AuNPs-CF4KYP) was synthesized for simultaneous detection and treatment of bacteria based on bacterial alkaline phosphatase (ALP). In solution, ALP can induce AuNPs-CF4KYP aggregation and produce significant color changes. After encountering bacteria, monodisperse AuNPs-CF4KYP can aggregate/assemble in situ on the surface of the bacterial membrane, change the color of the solution from wine red to grey, destroy the bacterial membrane structure, and induce the production of a large number of reactive oxygen species within the bacteria. The absorption change of AuNPs-CF4KYP solution has a good linear relationship with the number of bacteria. Furthermore, the aggregation of AuNPs-CF4KYP kills approximately 80% of Salmonella typhimurium. By combining enzyme-instructed peptide self-assembly technology and colorimetric analysis technology, we achieve rapid and sensitive colorimetric detection and killing of bacteria.
      Citation: Chemosensors
      PubDate: 2023-09-01
      DOI: 10.3390/chemosensors11090484
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 485: Enhanced Modification between Glucose
           Dehydrogenase and Mediator Using Epoxy Silane Assembly for Monitoring

    • Authors: Tae-Won Seo, Won-Yong Jeon, Young-Bong Choi
      First page: 485
      Abstract: Blood glucose monitoring (BGM) using disposable electrodes is commonly used in healthcare diagnosis. The BGM method is not suitable for people with diabetes requiring real-time monitoring who might experience sudden hypoglycemia or hyperglycemia owing to a single measurement at a specific moment. This study aimed to achieve an enhanced stability of glucose diagnosis for continuous glucose measurement systems (CGMs). A representative mediator of a second-generation glucose sensor was synthesized and coordinated with a polymer for immobilization on an indium tin oxide (ITO) electrode. For electrode immobilization, an electrode for enhanced stability was fabricated using the silanization method. The morphological properties of the electrodes were confirmed via cyclic voltammetry (CV), impedance spectroscopy, and SEM. The loss rate of the current density was only 10.11% of the initial current after 8 d. The electrode exhibited a coefficient of determination of R2 = 0.9924, sensitivity of 1.5454 μA/cm2·mM, limit of quantitation (LOQ) of 7.604 μM, and limit of detection (LOD) of 2.509 μM for glucose concentrations between 0.1 and 20.0 mM. The electrode system developed in this study is applicable to the CGM healthcare industry and is expected to be applicable to biofuel cells.
      Citation: Chemosensors
      PubDate: 2023-09-02
      DOI: 10.3390/chemosensors11090485
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 486: Single-Atom Nanomaterials in
           Electrochemical Sensors Applications

    • Authors: Jinglin Fu, Yang Liu
      First page: 486
      Abstract: In recent years, the development of highly sensitive sensors has become a popular research topic. Some functional nanomaterials occupy an important position in the sensing field by virtue of their unique structures and catalytic properties, but there are still problems such as low sensitivity and poor specificity. Single-atom nanomaterials (SANs) show significant advantages in amplifying sensing signals and improving sensor interference resistance due to their high atomic utilization, structural simplicity, and homogeneity. They are expected to achieve high sensitivity and high specificity monitoring by modulating the active sites. In this review, the recent progress on SANs for electrochemical sensing applications was summarized. We first briefly summarize the features and advantages of single-atom catalysts. Then recent advances in the regulation of reaction sites in noble and non-noble metal-based SANs, including the introduction of defects in the carrier, other metal atoms, and ligand atoms, were highlighted. After that, the SANs for the construction of electrochemical, electrochemiluminescent (ECL), and photoelectrochemical (PEC) sensors and their applications in biochemical and environmental analysis were demonstrated. Finally, the future research aspect of SANs-based electrochemical sensing and the challenges of the SANs design and structure-properties revelation were illustrated, giving guidance on sensitive and accurate biosensing toward clinic diagnostic and environmental analysis.
      Citation: Chemosensors
      PubDate: 2023-09-03
      DOI: 10.3390/chemosensors11090486
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 487: Development and Validation of a
           Solvent-Free Headspace GC-MS Method for the Screening of Benzyl Chloride
           in Pharmaceutical Products

    • Authors: Eunchae Song, Chanhong Min, Eunjae Kim, Sang Beom Han, Yong-Moon Lee, Kwang-Hyeon Liu, Jongki Hong, Han Bin Oh
      First page: 487
      Abstract: This study presents a solvent-free headspace gas chromatography–mass spectrometry (SF-HS-GC/MS) method for robustly screening benzyl chloride, a mutagenic carcinogen, impurities in active pharmaceutical ingredients (APIs) and drug products. The SF-HS-GC/MS method simplifies analysis by eliminating solvent use, reducing matrix interference. Optimized headspace parameters include incubation temperature, time, and sample amount. Validation, aligned with Q2(R1) ICH guidelines and ICH M7 recommendations, covers selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, system suitability, and robustness. Employing a DB-5MS column (30 m × 0.25 mm, 0.25 µm) with solvent-free split injection, the method’s calibration curve (0.05–5 μg/g) exhibits a strong correlation (>0.9998). The LOQ was 0.1 μg/g, with precision (%CV) consistently <5% and accuracy within 95–105%. Furthermore, an investigation confirmed the absence of artefactual benzyl chloride formation in drug products under headspace conditions. The developed SF-HS-GC/MS method successfully screened benzyl chloride in cinnarizine drug substances and products.
      Citation: Chemosensors
      PubDate: 2023-09-03
      DOI: 10.3390/chemosensors11090487
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 488: Recent Progress in Electrochemical
           Aptasensors: Construction and Application

    • Authors: Renqiang Yuan, Jing Cai, Haojie Ma, Yi Luo, Lianhui Wang, Shao Su
      First page: 488
      Abstract: Electrochemical aptasensors have gained significant attention due to their exceptional sensitivity, selectivity, stability, and rapid response, combining the advantages of electrochemical techniques with the specific recognition ability of aptamers. This review aims to provide a comprehensive summary of the recent advances in electrochemical aptasensors. Firstly, the construction method and the advantages of electrochemical aptasensors are introduced. Subsequently, the review highlights the application progress of electrochemical aptasensors in detecting various chemical and biological molecules, including metal ions, small biological molecules, drugs, proteins, exosomes, tumor cells, bacteria, and viruses. Lastly, the prospects and challenges associated with electrochemical aptasensors are discussed.
      Citation: Chemosensors
      PubDate: 2023-09-04
      DOI: 10.3390/chemosensors11090488
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 489: Emerging Luminescent Materials for
           Information Encryption and Anti-Counterfeiting: Stimulus-Response AIEgens
           and Room-Temperature Phosphorescent Materials

    • Authors: Yanjie Li, Pengfei Gao
      First page: 489
      Abstract: Information encryption and anti-counterfeiting play an important role in many aspects of daily life, such as in minimizing economic losses, protecting secure communication and public security, and so on. Owing to the high information capacity and ease of operation, luminescent materials for advanced information encryption and anti-counterfeiting are essential to meet the increasing demand on encryption security. Herein, we summarize two emerging luminescent materials for information encryption and anti-counterfeiting—AIE materials and room-temperature phosphorescent materials. Finally, we discuss the opportunities and anticipations of these two information encryption and anti-counterfeiting materials.
      Citation: Chemosensors
      PubDate: 2023-09-04
      DOI: 10.3390/chemosensors11090489
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 490: Semiconductor Heterojunction-AgNPs
           Mediated Surface-Enhanced Raman Spectroscopy (SERS) Sensor for Portable
           Miniaturized Detection Platform

    • Authors: Chenyu Wang, Xiaoyi Shi, Zhiyong Bao, Maofeng Zhang, Yonghui Shen, Yucheng Wu
      First page: 490
      Abstract: Micro/nanoplastic pollution in the water environment has received great attention worldwide. The rapid identification and analysis of micro/nanoplastics are crucial steps for monitoring animal safety and protecting human health. Herein, we developed a novel surface-enhanced Raman spectroscopy (SERS) sensor based on Co3O4/Co3S4/AgNPs array substrate for the detection and analysis of micro/nanoplastics. The semiconductor heterojunction-induced charge transfer, enhanced together with the electromagnetic enhancement of plasmon AgNPs, endow the sensor with high sensitivity, thus achieving exceptional analytical and detection capability for polystyrene (PS) nanospheres of different sizes ranging from 1 µm to 1 nm. The limits of detection (LOD) for PS nanospheres (size of 1 µm and 800 nm) was as low as 25 µg/mL, even with a portable Raman spectrometer. Additionally, the periodic Co3O4/Co3S4/AgNPs array generated high repeatability of Raman signals with relative standard deviation (RSD) values less than 7.6%. As proof of this concept, we further demonstrated the simulation detection of PS in actual water samples. We measured the SERS spectra of the different sizes and concentrations of PS spiked in lake water and city water. The results showed that the sensing platform realized trace detection of PS nanospheres in lake water with a detection limit of 14 µg/mL, and a quantitative detection of PS with linear relationship (R2 = 0.962). This SERS sensor has demonstrated fast analysis of PS nanospheres, which can provide a solid basis for the qualitative and quantitative detection of various micro/nanoplastics in the real water environments.
      Citation: Chemosensors
      PubDate: 2023-09-04
      DOI: 10.3390/chemosensors11090490
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 491: Acrylamide–Fat Correlation in
           Californian-Style Black Olives Using Near-Infrared Spectroscopy

    • Authors: Antonio Fernández, Ismael Montero-Fernández, Olga Monago-Maraña, Elísabet Martín-Tornero, Daniel Martín-Vertedor
      First page: 491
      Abstract: Californian-style is one of the most important black table olive elaborations. During its processing, table olives produce acrylamide, a potential carcinogen compound generated during sterilization. In the present study, total fat and acrylamide content in Californian-style table olives were determined and a regression between them was performed (acrylamide concentration range: below limit of detection—2500 ng g−1 and 8–22% for total fat). Nowadays, there are fast and efficient new techniques, such as Near-Infrared Spectroscopy (NIRS) to measure fat content parameters. In that sense, NIRS was used to perform a fat content quantification model in olives in order to indirectly determine acrylamide content. Calibration models for fat quantification were obtained in defatted olive pastes from a unique variety and for olive pastes from different varieties. In the first case, best results were obtained since only one variety was used (R2 = 0.9694; RMSECV = 1.31%; and REP = 8.4%). However, in the second case, results were still acceptable R2 = 0.678, RMSECV = 2.3%, REP = 17.7% and RMSEV = 2.17%. Regression coefficients showed the most influence variables corresponded with fat. The determination coefficient for the fat and acrylamide correlation was high (r = 0.877), being an efficient approach to find out the contribution of fat degradation to acrylamide synthesis in table olives.
      Citation: Chemosensors
      PubDate: 2023-09-06
      DOI: 10.3390/chemosensors11090491
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 492: Development of a New HiBiT Biosensor
           Monitoring Stability of YAP/TAZ Proteins in Cells

    • Authors: Liqing Wu, Anni Ge, Yawei Hao, Xiaolong Yang
      First page: 492
      Abstract: The Hippo signaling cascade is frequently dysregulated in a variety of cancers, such as breast cancer (BC), which is one of the most commonly diagnosed malignancies in women. Among BC subtypes, triple-negative BC (TNBC) stands out due to its poor prognosis and high metastatic potential. Despite extensive research aimed at establishing treatment options, existing therapies demonstrate limited efficacy for TNBC. Recently, it has been recognized that targeting the core components of the Hippo pathway (YAP and its paralog TAZ) is a promising strategy for developing anti-cancer treatment. However, no YAP/TAZ inhibitors have been approved by the FDA as anti-TNBC treatments, and only a few compounds have been identified that directly affect YAP and TAZ activity and stability to enhance the prospect of innovative HiBiT biosensors for monitoring of YAP and TAZ in cells. Employing these biosensors, we conducted a small-scale drug screen involving 279 compounds, leading to the identification of several small molecule inhibitors (SMIs) capable of inducing YAP/TAZ degradation in diverse TNBC cell lines. It is worth noting that some drugs may indirectly affect the protein stability following prolonged treatment, and a shorter exposure can be included in the future to identify drug candidates with more direct effects. Nevertheless, our study introduces a novel approach for assessing YAP and TAZ levels, which can have significant implications for developing anti-TNBC targeted therapies.
      Citation: Chemosensors
      PubDate: 2023-09-06
      DOI: 10.3390/chemosensors11090492
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 493: Recent Trends in Biosensors for
           Quinolone Detection: A Comprehensive Review

    • Authors: Fabian Thurner, Fatima AlZahra’a Alatraktchi
      First page: 493
      Abstract: Quinolones represent a vast family of antibiotics used extensively around the globe in human and veterinary medicine. Over the past decade, the field of biosensors for quinolone detection has experienced significant growth, thanks to the advancements in nanotechnology. These biosensors have emerged as a promising tool for fast and accurate point-of-care detection of quinolones. Although research efforts have proven that it is possible to detect quinolones in complex matrices and in relevant concentration ranges, the complexity of the sensor functionalization and the risk of limited reproducibility has hindered the transfer to real-life applications. This review holistically summarizes existing electrochemical quinolone sensors in comparison to optical and piezoelectric sensors and discusses the challenges that remain to be solved.
      Citation: Chemosensors
      PubDate: 2023-09-06
      DOI: 10.3390/chemosensors11090493
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 494: Correction: Dalapati et al. A Dual
           Fluorometric and Colorimetric Sulfide Sensor Based on Coordinating
           Self-Assembled Nanorods: Applicable for Monitoring Meat Spoilage.
           Chemosensors 2022, 10, 500

    • Authors: Rana Dalapati, Matthew Hunter, Ling Zang
      First page: 494
      Abstract: There was an error in the original publication [...]
      Citation: Chemosensors
      PubDate: 2023-09-06
      DOI: 10.3390/chemosensors11090494
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 495: Gas Sensing Properties of CuWO4@WO3 n-n
           Heterojunction Prepared by Direct Hydrolysis of Mesitylcopper (I) on
           WO3·2H2O Nanoleaves

    • Authors: Justyna Jońca, Kevin Castello-Lux, Katia Fajerwerg, Myrtil L. Kahn, Vincent Collière, Philippe Menini, Izabela Sówka, Pierre Fau
      First page: 495
      Abstract: The nanometer size Cu2O@WO3·H2O composite material has been prepared by the direct hydrolysis of mesitylcopper (I) on WO3·2H2O nanoleaves. The synthesis has been performed in toluene without the addition of any ancillary ligands. The prepared nanocomposite has been deposited as a gas-sensitive layer on miniaturized silicon devices and heated up gradually to 500 °C in the ambient air. During the heating, the CuWO4 phase is formed upon the reaction of Cu2O with the WO3 support as revealed by the XRD analyses. The as-prepared CuWO4@WO3 sensors have been exposed to 10 ppm of CO or 0.4 ppm of NO2 (RH = 50%). At the operating temperature of 445 °C, a normalized response of 620% towards NO2 is obtained whereas the response to CO is significantly lower (S = 30%). Under these conditions, the sensors prepared either with pristine CuO or WO3 nanostructures are sensitive to only one of the two investigated gases, i.e., CO and NO2, respectively. Interestingly, when the CuWO4@WO3 sensitive layer is exposed to UV light emitted from a 365 nm Schottky diode, its sensitivity towards CO vanishes whereas the response towards NO2 remains high. Thus, the application of UV illumination allowed us to modify the selectivity of the device. This new nanocomposite sensor is a versatile sensitive layer that will be integrated into a gas sensor array dedicated to electronic nose platforms.
      Citation: Chemosensors
      PubDate: 2023-09-09
      DOI: 10.3390/chemosensors11090495
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 496: Development of an Online Instrument for
           Continuous Gaseous PAH Quantification: Laboratory Evaluation and
           Comparison with The Offline Reference UHPLC-Fluorescence Method

    • Authors: Joana Vaz-Ramos, Mathilde Mascles, Anaïs Becker, Damien Bourgain, Audrey Grandjean, Sylvie Bégin-Colin, Franck Amiet, Damien Bazin, Stéphane Le Calvé
      First page: 496
      Abstract: Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants formed during incomplete combustion or pyrolysis of organic material. The reliable quantification of PAH in airborne samples is still difficult, costly, and time-consuming due to the use of offline techniques, including long sampling on filters/adsorbents, laboratory extraction, purification, and concentration steps before analysis. To tackle these drawbacks, this work focused on the development of a fully automatic gas chromatograph (GC) equipped with a flame ionization detector (FID) and a sample preconcentration unit (PC) for gas sampling. This instrument was validated under laboratory-controlled conditions in the range 0–10 ng for 18 PAH. The chromatographic separation was rather satisfactory except for two PAH pairs, which were quantified together. For all compounds, the peak areas increased perfectly with the gaseous PAH concentration (R2 > 0.98), without any significant memory effect between two consecutive analyses. Considering a gaseous sample volume of 1 L, the extrapolated limits of detections (LOD) were in the range 19.9–62.6 ng/m3, depending on the PAH. Its analytical performances were then compared to those of the offline reference UHPLC-fluorescence method, widely used for airborne PAH monitoring. This was also compared with the very few portable or continuously operating instruments.
      Citation: Chemosensors
      PubDate: 2023-09-09
      DOI: 10.3390/chemosensors11090496
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 497: Chemical Sensing and Analysis with
           Optical Nanostructures

    • Authors: Chenyu Dong, Yifan Wang, Xiaoyan Zhao, Jie Bian, Weihua Zhang
      First page: 497
      Abstract: Nanostructures and nanomaterials, especially plasmonic nanostructures, often show optical properties that conventional materials lack and can manipulate light, as well as various light–matter interactions, in both their near-field and far-field regions with a high efficiency. Thanks to these unique properties, not only can they be used to enhance the sensitivity of chemical sensing and analysis techniques, but they also provide a solution for designing new sensing devices and simplifying the design of analytical instruments. The earliest applications of optical nanostructures are surface-enhanced spectroscopies. With the help of the resonance field enhancement of plasmonic nanostructures, molecular signals, such as Raman, infrared absorption, and fluorescence can be significantly enhanced, and even single-molecule analysis can be realized. Moreover, the resonant field enhancements of plasmonic nanostructures are often associated with other effects, such as optical forces, resonance shifts, and photothermal effects. Using these properties, label-free plasmonic sensors, nano-optical tweezers, and plasmonic matrix-assisted laser desorption/ionization have also been demonstrated in the past two decades. In the last few years, the research on optical nanostructures has gradually expanded to non-periodic 2D array structures, namely metasurfaces. With the help of metasurfaces, light can be arbitrarily manipulated, leading to many new possibilities for developing miniaturized integrated intelligent sensing and analysis systems. In this review, we discuss the applications of optical nanostructures in chemical sensing and analysis from both theoretical and practical aspects, aiming at a concise and unified framework for this field.
      Citation: Chemosensors
      PubDate: 2023-09-09
      DOI: 10.3390/chemosensors11090497
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 498: Optimization of the Geometrical Design
           for an All-Dielectric Metasurface Sensor with a High Refractive-Index

    • Authors: Chia-Te Chang, Chia-Ming Yang, I-Hsuan Chen, Chih-Ching Ho, Yu-Jen Lu, Chih-Jen Yu
      First page: 498
      Abstract: This study aims to develop a refractive-index sensor operating in the visible region using an all-dielectric metasurface, which was chosen for its advantages of low optical loss and narrow spectral bandwidth, compared to those of conventional metallic metasurfaces. COMSOL software was utilized as a calculation tool to simulate the resonant properties of an all-dielectric metasurface composed of a circular nanohole-structured titanium oxide (TiO2) thin film, with the aim of enhancing the sensitivity of the refractive index for sensing targets. The simulation focused on finding the best geometrical conditions for the all-dielectric metasurface to achieve high sensitivity. Two resonance modes observed in this metasurface were considered: the quasi-bound-state-in-the-continuum (qBIC) mode and the perfect-reflection (PR) mode. The simulated results demonstrated that high sensitivities of 257 nm/RIU at the PR mode and 94 nm/RIU at the qBIC mode in the visible spectral range could be obtained by periodically constructing the metasurface with a unit cell having a lattice constant of 350 nm, a nanohole radius of 160 nm, and a nanohole depth of 250 nm. Furthermore, the study showed that the resonance mode that enabled high sensitivity was the PR mode, with a sensitivity nearly three times larger than that of the qBIC mode and the ability to reach the highest reflectance at the resonance wavelength. The optimized feature had the highest reflectance at a resonant wavelength of 570.19 nm, and although the quality factor was 25.50, these designed parameters were considered sufficient for developing a refractive index biosensor with high sensitivity and optical efficiency when operating in the visible spectral range.
      Citation: Chemosensors
      PubDate: 2023-09-11
      DOI: 10.3390/chemosensors11090498
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 499: Chemosensors for Ion Detection

    • Authors: Kien Wen Sun
      First page: 499
      Abstract: The advancement in chemosensory research towards the ionic species quantitation becomes vital to securing the environment for the future [...]
      Citation: Chemosensors
      PubDate: 2023-09-12
      DOI: 10.3390/chemosensors11090499
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 500: Modern Analytical Techniques for Berry

    • Authors: Celia Carrillo, Igor B. Tomasevic, Francisco J. Barba, Senem Kamiloglu
      First page: 500
      Abstract: The health-related properties attributed to berries and the subsequent interest awakened within the market of functional foods mean that these small fruits may be potential targets for food fraud. In this review, studies on berry authentication through modern analytical techniques are discussed in detail. Most of the studies reported to date are related to chemical approaches, mainly chromatographic techniques. Other chemical (NMR, NIR, and Raman spectroscopy), biomolecular, and isotopic methods have also delivered promising results in the field of berry authentication, although there is still limited information available in this respect. Despite the potential of the methods described in the present review, to date, there is no universal one. Therefore, combinations of different approaches in order to complement each other are increasingly used (e.g., HPTLC and mass spectrometry; Raman and IR spectroscopies; biomolecular and analytical techniques…). Considering that adulteration practices are increasingly evolving, continuous research in the field of food authentication is needed, especially in the case of berries, since there are still some berry species that have not yet been included in any authentication study.
      Citation: Chemosensors
      PubDate: 2023-09-14
      DOI: 10.3390/chemosensors11090500
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 501: Temperature Modulation of MOS Sensors
           for Enhanced Detection of Volatile Organic Compounds

    • Authors: Andrea Rescalli, Davide Marzorati, Simone Gelosa, Francesco Cellesi, Pietro Cerveri
      First page: 501
      Abstract: Disease diagnosis through biological fluids, particularly exhaled breath analysis, has gained increasing importance. Volatile organic compounds (VOCs) present in exhaled breath offer diagnostic potential as they reflect altered and disease-specific metabolic pathways. While gas chromatography–mass spectrometry (GC–MS) has been traditionally used for VOCs detection, electronic noses have emerged as a promising alternative for disease screening. Metal oxide semiconductor (MOS) sensors play an essential role in these devices due to their simplicity and cost-effectiveness. However, their limited specificity and sensitivity pose challenges for accurate diagnosis at lower VOCs concentrations, typical of exhaled breath. To address specificity and sensitivity issues, temperature modulation (TM) has been proposed in this paper, introducing a custom-developed electronic nose based on multiple and heterogeneous gas sensors located within an analysis chamber. Four different TM patterns (i.e., square, sine, triangular, and a combination of square and triangular) were applied to the gas sensors to test their response to three different analytes at three distinct concentrations. Data were analyzed by extracting meaningful features from the sensor raw data, and dimensionality reduction using principal component analysis (PCA) was performed. The results demonstrated distinct clusters for each experimental condition, indicating successful discrimination of analytes and concentrations. In addition, an analysis of which set of sensors and modulation pattern yielded the best results was performed. In particular, the most promising TM pattern proved to be the square and triangular combination, with optimal discrimination accuracy between both concentrations and analytes. One specific sensor, namely, TGS2600 from Figaro USA, Inc., provided the best performance. While preliminary results highlighted the potential of TM to improve the sensitivity of gas sensors in electronic nose devices, paving the way for further advancements in the field of exhaled breath analysis.
      Citation: Chemosensors
      PubDate: 2023-09-15
      DOI: 10.3390/chemosensors11090501
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 502: A Portable Nanoporous Gold Modified
           Screen-Printed Sensor for Reliable and Simultaneous Multi-Vitamins

    • Authors: Xinyu Gao, Siyu Chen, Xiaolei Wang, Honglei Liu, Xia Wang
      First page: 502
      Abstract: Despite being present in minimal amounts, vitamin B2 (VB2), vitamin C (VC), and vitamin B6 (VB6) each play indispensable roles in human metabolisms. Given that VB2, VC, and VB6 cannot be synthesized by the human body, detections of these three vitamins both in fermentation liquid where vitamins are industrially manufactured and in human serum where vitamin concentrations could be clinically controlled are of significant importance. Here, a nanoporous gold (NPAu) modified screen-printed electrode (NPAu/SPE) was fabricated to detect VB2, VC, and VB6 based on NPAu’s electro-oxidation towards vitamins. Owing to the wide separation of peak potentials among VB2, VC, and VB6, the simultaneous detection of these three vitamins was achieved by the NPAu/SPE within a potential range from −0.8 V to 0.8 V. The achieved limits of detection (LOD) for VB2, VC, and VB6 were 0.46, 6.44, and 1.92 μM, with sensitivities of 68.58, 4.77, and 15.94 μA/μM, respectively. Subsequent reliability experiments suggested that the NPAu/SPE exhibited solid anti-interference capability and repeatability. Additionally, the real-sample detection of the NPAu/SPE towards VB2, VC, and VB6 was achieved both in human serum and in fermentation liquid with comparable accuracy (the recovery rates were from 89.8% to 111.7%) as high-performance liquid chromatography (HPLC). Moreover, the portable NPAu/SPE showed comparable performance in terms of the LOD and linear dynamic range when compared to glassy carbon electrodes (GCE) limited to laboratory detection. The proposed NPAu/SPE possesses various advantageous properties including portability, easy fabrication, high sensitivity, and cost-efficiency, making it a potential candidate for clinical and industrial multi-vitamins analysis.
      Citation: Chemosensors
      PubDate: 2023-09-15
      DOI: 10.3390/chemosensors11090502
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 503: Detection of a Nerve Agent Simulant by a
           Fluorescent Sensor Array

    • Authors: Rossella Santonocito, Mario Spina, Roberta Puglisi, Andrea Pappalardo, Nunzio Tuccitto, Giuseppe Trusso Sfrazzetto
      First page: 503
      Abstract: Detection of nerve agents (NAs) gas in the environment through portable devices to protect people in case of emergencies still remains a challenge for scientists involved in this research field. Current detection strategies require the use of cumbersome, expensive equipment that is only accessible to specialized personnel. By contrast, emerging optical detection is one of the most promising strategies for the development of reliable, easy readout devices. However, the selectivity of the existing optical sensors needs to be improved. To overcome the lack of selectivity, the innovative strategy of the optical arrays is under evaluation due to the specific response, the ease of preparation, the portability of the equipment, and the possibility to use affordable detectors, such as smartphones, that are easily accessible to non-specialized operators. In this work, the first optical-based sensor array for the selective detection of gaseous dimethylmethylphosphonate (DMMP), a NAs simulant, is reported, employing a simple smartphone as a detector and obtaining remarkably efficient and selective detection.
      Citation: Chemosensors
      PubDate: 2023-09-15
      DOI: 10.3390/chemosensors11090503
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 504: MicroRNA Biosensors for Early Detection
           of Hepatocellular Carcinoma

    • Authors: Xiaogang Lin, Ke Wang, Chunfeng Luo, Mengjie Yang, Jayne Wu
      First page: 504
      Abstract: Hepatocellular carcinoma (HCC) is the main pathological type of liver cancer. Due to its insidious onset and the lack of specific early markers, HCC is often diagnosed at an advanced stage, and the survival rate of patients with partial liver resection is low. Non-coding RNAs (ncRNAs) have emerged as valuable biomarkers for HCC detection, with microRNAs (miRNAs) being a particularly relevant class of short ncRNAs. MiRNAs play a crucial role in gene expression regulation and can serve as biomarkers for early HCC detection. However, the detection of miRNAs poses a significant challenge due to their small molecular weight and low abundance. In recent years, biosensors utilizing electrochemical, optical, and electrochemiluminescent strategies have been developed to address the need for simple, rapid, highly specific, and sensitive miRNA detection. This paper reviews the recent advances in miRNA biosensors and discusses in detail the probe types, electrode materials, sensing strategies, linear ranges, and detection limits of the sensors. These studies are expected to enable early intervention and dynamic monitoring of tumor changes in HCC patients to improve their prognosis and survival status.
      Citation: Chemosensors
      PubDate: 2023-09-16
      DOI: 10.3390/chemosensors11090504
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 505: Surface-Enhance Raman Spectroscopy
           Detection of Thiabendazole in Frozen Food Products: The Case of
           Blueberries and Their Extracts

    • Authors: Csilla Müller Müller Molnár, Camelia Berghian-Groșan, Dana Alina Măgdaș, Simona Cîntă Cîntă Pînzaru
      First page: 505
      Abstract: To improve the control and detection methods of thiabendazole (TBZ), a fungicide and parasiticide often used in food products, we investigated the performance of the SERS technique applied to frozen blueberry fruits available on the market. TBZ-treated fruit extracts provided a multiplexed SERS feature, where the SERS bands of TBZ could be distinctly recorded among the characteristic anthocyanidins from blueberries. Quantitative SERS of TBZ in a concentration range from 20 µM to 0.2 µM has been achieved in solutions. However, quantitative multiplexed SERS is challenging due to the gradually increasing spectral background of polyphenols from extracts, which covers the TBZ signal with increasing concentration. The strategy proposed here was to employ food bentonite to filter a substantial amount of flavonoids to allow a higher SERS signal-to-background recording and TBZ recognition. Using bentonite, the LOD for SERS analysis of blueberry extracts provided a detection limit of 0.09 µM. From the relative intensity of the specific SERS bands as a function of concentration, we estimated the detection capability of TBZ to be 0.0001 mg/kg in blueberry extracts, which is two orders of magnitude lower than the maximum allowed by current regulations.
      Citation: Chemosensors
      PubDate: 2023-09-17
      DOI: 10.3390/chemosensors11090505
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 506: Surface-Catalyzed Zinc Oxide Nanorods
           and Interconnected Tetrapods as Efficient Methane Gas Sensing Platforms

    • Authors: Abbey Knoepfel, Bed Poudel, Sanju Gupta
      First page: 506
      Abstract: Nanostructured metal oxide semiconductors have proven to be promising for the gas sensing domain. However, there are challenges associated with the fabrication of high-performance, low-to-room-temperature operation sensors for methane and other gases, including hydrogen sulfide, carbon dioxide, and ammonia. The functional properties of these semiconducting oxides can be improved by altering the morphology, crystal size, shape, and topology. Zinc oxide (ZnO) is an attractive option for gas sensing, but the need for elevated operating temperatures has limited its practical use as a commercial gas sensor. In this work, we prepared ZnO nanorod (ZnO-NR) arrays and interconnected tetrapod ZnO (T-ZnO) network sensing platforms as chemiresistive methane sensors on silicon substrates with platinum interdigitated electrodes and systematically characterized their methane sensing response in addition to their structural and physical properties. We also conducted surface modification by photochemical-catalyzed palladium, Pd, and Pd-Ag alloy nanoparticles and compared the uniformly distributed Pd decoration versus arrayed dots. The sensing performance was assessed in terms of target gas response magnitude (RM) and response percentage (R) recorded by changes in electrical resistance upon exposure to varying methane concentration (100–10,000 ppm) under thermal (operating temperatures = 175, 200, 230 °C) and optical (UV A, 365 nm illumination) excitations alongside response/recovery times, and limit of detection quantification. Thin film sensing platforms based on T-ZnO exhibited the highest response at 200 °C (RM = 2.98; R = 66.4%) compared to ZnO-NR thin films at 230 °C (RM = 1.34; R = 25.5%), attributed to the interconnected network and effective bandgap and barrier height reduction of the T-ZnO. The Pd-Ag-catalyzed and Pd dot-catalyzed T-ZnO films had the fastest response and recovery rates at 200 °C and room temperature under UV excitation, due to the localized Pd nanoparticles dots resulting in nano Schottky barrier formation, as opposed to the films coated with uniformly distributed Pd nanoparticles. The experimental findings present morphological differences, identify various mechanistic aspects, and discern chemical pathways for methane sensing.
      Citation: Chemosensors
      PubDate: 2023-09-17
      DOI: 10.3390/chemosensors11090506
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 507: Electrochemical Perovskite-Based Sensors
           for the Detection of Relevant Biomarkers for Human Kidney Health

    • Authors: Claudia Ivone Piñón-Balderrama, César Leyva-Porras, Alain Salvador Conejo-Dávila, Anayansi Estrada-Monje, María Cristina Maldonado-Orozco, Simón Yobanny Reyes-López, Erasto Armando Zaragoza-Contreras
      First page: 507
      Abstract: The importance of biomarker quantification in technology cannot be overstated. It has numerous applications in medical diagnostics, drug delivery, and the timely implementation of prevention and control strategies for highly prevalent diseases worldwide. However, the discovery of new tools for detection has become increasingly necessary. One promising avenue is the use of perovskite-based materials, which exhibit excellent catalytic activity and redox properties. These make them ideal candidates for the development of electrochemical sensors. In this review, the advances of purely non-enzymatic electrochemical detection of bio-analytes, with ABO3 perovskite form, are presented. The work allows the visualization of some of the modifications in the composition and crystal lattice of the perovskites and some variations in the assembly of the electrodes, which can result in systems with a better response to the detection of analytes of interest. These findings have significant implications for improving the accuracy and speed of biomarker detection, ultimately benefiting patients and healthcare professionals alike.
      Citation: Chemosensors
      PubDate: 2023-09-17
      DOI: 10.3390/chemosensors11090507
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 508: Design of DNA-Based Artificial
           Transmembrane Channels for Biosensing and Biomedical Applications

    • Authors: Wanyu Xu, Hui Chen, Yang Li, Shuangna Liu, Kemin Wang, Jianbo Liu
      First page: 508
      Abstract: Biomolecular channels on the cell membrane are essential for transporting substances across the membrane to maintain cell physiological activity. Artificial transmembrane channels used to mimic biological membrane channels can regulate intra/extracellular ionic and molecular homeostasis, and they elucidate cellular structures and functionalities. Due to their program design, facile preparation, and high biocompatibility, DNA nanostructures have been widely used as scaffolds for the design of artificial transmembrane channels and exploited for ionic and molecular transport and biomedical applications. DNA-based artificial channels can be designed from two structural modules: DNA nanotubes/nanopores as transport modules for mass transportation and hydrophobic segments as anchor modules for membrane immobilization. In this review, various lipophilic modification strategies for the design of DNA channels and membrane insertion are outlined. Several types of DNA transmembrane channels are systematically summarized, including DNA wireframe channels, DNA helix bundle channels, DNA tile channels, DNA origami channels, and so on. We then discuss efforts to exploit them in biosensor and biomedical applications. For example, ligand-gated and environmental stimuli-responsive artificial transmembrane channels have been designed for transmembrane signal transduction. DNA-based artificial channels have been developed for cell mimicry and the regulation of cell behaviors. Finally, we provide some perspectives on the challenges and future developments of artificial transmembrane channel research in biomimetic science and biomedical applications.
      Citation: Chemosensors
      PubDate: 2023-09-18
      DOI: 10.3390/chemosensors11090508
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 509: Surface Enhanced Raman Spectroscopy Pb2+
           Ion Detection Based on a Gradient Boosting Decision Tree Algorithm

    • Authors: Minghao Wang, Jing Zhang
      First page: 509
      Abstract: Lead pollution poses a serious threat to the natural environment, and a fast and high-sensitivity method is urgently needed. SERS can be used for the detection of Pb2+ ions, which is urgently needed. Based on the SERS spectral reference data set of lead nitride (Pb(NO3)2), a model for detecting Pb2+ was established by using a traditional machine learning algorithm and the GBDT algorithm. Principal component analysis was used to compare the batch effect reduction in different pretreatment methods in order to find the optimal combination of such methods and machine learning models. The combination of LightGBM algorithms successfully identified Pb2+ from cross-batch data, exceeding the 84.6% balanced accuracy of the baseline correction+ radial basis function kernel support vector machine (BC+RBFSVM) model and showing satisfactory results, with a 91.4% balanced accuracy and a 0.9313 area under the ROC curve.
      Citation: Chemosensors
      PubDate: 2023-09-21
      DOI: 10.3390/chemosensors11090509
      Issue No: Vol. 11, No. 9 (2023)
  • Chemosensors, Vol. 11, Pages 418: L-Glutamate Biosensor for In Vitro
           Investigations: Application in Brain Extracts

    • Authors: Julija Razumiene, Damiana Leo, Vidute Gureviciene, Dalius Ratautas, Justina Gaidukevic, Ieva Sakinyte-Urbikiene
      First page: 418
      Abstract: Investigations of L-glutamate release in living organisms can help to identify novel L-glutamate-related pathophysiological pathways, since abnormal transmission of L-glutamate can cause many neurological diseases. For the first time, a nitrogen-modified graphene oxide (GO) sample (RGO) is prepared through a simple and facile one-pot hydrothermal reduction of GO in the presence of 20 wt.% of the dye malachite green and is used for amperometric biosensing. The biosensor demonstrates adequate stability and is easy to prepare and calibrate. The biosensor detects the current generated during the electrooxidation of hydrogen peroxide released in the L-glutamate that is converted to the alpha-ketoglutarate catalyzed by L-glutamate oxidase. The biosensor consists of a semipermeable membrane, with L-glutamate oxidase (EC immobilized in albumin and RGO and the working Pt electrode. First, the basic version of the L-glutamate biosensor is examined in PBS to investigate its sensitivity, reliability, and stability. To demonstrate the applicability of the L-glutamate biosensor in the analysis of complex real samples, quantification of L-glutamate in bovine brain extract is performed and the accuracy of the biosensor is confirmed by alternative methods. The enhanced version of the L-glutamate biosensor is applied for L-glutamate release investigations in a newly developed strain of rats (DAT-knockout, DAT-KO).
      Citation: Chemosensors
      PubDate: 2023-07-25
      DOI: 10.3390/chemosensors11080418
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 419: Mass Spectrometry-Based Biosensing and
           Biopsy Technology

    • Authors: Fengjian Chu, Wei Wei, Nazifi Sani Shuaibu, Hongru Feng, Xiaozhi Wang, Yuanjiang Pan
      First page: 419
      Abstract: Sensitive and accurate detection of biomolecules by multiplexed methods is important for disease diagnosis, drug research, and biochemical analysis. Mass spectrometry has the advantages of high sensitivity, high throughput, and high resolution, making it ideal for biomolecular sensing. As a result of the development of atmospheric pressure mass spectrometry, researchers have been able to use a variety of means to identify target biomolecules and recognize the converted signals by mass spectrometry. In this review, three main approaches and tools are summarized for mass spectrometry sensing and biopsy techniques, including array biosensing, probe/pen-based mass spectrometry, and other biosensor–mass spectrometry coupling techniques. Portability and practicality of relevant mass spectrometry sensing methods are reviewed, together with possible future directions to promote the advancement of mass spectrometry for target identification of biomolecules and rapid detection of real biological samples.
      Citation: Chemosensors
      PubDate: 2023-07-26
      DOI: 10.3390/chemosensors11080419
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 420: Investigation of the Synergistic Effect
           of Layer-by-Layer Films of Carbon Nanotubes and Polypyrrole on a Flexible
           Electrochemical Device for Paraquat Sensing

    • Authors: Stefanny F. Amaro, Cristiane C. Maciel, Jéssica S. Rodrigues, Amanda de S. M. de Freitas, Lucas V. B. V. Fré, Anerise de Barros, Marystela Ferreira
      First page: 420
      Abstract: This research aims to study flexible sensors based on a poly(butylene adipate-co-terephthalate) (PBAT) biodegradable polymer and graphite. Sensors were modified through the layer-by-layer (LbL) technique to improve their electrochemical behavior for paraquat (PQ) detection. Nanostructured films were obtained by alternating layers of anionic and cationic materials, carbon nanotubes (CNTs), and polypyrrole (PPY), respectively. The devices, with and without modification, were characterized by contact angle, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Electrochemical characterization was labeled via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). PQ molecules were detected using the differential pulse voltammetry (DPV) technique in a concentration range of 0.1 to 2.1 µM. The sensor detection limit (LOD) was obtained using the analytical curve, with it being equal to 0.073 µM. The LbL film gPBAT(PPY/CNT)n sensor showed good stability, reproducibility, and repeatability, with recovery values ranging from 99.4% to 109.3% for PQ when the analyzed samples were contaminated with tap water. The produced electrodes have the advantage of being flexible, disposable, reproducible, and of low manufacturing cost, which makes them attractive for portable environmental analysis.
      Citation: Chemosensors
      PubDate: 2023-07-26
      DOI: 10.3390/chemosensors11080420
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 421: Exploiting the Advantages of
           Ag/ITO/Enzyme Trapped Gel Layers to Develop a Highly Sensitive and
           Selective Fiber Optic Plasmonic Urea Sensor

    • Authors: Sonika Sharma, Satyendra K. Mishra
      First page: 421
      Abstract: The fabrication and characterization of a surface plasmon resonance (SPR)-based urea biosensor, with thin silver (Ag), ITO (In2O3: SnO2), and enzyme-trapped gel over an unclad portion of plastic-clad silica fiber as a sensing element, is represented. The working principle is to identify changes in the refractive index of the enzyme (urease) entrapped gel layer following the interaction with the incoming analyte. This interaction causes swelling and shrinkage of the gel layer, which alters the effective refractive index of the sensing layer. The wavelength interrogation method is used, and the optimized sensor probe is characterized by urea samples having different pH values. Scanning electron microscopy confirmed the uniformity of the silver layer over the unclad core of the fiber. The sensor operates from 0 to 160 mM of urea concentrations to cover the physiological concentration range of blood urea normally present in the human body. The sensitivity and limit of detection (LOD) offered by the sensor are marked 0.59387 nm/mM near zero concentration of the urea sample and 0.56 mM, respectively, along with the provisions of high stability, remote sensing, and online monitoring of urea. The proposed sensor has proven to be one of a kind due to its fast response time.
      Citation: Chemosensors
      PubDate: 2023-07-26
      DOI: 10.3390/chemosensors11080421
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 422: Framework-Enhanced
           Electrochemiluminescence in Biosensing

    • Authors: Haomin Fu, Zhiyuan Xu, Hanlin Hou, Rengan Luo, Huangxian Ju, Jianping Lei
      First page: 422
      Abstract: Electrochemiluminescence (ECL) has attracted increasing attention owing to its intrinsic advantages of high sensitivity, good stability, and low background. Considering the fact that framework nanocrystals such as metal–organic frameworks and covalent organic frameworks have accurate molecular structures, a series of framework-based ECL platforms are developed for decoding emission fundamentals. The integration of fluorescent ligands into frameworks significantly improves the ECL properties due to the arrangement of molecules and intramolecular electron transfer. Moreover, the various framework topologies can be easily functionalized with the recognition elements to trace the targets for signal readout. These ECL enhancement strategies lead to a series of sensitive analytical methods for protein biomarkers, DNA, small biomolecules, and cells. In this review, we summarize recent advances in various functions of frameworks during the ECL process, and constructions of framework-based ECL platforms for biosensing. The framework-based ECL nanoemitters and enhancement mechanisms show both theoretical innovation and potential applications in designing ECL biosensing systems. Perspectives are also discussed, which may give a guideline for researchers in the fields of ECL biosensing and reticular materials.
      Citation: Chemosensors
      PubDate: 2023-07-28
      DOI: 10.3390/chemosensors11080422
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 423: Enhancing Polyantimonic-Based
           Materials’ Moisture Response with Binder Content Tuning

    • Authors: Sofia Mendes, Olga Kurapova, Pedro Faia
      First page: 423
      Abstract: Humidity sensors are of huge importance in diverse domains. Several types of materials present a moisture-sensing capacity; however, frequently, their electrical response does not display time stability. Due to its high thermal stability, high ionic conductivity, and different conduction mechanism contributing to its overall conductivity, polyantimonic acid (PAA) is seen as a promising material for humidity-sensing devices. In the present work, crystalline PAA was obtained via a simple and safe hydrolysis technique using SbCl3 as a precursor. Bulky sensor samples were produced using different amounts of polyvinyl alcohol (10–20 wt.% PVA) as a binder. The obtained PAA solid sensors were tested at room temperature (RT) in order to evaluate their moisture detection/measuring ability in the relative humidity range 0–100%; the evaluation was carried out with electrical impedance spectroscopy. The sample’s structure and morphology were studied using diverse experimental techniques (porosimetry, scanning electron microscopy, X-ray diffraction analysis, and thermogravimetry analysis, etc.). The sensors’ electrical response was in line with the found structural and morphological features. The slope of the resistance variation with an RH percentage concentration between 1 kΩ and 1.5 kΩ was noted for all sensors (showing no changes with time) in the interval between 30 and 100% RH. A good repeatability and reproducibility of the evaluated sensors’ electrical response was observed: the ones that displayed a higher sensitivity were the ones with a high PVA binder content, higher than previously published results for PAA, as well as a very good time stability along the time and low hysteresis.
      Citation: Chemosensors
      PubDate: 2023-07-30
      DOI: 10.3390/chemosensors11080423
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 424: Electrochemical Biosensing Methods for
           Detecting Epigenetic Modifications

    • Authors: Ziyue Huang, Yanzhi Dou, Jing Su, Tie Li, Shiping Song
      First page: 424
      Abstract: Epigenetic modifications are closely related to diseases and physiological health, mainly including DNA methylation, RNA methylation, histone acetylation, and noncoding RNA. Recently, a large amount of research has been conducted on the detection of epigenetic modifications. Electrochemical biosensors, with their low cost, high sensitivity, high compatibility, and simple operation, have been widely used in the detection of epigenetic biomarkers. This review discusses the detection of epigenetic biomarkers using different electrochemical sensing methods. Here we discuss various aspects, including free labels, signal labeling, signal amplification, nano-based electrodes, and the combined use of other methods. By summarizing the existing electrochemical detection methods for epigenetic modifications, this review also proposes future development trends and challenges for electrochemical biosensors in this field.
      Citation: Chemosensors
      PubDate: 2023-08-01
      DOI: 10.3390/chemosensors11080424
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 425: Determination of Extra- and
           Intra-Cellular pH Using Characteristic Absorption of Water by
           Near-Infrared Spectroscopy

    • Authors: Jiani Li, Fanfan Liang, Li Han, Xiaoxuan Yu, Dingbin Liu, Wensheng Cai, Xueguang Shao
      First page: 425
      Abstract: Accurate determination of extra-cellular pH (pHe) and intra-cellular pH (pHi) is important to cancer diagnosis and treatment because tumor cells exhibit a lower pHe and a slightly higher pHi than normal cells. In this work, the characteristic absorption of water in the near-infrared (NIR) region was utilized for the determination of pHe and pHi. Dulbecco’s modified eagle medium (DMEM) and bis (2-ethylhexyl) succinate sodium sulfonate reverse micelles (RM) were employed to simulate the extra- and intra-cellular fluids, respectively. Continuous wavelet transform (CWT) was used to enhance the resolution of the spectra. Quantitative models for pHe and pHi were established using partial least squares (PLS) regression, producing relative errors of validation samples in a range of −0.74–2.07% and −1.40–0.83%, respectively. Variable selection was performed, and the correspondence between the selected wavenumbers and water structures was obtained. Therefore, water with different hydrogen bonds may serve as a good probe to sense pH within biological systems.
      Citation: Chemosensors
      PubDate: 2023-08-01
      DOI: 10.3390/chemosensors11080425
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 426: Fluorophores-Assisted Excitation
           Emission Matrix Fluorescence Method for the Origin Traceability of Lily

    • Authors: Huan Fang, Hailong Wu, Tong Wang, Yao Chen, Ruqin Yu
      First page: 426
      Abstract: In this work, a fluorophores-assisted excitation/emission matrix (EEM) fluorescence method was proposed to trace the origin of lily in the Chinese market. There are few active components in lilies that have fluorescent signals, and too few characteristic variables may lead to unsatisfactory accuracy in the subsequent classification. Therefore, three fluorophores, 2-Aminoethyl diphenylborinate (DPBA), o-Phthalaldehyde (OPA) and Rhodamine B (RB), were used to enrich the information of the fluorescent fingerprint of lily, which can improve the classification accuracy. The lily samples were characterized by using EEM fluorescence coupled with the alternating trilinear decomposition (ATLD) algorithm, which was able to extract information of various fluorophores in lily samples. Two chemical pattern recognition methods, principal component analysis-linear discriminant analysis (PCA-LDA) and partial least squares-discrimination analysis (PLS-DA), were used to model and trace the origin of different lilies. When the fluorophores were added, the accuracy of the test set and prediction set obtained by the classification model increased from 71.4% to 92.9% and 66.7% to 100%, respectively. The proposed method combined fluorophores-assisted EEM fluorescence with multi-way chemometric methods to extract comprehensive information on the samples, which provided a potential method for the origin traceability of traditional Chinese medicine.
      Citation: Chemosensors
      PubDate: 2023-08-01
      DOI: 10.3390/chemosensors11080426
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 427: A Review on Non-Noble Metal Substrates
           for Surface-Enhanced Raman Scattering Detection

    • Authors: Ying Chen, Yuling Hu, Gongke Li
      First page: 427
      Abstract: Surface-enhanced Raman scattering (SERS), a powerful spectroscopic technique owing to its abundant vibrational fingerprints, has been widely employed for the assay of analytes. It is generally considered that one of the critical factors determining the SERS performance is the property of the substrate materials. Apart from noble metal substrates, non-noble metal nanostructured materials, as emerging new substrates, have been extensively studied for SERS research by virtue of their superior biocompatibility, good chemical stability, outstanding selectivity, and unique physicochemical properties such as adjustable band structure and carrier concentration. Herein, in this review, we summarized the research on the analytical application of non-noble metal SERS substrates from three aspects. Firstly, we started with an introduction to the possible enhancement mechanism of non-noble metal substrates. Then, as a guideline for substrates design, several main types of materials, including carbon nanomaterials, transition metal dichalcogenides (TMDs), metal oxides, metal-organic frameworks (MOFs), transition metal carbides and nitrides (MXenes), and conjugated polymers were discussed. Finally, we especially emphasized their analytical application, such as the detection of pollutants and biomarkers. Moreover, the challenges and attractive research prospects of non-noble metal SERS substrates in practical application were proposed. This work may arouse more awareness of the practical application of the non-noble metal material-based SERS substrates, especially for bioanalysis.
      Citation: Chemosensors
      PubDate: 2023-08-01
      DOI: 10.3390/chemosensors11080427
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 428: Development of a New Hydrogen Sulfide
           Fluorescent Probe Based on Coumarin–Chalcone Fluorescence Platform
           and Its Imaging Application

    • Authors: Hanwen Chi, Lei Gu, Qian Zhang, Yonghe Tang, Rui Guo, Weiying Lin
      First page: 428
      Abstract: Hydrogen sulfide (H2S), as one of the critical gaseous signaling molecules, has important physiological functions in the human body, and abnormal levels of hydrogen sulfide are closely related to tumors, Parkinson’s disease, Alzheimer’s disease, and other diseases. In order to enable the detection of H2S in the physiological environment, herein, a new H2S fluorescence probe, named C-HS, based on a coumarin–chalcone fluorescence platform was developed. The fluorescence probe provides specific recognition of H2S within a wide pH detection range (5.5–8.5), a rapid recognition response (within 10 min) for H2S molecules, and a high selectivity for competing species. The probe C-HS possesses low cytotoxicity and is used to achieve the detection of exogenous/ endogenous H2S in living cells, indicating that the constructed probe C-HS has the ability to track changes in intracellular H2S levels. Therefore, probe C-HS could be a potential tool for the early diagnosis of H2S-related diseases.
      Citation: Chemosensors
      PubDate: 2023-08-02
      DOI: 10.3390/chemosensors11080428
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 429: MOF-Based Materials for Glucose

    • Authors: Yiling Zhang, Qian Lin, Yiteng Song, Jiaqi Huang, Miaomiao Chen, Runqi Ouyang, Si-Yang Liu, Zong Dai
      First page: 429
      Abstract: Metal–organic frameworks (MOFs), constructed by coordination between metal-containing nodes and organic linkers, are widely used in various fields due to the advantages of tunable pores, diverse functional sites, stable structure, and multi-functionality. It should be noted that MOF-based materials play a major role in glucose detection, serving as a signal transducer or functional substrate for embedding nanoparticles/enzymes. Diabetes is one of the most common and fast-growing diseases worldwide, whose main clinical manifestation is high blood sugar levels. Therefore, accurate, sensitive, and point-of-care glucose detection is necessary. This review orderly introduces general synthetic strategies of MOF-based materials (pristine MOF, nanoparticles, or enzymes-modified MOF and MOF-derived materials) and detection methods (electrochemical and optical methods) for glucose detection. Then, the review refers to the novel MOF-based glucose detection devices (flexible wearable devices and microfluidic chips), which enable non-invasive continuous glucose monitoring or low-cost microscale detection. On the basis of describing the development of glucose sensors based on MOF materials in the past five years, the review presents merits, demerits, and possible improvements of various detection methods.
      Citation: Chemosensors
      PubDate: 2023-08-02
      DOI: 10.3390/chemosensors11080429
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 430: Optical Immunosensors for Bacteria
           Detection in Food Matrices

    • Authors: Dimitra Kourti, Michailia Angelopoulou, Panagiota Petrou, Sotirios Kakabakos
      First page: 430
      Abstract: Optical immunosensors are one of the most popular categories of immunosensors with applications in many fields including diagnostics and environmental and food analysis. The latter field is of particular interest not only for scientists but also for regulatory authorities and the public since food is essential for life but can also be the source of many health problems. In this context, the current review aims to provide an overview of the different types of optical immunosensors focusing on their application for the determination of pathogenic bacteria in food samples. The optical immunosensors discussed include sensors based on evanescent wave transduction principles including surface plasmon resonance (SPR), fiber-optic-, interferometric-, grating-coupler-, and ring-resonator-based sensors, as well as reflectometric, photoluminescence, and immunosensors based on surface-enhanced Raman scattering (SERS). Thus, after a short description of each transduction technique, its implementation for the immunochemical determination of bacteria is discussed. Finally, a short commentary about the future trends in optical immunosensors for food safety applications is provided.
      Citation: Chemosensors
      PubDate: 2023-08-03
      DOI: 10.3390/chemosensors11080430
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 431: Ratio-Metric Fluorescence/Colorimetric
           and Smartphone-Assisted Visualization for the Detection of Dopamine Based
           on Cu-MOF with Catecholase-like Activity

    • Authors: Yushuang Guo, Mingli Chen, Ting Yang, Jianhua Wang
      First page: 431
      Abstract: As the most abundant catecholamine neurotransmitter in the brain, dopamine plays an important role in the normal physiological process, and its level in urine also changes during human pathological processes. In clinic, the detection of dopamine in urine is a potential marker for the diagnosis and the treatment of endocrine-related diseases. In this work, a copper metal organic framework with catecholase-like activity was prepared via the precipitation of Cu2+ and imidazole, simulating the N-Cu coordination environment in the active site of catecholase. Cu-MOF (the copper–metal organic framework) can catalyze the oxidation of DA (dopamine) to dopaquinone using O2 in the air. The oxidation product can further react with 1,3-dihydroxynaphthalene to produce a fluorophore product. Based on the above reaction, a multimodal sensing platform with three signal outputs, including ratio-metric fluorescence, absorbance and digital information extracted from smartphone images for simple and sensitive determination of DA, was proposed, with detection limits of 0.0679, 0.3206, and 0.3718 μM, respectively. This multimodal sensing platform was able to detect DA in body fluid in a self-correcting way, as demonstrated by the successful determination of DA in normal human urine samples, and samples with a high level of interference.
      Citation: Chemosensors
      PubDate: 2023-08-03
      DOI: 10.3390/chemosensors11080431
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 432: Recent Advances in
           Electrochemiluminescence Emitters for Biosensing and Imaging of Protein

    • Authors: Lei Yang, Jinghong Li
      First page: 432
      Abstract: Electrochemiluminescence (ECL) is a light-emitting process triggered by the high energy redox between electrochemically oxidized and reduced luminophores or some coreactive intermediate radicals, representing a blooming hot topic over decades with a wide variety of bioanalytical applications. Due to the superb sensitivity, ultralow background noise, specificity, ease of integration, and real-time and in situ analysis, ECL has been developed as a convenient and versatile technique for immunodiagnostics, nucleic acid analysis, and bioimaging. Discovering highly-efficient ECL emitters has been a promising subject that will benefit the development of sensitive bioanalytical methods with prominent potential prospects. To date, the interdisciplinary integrations of electrochemistry, spectroscopy, and nanoscience have brought up the continuous emergences of novel nanomaterials which can be flexibly conjugated with specific bio-recognition elements as functional ECL emitters for bioassays. Therefore, a critical overview of recent advances in developing highly-efficient ECL emitters for ultrasensitive detection of protein biomarkers is presented in this review, where six kinds of the most promising ECL nanomaterials for biosensing and imaging of various disease-related protein biomarkers are separately introduced with references to representative works. Finally, this review discusses the ongoing opportunities and challenges of ECL emitters in developing advanced bioassays for single-molecule analysis and spatiotemporally resolved imaging of protein biomarkers with future perspectives.
      Citation: Chemosensors
      PubDate: 2023-08-04
      DOI: 10.3390/chemosensors11080432
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 433: Near-Infrared-II Fluorophores for In
           Vivo Multichannel Biosensing

    • Authors: Feng Ren, Tuanwei Li, Tingfeng Yao, Guangcun Chen, Chunyan Li, Qiangbin Wang
      First page: 433
      Abstract: The pathological process involves a range of intrinsic biochemical markers. The detection of multiple biological parameters is imperative for providing precise diagnostic information on diseases. In vivo multichannel fluorescence biosensing facilitates the acquisition of biochemical information at different levels, such as tissue, cellular, and molecular, with rapid feedback, high sensitivity, and high spatiotemporal resolution. Notably, fluorescence imaging in the near-infrared-II (NIR-II) window (950–1700 nm) promises deeper optical penetration depth and diminished interferential autofluorescence compared with imaging in the visible (400–700 nm) and near-infrared-I (NIR-I, 700–950 nm) regions, making it a promising option for in vivo multichannel biosensing toward clinical practice. Furthermore, the use of advanced NIR-II fluorophores supports the development of biosensing with spectra-domain, lifetime-domain, and fluorescence-lifetime modes. This review summarizes the versatile designs and functions of NIR-II fluorophores for in vivo multichannel biosensing in various scenarios, including biological process monitoring, cellular tracking, and pathological analysis. Additionally, the review briefly discusses desirable traits required for the clinical translation of NIR-II fluorophores such as safety, long-wavelength emission, and clear components.
      Citation: Chemosensors
      PubDate: 2023-08-04
      DOI: 10.3390/chemosensors11080433
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 434: Ammonia Mediated Silver Nanoparticles
           Based Detection of Bisphenol A, an Endocrine Disruptor, in Water Samples
           after Vortex-Assisted Liquid–Liquid Microextraction

    • Authors: Zaibi, Zafar Ali Shah, Riaz Ullah, Essam A. Ali, Carlos A. T. Toloza, Rachel Ann Hauser-Davis, Uzair Muhammad, Sarzamin Khan
      First page: 434
      Abstract: Bisphenol A (BPA), an alkylphenolic compound, is one of the most polluting and hazardous organic chemicals. Its routine detection is, however, still rather expensive due to high-cost equipment. In this context, we applied the effect caused by BPA to the optical properties of surfactant-stabilized silver nanoparticles further modified with the use of ammonia (AgNP-NH3) to develop a simple and quantitative approach for BPA determination. The experimental conditions of the AgNP-NH3 probe were adjusted to establish a stable and sensitive response toward BPA in aqueous media. The use of probe dispersion measured at a wavelength of 403 nm enabled a limit of detection of 2.0 nmol L−1 (0.5 ng mL−1), with a linear response as a function of a concentration of BPA ranging from 10 to 120 nmol L−1 (from 2.2 to 27 ng mL−1). The use of vortex-assisted liquid–liquid microextraction ensured the application of selective determination to real tap and stream water samples, with recoveries ranging from 85.0 to 111%. The protocol developed herein is simple, sensitive, and selective, does not require the use of toxic labeling agents, and can be easily adapted for the routine analysis of BPA in different real samples.
      Citation: Chemosensors
      PubDate: 2023-08-05
      DOI: 10.3390/chemosensors11080434
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 435: NaBH4-Mediated Co-Reduction Synthesis of
           Glutathione Stabilized Gold/Silver Nanoclusters for Detection of Magnesium

    • Authors: Weiwei Chen, Yiying Chen, Xianhu Zhu, Miaomiao Xu, Zhihao Han, Lianhui Wang, Lixing Weng
      First page: 435
      Abstract: The content of magnesium ions (Mg2+) in drinking water is relatively high and the excessive Mg2+ ingestion may lead to pathological lesions in the human body system. At present, the detection of Mg2+ still relies on costly devices or/and complex organic fluorescence probes. To solve this problem, this work proposed a NaBH4-mediated co-reduction strategy for the synthesis of glutathione-stabilized bimetallic AuAg nanoclusters (GSH@AuAg NCs) with performance recognition to Mg2+. The preparation of GSH@AuAg NCs was simple and rapid and could be performed at mild conditions. The reaction parameters and sampling orders were optimized to understand the formation mechanism of GSH@AuAg NCs. The GSH@AuAg NCs exhibited a sensitive “light on” fluorescence response to Mg2+ due to the re-molding of the interfacial physicochemical environment following the Mg2+ coordination, which affected the surface charge transfer process, and thus led to a novel method for fluorescence detection of Mg2+ with admirable selectivity for Mg2+. The proposed method showed a detection limit of 0.2 μM, and its practical utility for the detection of Mg2+ in a real sample of purified drinking water was also demonstrated, confirming its practicability in monitoring the Mg2+ concentration in drinking water.
      Citation: Chemosensors
      PubDate: 2023-08-05
      DOI: 10.3390/chemosensors11080435
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 436: Layer-by-Layer Film Based on Sn3O4
           Nanobelts as Sensing Units to Detect Heavy Metals Using a Capacitive
           Field-Effect Sensor Platform

    • Authors: Paulo V. Morais, Pedro H. Suman, Michael J. Schöning, José R. Siqueira, Marcelo O. Orlandi
      First page: 436
      Abstract: Lead and nickel, as heavy metals, are still used in industrial processes, and are classified as “environmental health hazards” due to their toxicity and polluting potential. The detection of heavy metals can prevent environmental pollution at toxic levels that are critical to human health. In this sense, the electrolyte–insulator–semiconductor (EIS) field-effect sensor is an attractive sensing platform concerning the fabrication of reusable and robust sensors to detect such substances. This study is aimed to fabricate a sensing unit on an EIS device based on Sn3O4 nanobelts embedded in a polyelectrolyte matrix of polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) using the layer-by-layer (LbL) technique. The EIS-Sn3O4 sensor exhibited enhanced electrochemical performance for detecting Pb2+ and Ni2+ ions, revealing a higher affinity for Pb2+ ions, with sensitivities of ca. 25.8 mV/decade and 2.4 mV/decade, respectively. Such results indicate that Sn3O4 nanobelts can contemplate a feasible proof-of-concept capacitive field-effect sensor for heavy metal detection, envisaging other future studies focusing on environmental monitoring.
      Citation: Chemosensors
      PubDate: 2023-08-05
      DOI: 10.3390/chemosensors11080436
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 437: An Upgraded Protocol for the
           Silanisation of the Solid Phase for the Synthesis of Molecularly Imprinted

    • Authors: Fabiana Grillo, Francesco Canfarotta, Thomas Sean Bedwell, Magaly Arnold, William Le Saint, Rajdeep Sahota, Krunal Ladwa, Joshua Crane, Tobias Heavens, Elena Piletska, Sergey Piletsky
      First page: 437
      Abstract: The introduction of solid-phase imprinting has had a significant impact in the molecular imprinting field, mainly due to its advantage of orienting the template immobilisation, affinity separation of nanoMIPs and faster production time. To date, more than 600 documents on Google Scholar involve solid-phase synthesis, mostly relying on silanes mediating template immobilisation on the solid phase. Organosilanes are the most explored functionalisation compounds due to their straightforward use and ability to promote the binding of organic molecules to inorganic substrates. However, they also suffer from well-known issues, such as lack of control in the layer’s deposition and poor stability in water. Since the first introduction of solid-phase imprinting, few efforts have been made to overcome these limitations. The work presented in this research focuses on optimising the silane stability on glass beads (GBs) and iron oxide nanoparticles (IO-NPs), to subsequently function as solid phases for imprinting. The performance of three different aminosilanes were investigated; N-(6-aminohexyl) aminomethyltriethoxy silane (AHAMTES), 3-Aminopropyltriethoxysilane (APTES), and N-(2-aminoethyl)-3-aminopropyltriethoxysilane (AEAPTES), as well as studying the effect of dipodal silane bis(triethoxysilyl)ethane (BTSE). A stable solid phase was consequently achieved with 3% v/v AEAPTES and 2.4% BTSE, providing an upgraded protocol from Canfarotta et al. for the silanisation of the solid phase for molecular imprinting purposes.
      Citation: Chemosensors
      PubDate: 2023-08-05
      DOI: 10.3390/chemosensors11080437
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 438: Current Trends in the Use of
           Semiconducting Materials for Electrochemical Aptasensing

    • Authors: Leda Bousiakou, Omar Al-Dosary, Anastasios Economou, Veronika Subjakova, Tibor Hianik
      First page: 438
      Abstract: Aptamers are synthetic single-stranded oligonucleotides that exhibit selective binding properties to specific targets, thereby providing a powerful basis for the development of selective and sensitive (bio)chemical assays. Electrochemical biosensors utilizing aptamers as biological recognition elements, namely aptasensors, are at the forefront of current research. They exploit the combination of the unique properties of aptamers with the advantages of electrochemical detection with the view to fabricate inexpensive and portable analytical platforms for rapid detection in point-of-care (POC) applications or for on-site monitoring. The immobilization of aptamers on suitable substrates is of paramount importance in order to preserve their functionality and optimize the sensors’ sensitivity. This work describes different immobilization strategies for aptamers on the surface of semiconductor-based working electrodes, including metal oxides, conductive polymers, and carbon allotropes. These are presented as platforms with tunable band gaps and various surface morphologies for the preparation of low cost, highly versatile aptasensor devices in analytical chemistry. A survey of the current literature is provided, discussing each analytical method. Future trends are outlined which envisage aptamer-based biosensing using semiconductors.
      Citation: Chemosensors
      PubDate: 2023-08-06
      DOI: 10.3390/chemosensors11080438
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 439: WO3-LaFeO3 Nanocomposites for Highly
           Sensitive Detection of Acetone Vapor at Low Operating Temperatures

    • Authors: Ensi Cao, Yixuan Zhang, Li Sun, Bing Sun, Wentao Hao, Yongjia Zhang, Zhongquan Nie
      First page: 439
      Abstract: The development of a rapid, highly sensitive, and dependable acetone sensor holds significant importance for human health and safety. To enhance the acetone sensing performance of LaFeO3 nanoparticles for practical applications, commercial n-type WO3 nanoparticles were incorporated as additives. They were directly mixed with LaFeO3 nanoparticles produced through a sol-gel method, creating a series of WO3-LFO nanocomposites with varying mass ratios. These nanocomposites were characterized using XRD, SEM, BET, and XPS techniques. Compared to pure LFO nanoparticles, the prepared nanocomposites exhibited larger specific surface areas with enhanced surface reactivity. The introduction of p-n heterojunctions through the mixing process improved the regulation of acetone molecules on internal carrier conduction within nanocomposites. As a result, the nanocomposites demonstrated superior acetone sensing performance in terms of optimal operating temperature, vapor response value, selectivity, and response/recovery speed. Notably, the nanocomposites with a 5wt% addition of WO3 showed the lowest optimal operating temperature (132 °C), the fastest response/recovery speed (28/9 s), and the highest selectivity against ethanol, methanol, and EG. On the other hand, the nanocomposites with a 10wt% addition of WO3 displayed the maximum vapor response value (55.1 to 100 ppm) at an optimal operating temperature of 138 °C, along with relatively good repeatability, stability, and selectivity.
      Citation: Chemosensors
      PubDate: 2023-08-06
      DOI: 10.3390/chemosensors11080439
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 440: Advances in the Application of
           Nano-Enzymes in the Electrochemical Detection of Reactive Oxygen Species:
           A Review

    • Authors: Rongwei Gao, Shujuan Bao
      First page: 440
      Abstract: Reactive oxygen species (ROS) play an important role in maintaining human health and are recognized as indicators of oxidative stress linked to various conditions such as neurodegenerative and cardiovascular diseases, as well as cancer. Consequently, detecting ROS levels in biological systems is crucial for biomedical and analytical research. Electrochemical approaches offer promising opportunities for ROS determination due to their exceptional sensitivity, speed, and simplicity of equipment. This review covers studies using advanced electrochemical nanozyme sensors for detecting ROS in biological samples that were published over the last ten years, from 2013 to 2023. Emphasis is placed on the sensor materials and different types of modifiers employed for selective ROS detection. Furthermore, a comprehensive analysis of the sensors’ selectivity was performed.
      Citation: Chemosensors
      PubDate: 2023-08-07
      DOI: 10.3390/chemosensors11080440
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 441: Fabrication and Characterization of
           Hybrid and Tunable ZnO@Ag Flexible Thin Films Used as SERS Substrates

    • Authors: Ioana Andreea Brezeștean, Daniel Marconi, Nicoleta Elena Dina, Maria Suciu, Alia Colniță
      First page: 441
      Abstract: Flexible substrates have known increased popularity over rigid ones due to their use in surface-enhanced Raman scattering (SERS). They provide irregular surfaces, ideal for in situ sensing. In this context, we report the SERS performance of hybrid ZnO@Ag thin films deposited by magnetron sputtering (MS) on flexible, thermoplastic substrates. This physical deposition method is acknowledged for obtaining high-quality and reproducible ZnO films that can be embedded in (bio)sensing devices with various applications. Three types of thermoplastic-based, commercially available substrates with different glass transition temperatures (Tg) were chosen for the variation in flexibility, transparency, and thickness. Zeonor® (Tg = 136 °C, thickness of 188 μm) and two types of Topas (Topas®: Tg = 142 °C, thickness of 176 μm; Topas2: Tg = 78 °C, thickness of 140 μm) thermoplastic sheets are nonpolar and amorphous cyclo-olefin polymer (COP) and cyclo-olefin copolymers (COC), respectively. Their thicknesses and different values of Tg can greatly affect the topographical and roughness properties of films with small thicknesses and, thus, can greatly influence the enhancement of the Raman signal. The ZnO films deposited on top of Zeonor® or Topas® have identical morphological properties, as shown by the scanning electron microscopy (SEM) characterization. Subsequently, by using the MS technique, we tuned the thickness of the deposited silver (Ag) films in the range of 7–30 nm to assess the growth influence on the morphology and the SERS signal amplification of the substrates with and without the ZnO intermediate layer. The SEM analysis showed that the Ag atoms migrated both into the interstitial areas, filling the voids between the ZnO granular structures, and over the latter, forming, in this case, isolated Ag clusters. SERS analysis performed on the ZnO-Ag hybrid films using crystal violet (CV) molecule revealed a limit of detection (LOD) of 10−7 M in the case of 15 nm thick Ag/Zeonor® interlayer films ZnO and relative standard deviation (RSD) below 10%.
      Citation: Chemosensors
      PubDate: 2023-08-07
      DOI: 10.3390/chemosensors11080441
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 442: Fabrication of Electrochemical Sensor
           for the Detection of Mg(II) Ions Using CeO2 Microcuboids as an Efficient

    • Authors: Girdega Muruganandam, Noel Nesakumar, Arockia Jayalatha Kulandaisamy, John Bosco Balaguru Rayappan, Balu Mahendran Gunasekaran
      First page: 442
      Abstract: In human blood serum, the concentration of magnesium ions typically ranges from 0.7 mM to 1.05 mM. However, exceeding the upper limit of 1.05 mM can lead to the condition known as hypermagnesemia. In this regard, a highly sensitive and selective electrochemical sensor for Mg(II) ion detection was successfully fabricated by immobilizing cerium oxide (CeO2) microcuboids, synthesized via microwave radiation method, onto the surface of glassy carbon electrode (GCE). Cyclic voltammetry studies revealed the exceptional electrocatalytic effect of CeO2 microcuboid-modified GC electrode, particularly in relation to the irreversible reduction signal of Mg(II). The microcuboid-like structure of CeO2 microparticles facilitated enhanced adsorption of Mg(II) ion (Γ=2.17×10−7mol cm−2) and electron transfer (ks=8.94 s−1) between the adsorbed Mg(II) ions and GCE. A comprehensive analysis comparing the performance characteristics of amperometry, differential pulse voltammetry, cyclic voltammetry, and square wave voltammetry was conducted. The square wave voltammetry-based Mg(II) sensor exhibited remarkable sensitivity of 2.856 μA mM−1, encompassing a broad linear detection range of 0–3 mM. The detection and quantification limits were impressively low, with values of 19.84 and 66.06 μM, respectively. Remarkably, the developed electrode showed a rapid response time of less than 140 s. Multiple linear regression and partial least squares regression models were employed to establish a mathematical relationship between magnesium ion levels and electrochemical parameters. Notably, the proposed sensor exhibited excellent anti-interferent ability, repeatability, stability, and reproducibility, enabling the fabricated electrode to be used effectively for Mg(II) ion sensing in real-world samples.
      Citation: Chemosensors
      PubDate: 2023-08-07
      DOI: 10.3390/chemosensors11080442
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 443: Heater Topology Influence on the
           Functional Characteristics of Thin-Film Gas Sensors Made by MEMS-Silicon

    • Authors: Gennady Gorokh, Igor Taratyn, Uladzimir Fiadosenka, Olga Reutskaya, Andrei Lozovenko
      First page: 443
      Abstract: The design of the heater plays a decisive role in the energy consumption, sensitivity, and speed of chemical sensors. The paper analyzes various options for the topology of meander-type platinum heaters in chemical sensors fabricated on thin dielectric membranes using MEMS-silicon technology. Comprehensive studies of the heater’s current–voltage characteristics have been carried out, heating rates have been measured at various currents, experimental temperature characteristics for various meander topologies have been obtained, heater options have been determined, and optimal heat transfer processes are ensured at a low power consumption of about 20–25 mW. Sensors with an optimal heater topology based on a double dielectric membrane were fabricated according to the described technological process, and sensory responses to 0.5 vol.% CH4 and 0.2% C3H8 were studied. The obtained results showed good results and confirmed the need to choose the optimal heater topology when designing sensors for recording the given type of gas mixtures in a certain temperature range.
      Citation: Chemosensors
      PubDate: 2023-08-09
      DOI: 10.3390/chemosensors11080443
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 444: Linkage Pathways of
           DNA–Nanoparticle Conjugates and Biological Applications

    • Authors: Shan Huang, Jun-Jie Zhu
      First page: 444
      Abstract: DNA–nanoparticle conjugates have extraordinary optical and catalytic properties that have attracted great interest in biosensing and biomedical applications. Combining these special qualities has made it possible to create extremely sensitive and selective biomolecule detection methods, as well as effective nanopharmaceutical carriers and therapy medications. In particular, inorganic nanoparticles, such as metal nanoparticles, metal–organic framework nanoparticles, or upconversion nanoparticles with relatively inert surfaces can easily bind to DNA through covalent bonds, ligand bonds, electrostatic adsorption, biotin–streptavidin interactions and click chemistry to form DNA–nanoparticle conjugates for a broad range of applications in biosensing and biomedicine due to their exceptional surface modifiability. In this review, we summarize the recent advances in the assembly mechanism of DNA–nanoparticle conjugates and their biological applications. The challenges of designing DNA–nanoparticle conjugates and their further applications are also discussed.
      Citation: Chemosensors
      PubDate: 2023-08-10
      DOI: 10.3390/chemosensors11080444
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 445: Real-Time Monitoring of H2O2
           Sterilization on Individual Bacillus atrophaeus Spores by Optical Sensing
           with Trapping Raman Spectroscopy

    • Authors: Morten Bertz, Denise Molinnus, Michael J. Schöning, Takayuki Homma
      First page: 445
      Abstract: Hydrogen peroxide (H2O2), a strong oxidizer, is a commonly used sterilization agent employed during aseptic food processing and medical applications. To assess the sterilization efficiency with H2O2, bacterial spores are common microbial systems due to their remarkable robustness against a wide variety of decontamination strategies. Despite their widespread use, there is, however, only little information about the detailed time-resolved mechanism underlying the oxidative spore death by H2O2. In this work, we investigate chemical and morphological changes of individual Bacillus atrophaeus spores undergoing oxidative damage using optical sensing with trapping Raman microscopy in real-time. The time-resolved experiments reveal that spore death involves two distinct phases: (i) an initial phase dominated by the fast release of dipicolinic acid (DPA), a major spore biomarker, which indicates the rupture of the spore’s core; and (ii) the oxidation of the remaining spore material resulting in the subsequent fragmentation of the spores’ coat. Simultaneous observation of the spore morphology by optical microscopy corroborates these mechanisms. The dependence of the onset of DPA release and the time constant of spore fragmentation on H2O2 shows that the formation of reactive oxygen species from H2O2 is the rate-limiting factor of oxidative spore death.
      Citation: Chemosensors
      PubDate: 2023-08-10
      DOI: 10.3390/chemosensors11080445
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 446: Disposable Stochastic Platform for the
           Simultaneous Determination of Calcipotriol and Betamethasone in
           Pharmaceutical and Surface Water Samples

    • Authors: Bianca-Maria Tuchiu, Raluca-Ioana Stefan-van Staden, Jacobus (Koos) Frederick van Staden, Hassan Y. Aboul-Enein
      First page: 446
      Abstract: A disposable stochastic platform based on calix [6]arene modified multi-walled carbon nanotubes-gold nanoparticles screen-printed electrode has been developed for the simultaneous determination of calcipotriol and betamethasone. For both analytes, very wide linear concentration ranges and extremely low limits of quantification (LOQ) were obtained: from 1.0 × 10−15 to 1.0 × 10−3 mol L−1 and with a 1.0 × 10−15 mol L−1 LOQ for calcipotriol, and from 1.0 × 10−16 to 1.0 × 10−2 mol L−1 with a 1.0 × 10−16 mol L−1 LOQ for betamethasone. The applicability of the sensing platform was successfully tested in commercially available topical pharmaceutical gel and surface water samples, obtaining recovery values ranging from 99.10 to 99.99% and relative standard deviation values under 0.05%. The obtained results render the proposed platform a viable, robust, selective, and sensitive tool that can be employed for the determination of the analytes in on-site routine quality control of pharmaceuticals and water quality monitoring.
      Citation: Chemosensors
      PubDate: 2023-08-10
      DOI: 10.3390/chemosensors11080446
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 447: GC/MS Profile and Antifungal Activity of
           Zanthoxylum caribaeum Lam Essential Oil against Moniliophthora roreri Cif
           and Par, a Pathogen That Infects Theobroma cacao L Crops in the Tropics

    • Authors: Marcial Fuentes-Estrada, Andrea Jiménez-González, Diannefair Duarte, Rogerio Saavedra-Barrera, Carlos Areche, Elena Stashenko, Nayive Pino Benítez, Daniela Bárcenas-Pérez, José Cheel, Olimpo García-Beltrán
      First page: 447
      Abstract: The species Zanthoxylum caribaeum belongs to the Rutaceae family, from which several chemical nuclei are known, including alkaloids and coumarins. In addition, its essential oil has been characterized, showing differences in composition and various antimicrobial activities. In the present study, the essential oil of Z. caribaeum collected in the department of Tolima, central Colombia, was characterized by gas chromatography with mass selective detector (GC-MS). The essential oil showed a composition of about 43 compounds (including major and minor), whose main components, according to their abundance, are the following: germacrene D (228.0 ± 1.6 mg/g EO), (E)-β-farnesene (128.0 ± 1.5 mg/g EO), β-elemene (116.0 ± 1.6 mg/g EO) and (E)-nerolidol (74.0 ± 2.2 mg/g EO). This oil was tested against microorganisms that affect cocoa production in Colombia and in tropical countries where the production of this commodity is very important for the economy. The antifungal tests were performed on the fungal species Moniliophthora roreri and showed promising and significant activity, inhibiting growth by more than 95% at concentrations of 50 µL/mL and 100 µL/mL. This remarkable antifungal activity could be due to the presence of major and minor compounds that synergistically enhance the activity.
      Citation: Chemosensors
      PubDate: 2023-08-10
      DOI: 10.3390/chemosensors11080447
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 448: Enhanced Fluorescence in a Lens-Less
           Fiber-Optic Sensor for C-Reactive Protein Detection

    • Authors: Victoria Esteso, Pietro Lombardi, Francesco Chiavaioli, Prosenjit Majumder, Maja Colautti, Steffen Howitz, Paolo Cecchi, Francesco Baldini, Ambra Giannetti, Costanza Toninelli
      First page: 448
      Abstract: In today’s medicine, the celerity of the bio-assays analysis is crucial for the timely selection of the appropriate therapy and hence its effectiveness, especially in case of diseases characterized by the late onset of symptoms. In this paper, a lens-less fiber optics-based fluorescence sensor designed for the measurement of labeled bio-assays is presented and its potential for the early diagnosis of sepsis via C-reactive protein (CRP) detection is demonstrated. The sensor performance results from the combination of two key elements: a planar antenna that redirects fluorescence the marker emission and an automated fiber-based optical system for multi-spot analysis. First, the working principle of the device is demonstrated with a well-established antibody–antigen format (immunoglobulin IgG/anti-IgG assay), reporting more than one order of magnitude enhanced limit of detection (LOD) and limit of quantification (LOQ) for the planar antenna with respect to a standard glass substrate. The prototype is then tested against a sample mimicking a realistic case, prepared with commercially available human serum, showing a LOD and LOQ in the clinical range of interest (0.0015 μg/mL and 0.005 μg/mL, respectively) for the investigation of the sepsis biomarker CRP. These results validate the developed prototype as a simple and easy-to-operate device, compatible with standardized micro-well arrays, and potentially suitable for POC applications.
      Citation: Chemosensors
      PubDate: 2023-08-11
      DOI: 10.3390/chemosensors11080448
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 449: Real-Time Monitoring of Cement Paste
           Carbonation with In Situ Optical Fiber Sensors

    • Authors: Pedro M. da Silva, João P. Mendes, Luís C. C. Coelho, José M. M. M. de Almeida
      First page: 449
      Abstract: Reinforced concrete structures are prevalent in infrastructure and are of significant economic and social importance to humanity. However, they are prone to decay from cement paste carbonation. pH sensors have been developed to monitor cement paste carbonation, but their adoption by the industry remains limited. This work introduces two new methods for monitoring cement paste carbonation in real time that have been validated through the accelerated carbonation of cement paste samples. Both configurations depart from traditional pH monitoring. In the first configuration, the carbonation depth of a cement paste sample is measured using two CO2 optical fiber sensors. One sensor is positioned on the surface of the sample, while the other is embedded in the middle. As the carbonation depth progresses and reaches the embedded CO2 sensor, the combined response of the sensors changes. In the second configuration, a multimode fiber is embedded within the paste, and its carbonation is monitored by observing the increase in reflected light intensity (1.6–18%) resulting from the formation of CaCO3. Its applicability in naturally occurring carbonation is tested at concentrations of 3.2% CO2, and the influence of water is positively evaluated; thus, this setup is suitable for real-world testing and applications.
      Citation: Chemosensors
      PubDate: 2023-08-11
      DOI: 10.3390/chemosensors11080449
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 450: Effect of pH on Electrochemical
           Impedance Response of Tethered Bilayer Lipid Membranes: Implications for
           Quantitative Biosensing

    • Authors: Arun Prabha Shivabalan, Filipas Ambrulevicius, Martynas Talaikis, Vaidas Pudzaitis, Gediminas Niaura, Gintaras Valincius
      First page: 450
      Abstract: Tethered bilayer lipid membranes (tBLMs) are increasingly used in biosensor applications where electrochemical impedance spectroscopy (EIS) is the method of choice for amplifying and recording the activity of membrane-damaging agents such as pore-forming toxins or disrupting peptides. While the activity of these biological agents may depend on the pH of the analytes, there is increasing evidence that the sensitivity of tethered bilayer sensors depends on the pH of the solutions. In our study, we addressed the question of what are the fundamental reasons for the variability of the EIS signal of the tBLMs with pH. We designed an experiment to compare the EIS response of tBLMs with natural membrane defects and two different membrane disruptors: vaginolysin and melittin. Our experimental design ensured that the same amount of protein and peptide was present in the tBLMs, while the pH was varied by replacing the buffers with different pH values. Using a recently developed EIS data analysis algorithm from our research group, we were able to demonstrate that, in contrast to previous literature which relates the variability of tBLM, EIS response to the variation in defect density, the main reason for the observed variability in EIS response is the change in the sub-membrane properties of tBLMs with pH. Using surface-enhanced infrared absorption spectroscopy (SEIRAS), we have shown that pH changes from neutral to slightly acidic leads to an expulsion of water, presumably bound to ions, from the sub-membrane reservoir, resulting in a marked decrease in the carrier concentration and specific conductance of the sub-membrane reservoir. Such a decrease is recorded by the EIS as a decrease in the conductance of the tBLM complex and affects the sensitivity of a biosensor. Our data provide important evidence of pH-sensitive effects that should be considered in both the development and operation of biosensors.
      Citation: Chemosensors
      PubDate: 2023-08-11
      DOI: 10.3390/chemosensors11080450
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 451: Visual Measurement of Fumonisin B1 with
           Bipolar Electrodes Array-Based Electrochemiluminescence Biosensor

    • Authors: Longsheng Jin, Huihui Yu, Weishuai Liu, Ziying Xiao, Haijian Yang, Bing Jin, Meisheng Wu
      First page: 451
      Abstract: Fumonisin B1 (FB1) is a toxin produced by the metabolism of Fusarium oxysporum, which can cause serious effects on the nervous, respiratory, digestive, and reproductive systems of humans or animals; it is known as one of the highly toxic epidemic contaminants. Herein, we report the visual inspection of FB1 using bipolar electrodes (BPEs) with an array-based electrochemiluminescence (ECL) platform. The sensor consists of a PDMS cover and a glass substrate containing an array of 10 ITO electrodes. A specific sensing interface was constructed on the cathode of the BPE, which could modulate the ECL reactions that occurred at the anode of BPEs. To amplify the ECL signal, methylene blue (MB)-encapsulated Zr-MOFs (MB@Zr-MOFs) were synthesized and immobilized on the cathode of the BPE, which could amplify the ECL signal at the anode. By coupling the cyclic amplification effect of the DNA walker and nicking endonuclease (Nb.BbvCI), the biosensor can realize the visual measurement of FB1 in the range of 5 × 10−5~0.5 ng/mL. In addition, the developed biosensor was used to monitor the concentration of FB1 in maize and peanut samples. The recoveries were in the range of 99.2%~110.6%, which demonstrated the good accuracy of the designed BPE-ECL biosensor for FB1 assay in food samples.
      Citation: Chemosensors
      PubDate: 2023-08-12
      DOI: 10.3390/chemosensors11080451
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 452: Facile Fabrication of a Selective
           Poly(caffeic acid)@MWCNT-Ni(OH)2 Hybrid Nanomaterial and Its Application
           as a Non-Enzymatic Glucose Sensor

    • Authors: Maria Kuznowicz, Tomasz Rębiś, Artur Jędrzak, Grzegorz Nowaczyk, Teofil Jesionowski
      First page: 452
      Abstract: A novel catechol-based PCA@MWCNT-Ni(OH)2 hybrid material was prepared and used to construct a non-enzymatic glucose biosensor. In this synthesis, MWCNTs were covered with a poly(caffeic acid) coating and then subjected to a straightforward electrochemical process to decorate the hybrid material with Ni(OH)2 particles. The physicochemical properties and morphology of the nanomaterial were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM). Amperometry and cyclic voltammetric studies demonstrated the enhanced redox properties of a GC/PCA@MWCNT-Ni(OH)2 electrode and its electrocatalytic activity in glucose detection, with a low detection limit (0.29 μM), a selectivity of 232.7 μA mM−1 cm−2, and a linear range of 0.05–10 mM, with good stability (5 months) and reproducibility (n = 8). The non-enzymatic sensor was also used for glucose determination in human serum and human blood, with recovery values ranging from 93.3% to 98.2%. In view of the properties demonstrated, the described GC/PCA@MWCNT-Ni(OH)2 sensor represents a facile synthesis method of obtaining the hybrid nanomaterial and a low-cost approach to electrochemical glucose measurement in real samples (human serum, human blood).
      Citation: Chemosensors
      PubDate: 2023-08-13
      DOI: 10.3390/chemosensors11080452
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 453: A Metal Organic Framework-Based Light
           Scattering ELISA for the Detection of Staphylococcal Enterotoxin B

    • Authors: Kai Mao, Lili Tian, Yujie Luo, Qian Li, Xi Chen, Lei Zhan, Yuanfang Li, Chengzhi Huang, Shujun Zhen
      First page: 453
      Abstract: Enzyme-linked immunosorbent assay (ELISA) is one of the most commonly used method for the detection of staphylococcal enterotoxin B (SEB), the main protein toxin causing staphylococcal food poisoning. However, the traditional ELISA reaction needs to be stopped by sulfuric acid to obtain stable colorimetric signal, and it is easily influenced by a colored sample. In order to address this problem, a new ELISA method using zeolite imidazolate skeleton-8 metal-organic framework (ZIF-8 MOF) as a light scattering (LS) reporter for SEB detection was developed in this work. ZIF-8 MOF has the characteristics of high porosity, large specific surface area, clear pore structure, and adjustable size, which is one of the most representative MOFs constructed from Zn2+ and 2-methylimidazole (2-mIM). The 2-mIM ligand of ZIF-8 exhibited antioxidant activity and can strongly react with H2O2, which could destroy the structure of ZIF-8, resulting in the obvious decrease in LS intensity. We combined this specific reaction with the sandwich immune reaction to construct the LS ELISA method for the successful detection of SEB. This method is more reliable than commercial tests kits for the detection of colored samples, and it is simple, sensitive, and selective, and has great potential in the detection of other toxins by simply changing the corresponding recognition units.
      Citation: Chemosensors
      PubDate: 2023-08-13
      DOI: 10.3390/chemosensors11080453
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 454: Optical Dual Gas Sensor for Simultaneous
           Detection of Nitric Oxide and Oxygen

    • Authors: Rispandi Mesin, Cheng-Shane Chu
      First page: 454
      Abstract: This work presents a new optical dual sensor based on PtTFPP-containing electrospun fibers and CsPbBr3 perovskite quantum dots (PQDs) for simultaneous detection of oxygen (O2) and nitric oxide (NO) gases, wherein PtTFPP-containing electrospun fibers for O2 sensing was based on electrospinning process fabricated by platinum(II) meso-tetrakis (pentafluorophenyl) porphyrin (PtTFPP) complex immobilized in cellulose acetate (CA) matrix. CsPbBr3 PQDs were used as NO-sensitive material and coated on the surface of PtTFPP-containing electrospun fibers. Both materials were excited by a UV LED with a central wavelength of 380 nm, and the fluorescence intensities of sensing materials were recorded and analyzed with a spectrometer. The experiment results show that the optical NO and O2 sensors have linear Stern–Volmer plots, and the sensitivities are around 2.7 and 10.7, respectively. The response and recovery times of the optical NO sensor are 71 and 109 s, respectively. For optical O2, response and recovery times are 60 and 65 s, respectively. The optical dual sensor with a new method based on fluorescent dye containing electrospun fibers and coated with CsPbBr3 PQDs has been successfully developed to detect NO and O2 gases simultaneously. The optical dual gas sensor provides great potential for practical applications with low cost and ease of fabrication.
      Citation: Chemosensors
      PubDate: 2023-08-14
      DOI: 10.3390/chemosensors11080454
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 455: One-Step Chemiluminescent Assay for
           Hydrogen Peroxide Analysis in Water

    • Authors: Ahlem Teniou, Ibrahim A. Madi, Riane Mouhoub, Jean Louis Marty, Amina Rhouati
      First page: 455
      Abstract: The detection of hydrogen peroxide is of great importance in the environmental field. For this, a homogeneous technique has been developed here for sensitive and rapid quantification of hydrogen peroxide. In this technique, hemoglobin was used as a bioreceptor, where heme groups acted as electroactive centers to catalyze hydrogen peroxide reduction. The chemiluminescence reagent luminol is also a peroxidase substrate and can be oxidized by hemoglobin—thus generating a CL signal. The principle of the designed biosensor was based on the competition between hydrogen peroxide and luminol towards hemoglobin. Under optimized conditions, the chemiluminescent signal decreased with increasing hemoglobin concentrations within the linear range of 0.5 to 12 mM, with a correlation coefficient R2 of 0.99762. The limit of detection was calculated to be as low as 0.308 mM. The selectivity of the biosensor was successfully demonstrated against different interferents. The developed strategy provides a one step, simple, and low-cost bioanalytical method which can be applied for the monitoring of other peroxidase substrates.
      Citation: Chemosensors
      PubDate: 2023-08-14
      DOI: 10.3390/chemosensors11080455
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 456: Methods for Calibrating the
           Electrochemical Quartz Crystal Microbalance: Frequency to Mass and
           Compensation for Viscous Load

    • Authors: Claes-Olof A. Olsson, Anna Neus Igual-Muñoz, Stefano Mischler
      First page: 456
      Abstract: The main output from an Electrochemical Quartz Crystal Microbalance is a frequency shift. This note describes how to separate the mass- and viscous load contributions to this shift by a calibration procedure. The mass calibration is made by electroplating from a copper sulfate solution in ethanol/water with 100% current efficiency. An estimate of viscous load is obtained by measuring the energy dissipation and is related to frequency change using the Kanazawa–Gordon equation. Two approaches are discussed: either by performing calibration experiments in a series of water–glycerol mixtures or by following oscillations in frequency and dissipation by collecting data during the stabilization phase of the experiment.
      Citation: Chemosensors
      PubDate: 2023-08-14
      DOI: 10.3390/chemosensors11080456
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 457: Eco-Friendly, High-Performance Humidity
           Sensor Using Purple Sweet-Potato Peel for Multipurpose Applications

    • Authors: Sheik Abdur Rahman, Shenawar Ali Khan, Shahzad Iqbal, Muhammad Muqeet Rehman, Woo Young Kim
      First page: 457
      Abstract: Biomaterials offer great potential for enhancing the performance of humidity sensors, which play a critical role in controlling moisture levels across different applications. By utilizing environmentally friendly, sustainable, and cost-effective biomaterials, we can improve the manufacturing process of these sensors while reducing our environmental impact. In this study, we present a high-performance humidity sensor that utilizes purple sweet potato peel (PSPP) as both the substrate and sensing layer. The PSPP is chosen for its polar hydrophilic functional groups, as well as its environmentally friendly nature, sustainability, and cost-effectiveness. Remarkably, this humidity sensor does not require an external substrate. It exhibits a wide detection range of 0 to 85% relative humidity at various operating frequencies (100 Hz, 1 kHz, and 10 kHz) in ambient temperature, demonstrating its effectiveness in responding to different humidity levels. The sensor achieves a high sensitivity value of 183.23 pF/%RH and minimal hysteresis of only 5% at 10 kHz under ambient conditions. It also boasts rapid response and recovery times of 1 and 2 s, respectively, making it suitable for use in high-end electronic devices. Moreover, the sensor’s applications extend beyond environmental monitoring. It has proven effective in monitoring mouth and nasal breathing, indicating its potential for respiratory monitoring and noncontact proximity response. These findings suggest that sweet potato peel material holds great promise as a highly stable, non-toxic, biodegradable, cost-effective, and environmentally friendly option for various domains, including healthcare monitoring.
      Citation: Chemosensors
      PubDate: 2023-08-15
      DOI: 10.3390/chemosensors11080457
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 458: Development and Application of an
           Electrochemical Sensor with 1,10-Phenanthroline-5,6-dione-Modified
           Electrode for the Detection of Escherichia coli in Water

    • Authors: Yining Fan, Yanran Liu, Guanyue Gao, Hanxin Zhang, Jinfang Zhi
      First page: 458
      Abstract: The routine monitoring of bacterial populations is crucial for ensuring water quality and safeguarding public health. Thus, an electrochemical sensor based on a 1,10-phenanthroline-5,6-dione-modified electrode was developed and explored for the detection of E. coli. The modified electrode exhibited enhanced NADH oxidation ability at a low potential of 0.1 V, which effectively eliminated the interference from other redox compounds in bacteria. The sensitivity for NADH was 0.222 μA/μM, and the limit of detection was 0.0357 μM. Upon cell lysis, the intracellular NADH was released, and the concentration of E. coli was determined through establishing the relationship between the oxidation current signal and NADH concentration. The performance of the electrochemical sensor in the detection of NADH and E. coli suspensions was validated using the WST-8 colorimetric method. The blank recovery experiment in real water samples exhibited good accuracy, with recovery rates ranging from 89.12% to 93.26% and relative standard deviations of less than 10%. The proposed electrochemical sensor realized the detection of E. coli without the usage of biomarkers, which provides a promising approach for the broad-spectrum detection of microbial contents in complex water environments.
      Citation: Chemosensors
      PubDate: 2023-08-15
      DOI: 10.3390/chemosensors11080458
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 459: Wearable Chemosensors in Physiological

    • Authors: Zeyi Tang, Tianrui Cui, Houfang Liu, Jinming Jian, Ding Li, Yi Yang, Tianling Ren
      First page: 459
      Abstract: The development of flexible electronic technology has led to significant advancements in wearable sensors. In the past decades, wearable chemosensors have received much attention from researchers worldwide due to their high portability, flexibility, lightweight, and adaptability. It allows real-time access to the user’s physiological status at the molecular level to analyze their health status. Therefore, it can be widely used in the field of precision medicine. This review introduces the sensing mechanisms of wearable chemosensors and recent progress in wearable sweat and interstitial fluid-based chemosensors. The complexities of wearable chemosensors are not to be underestimated, as there are considerable challenges in this field. This review aims to shed light on the difficulties associated with designing wearable sweat and interstitial fluid-based chemosensors and their potential development directions.
      Citation: Chemosensors
      PubDate: 2023-08-15
      DOI: 10.3390/chemosensors11080459
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 460: Gas-Sensing Properties of Graphene
           Functionalized with Ternary Cu-Mn Oxides for E-Nose Applications

    • Authors: Margus Kodu, Rainer Pärna, Tea Avarmaa, Indrek Renge, Jekaterina Kozlova, Tauno Kahro, Raivo Jaaniso
      First page: 460
      Abstract: Chemiresistive gas sensors were produced by functionalizing graphene with a ~3 nm layer of mixed oxide xCu2O⸱yMnO using pulsed laser deposition (PLD) from a hopcalite CuMn2O4 target. Sensor response time traces were recorded for strongly oxidizing (NO2, O3) and reducing (NH3, H2S) poisonous gases at ppb and ppm levels, respectively. The morphology of the MOX layer was modified by growth temperature during PLD, resulting in the optimization of the sensor response. Differences in decomposition or oxidation rates on catalytically active metal oxide (MOX) were utilized to achieve partial selectivity for pairs of gases that have similar adsorption and redox properties. The predominant selectivity towards ozone in most samples at different measuring conditions remained difficult to suppress. A distinct selectivity for H2S emerged at higher measurement temperatures (100–150 °C), which was assigned to catalytic oxidation with O2. Several gas–MOX interaction mechanisms were advanced to tentatively explain the sensor behavior, including reversible electron transfer in the simplest case of NO2, decomposition via ionic transients for O3, and complex catalytic oxidative transformations for NH3 and H2S.
      Citation: Chemosensors
      PubDate: 2023-08-15
      DOI: 10.3390/chemosensors11080460
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 461: Recent Advances in Rational Design and
           Engineering of Signal-Amplifying Substrates for Surface-Enhanced Raman
           Scattering-Based Bioassays

    • Authors: Song Gao, Zhanchen Guo, Zhen Liu
      First page: 461
      Abstract: In recent decades, surface-enhanced Raman spectroscopy (SERS) has become a powerful detection scheme for many applications, particularly bioassays, due to its unique strengths, such as its ultrasensitive performance. Due to the development of various SERS substrates, more SERS-based bioassays with improved sensitivity and reproducibility have been designed and manufactured. SERS is able to provide the intrinsic vibration information of molecules through the unique Raman fingerprint to enable direct detection and quantitation. Meanwhile, with the assistance of Raman-active labels, biomolecules, like proteins and nucleic acids, can be detected by the immunosandwich assay. In this review, we focus on the rational design and engineering of signal-enhancing substrates for SERS-based bioassays. Those substrates are classified into two categories, i.e., nanoparticles in colloidal suspension and nanostructures on a solid support. Each category is discussed in detail with stress on their biomedical application potential. Afterward, we summarize the SERS-based assays of proteins, nucleic acids, and viruses, for which both label-free and labeled approaches play important roles. Finally, we present the remaining challenges in the field of SERS-based bioassays and sketch out promising directions for future development.
      Citation: Chemosensors
      PubDate: 2023-08-16
      DOI: 10.3390/chemosensors11080461
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 462: Highly Polarized SERS Based on Random
           Working Domains Composed of Nanorod Arrays for Self-Referenced Detection

    • Authors: Xiaoyu Zhao, Deyuan Mao, Shuangshuang Zhao, Yuxia Wang, Xiaojie Guo, Yaxin Wang, Renxian Gao, Yongjun Zhang
      First page: 462
      Abstract: When Ag film is sputtered onto polystyrene (PS) spheres, the curved Ag nanocaps form with scattered Ag nanoparticles along the brim of the Ag nanocap. Ion etching results in parallel PS nanorods due to the masking effects of the scattered Ag nanoparticles when the Ag cap array is transferred to another substrate with the top down. The highly polarized SERS substrate of random working domains composed of parallel nanorods is prepared when another 5 nm film is deposited. The nanorod diameters range from 10 nm to 20 nm, depending on the sizes of the masking Ag nanoparticles prepared by the magnetron control system and the ion etching process. Compared with other techniques, our nanorods have the advantages of highly ordered patterns in each domain, which show the excellent behavior of the polarized SERS for all PS spheres. This polarized SERS substrate is used to detect thiram with a concentration as low as 10−9 M when the background noise is successfully removed by a self-reference technique.
      Citation: Chemosensors
      PubDate: 2023-08-16
      DOI: 10.3390/chemosensors11080462
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 463: Remote Measurements of Tear Electrolyte
           Concentrations on Both Sides of an Inserted Contact Lens

    • Authors: Joseph R. Lakowicz, Ramachandram Badugu, Kundan Sivashanmugan, Albert Reece
      First page: 463
      Abstract: In this paper, a method is described to perform ion concentration measurements on both sides of an inserted contact lens, without physical contact with the eye or the contact lens. The outer surface of an eye is covered with a tear film that has multiple layers. The central aqueous layer contains electrolytes and proteins. When a contact lens is inserted, it becomes localized in the central layer, which creates two layers known as the pre-lens tear film (PLTF) and the post-lens tear film (PoLTF). The PoLTF is in direct contact with the sensitive corneal epithelial cells which control electrolyte concentrations in tears. It is difficult to measure the overall electrolyte concentration in tears because of the small 7 μL volume of bulk tears. No methods are known, and no method has been proposed, to selectively measure the concentrations of electrolytes in the smaller volumes of the PLTF and the PoLTF. In this paper, we demonstrate the ability to localize fluorophores on each side of a contact lens without probe mixing or diffusion across the lens. We measured the concentration of sodium in the region of the PoLTF using a sodium-sensitive fluorophore positioned on the inner surface of a contact lens. The fluorescence measurements do not require physical contact and are mostly independent of eye motion and fluorophore concentration. The method is generic and can be combined with ion-sensitive fluorophores for the other electrolytes in tears. Instrumentation for non-contact measurements is likely to be inexpensive with modern opto-electronic devices. We expect these lenses to be used for measurements of other ions in the PLTF and the PoLTF, and thus become useful for both research and in the diagnosis of infections, keratitis and biomarkers for diseases.
      Citation: Chemosensors
      PubDate: 2023-08-17
      DOI: 10.3390/chemosensors11080463
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 464: Quantitative Detection of the Influenza
           a Virus by an EGOFET-Based Portable Device

    • Authors: Elena Y. Poimanova, Elena G. Zavyalova, Elena A. Kretova, Anton A. Abramov, Askold A. Trul, Oleg V. Borshchev, Anna K. Keshek, Sergey A. Ponomarenko, Elena V. Agina
      First page: 464
      Abstract: Elaboration of biosensors on the base of organic transistors with embedded biomolecules which can operate in an aqueous environment is of paramount importance. Electrolyte-gated organic field-effect transistors demonstrate high sensitivity in detection of various analytes. In this paper, we demonstrated the possibility of quantitative fast specific determination of virus particles by an aptasensor based on EGOFET. The sensitivity and selectivity of the devices were examined with the influenza A virus as well as with control bioliquids like influenza B, Newcastle disease viruses or allantoic fluid with different dilutions. The influence of the semiconducting layer thickness on EGOFETs sensory properties is discussed. The fabrication of a multi-flow cell that simultaneously registers the responses from several devices on the same substrate and the creation of a multi-sensor flow device are reported. The responses of the elaborated bioelectronic platform to the influenza A virus obtained with application of the portable multi-flow mode are well correlated with the responses obtained in the laboratory stationary mode.
      Citation: Chemosensors
      PubDate: 2023-08-17
      DOI: 10.3390/chemosensors11080464
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 465: Aptamer–Molecularly Imprinted
           Polymer Multiple-Recognition System: Construction and Application

    • Authors: Kangping Ning, Yingzhuo Shen, Yao Yao, Wenzheng Xie, Cheng Ma, Qin Xu
      First page: 465
      Abstract: Molecularly imprinted polymers (MIPs) and aptamers (Apts) are widely used in substance detection due to their specific recognition abilities. However, both of them have limitations in terms of stability or sensitivity. Therefore, an increasingly employed strategy is to combine MIPs and aptamers to form mixed components for detecting various substances, such as viruses, bacteria, proteins, heavy-metal ions, and hormones. The aim of this review is to provide a comprehensive summary of the scientific research conducted on the construction and application of aptamer–MIP multiple-recognition components in the past five years. It also aims to analyze their research and development strategies, construction mechanisms, advantages, and potential applications, as well as limitations and current challenges that need to be addressed.
      Citation: Chemosensors
      PubDate: 2023-08-18
      DOI: 10.3390/chemosensors11080465
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 466: Anodic Stripping Voltammetric
           Determination of Copper Ions in Cell Culture Media: From Transwell® to
           Organ-on-Chip Systems

    • Authors: Carmela Tania Prontera, Elisa Sciurti, Chiara De Pascali, Lucia Giampetruzzi, Francesco Biscaglia, Laura Blasi, Vanessa Esposito, Flavio Casino, Pietro Aleardo Siciliano, Luca Nunzio Francioso
      First page: 466
      Abstract: The integration of sensing devices into cell culture systems is a topic of great interest in the study of pathologies and complex biological mechanisms in real-time. In particular, the fit-for-purpose microfluidic devices called organ-on-chip (OoC), which host living engineered organs that mimic in vivo conditions, benefit greatly from the integration of sensors, enabling the monitoring of specific chemical-physical parameters that can be correlated with biological processes. In this context, copper is an essential trace element whose total concentration may be associated with specific pathologies, and it is therefore important to develop reliable analytical techniques in cell systems. Copper can be determined by using the anodic stripping voltammetry (ASV) technique, but its applicability in cell culture media presents several challenges. Therefore, in this work, the performance of ASV in cell culture media was evaluated, and an acidification protocol was tested to improve the voltammetric signal intensity. A Transwell® culture model with Caco-2 cells was used to test the applicability of the developed acidification protocol by performing an off-line measurement. Finally, a microfluidic device was designed in order to perform the acidification of the cell culture medium in an automated manner and then integrated with a silicon microelectrode to perform in situ measurements. The resulting sensor-integrated microfluidic chip could be used to monitor the concentration of copper or other ions concentration in an organ-on-chip model; these functionalities represent a great opportunity for the non-destructive strategic experiments required on biological systems under conditions close to those in vivo.
      Citation: Chemosensors
      PubDate: 2023-08-21
      DOI: 10.3390/chemosensors11080466
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 467: Progress on Electrochemical Sensing of
           Pharmaceutical Drugs in Complex Biofluids

    • Authors: Elain Fu, Khadijeh Khederlou, Noël Lefevre, Stephen A. Ramsey, Matthew L. Johnston, Lael Wentland
      First page: 467
      Abstract: Electrochemical detection, with its advantages of being rapid, multi-time point, compatible with cost-effective fabrication methods, and having the potential for miniaturization and portability, has great promise for point-of-care drug monitoring. However, a continuing challenge concerns the robust and sensitive electrochemical detection of pharmaceutical analytes from biological fluids. These complex matrices, such as saliva, sweat, interstitial fluid, urine, and blood/serum, contain multiple components that can contribute to an increased background or reduced analyte signal. In this mini-review, we discuss progress on electrochemical sensing in complex biofluids. We first introduce the challenge of drug titration in the management of various health conditions and provide an overview of the motivation for improved therapeutic drug monitoring, including current limitations. We then review progress on pharmaceutical drug detection from these biofluids with a focus on sample preprocessing, electrode modification for signal amplification, and/or electrode passivation to minimize fouling. Finally, we highlight promising strategies that have enabled robust drug quantification for clinical relevance and that may be useful for field-use systems.
      Citation: Chemosensors
      PubDate: 2023-08-21
      DOI: 10.3390/chemosensors11080467
      Issue No: Vol. 11, No. 8 (2023)
  • Chemosensors, Vol. 11, Pages 410: Preparation and Hydrogen-Sensitive
           Property of WO3/Graphene/Pd Ternary Composite

    • Authors: Lin Wang, Fei An, Xinmei Liu, Dongzhi Zhang, Zhe Yang
      First page: 410
      Abstract: Hydrogen (H2) is a renewable energy source that has the potential to reduce greenhouse gas emissions. However, H2 is also highly flammable and explosive, requiring sensitive and safe sensors for its detection. This work presents the synthesis and characterization of WO3/graphene binary and WO3/graphene/Pd (WG-Pd) ternary nanocomposites with varying graphene and Pd contents using the microwave-assisted hydrothermal method. The excellent catalytic efficacy of Pd nanoparticles facilitated the disintegration of hydrogen molecules into hydrogen atoms with heightened activity, consequently improving the gas-sensing properties of the material. Furthermore, the incorporation of graphene, possessing high conductivity, serves to augment the mobility of charge carriers within the ternary materials, thereby expediting the response/recovery rates of gas sensors. Both graphene and Pd nanoparticles, with work functions distinct from WO3, engender the formation of a heterojunction at the interface of these diverse materials. This enhances the efficacy of electron–hole pair separation and further amplifies the gas-sensing performance of the ternary materials. Consequently, the WG-Pd based sensors exhibited the best gas-sensing performance when compared to anther materials, such as a wide range of hydrogen concentrations (0.05–4 vol.%), a short response time and a good selectivity below 100 °C, even at room temperature. This result indicates that WG-Pd ternary materials are a promising room-temperature hydrogen-sensing materials for H2 detection.
      Citation: Chemosensors
      PubDate: 2023-07-21
      DOI: 10.3390/chemosensors11070410
      Issue No: Vol. 11, No. 7 (2023)
  • Chemosensors, Vol. 11, Pages 411: Theoretical Study of 3d VIII
           Atom-Decorated γ-Graphyne for Adsorbing and Detecting

    • Authors: Ziang Zheng, Renchu Zhao, Dachang Chen, Qing Miao, Ke Liu, Beibei Xiao
      First page: 411
      Abstract: Recently, Heptafluoroisobutyronitrile (C4F7N) has received widespread attention in replacing one of the most greenhouse-insulating gas, SF6. However, gas leakage is incredibly harmful to the health of operational personnel and the security of industry production, and developing C4F7N detection technology is of great necessity. In this work, the adsorption properties, as well as the sensing performance of C4F7N on 3d VIII atom-decorated γ-graphyne (γ-GY), were theoretically discussed. The adsorption structures, adsorption energies, electron transfer, adsorption distance, electron distribution, and electronic properties were compared. The results show that the introduction of Fe and Co atom enhance the chemisorption of C4F7N, and the adsorption of C4F7N brings the maximum electron redistribution of Fe/γ-GY among three TM/γ-GY. Only the adsorption on Fe/γ-GY leads to the vanishing of the magnetic moment and creates a band gap. For three different modifications of γ-GY, the chemical interactions are highly related to the overlapping of transition metal 3d and N 2p orbitals in the density of states. The adsorption on Co/γ-GY causes the maximum change in work function from 5.06 eV to 5.26 eV. In addition, based on the band structure, work function, and desorption properties, the sensing properties of 3d VIII atom-decorated γ-GY were evaluated in order to promote the experimental exploration and development of high-performance C4F7N gas sensors.
      Citation: Chemosensors
      PubDate: 2023-07-21
      DOI: 10.3390/chemosensors11070411
      Issue No: Vol. 11, No. 7 (2023)
  • Chemosensors, Vol. 11, Pages 412: Recent Advances in Photoelectrochemical
           Sensors for Analysis of Toxins and Abused Drugs in the Environment

    • Authors: Yan Mao, Xiaoxin Liu, Yu Bao, Li Niu
      First page: 412
      Abstract: Toxic pollutants in the environment, such as toxins and abused drugs, have posed a major threat to human health and ecosystem security. It is extremely desirable to develop simple, low-cost, sensitive, and reliable techniques for the detection of these pollutants in the environment. As a booming analytical method, photoelectrochemical (PEC) sensors possess low background noise and high sensitivity. The performances of PEC sensors are fundamentally related to the photoelectric conversion efficiency, which mainly depends on the properties of photoactive materials. This review aims to summarize the engineered photoactive materials, i.e., semiconductors and semiconductor-based heterojunctions, as well as their actual applications, with emphasis on sensing mechanisms in PEC sensors for the analysis of toxins and abused drugs in the environment. Finally, the future research perspectives in this field are also discussed.
      Citation: Chemosensors
      PubDate: 2023-07-22
      DOI: 10.3390/chemosensors11070412
      Issue No: Vol. 11, No. 7 (2023)
  • Chemosensors, Vol. 11, Pages 413: Capacitive, Highly Selective
           Zeolite-Based Ammonia Sensor for Flue Gas Applications

    • Authors: Thomas Wöhrl, Jaroslaw Kita, Ralf Moos, Gunter Hagen
      First page: 413
      Abstract: The selective detection of different gas components will remain of huge importance in the future, either in the ambient air or in flue gases, e.g., for controlling purposes of combustion processes. The focus here is on the development of a highly selective ammonia sensor that will be exemplarily used in the flue gas of biomass combustion plants with catalysts for nitrogen oxide reduction. Such applications require a robust sensor design, in this case, based on a ceramic substrate. The gaseous ammonia is detected with the help of a zeolite film, whose selective adsorption properties towards ammonia are already intensively being used in the field of flue gas catalysis. The adsorption and desorption of ammonia on the gas-sensitive zeolite film lead to changes in the dielectric properties of the functional material. Using an interdigital electrode (IDE) structure below the zeolite film, the capacitance was determined as a measure of the ammonia concentration in the gas. In this context, the fabrication of all layers of the sensor in the thick film with subsequent laser patterning of the IDE structure enables a cost-efficient and effective method. The functionality of this sensor principle was extensively tested during measurements in the laboratory. A high and fast response to ammonia was detected at different sensor temperatures. In addition, very low cross-sensitivities to other gas components such as water (very low) and oxygen (zero) were found.
      Citation: Chemosensors
      PubDate: 2023-07-22
      DOI: 10.3390/chemosensors11070413
      Issue No: Vol. 11, No. 7 (2023)
  • Chemosensors, Vol. 11, Pages 414: MIP-Assisted 3-Hole POF Chip Faced with
           SPR-POF Sensor for Glyphosate Detection

    • Authors: Giancarla Alberti, Stefano Spina, Francesco Arcadio, Maria Pesavento, Letizia De Maria, Nunzio Cennamo, Luigi Zeni, Daniele Merli
      First page: 414
      Abstract: The present study proposes the application of a recently developed optical–chemical sensor system to glyphosate detection. The device probes the refractive index variation in a chip based on a plastic optical fiber (POF) in which three orthogonal micro-holes were created and filled with an acrylic-based molecularly imprinted polymer (MIP). This sensitive chip, connected in series to a gold-coated SPR-POF platform, can modify the surface plasmon resonance (SPR) phenomena by exploiting the multimode characteristic of the POFs. Therefore, the gold film of the SPR-POF platform is not covered by the MIP layer, improving the sensor’s performance because the interaction between the analyte (glyphosate) and the polymer recognition cavities occurs in the core and not in the cladding of the waveguide. Indeed, the sample solution is dropped on the MIP-based chip while a water drop is constantly maintained above the gold surface of the reference SPR-POF platform to excite the surface plasmons, modulated by the MIP interaction with the target analyte. The device is here for the first time applied for glyphosate sensing in water samples. The high sensitivity and selectivity are proven, and tests on real samples highlight the good performances of the developed sensors.
      Citation: Chemosensors
      PubDate: 2023-07-22
      DOI: 10.3390/chemosensors11070414
      Issue No: Vol. 11, No. 7 (2023)
  • Chemosensors, Vol. 11, Pages 415: Electrochemical Detection of Tumor
           Cell-Derived Exosomes Based on Cyclic Enzyme Scission and Hybridization
           Chain Reaction Dual-Signal Amplification

    • Authors: Die Sun, Qunqun Guo, Hui Zhang, Chenxin Cai
      First page: 415
      Abstract: Tumor cell-derived exosomes are considered a potential source of cancer biomarkers. Here, we developed an electrochemical sensing platform for the rapid and simple detection of exosomes, using the CCRF-CEM exosome as a model. The platform utilizes cyclic nicking enzyme cleavage and a hybridization chain reaction (HCR) for dual-signal amplification. A hairpin aptamer probe (HAP) containing an aptamer was designed for the assay. The specific binding between the aptamer and PTK7, present on the exosome surface, causes a conformational change in the HAP. This facilitates hybridization between the HAP and the linker DNA, which subsequently triggers cyclic cleavage of the nicking endonuclease towards the linker DNA. Therefore, exosome detection is transformed into DNA detection. By combining this approach with HCR signal amplification, we achieved high-sensitivity electrochemical detection of CCRF-CEM exosomes, down to 1.1 × 104 particles/mL. Importantly, this assay effectively detected tumor exosomes in complex biological fluids, demonstrating the potential for clinical diagnosis.
      Citation: Chemosensors
      PubDate: 2023-07-23
      DOI: 10.3390/chemosensors11070415
      Issue No: Vol. 11, No. 7 (2023)
  • Chemosensors, Vol. 11, Pages 416: Electrochemical Multiplexed N-Terminal
           Natriuretic Peptide and Cortisol Detection in Human Artificial Saliva:
           Heart Failure Biomedical Application

    • Authors: El Kahina Ghedir, Abdoullatif Baraket, Messaoud Benounis, Nadia Zine, Abdelhamid Errachid
      First page: 416
      Abstract: The early detection at low concentration, by non-invasive methods, of cardiac biomarkers in physiological fluids has attracted the interest of researchers over the last decade. This enables early diagnosis and prediction of the first signs of heart failure (HF). In this respect, the analysis of human saliva remains the most suitable medium for this non-invasive approach, as it contains a highly interesting biological matrix for general health and disease monitoring. In this work, we developed a highly sensitive multiplexed immunosensor for direct simultaneous detection of both N-terminal Natriuretic Peptide (NT-proBNP) and Cortisol in human artificial saliva (AS). The developed biosensor platform based on silicon nitride substrate was composed from four gold working microelectrodes (WEs) and an integrated counter and reference microelectrode. Gold WEs were biofunctionalized through carboxyl diazonium (4-APA) to immobilize both anti-NT-proBNP and anti-Cortisol antibodies for simultaneous detection. The electroaddressing of the 4-APA onto the gold WE surfaces was realized with cyclic voltammetry (CV), while the interaction between antibodies and antigens in PBS was monitored using electrochemical impedance spectroscopy (EIS). The antigen detection in human AS was realized with EIS combined with the standard addition method. The immunosensor was highly sensitive and selective toward the corresponding biomarkers in both PBS and artificial human saliva as well as in the presence of other potential interfering biomarkers such as tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10). The limit of detection (LOD) was at 0.2 pg/mL for NT-proBNP within the range of 0.03 to 0.9 pg/mL, while the LOD for Cortisol was 0.06 ng/mL within the range of 0.02 to 0.6 ng/mL for Cortisol in artificial saliva. The developed immunosensor is very promising for significant detection in physiological media, and time reducing as it allows the simultaneous detection of various biomarkers.
      Citation: Chemosensors
      PubDate: 2023-07-24
      DOI: 10.3390/chemosensors11070416
      Issue No: Vol. 11, No. 7 (2023)
  • Chemosensors, Vol. 11, Pages 417: Recent Advances in Design Strategies and
           Imaging Applications of Fluorescent Probes for ATP

    • Authors: Qing-Song Gu, Ting Li, Ting Liu, Guo Yu, Guo-Jiang Mao, Fen Xu, Chun-Yan Li
      First page: 417
      Abstract: Adenosine 5′-triphosphate (ATP) is the energy currency in cells. It is involved in numerous cellular life activities and exhibits a close association with the development of certain diseases. Thus, the precise detection of ATP within cells holds immense significance in understanding cell biological events and related disease development. Fluorescent probes have obvious advantages in imaging ATP in cells and in vivo due to their high sensitivity, good selectivity, real-time imaging, and good biocompatibility. Thus far, an extensive array of fluorescent probes targeting ATP has been formulated to enable the visualization of ATP within cells and in vivo. This review summarizes the recent advances in ATP fluorescent probes according to different design strategies, mainly including those based on organic small molecules, metal complexes, and water-soluble conjugated polymers. In addition, the practical applications of ATP fluorescent probes in the imaging of target organelles, cell biological events, and disease markers are highlighted. Finally, the challenges and future trends of ATP detection based on fluorescent probes are discussed.
      Citation: Chemosensors
      PubDate: 2023-07-24
      DOI: 10.3390/chemosensors11070417
      Issue No: Vol. 11, No. 7 (2023)
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