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  
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 30)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 8)
ACS Catalysis     Hybrid Journal   (Followers: 52)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 23)
ACS Combinatorial Science     Hybrid Journal   (Followers: 21)
ACS Environmental Au     Open Access   (Followers: 8)
ACS Macro Letters     Hybrid Journal   (Followers: 25)
ACS Materials Letters     Open Access   (Followers: 2)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 42)
ACS Nano     Hybrid Journal   (Followers: 181)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 30)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 8)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 7)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 7)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 71)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 3)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 1)
Advanced Science Focus     Free   (Followers: 6)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 2)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 109)
Advances in Chemical Science     Open Access   (Followers: 51)
Advances in Chemistry     Open Access   (Followers: 34)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Environmental Chemistry     Open Access   (Followers: 10)
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: 33)
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: 51)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Sample Preparation     Open Access   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 16)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Chemical Education     Open Access   (Followers: 5)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Aggregate     Open Access  
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: 4)
Alchemy : Jurnal Penelitian Kimia     Open Access  
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 43)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 19)
American Journal of Chemistry     Open Access   (Followers: 37)
American Journal of Plant Physiology     Open Access   (Followers: 8)
Analyst     Hybrid Journal   (Followers: 35)
Analytical Science Advances     Open Access   (Followers: 1)
Angewandte Chemie     Hybrid Journal   (Followers: 150)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 228)
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: 12)
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: 24)
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  
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: 7)
Autophagy     Hybrid Journal   (Followers: 7)
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 200)
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: 23)
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: 90)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 66)
Bioorganic Chemistry     Hybrid Journal   (Followers: 9)
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: 24)
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: 12)
Canadian Mineralogist     Full-text available via subscription   (Followers: 5)
Carbohydrate Polymer Technologies and Applications     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Carbohydrate Research     Hybrid Journal   (Followers: 24)
Carbon     Hybrid Journal   (Followers: 65)
Carbon Capture Science & Technology     Open Access  
Carbon Trends     Open Access   (Followers: 3)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 9)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 11)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
Chem     Hybrid Journal  
Chem Catalysis     Hybrid Journal  
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: 81)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 26)
Chemical Physics Impact     Full-text available via subscription  
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 168)
Chemical Science     Open Access   (Followers: 39)
Chemical Science International Journal     Open Access  
Chemical Technology     Open Access   (Followers: 75)
Chemical Thermodynamics and Thermal Analysis     Open Access   (Followers: 2)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 54)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 22)
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: 121)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 19)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 18)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 6)
Chemistry Education Review     Open Access   (Followers: 1)
Chemistry in Education     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 161)
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  
Chemistry–Methods     Open Access   (Followers: 1)
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: 22)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 4)
Ciencia     Open Access  
Clay Minerals     Hybrid Journal   (Followers: 8)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 6)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
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: 6)
Comptes Rendus : Chimie     Open Access  
Comptes Rendus : Physique     Open Access   (Followers: 2)

        1 2 3 4 | Last

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Journal Prestige (SJR): 0.829
Citation Impact (citeScore): 4
Number of Followers: 3  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2079-6374
Published by MDPI Homepage  [84 journals]
  • Biosensors, Vol. 12, Pages 258: The Structure of Bilirubin Oxidase from
           Bacillus pumilus Reveals a Unique Disulfide Bond for Site-Specific Direct
           Electron Transfer

    • Authors: Shalev Gihaz, Nidaa Shrara Herzallh, Yifat Cohen, Oren Bachar, Ayelet Fishman, Omer Yehezkeli
      First page: 258
      Abstract: Efficient oxygen-reducing biocatalysts are essential for the development of biofuel cells or photo-bioelectrochemical applications. Bilirubin oxidase (BOD) is a promising biocatalyst for oxygen reduction processes at neutral pH and low overpotentials. BOD has been extensively investigated over the last few decades. While the enzyme’s internal electron transfer process and methods to establish electrical communication with electrodes have been elucidated, a crystal structure of BOD from bacterial origin has never been determined. Here we present the first crystal structure of BOD from Bacillus pumilus (BpBOD) at 3.5 Å resolution. Overall, BpBOD shows high homology with the fungal enzymes; however, it holds a unique surface-exposed disulfide bond between Cys229 and Cys322 residues. We present methodologies to orient the T1 site towards the electrode by coupling the reduced disulfide bond with maleimide moiety on the electrodes. The developed configurations were further investigated and revealed improved direct electron transfer rates with the electrodes. The work presented here may contribute to the construction of rationally designed bioanodes or biocathode configurations that are based on redox-active enzymes.
      Citation: Biosensors
      PubDate: 2022-04-19
      DOI: 10.3390/bios12050258
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 259: A Portable Biosensor Based on Au
           Nanoflower Interface Combined with Electrochemical Immunochromatography
           for POC Detection of Prostate-Specific Antigen

    • Authors: Yanzhi Dou, Zhenhua Li, Jing Su, Shiping Song
      First page: 259
      Abstract: Serum prostate-specific antigen (PSA) is a widely used for the detection of prostate cancer and is considered the most reliable biomarker. However, the currently reported detection methods cannot achieve rapid monitoring. Here, we report a novel electrochemical immunochromatography (EIC) system for clinically accurate PSA detection. First, we constructed a carbon interface modified with gold nanoflowers (Au NFs) based on screen-printed carbon electrodes (SPCE), which acted as nanostructures with larger specific surface area that increased the number of PSA capture antibodies and can further improve detection signal-to-noise (S/N) ratio. Then, we fabricated detection chips by combining the SPCE/Au NFs with EIC. Under optimized conditions, the proposed biosensor exhibits high accuracy, taking only 15 minutes to complete detection. By measuring the levels of PSA in clinical blood samples, the biosensor can successfully discriminate clinically diagnosed prostate cancer patients from healthy controls.
      Citation: Biosensors
      PubDate: 2022-04-19
      DOI: 10.3390/bios12050259
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 260: Prussian Blue Nanoparticle Supported MoS2
           Nanocomposites as a Peroxidase-Like Nanozyme for Colorimetric Sensing of

    • Authors: Zhiqiang Zhu, Lingbo Gong, Xiangyang Miao, Chaoyang Chen, Shao Su
      First page: 260
      Abstract: An abnormal level of dopamine (DA) is usually related to neurological disorders, including Parkinson’s disease. Herein, cubic-shaped, Prussian blue nanoparticle-supported MoS2 nanocomposites (MoS2-CPBNPs) were prepared as peroxidase-like nanozymes for the label-free, colorimetric detection of DA. As expected, the as-prepared MoS2-CPBNPs nanozymes have outstanding peroxidase-like mimicking activity, which can catalyze 3,3′,5,5′-Tetramethylbenzidine (TMB) to generate blue, oxidized TMB in the presence of hydrogen peroxide (H2O2). DA can inhibit the oxidation of TMB, which causes blue solutions to fade and become colorless. According to this phenomenon, the developed colorimetric sensor can qualitatively and quantitatively analyze DA ranging from 0 to 300 μM with a detection limit of 0.09 μM. In addition, the high recovery and low relative standard deviation for practical DA determination suggested that this colorimetric sensor has potential for application in biological biosensing and diagnostic fields.
      Citation: Biosensors
      PubDate: 2022-04-20
      DOI: 10.3390/bios12050260
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 261: Passivated Impedimetric Sensors for
           Immobilization-Free Pathogen Detection by Isothermal Amplification and
           Melt Curve Analysis

    • Authors: Matthias Steinmaßl, Jamila Boudaden, Gueven Edgue, Lena Julie Freund, Simon Meyer, Noa Mordehay, Melissa Soto, Hanns-Erik Endres, Jost Muth, Dirk Prüfer, Wilfried Lerch, Christoph Kutter
      First page: 261
      Abstract: The ongoing SARS-CoV-2 pandemic demonstrates that the capacity of centralized clinical diagnosis laboratories represents a significant limiting factor in the global fight against the newly emerged virus. Scaling up these capacities also requires simple and robust methods for virus diagnosis to be easily driven by untrained personnel in a point-of-care (POC) environment. The use of impedance sensors reduces the complexity and costs of diagnostic instruments and increases automation of diagnosis processes. We present an impedance point-of-care system (IMP-POCS) that uses interdigitated electrodes surrounded by an integrated heating meander to monitor loop-mediated isothermal amplification (LAMP) and melt curve analysis (MCA) consecutively in a short time. MCA permits distinguishing false- from true-positive results and significantly raises the validity of pathogen detection. Conclusively, the herein-developed miniaturized total analysis system (µTAS) represents a powerful and promising tool for providing reliable, low-cost alternatives to standard clinical diagnosis.
      Citation: Biosensors
      PubDate: 2022-04-20
      DOI: 10.3390/bios12050261
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 262: Chaperone Copolymer Assisted
           G-Quadruplex-Based Signal Amplification Assay for Highly Sensitive
           Detection of VEGF

    • Authors: Jialun Han, Chenxin Fang, Ping Ouyang, Yang Qing, Yuxing Yang, Haiyu Li, Zhencui Wang, Jie Du
      First page: 262
      Abstract: Vascular endothelial growth factor (VEGF) is a critical biomarker in the angiogenesis of several cancers. Nowadays, novel approaches to rapid, sensitive, and reliable VEGF detection are urgently required for early cancer diagnosis. Cationic comb-type copolymer, poly(L-lysine)-graft-dextran (PLL-g-Dex) accelerates DNA hybridization and chain exchange reaction while stabilizing the DNA assembly structure. In this work, we examined the chaperone activity of PLL-g-Dex to assist G-quadruplex-based fluorescent DNA biosensors for sensitive detection of VEGF. This convenient and effective strategy is based on chitosan hydrogel, c-myc, Thioflavin T (ThT), VEGF aptamer, and its partially complementary strand. The results show that chaperone copolymer PLL-g-Dex significantly promotes the accumulation of G-quadruplex and assembles into G-wires, allowing an effective signal amplification. Using this method, the detection limit of VEGF was as low as 23 pM, better than many previous works on aptamer-based VEGF detection. This chaperone copolymer-assisted signal amplification strategy has potential applications in the highly sensitive detection of target proteins, even including viruses.
      Citation: Biosensors
      PubDate: 2022-04-20
      DOI: 10.3390/bios12050262
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 263: Recent Progress in Non-Enzymatic
           Electroanalytical Detection of Pesticides Based on the Use of Functional
           Nanomaterials as Electrode Modifiers

    • Authors: Tanja Vrabelj, Matjaž Finšgar
      First page: 263
      Abstract: This review presents recent advances in the non-enzymatic electrochemical detection and quantification of pesticides, focusing on the use of nanomaterial-based electrode modifiers and their corresponding analytical response. The use of bare glassy carbon electrodes, carbon paste electrodes, screen-printed electrodes, and other electrodes in this research area is presented. The sensors were modified with single nanomaterials, a binary composite, or triple and multiple nanocomposites applied to the electrodes’ surfaces using various application techniques. Regardless of the type of electrode used and the class of pesticides analysed, carbon-based nanomaterials, metal, and metal oxide nanoparticles are investigated mainly for electrochemical analysis because they have a high surface-to-volume ratio and, thus, a large effective area, high conductivity, and (electro)-chemical stability. This work demonstrates the progress made in recent years in the non-enzymatic electrochemical analysis of pesticides. The need for simultaneous detection of multiple pesticides with high sensitivity, low limit of detection, high precision, and high accuracy remains a challenge in analytical chemistry.
      Citation: Biosensors
      PubDate: 2022-04-20
      DOI: 10.3390/bios12050263
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 264: Design and Optimization of All-Dielectric
           Fluorescence Enhancing Metasurfaces: Towards Advanced Metasurface-Assisted

    • Authors: Hiba Alhalaby, Maria Principe, Haitham Zaraket, Patrizio Vaiano, Anna Aliberti, Giuseppe Quero, Alessio Crescitelli, Valentina Di Meo, Emanuela Esposito, Marco Consales, Andrea Cusano
      First page: 264
      Abstract: The need for miniaturized biological sensors which can be easily integrated into medical needles and catheters for in vivo liquid biopsies with ever-increasing performances has stimulated the interest of researchers in lab-on-fiber (LOF) technology. LOF devices arise from the integration of functional materials at the nanoscale on the tip of optical fibers, thus endowing a simple optical fiber with advanced functionalities and enabling the realization of high-performance LOF biological sensors. Consequently, in 2017, we demonstrated the first optical fiber meta-tip (OFMT), consisting of the integration of plasmonic metasurfaces (MSs) on the optical fiber end-face which represented a major breakthrough along the LOF technology roadmap. Successively, we demonstrated that label-free biological sensors based on the plasmonic OFMT are able to largely overwhelm the performance of a standard plasmonic LOF sensor, in view of the extraordinary light manipulation capabilities of plasmonic array exploiting phase gradients. To further improve the overall sensitivity, a labelled sensing strategy is here suggested. To this end, we envision the possibility to realize a novel class of labelled LOF optrodes based on OFMT, where an all-dielectric MS, designed to enhance the fluorescence emission by a labelled target molecule, is integrated on the end-face of a multimode fiber (MMF). We present a numerical environment to compute the fluorescence enhancement factor collected by the MMF, when on its tip a Silicon MS is laid, consisting of an array of cylindrical nanoantennas, or of dimers or trimers of cylindrical nanoantennas. According to the numerical results, a suitable design of the dielectric MS allows for a fluorescence enhancement up to three orders of magnitudes. Moreover, a feasibility study is carried out to verify the possibility to fabricate the designed MSs on the termination of multimode optical fibers using electron beam lithography followed by reactive ion etching. Finally, we analyze a real application scenario in the field of biosensing and evaluate the degradation in the fluorescence enhancement performances, taking into account the experimental conditions. The present work, thus, provides the main guidelines for the design and development of advanced LOF devices based on the fluorescence enhancement for labelled biosensing applications.
      Citation: Biosensors
      PubDate: 2022-04-21
      DOI: 10.3390/bios12050264
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 265: A Label-Free Electrochemical Impedimetric
           Immunosensor with Biotinylated-Antibody for SARS-CoV-2 Nucleoprotein
           Detection in Saliva

    • Authors: Ching-Chou Wu, Yu-Huan Chiang, Hsin-Yu Chiang
      First page: 265
      Abstract: The timely detecting of SARS-CoV-2 coronavirus antigens for infection validation is an urgent request for COVID-19 pandemic control. This study constructed label-free electrochemical impedance spectroscopy (EIS)-based immunosensors based on gold nanostructured screen-printed carbon electrodes (AuNS/SPCEs) to detect the SARS-CoV-2 nucleocapsid protein (N-protein) in saliva. Using short-chain 3-mercaptopropionic acid (MPA) as a linker to covalently bond streptavidin (SA) and bovine serum albumin (BSA) for controlling the oriented immobilization of the biotinylated anti-N-protein antibody (BioAb) can offer a greater sensitivity, a lower limit of detection (LOD), and better reproducibility of immunosensors (defined as BioAb/SA-BSA/MPA/AuNS/SPCEs) than the antibody randomly immobilized immunosensors and the long-chain 11-mercaptoundecanoic acid (MUA)-modified immunosensors (BioAb/SA-BSA/MUA/AuNS/SPCEs). The BioAb/SA-BSA/MPA/AuNS/SPCE-based immunosensors presented good linearity from 0.01 ng/mL to 100 ng/mL and a low LOD of 6 pg/mL in a phosphate buffer solution (PBS) and PBS-diluted saliva. Moreover, the immunosensor exhibited little cross-activity with other viral antigens such as MERS-CoV N-protein, influenza A N-protein, influenza B N-protein, and SARS-CoV-2 spike protein, indicating the high specificity of the immunosensors. The disposable label-free EIS-based immunosensors have promising potential in facilitating the rapid and sensitive tests of saliva-based COVID-19 diagnostics.
      Citation: Biosensors
      PubDate: 2022-04-22
      DOI: 10.3390/bios12050265
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 266: Paper-Based Substrate for a
           Surface-Enhanced Raman Spectroscopy Biosensing Platform—A
           Silver/Chitosan Nanocomposite Approach

    • Authors: Yuri Kang, Hyeok Jung Kim, Sung Hoon Lee, Hyeran Noh
      First page: 266
      Abstract: Paper is a popular platform material in all areas of sensor research due to its porosity, large surface area, and biodegradability, to name but a few. Many paper-based nanocomposites have been reported in the last decade as novel substrates for surface-enhanced Raman spectroscopy (SERS). However, there are still limiting factors, like the low density of hot spots or loss of wettability. Herein, we designed a process to fabricate a silver–chitosan nanocomposite layer on paper celluloses by a layer-by-layer method and pH-triggered chitosan assembly. Under microscopic observation, the resulting material showed a nanoporous structure, and silver nanoparticles were anchored evenly over the nanocomposite layer. In SERS measurement, the detection limit of 4-aminothiophenol was 5.13 ppb. Furthermore, its mechanical property and a strategy toward further biosensing approaches were investigated.
      Citation: Biosensors
      PubDate: 2022-04-22
      DOI: 10.3390/bios12050266
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 267: Plasmonic Azobenzene Chemoreporter for
           Surface-Enhanced Raman Scattering Detection of Biothiols

    • Authors: Mariacristina Turino, Ramon A. Alvarez-Puebla, Luca Guerrini
      First page: 267
      Abstract: Low molecular weight thiols (biothiols) are highly active compounds extensively involved in human physiology. Their abnormal levels have been associated with multiple diseases. In recent years, major efforts have been devoted to developing new nanosensing methods for the low cost and fast quantification of this class of analytes in minimally pre-treated samples. Herein, we present a novel strategy for engineering a highly efficient surface-enhanced Raman scattering (SERS) spectroscopy platform for the dynamic sensing of biothiols. Colloidally stable silver nanoparticles clusters equipped with a specifically designed azobenzene derivative (AzoProbe) were generated as highly SERS active substrates. In the presence of small biothiols (e.g., glutathione, GSH), breakage of the AzoProbe diazo bond causes drastic spectral changes that can be quantitatively correlated with the biothiol content with a limit of detection of ca. 5 nM for GSH. An identical response was observed for other low molecular weight thiols, while larger macromolecules with free thiol groups (e.g., bovine serum albumin) do not produce distinguishable spectral alterations. This indicates the suitability of the SERS sensing platform for the selective quantification of small biothiols.
      Citation: Biosensors
      PubDate: 2022-04-22
      DOI: 10.3390/bios12050267
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 268: Cas14a1-Mediated Nucleic Acid Diagnostics
           for Spinal Muscular Atrophy

    • Authors: Zhiqing Hu, Miaomiao Chen, Chunhua Zhang, Zhuo Li, Mai Feng, Lingqian Wu, Miaojin Zhou, Desheng Liang
      First page: 268
      Abstract: Spinal muscular atrophy (SMA) is the main genetic cause of infant death. In >95% of the patients with SMA, the disease is caused by a single hotspot pathogenic mutation: homozygous deletion of exon 7 of the survival motor neuron 1 gene (SMN1). Recently, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein (Cas)-based assays have been developed as a promising new option for nucleic acid detection. Here, we developed a Cas14a1-based assay combined with asymmetric PCR to establish a method for detection of the homozygous deletion of SMN1 exon 7 in SMA patients. The minimum detectable concentration of genomic DNA reached 5.26 aM with our method, and the assessment of its detection performance in 33 clinical samples revealed that the results were completely consistent with those of multiple ligation-dependent probe amplification and quantitative PCR. Thus, our novel nucleic acid diagnostics combining CRISPR/Cas14a1 and asymmetric PCR not only provides specific and sensitive testing of the deletion of SMN1 exon 7, but also holds promise for an accurate detection platform of genetic diseases and pathogens in multiple sample types.
      Citation: Biosensors
      PubDate: 2022-04-23
      DOI: 10.3390/bios12050268
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 269: Properties and Applications of Graphene
           and Its Derivatives in Biosensors for Cancer Detection: A Comprehensive

    • Authors: Mehrab Pourmadadi, Homayoon Soleimani Dinani, Fatemeh Saeidi Tabar, Kajal Khassi, Sajjad Janfaza, Nishat Tasnim, Mina Hoorfar
      First page: 269
      Abstract: Cancer is one of the deadliest diseases worldwide, and there is a critical need for diagnostic platforms for applications in early cancer detection. The diagnosis of cancer can be made by identifying abnormal cell characteristics such as functional changes, a number of vital proteins in the body, abnormal genetic mutations and structural changes, and so on. Identifying biomarker candidates such as DNA, RNA, mRNA, aptamers, metabolomic biomolecules, enzymes, and proteins is one of the most important challenges. In order to eliminate such challenges, emerging biomarkers can be identified by designing a suitable biosensor. One of the most powerful technologies in development is biosensor technology based on nanostructures. Recently, graphene and its derivatives have been used for diverse diagnostic and therapeutic approaches. Graphene-based biosensors have exhibited significant performance with excellent sensitivity, selectivity, stability, and a wide detection range. In this review, the principle of technology, advances, and challenges in graphene-based biosensors such as field-effect transistors (FET), fluorescence sensors, SPR biosensors, and electrochemical biosensors to detect different cancer cells is systematically discussed. Additionally, we provide an outlook on the properties, applications, and challenges of graphene and its derivatives, such as Graphene Oxide (GO), Reduced Graphene Oxide (RGO), and Graphene Quantum Dots (GQDs), in early cancer detection by nanobiosensors.
      Citation: Biosensors
      PubDate: 2022-04-24
      DOI: 10.3390/bios12050269
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 270: Effective Enrichment of Plasmonic Hotspots
           for SERS by Spinning Droplets on a Slippery Concave Dome Array

    • Authors: Jialin Wu, Jianpeng Cai, Yuan Fan, Ying Zhang, Hui Fang, Sheng Yan
      First page: 270
      Abstract: Surface-enhanced Raman scattering (SERS) detection requires dense hotspots and a uniform distribution of analytes to obtain a stable signal with good repeatability. However, due to the coffee-ring effect on the hydrophilic substrate, and the difficulty of droplet manipulation on the superhydrophobic substrate, few substrates can ensure that the analytes are evenly distributed. In this work, we develop a method that can efficiently enrich plasmonic hotspots for SERS measurement on the superhydrophobic concave dome array (SCDA). The SCDA is formed by spraying hydrophobic silica nanoparticles onto a polydimethylsiloxane (PDMS) slab with a concave dome array that can physically confine the droplets and overcome the coffee-ring effect. During droplet evaporation, the SCDA is driven by a horizontal spinner, and the droplets spin on the SCDA, enabling the plasmonic nanoparticles to become closely packed to form the SERS hotspots. The limit of detection (LOD) of the dynamic-enriched SERS hotspots for crystal violet and methylene blue can reach up to 10−11 M. Moreover, the LOD for melamine in milk can reach 5 × 10−7 M, which is lower than the safety threshold defined by the Food and Drug Administration (FDA). Based on this SERS platform, an effective, low-cost, and simple method for SERS detection in analytical chemistry and food safety is highly expected.
      Citation: Biosensors
      PubDate: 2022-04-24
      DOI: 10.3390/bios12050270
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 271: Genetically Encoded Ratiometric pH Sensors
           for the Measurement of Intra- and Extracellular pH and Internalization

    • Authors: Lennard Karsten, Lukas Goett-Zink, Julian Schmitz, Raimund Hoffrogge, Alexander Grünberger, Tilman Kottke, Kristian M. Müller
      First page: 271
      Abstract: pH-sensitive fluorescent proteins as genetically encoded pH sensors are promising tools for monitoring intra- and extracellular pH. However, there is a lack of ratiometric pH sensors, which offer a good dynamic range and can be purified and applied extracellularly to investigate uptake. In our study, the bright fluorescent protein CoGFP_V0 was C-terminally fused to the ligand epidermal growth factor (EGF) and retained its dual-excitation and dual-emission properties as a purified protein. The tandem fluorescent variants EGF-CoGFP-mTagBFP2 (pK′ = 6.6) and EGF-CoGFP-mCRISPRed (pK′ = 6.1) revealed high dynamic ranges between pH 4.0 and 7.5. Using live-cell fluorescence microscopy, both pH sensor molecules permitted the conversion of fluorescence intensity ratios to detailed intracellular pH maps, which revealed pH gradients within endocytic vesicles. Additionally, extracellular binding of the pH sensors to cells expressing the EGF receptor (EGFR) enabled the tracking of pH shifts inside cultivation chambers of a microfluidic device. Furthermore, the dual-emission properties of EGF-CoGFP-mCRISPRed upon 488 nm excitation make this pH sensor a valuable tool for ratiometric flow cytometry. This high-throughput method allowed for the determination of internalization rates, which represents a promising kinetic parameter for the in vitro characterization of protein–drug conjugates in cancer therapy.
      Citation: Biosensors
      PubDate: 2022-04-25
      DOI: 10.3390/bios12050271
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 272: Rapid Detection of Anti-SARS-CoV-2
           Antibodies with a Screen-Printed Electrode Modified with a Spike
           Glycoprotein Epitope

    • Authors: Wilson A. Ameku, David W. Provance, Carlos M. Morel, Salvatore G. De-Simone
      First page: 272
      Abstract: Background: The coronavirus disease of 2019 (COVID-19) is caused by an infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was recognized in late 2019 and has since spread worldwide, leading to a pandemic with unprecedented health and financial consequences. There remains an enormous demand for new diagnostic methods that can deliver fast, low-cost, and easy-to-use confirmation of a SARS-CoV-2 infection. We have developed an affordable electrochemical biosensor for the rapid detection of serological immunoglobulin G (IgG) antibody in sera against the spike protein. Materials and Methods: A previously identified linear B-cell epitope (EP) specific to the SARS-CoV-2 spike glycoprotein and recognized by IgG in patient sera was selected for the target molecule. After synthesis, the EP was immobilized onto the surface of the working electrode of a commercially available screen-printed electrode (SPE). The capture of SARS-CoV-2-specific IgGs allowed the formation of an immunocomplex that was measured by square-wave voltammetry from its generation of hydroquinone (HQ). Results: An evaluation of the performance of the EP-based biosensor presented a selectivity and specificity for COVID-19 of 93% and 100%, respectively. No cross-reaction was observed to antibodies against other diseases that included Chagas disease, Chikungunya, Leishmaniosis, and Dengue. Differentiation of infected and non-infected individuals was possible even at a high dilution factor that decreased the required sample volumes to a few microliters. Conclusion: The final device proved suitable for diagnosing COVID-19 by assaying actual serum samples, and the results displayed good agreement with the molecular biology diagnoses. The flexibility to conjugate other EPs to SPEs suggests that this technology could be rapidly adapted to diagnose new variants of SARS-CoV-2 or other pathogens.
      Citation: Biosensors
      PubDate: 2022-04-26
      DOI: 10.3390/bios12050272
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 273: Hydrophobic Wafer-Scale
           High-Reproducibility SERS Sensor Based on Silicon Nanorods Arrays
           Decorated with Au Nanoparticles for Pesticide Residue Detection

    • Authors: Fanhong Chen, Yupeng Zhao, Shaoxun Zhang, Shuhua Wei, Anjie Ming, Changhui Mao
      First page: 273
      Abstract: High sensitivity and reproducibility are highly desirable to a SERS sensor in diverse detection applications. Moreover, it is a great challenge to determine how to promote the target molecules to be more concentrated on the hotspots of the SERS substrate by engineering a surface with switching interfacial wettability. Along these lines, wafer-scale uniformly hydrophobic silicon nanorods arrays (SiNRs) decorated with Au nanoparticles were designed as the SERS substrate. Typically, the SERS substrate was fabricated by enforcing the polystyrene (PS) sphere self-assembly, as well as the plasma etching and the magnetron sputtering techniques. Consequently, the SERS substrate was treated by soaking within a n-dodecyl mercaptan (NDM) solution at different times in order to obtain adjustable wettabilities. By leveraging the electromagnetic enhancement resulted from the Au nanostructures and enrichment effect induced by the hydrophobicity, the SERS substrate is endowed with efficient SERS capabilities. During the detection of malachite green (MG), an ultralow relative standard deviation (RSD) 4.04–6.14% is achieved and the characteristic signal of 1172 cm−1 can be detected as low as 1 ng/mL. The proposed SiNRs’ structure presents outstanding SERS activity with sensitivity and reproducibility rendering thus an ideal candidate for potential application in analytical detection fields.
      Citation: Biosensors
      PubDate: 2022-04-26
      DOI: 10.3390/bios12050273
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 274: Detection of Unamplified E. coli O157 DNA
           Extracted from Large Food Samples Using a Gold Nanoparticle Colorimetric

    • Authors: Emma Dester, Kaily Kao, Evangelyn C. Alocilja
      First page: 274
      Abstract: Rapid detection of foodborne pathogens such as E. coli O157 is essential in reducing the prevalence of foodborne illness and subsequent complications. Due to their unique colorimetric properties, gold nanoparticles (GNPs) can be applied in biosensor development for affordability and accessibility. In this work, a GNP biosensor was designed for visual differentiation between target (E. coli O157:H7) and non-target DNA samples. Results of DNA extracted from pure cultures indicate high specificity and sensitivity to as little as 2.5 ng/µL E. coli O157 DNA. Further, the biosensor successfully identified DNA extracted from flour contaminated with E. coli O157, with no false positives for flour contaminated with non-target bacteria. After genomic extraction, this assay can be performed in as little as 30 min. In addition, food sample testing was successful at detecting approximately 103 CFU/mL of E. coli O157 magnetically extracted from flour after only a 4 h incubation step. As a proof of concept, these results demonstrate the capabilities of this GNP biosensor for low-cost and rapid foodborne pathogen detection.
      Citation: Biosensors
      PubDate: 2022-04-26
      DOI: 10.3390/bios12050274
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 275: DNA-Modified Liquid Crystal Droplets

    • Authors: Xiuxiu Yang, Xiao Liang, Rajib Nandi, Yi Tian, Yiyang Zhang, Yan Li, Jingsheng Zhou, Yuanchen Dong, Dongsheng Liu, Zhengwei Zhong, Zhongqiang Yang
      First page: 275
      Abstract: In this work, we have combined the advantages of sequence programmability of DNA nanotechnology and optical birefringence of liquid crystals (LCs). Herein, DNA amphiphiles were adsorbed onto LC droplets. A unique phenomenon of LC droplet aggregation was demonstrated, using DNA-modified LC droplets, through complementary DNA hybridization. Further functionalization of DNA-modified LC droplets with a desired DNA sequence was used to detect a wide range of chemicals and biomolecules, such as Hg2+, thrombin, and enzymes, through LC droplet aggregation and vice versa, which can be seen through the naked eye. These DNA-modified LC droplets can be printed onto a desired patterned surface with temperature-induced responsiveness and reversibility. Overall, our work is the first to report DNA-modified LC droplet, which provides a general detection platform based on the development of DNA aptamers. Additionally, this work inspires the exploration of surface information visualization combined with microcontact printing.
      Citation: Biosensors
      PubDate: 2022-04-27
      DOI: 10.3390/bios12050275
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 276: Signal-On Fluorescence Biosensor for
           Highly Sensitive Detection of miRNA-21 Based on DNAzyme Assisted
           Double-Hairpin Molecular Beacon

    • Authors: Chenxin Fang, Yuxing Yang, Shuhao Zou, Ping Ouyang, Yang Qing, Jialun Han, Haiyu Li, Zhencui Wang, Jie Du
      First page: 276
      Abstract: Although miRNAs exist in small quantities in the human body, they are closely related to the abnormal expression of genes in diseases such as tumors. Therefore, sensitive detection of miRNAs is very important for the prevention and treatment of various tumors and major diseases. The purpose of this study is to develop a label-free sensing strategy based on the co-action of double-hairpin molecular beacons and deoxyribozymes (DNAzymes) for highly sensitive detection of miRNA-21. The target miRNA-21 promotes the assembly of DNAzyme with a complete catalytic core region. At the presence of Mg2+, DNAzyme cuts a substrate into short chains, which open the double hairpin molecular beacon, and then form G-quadruplexs at both ends, specifically binding more ThT to generate a amplified fluorescent signal. The cut substrate will be replaced by the uncut ones in the next stage, increasing the concentration of reactants, and thus further improving the fluorescence intensity. This DNAzyme assisted double hairpin molecular beacon has a certain degree of discrimination for substances with single base mismatches, and the detection limit of miRNA-21 is 0.13 pM, lower than that of the many other analysis. Further, this detection has good selectivity and sensitivity in serum. Therefore, this strategy provides a simple, fast and low-cost platform for the sensitive detection of miRNA-21, having potential applications in early cancer diagnosis.
      Citation: Biosensors
      PubDate: 2022-04-27
      DOI: 10.3390/bios12050276
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 277: Minimization of MEDA Biochip-Size in
           Droplet Routing

    • Authors: Chiharu Shiro, Hiroki Nishikawa, Xiangbo Kong, Hiroyuki Tomiyama, Shigeru Yamashita
      First page: 277
      Abstract: With the increasing demand for fast, accurate, and reliable biological sensor systems, miniaturized systems have been aimed at droplet-based sensor systems and have been promising. A micro-electrode dot array (MEDA) biochip, which is one kind of the miniaturized systems for biochemical protocols such as dispensing, dilutions, mixing, and so on, has become widespread due to enabling dynamical control of the droplets in microfluidic manipulations. In MEDA biochips, the electrowetting-on-dielectric (EWOD) technique stands out since it can actuate droplets with nano/picoliter volumes. Microelectrode cells on MEDA actuate multiple droplets simultaneously to route locations for the purpose of the biochemical operations. Taking advantage of the feature, droplets are often routed in parallel to achieve high-throughput outcomes. Regarding parallel manipulation of multiple droplets, however, the droplets are known to be initially placed at a distant position to avoid undesirable mixing. The droplets thus result in traveling a long way for a manipulation, and the required biochip size for routing is also enlarged. This paper proposes a routing method for droplets to reduce the biochip size on a MEDA biochip with the allowance of splitting during routing operations. We mathematically derive the routing problem, and the experiments demonstrate that our proposal can significantly reduce the biochip size by 70.8% on average, compared to the state-of-the-art method.
      Citation: Biosensors
      PubDate: 2022-04-27
      DOI: 10.3390/bios12050277
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 278: Evaluation of the Interaction of
           Cinacalcet with Calf Thymus dsDNA: Use of Electrochemical,
           Spectrofluorimetric, and Molecular Docking Methods

    • Authors: Cem Erkmen, Didem Nur Unal, Sevinc Kurbanoglu, Gokcen Eren, Bengi Uslu
      First page: 278
      Abstract: The binding of drugs to DNA plays a critical role in new drug discovery and is important for designing better drugs. In this study, the interaction and binding mode of calf-thymus double-stranded deoxyribonucleic acid (ct-dsDNA) with cinacalcet (CIN) from the calcimimetic drug that mimics the action of calcium on tissues group were investigated. The interaction of CIN with ct-dsDNA was observed by the differential pulse voltammetry (DPV) technique by following the decrease in electrochemical oxidation signals to deoxyguanosine and adenosine. A competitive study was performed on an indicator, methylene blue, to investigate the interaction of the drug with ct-dsDNA by fluorescence spectroscopy. Interaction studies have shown that the binding mode for the interaction of CIN with ct-dsDNA could be groove-binding. According to the results obtained, the binding constant values were found to be 6.30 × 104 M−1 and 3.16 × 105 M−1, respectively, at 25 °C as obtained from the cyclic voltammetry (CV) and spectroscopic techniques. Possible molecular interactions of CIN with dsDNA were explored via molecular docking experiments. The docked structure indicated that CIN could fit well into the minor groove of the DNA through H-bonding and π-π stacking contact with CIN.
      Citation: Biosensors
      PubDate: 2022-04-27
      DOI: 10.3390/bios12050278
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 279: Scalable Functionalization of
           Polyaniline-Grafted rGO Field-Effect Transistors for a Highly Sensitive
           Enzymatic Acetylcholine Biosensor

    • Authors: Dongsung Park, Dongtak Lee, Hye Jin Kim, Dae Sung Yoon, Kyo Seon Hwang
      First page: 279
      Abstract: For decades, acetylcholine (Ach) has been considered a critical biomarker for several degenerative brain diseases, including Alzheimer’s, Parkinson’s disease, Huntington’s disease, and schizophrenia. Here, we propose a wafer-scale fabrication of polyaniline (PAni)-grafted graphene-based field-effect transistors (PGFET) and their biosensing applications for highly sensitive and reliable real-time monitoring of Ach in flow configuration. The grafted PAni provides suitable electrostatic binding sites for enzyme immobilization and enhances the pH sensitivity (2.68%/pH), compared to that of bare graphene-FET (1.81%/pH) for a pH range of 3–9 without any pH-hysteresis. We further evaluated the PGFET’s sensing performance for Ach detection with a limit of detection at the nanomolar level and significantly improved sensitivity (~103%) in the concentration range of 108 nM to 2 mM. Moreover, the PGFET exhibits excellent selectivity against various interferences, including glucose, ascorbic acid, and neurotransmitters dopamine and serotonin. Finally, we investigated the effects of an inhibitor (rivastigmine) on the AchE activity of the PGFET. From the results, we demonstrated that the PGFET has great potential as a real-time drug-screening platform by monitoring the inhibitory effects on enzymatic activity.
      Citation: Biosensors
      PubDate: 2022-04-27
      DOI: 10.3390/bios12050279
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 280: Compact Microfluidic Platform with LED
           Light-Actuated Valves for Enzyme-Linked Immunosorbent Assay Automation

    • Authors: Mireia Burdó-Masferrer, María Díaz-González, Ana Sanchis, Álvaro Calleja, María-Pilar Marco, César Fernández-Sánchez, Antonio Baldi
      First page: 280
      Abstract: Lab-on-a-chip devices incorporating valves and pumps can perform complex assays involving multiple reagents. However, the instruments used to drive these chips are complex and bulky. In this article, a new wax valve design that uses light from a light emitting diode (LED) for both opening and closing is reported. The valves and a pumping chamber are integrated in lab-on-a-foil chips that can be fabricated at low cost using rapid prototyping techniques. A chip for the implementation of enzyme-linked immunosorbent assays (ELISA) is designed. A porous nitrocellulose material is used for the immobilization of capture antibodies in the microchannel. A compact generic instrument with an array of 64 LEDs, a linear actuator to drive the pumping chamber, and absorbance detection for a colorimetric readout of the assay is also presented. Characterization of all the components and functionalities of the platform and the designed chip demonstrate their potential for assay automation.
      Citation: Biosensors
      PubDate: 2022-04-27
      DOI: 10.3390/bios12050280
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 281: Rapid Capturing and Chemiluminescent
           Sensing of Programmed Death Ligand-1 Expressing Extracellular Vesicles

    • Authors: Adeel Khan, Kaili Di, Haroon Khan, Nongyue He, Zhiyang Li
      First page: 281
      Abstract: Cancer specific extracellular vesicles (EVs) are of significant clinical relevance, for instance programmed death ligand-1 (PD-L1) expressing EVs (PD-L1@EVs) have been shown to be ideal biomarker for non-invasive diagnosis of cancer and can predate the response of cancer patients to anti-PD-1/PD-L-1 immunotherapy. The development of sensitive and straightforward methods for detecting PD-L1@EVs can be a vital tool for non-invasive diagnosis of cancer. Most of the contemporary methods for EVs detection have limitations such as involvement of long and EV’s loss prone isolation methods prior to detection or they have employed expensive antibodies and instruments to accomplish detection. Therefore, we designed an ultracentrifugation-free and antibody-free sensing assay for PD-L1@EV by integrating Titanium oxide (TiO2) coated magnetic beads (Fe3O4@TiO2) rapid capturing of EVs from undiluted serum with aptamers specificity and chemiluminescence (CL) sensitivity. To accomplish this we used Fe3O4@TiO2 beads to rapidly capture EVs from the undiluted patient serum and added biotin labelled PD-L1 aptamer to specifically recognize PD-L1@EVs. Later, added streptavidin-modified Alkaline phosphates (ALP) taking advantage of biotin-streptavidin strong binding. Addition of CDP-star, a chemiluminescent substrate of ALP, initiates the chemiluminiscense that was recorded using spectrophotometer. The sensing assay showed high sensitivity with limit of detection (LOD) as low as 2.584×105 EVs/mL and a wider linear correlation of CL intensity (a.u.) with the concentration of PD-L1@EVs from 105 to 108 EVs/mL. To examine the clinical utility of sensing assay we used undiluted serum samples from lung cancer patients and healthy individuals and successfully discern between healthy individuals and lung cancer patients. We are optimistic that the sensing assay can ameliorate our ability to be able to diagnose lung cancer non-invasively and can be helpful to predate the patient’s response to anti-PD-1/PD-L1 immunotherapy.
      Citation: Biosensors
      PubDate: 2022-04-28
      DOI: 10.3390/bios12050281
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 282: Combined Experimental and Theoretical
           Investigation on Formation of Size-Controlled Silver Nanoclusters under
           Gas Phase

    • Authors: Chuhang Zhang
      First page: 282
      Abstract: Metallic nanoclusters (NCs) have been predicted to achieve the best Surface-Enhanced Raman Scattering (SERS) due to the controllable amount of atoms and structures in NCs. The Local Surface Plasmon Resonance (LSPR) effect on silver metal NCs (Agn) enables it to be a promising candidate for manipulating the LSPR peak by controlling the size of NCs, which in turn demands a full understanding of the formation mechanism of Agn. Here, we apply an extended Smoluchowski rate equation coupled with a fragmentation scheme to investigate the growth of size-selected silver NCs generated via a modulated pulsed power magnetron sputtering (MPP-MSP). A temperature-dependent fragmentation coefficient D is proposed and integrated into the rate equations. The consistency between the computational and experimental results shows that in relative low peak power (Pp≤800 W), the recombination of cation and anion species are the dominant mechanism for NC growth. However, in the higher Pp region (≥800 W), the fragmentation mechanism becomes more impactful, leading to the formation of smaller NCs. The scanning electron microscopy observation shows the Ag36 is successfully soft-landed and immobilized on a strontium titanate crystal, which facilitates the application of the Agn/STO to the SERS research.
      Citation: Biosensors
      PubDate: 2022-04-28
      DOI: 10.3390/bios12050282
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 283: Intein-Mediated Protein Engineering for
           Cell-Based Biosensors

    • Authors: Chungwon Kang, Keshab Lal Shrestha, San Kwon, Seungil Park, Jinsik Kim, Youngeun Kwon
      First page: 283
      Abstract: Cell-based sensors provide a flexible platform for screening biologically active targets and for monitoring their interactions in live cells. Their applicability extends across a vast array of biological research and clinical applications. Particularly, cell-based sensors are becoming a potent tool in drug discovery and cell-signaling studies by allowing function-based screening of targets in biologically relevant environments and enabling the in vivo visualization of cellular signals in real-time with an outstanding spatiotemporal resolution. In this review, we aim to provide a clear view of current cell-based sensor technologies, their limitations, and how the recent improvements were using intein-mediated protein engineering. We first discuss the characteristics of cell-based sensors and present several representative examples with a focus on their design strategies, which differentiate cell-based sensors from in vitro analytical biosensors. We then describe the application of intein-mediated protein engineering technology for cell-based sensor fabrication. Finally, we explain the characteristics of intein-mediated reactions and present examples of how the intein-mediated reactions are used to improve existing methods and develop new approaches in sensor cell fabrication to address the limitations of current technologies.
      Citation: Biosensors
      PubDate: 2022-04-28
      DOI: 10.3390/bios12050283
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 284: An Improved Automated High-Throughput
           Efficient Microplate Reader for Rapid Colorimetric Biosensing

    • Authors: Jinhu Yang, Yue Wu, Hao Wang, Wenjian Yang, Zhongyuan Xu, Dong Liu, Hui-Jiuan Chen, Diming Zhang
      First page: 284
      Abstract: A high-throughput instrument to measure the full spectral properties of biochemical agents is necessary for fast screening in fields such as medical tests, environmental monitoring, and food analysis. However, this need has currently not been fully met by the commercial microplate reader (CMR). In this study, we have developed an automated high-throughput efficient microplate reader (AHTEMR) platform by combining a spectrometer and high-precision ball screw two-dimensional motion slide together, for high-throughput and full-spectrum-required biochemical assays. A two-dimensional slide working on a ball screw was driven by a stepper motor with a custom-designed master control circuit and used as a motion system of the AHTEMR platform to achieve precise positioning and fast movement of the microplate during measurements. A compact spectrometer was coupled with an in-house designed optical pathway system and used to achieve rapid capture of the full spectral properties of biochemical agents. In a performance test, the AHTEMR platform successfully measured the full spectral absorbance of bovine serum albumin (BSA) and glucose solution in multiple wells of the microplate within several minutes and presented the real-time full spectral absorbance of BSA and glucose solution. Compared with the CMR, the AHTEMR is 79 times faster in full-spectrum measurements and 2.38 times more sensitive at the optimal wavelength of 562 nm. The rapid measurement also demonstrated the great capacity of the AHTEMR platform for screening out the best colorimetric wavelengths for tests of BSA and glucose development, which will provide a promising approach to achieving high-throughput and full-spectrum-required biochemical assays.
      Citation: Biosensors
      PubDate: 2022-04-28
      DOI: 10.3390/bios12050284
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 285: Field and Remote Sensors for Environmental
           Health and Food Safety Diagnostics: An Open Challenge

    • Authors: Gerardo Grasso, Daniela Zane, Roberto Dragone
      First page: 285
      Abstract: Major foodborne disease outbreaks have clarified the close interconnection and interdependence between the health of humans, animals, and the environment [...]
      Citation: Biosensors
      PubDate: 2022-04-28
      DOI: 10.3390/bios12050285
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 286: Recent Advances in Plasma-Engineered
           Polymers for Biomarker-Based Viral Detection and Highly Multiplexed

    • Authors: Seyyed Mojtaba Mousavi, Seyyed Alireza Hashemi, Masoomeh Yari Kalashgrani, Ahmad Gholami, Navid Omidifar, Aziz Babapoor, Neralla Vijayakameswara Rao, Wei-Hung Chiang
      First page: 286
      Abstract: Infectious diseases remain a pervasive threat to global and public health, especially in many countries and rural urban areas. The main causes of such severe diseases are the lack of appropriate analytical methods and subsequent treatment strategies due to limited access to centralized and equipped medical centers for detection. Rapid and accurate diagnosis in biomedicine and healthcare is essential for the effective treatment of pathogenic viruses as well as early detection. Plasma-engineered polymers are used worldwide for viral infections in conjunction with molecular detection of biomarkers. Plasma-engineered polymers for biomarker-based viral detection are generally inexpensive and offer great potential. For biomarker-based virus detection, plasma-based polymers appear to be potential biological probes and have been used directly with physiological components to perform highly multiplexed analyses simultaneously. The simultaneous measurement of multiple clinical parameters from the same sample volume is possible using highly multiplexed analysis to detect human viral infections, thereby reducing the time and cost required to collect each data point. This article reviews recent studies on the efficacy of plasma-engineered polymers as a detection method against human pandemic viruses. In this review study, we examine polymer biomarkers, plasma-engineered polymers, highly multiplexed analyses for viral infections, and recent applications of polymer-based biomarkers for virus detection. Finally, we provide an outlook on recent advances in the field of plasma-engineered polymers for biomarker-based virus detection and highly multiplexed analysis.
      Citation: Biosensors
      PubDate: 2022-04-28
      DOI: 10.3390/bios12050286
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 287: An Interfacial Affinity Interaction-Based
           Method for Detecting HOTAIR lncRNA in Cancer Plasma Samples

    • Authors: Kimberley Clack, Narshone Soda, Surasak Kasetsirikul, Richard Kline, Carlos Salomon, Muhammad J. A. Shiddiky
      First page: 287
      Abstract: Long non-coding RNA Homeobox transcript antisense intergenic RNA (HOTAIR) is recognized as a participant in different processes of normal cell development. Aberrant overexpression of HOTAIR contributes to the initiation, growth, and invasiveness of ovarian cancer. Using the affinity interaction of target HOTAIR lncRNA sequences towards a screen-printed gold electrode (SPE-Au), herein we report on a novel, rapid and simple method to detect HOTAIR sequences. HOTAIR lncRNA sequences were first extracted from ovarian cancer cell lines and patient plasma samples and were magnetically captured and purified by complimentary capture probe-functionalized magnetic beads. Isolated target HOTAIR lncRNAs were directly adsorbed onto unmodified screen-printed gold electrodes (SPE-Au) for direct quantification with [Fe(CN)6]3−/4− redox couple. Our assay achieved a linear dynamic range of 100 nM and 1 pM for detecting pre-clinical model HOTAIR lncRNA samples (%RSD ≤ 5%, for n = 3) and was highly specific, showing clear distinction between HOTAIR lncRNA targets and non-specific miR-891 and miR-486 (100 nM) (%RSD ≤ 5%, for n = 3). The method was tested using ovarian cancer-specific cell lines (SKOV3 and OVCAR3) and mesothelial cell line (MeT-5A)-derived lncRNAs. The analytical performance of our method was validated using RT-qPCR. Finally, the method was tested using clinical samples from ovarian cancer patients and the resulting electrochemical responses show a clear distinction between the ovarian carcinoma and benign samples.
      Citation: Biosensors
      PubDate: 2022-04-28
      DOI: 10.3390/bios12050287
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 288: HbA1c and Glucose Management Indicator
           Discordance Associated with Obesity and Type 2 Diabetes in Intermittent
           Scanning Glucose Monitoring System

    • Authors: Paul Fellinger, Karin Rodewald, Moritz Ferch, Bianca Itariu, Alexandra Kautzky-Willer, Yvonne Winhofer
      First page: 288
      Abstract: Glucose management indicator (GMI) is frequently used as a substitute for HbA1c, especially when using telemedicine. Discordances between GMI and HbA1c were previously mostly reported in populations with type 1 diabetes (T1DM) using real-time CGM. Our aim was to investigate the accordance between GMI and HbA1c in patients with diabetes using intermittent scanning CGM (isCGM). In this retrospective cross-sectional study, patients with diabetes who used isCGM >70% of the time of the investigated time periods were included. GMI of four different time spans (between 14 and 30 days), covering a period of 3 months, reflected by the HbA1c, were investigated. The influence of clinical- and isCGM-derived parameters on the discordance was assessed. We included 278 patients (55% T1DM; 33% type 2 diabetes (T2DM)) with a mean HbA1c of 7.63%. The mean GMI of the four time periods was between 7.19% and 7.25%. On average, the absolute deviation between the four calculated GMIs and HbA1c ranged from 0.6% to 0.65%. The discordance was greater with increased BMI, a diagnosis of T2DM, and a greater difference between the most recent GMI and GMI assessed 8 to 10 weeks prior to HbA1c assessment. Our data shows that, especially in patients with increased BMI and T2DM, this difference is more pronounced and should therefore be considered when making therapeutic decisions.
      Citation: Biosensors
      PubDate: 2022-04-29
      DOI: 10.3390/bios12050288
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 289: The Relevance of Calibration in Machine
           Learning-Based Hypertension Risk Assessment Combining Photoplethysmography
           and Electrocardiography

    • Authors: Jesús Cano, Lorenzo Fácila, Juan M. Gracia-Baena, Roberto Zangróniz, Raúl Alcaraz, José J. Rieta
      First page: 289
      Abstract: The detection of hypertension (HT) is of great importance for the early diagnosis of cardiovascular diseases (CVDs), as subjects with high blood pressure (BP) are asymptomatic until advanced stages of the disease. The present study proposes a classification model to discriminate between normotensive (NTS) and hypertensive (HTS) subjects employing electrocardiographic (ECG) and photoplethysmographic (PPG) recordings as an alternative to traditional cuff-based methods. A total of 913 ECG, PPG and BP recordings from 69 subjects were analyzed. Then, signal preprocessing, fiducial points extraction and feature selection were performed, providing 17 discriminatory features, such as pulse arrival and transit times, that fed machine-learning-based classifiers. The main innovation proposed in this research uncovers the relevance of previous calibration to obtain accurate HT risk assessment. This aspect has been assessed using both close and distant time test measurements with respect to calibration. The k-nearest neighbors-classifier provided the best outcomes with an accuracy for new subjects before calibration of 51.48%. The inclusion of just one calibration measurement into the model improved classification accuracy by 30%, reaching gradually more than 96% with more than six calibration measurements. Accuracy decreased with distance to calibration, but remained outstanding even days after calibration. Thus, the use of PPG and ECG recordings combined with previous subject calibration can significantly improve discrimination between NTS and HTS individuals. This strategy could be implemented in wearable devices for HT risk assessment as well as to prevent CVDs.
      Citation: Biosensors
      PubDate: 2022-05-01
      DOI: 10.3390/bios12050289
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 290: A Multianalyte Electrochemical Genosensor

    • Authors: Thanyarat Chaibun, Patcharanin Thanasapburachot, Patutong Chatchawal, Lee Su Yin, Sirimanas Jiaranuchart, Patcharee Jearanaikoon, Chamras Promptmas, Waranun Buajeeb, Benchaporn Lertanantawong
      First page: 290
      Abstract: Infection with high-risk human papillomavirus (HPV) is a major risk factor for oral and cervical cancers. Hence, we developed a multianalyte electrochemical DNA biosensor that could be used for both oral and cervical samples to detect the high-risk HPV genotypes 16 and 18. The assay involves the sandwich hybridization of the HPV target to the silica-redox dye reporter probe and capture probe, followed by electrochemical detection. The sensor was found to be highly specific and sensitive, with a detection limit of 22 fM for HPV-16 and 20 fM for HPV-18, between the range of 1 fM and 1 µM. Evaluation with oral and cervical samples showed that the biosensor result was consistent with the nested PCR/gel electrophoresis detection. The biosensor assay could be completed within 90 min. Due to its simplicity, rapidity, and high sensitivity, this biosensor could be used as an alternative method for HPV detection in clinical laboratories as well as for epidemiological studies.
      Citation: Biosensors
      PubDate: 2022-05-02
      DOI: 10.3390/bios12050290
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 291: Molecularly Imprinted Polymer-Amyloid
           Fibril-Based Electrochemical Biosensor for Ultrasensitive Detection of

    • Authors: Ibrar Alam, Benchaporn Lertanantawong, Thana Sutthibutpong, Primana Punnakitikashem, Piyapong Asanithi
      First page: 291
      Abstract: A tryptophan (Trp) sensor was investigated based on electrochemical impedance spectroscopy (EIS) of a molecularly imprinted polymer on a lysozyme amyloid fibril (MIP-AF). The MIP-AF was composed of aniline as a monomer chemically polymerized in the presence of a Trp template molecule onto the AF surface. After extracting the template molecule, the MIP-AF had cavities with a high affinity for the Trp molecules. The obtained MIP-AF demonstrated rapid Trp adsorption and substantial binding capacity (50 µM mg−1). Trp determination was studied using non-Faradaic EIS by drop drying the MIP-AF on the working electrode of a screen-printed electrode. The MIP-AF provided a large linear range (10 pM–80 µM), a low detection limit (8 pM), and high selectivity for Trp determination. Furthermore, the proposed method also indicates that the MIP-AF can be used to determine Trp in real samples such as milk and cancer cell media.
      Citation: Biosensors
      PubDate: 2022-05-02
      DOI: 10.3390/bios12050291
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 292: Wearable Devices for Physical Monitoring
           of Heart: A Review

    • Authors: Guillermo Prieto-Avalos, Nancy Aracely Cruz-Ramos, Giner Alor-Hernández, José Luis Sánchez-Cervantes, Lisbeth Rodríguez-Mazahua, Luis Rolando Guarneros-Nolasco
      First page: 292
      Abstract: Cardiovascular diseases (CVDs) are the leading cause of death globally. An effective strategy to mitigate the burden of CVDs has been to monitor patients’ biomedical variables during daily activities with wearable technology. Nowadays, technological advance has contributed to wearables technology by reducing the size of the devices, improving the accuracy of sensing biomedical variables to be devices with relatively low energy consumption that can manage security and privacy of the patient’s medical information, have adaptability to any data storage system, and have reasonable costs with regard to the traditional scheme where the patient must go to a hospital for an electrocardiogram, thus contributing a serious option in diagnosis and treatment of CVDs. In this work, we review commercial and noncommercial wearable devices used to monitor CVD biomedical variables. Our main findings revealed that commercial wearables usually include smart wristbands, patches, and smartwatches, and they generally monitor variables such as heart rate, blood oxygen saturation, and electrocardiogram data. Noncommercial wearables focus on monitoring electrocardiogram and photoplethysmography data, and they mostly include accelerometers and smartwatches for detecting atrial fibrillation and heart failure. However, using wearable devices without healthy personal habits will cause disappointing results in the patient’s health.
      Citation: Biosensors
      PubDate: 2022-05-02
      DOI: 10.3390/bios12050292
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 293: ECIS Based Electric Fence Method for
           Measurement of Human Keratinocyte Migration on Different Substrates

    • Authors: Yu-Han Hung, Wei-Chih Chiu, Shyh-Rong Fuh, Yi-Ting Lai, Tse-Hua Tung, Chun-Chung Huang, Chun-Min Lo
      First page: 293
      Abstract: Electric Cell-substrate Impedance Sensing (ECIS) is an impedance-based, real-time, and label-free measuring system for monitoring cellular activities in tissue culture. Previously, ECIS wound healing assay has been used to wound cells with high electric current and monitor the subsequent cell migration. In this study, we applied ECIS electric fence (EF) method, an alternative to electrical wounding, to assess the effects of different surface coatings on human keratinocyte (HaCaT) migration. The EF prevents inoculated cells from attaching or migrating to the fenced electrode surface while maintaining the integrity of the surface coating. After the EF is turned off, cells migrate into the cell-free area, and the increase in measured impedance is monitored. We cultured HaCaT cells on gold electrodes without coating or coated with poly-L-lysin (PLL), poly-D-lysine (PDL), or type-I collagen. We quantified migration rates according to the different slopes in the impedance time series. It was observed that either poly-L-lysine (PLL) or poly-D-lysine (PDL) limits cell adhesion and migration rates. Furthermore, the surface charge of the coated substrate in the culture condition positively correlates with the cell adhesion and migration process. Our results indicate that the EF method is useful for determining cell migration rates on specific surface coatings.
      Citation: Biosensors
      PubDate: 2022-05-03
      DOI: 10.3390/bios12050293
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 294: A Facile Single-Phase-Fluid-Driven Bubble
           Microfluidic Generator for Potential Detection of Viruses Suspended in Air

    • Authors: Jia Man, Luming Man, Chenchen Zhou, Jianyong Li, Shuaishuai Liang, Song Zhang, Jianfeng Li
      First page: 294
      Abstract: Microfluidics devices have widely been employed to prepare monodispersed microbubbles/droplets, which have promising applications in biomedical engineering, biosensor detection, drug delivery, etc. However, the current reported microfluidic devices need to control at least two-phase fluids to make microbubbles/droplets. Additionally, it seems to be difficult to make monodispersed microbubbles from the ambient air using currently reported microfluidic structures. Here, we present a facile approach to making monodispersed microbubbles directly from the ambient air by driving single-phase fluid. The reported single-phase-fluid microfluidic (SPFM) device has a typical co-flow structure, while the adjacent space between the injection tube and the collection tube is open to the air. The flow condition inside the SPFM device was systematically studied. By adjusting the flow rate of the single-phase fluid, bubbles were generated, the sizes of which could be tuned precisely. This facile bubble generator may have significant potential as a detection sensor in detecting viruses in spread droplets or haze particles in ambient air.
      Citation: Biosensors
      PubDate: 2022-05-03
      DOI: 10.3390/bios12050294
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 295: Identifying the Posture of Young Adults in
           Walking Videos by Using a Fusion Artificial Intelligent Method

    • Authors: Posen Lee, Tai-Been Chen, Chin-Hsuan Liu, Chi-Yuan Wang, Guan-Hua Huang, Nan-Han Lu
      First page: 295
      Abstract: Many neurological and musculoskeletal disorders are associated with problems related to postural movement. Noninvasive tracking devices are used to record, analyze, measure, and detect the postural control of the body, which may indicate health problems in real time. A total of 35 young adults without any health problems were recruited for this study to participate in a walking experiment. An iso-block postural identity method was used to quantitatively analyze posture control and walking behavior. The participants who exhibited straightforward walking and skewed walking were defined as the control and experimental groups, respectively. Fusion deep learning was applied to generate dynamic joint node plots by using OpenPose-based methods, and skewness was qualitatively analyzed using convolutional neural networks. The maximum specificity and sensitivity achieved using a combination of ResNet101 and the naïve Bayes classifier were 0.84 and 0.87, respectively. The proposed approach successfully combines cell phone camera recordings, cloud storage, and fusion deep learning for posture estimation and classification.
      Citation: Biosensors
      PubDate: 2022-05-03
      DOI: 10.3390/bios12050295
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 296: Advanced Electrochemical and
           Opto-Electrochemical Biosensors for Quantitative Analysis of Disease
           Markers and Viruses

    • Authors: Najmeh Karimian, Federico Polo, Paolo Ugo
      First page: 296
      Abstract: Instrumental laboratory methods for biochemical and chemical analyses have reached a high level of reliability with excellent sensitivity and specificity [...]
      Citation: Biosensors
      PubDate: 2022-05-04
      DOI: 10.3390/bios12050296
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 297: Design of a Quencher-Free Fluorescent
           Aptasensor for Ochratoxin A Detection in Red Wine Based on the
           Guanine-Quenching Ability

    • Authors: Cheng Yang, Fathimath Abbas, Amina Rhouati, Yingying Sun, Xiaolin Chu, Shengnan Cui, Bingbing Sun, Changying Xue
      First page: 297
      Abstract: This study describes a quencher-free fluorescent aptasensor for ochratoxin A (OTA) detection using the specific quenching ability of guanine for fluorescein (FAM) molecules based on photo-induced electron transfer (PIET). In this strategy, OTA is detected by monitoring the fluorescence change induced by the conformational change of the aptamer after target binding. A new shorter OTA aptamer compromising three guanine bases at the 5′ end was used in this study. This new aptamer, named G3-OTAapt1-FAM (F1), was labeled with FAM on the 3′ end as a fluorophore. In order to increase the binding affinity of the aptamer and OTA, G3-OTAapt2-FAM (F2) was designed; this added a pair of complementary bases at the end compared with F1. To prevent the strong self-quenching of F2, a complementary chain, A13, was added. Although the F1 aptasensor was simpler to implement, the sensitivity of the F2 aptasensor with A13 was better than that of F1. The proposed F1 and F2 sensors can detect OTA with a concentration as low as 0.69 nmol/L and 0.36 nmol/L, respectively.
      Citation: Biosensors
      PubDate: 2022-05-05
      DOI: 10.3390/bios12050297
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 298: RT-LAMP-Based Molecular Diagnostic Set-Up
           for Rapid Hepatitis C Virus Testing

    • Authors: Sandhya Sharma, Emmanuel Thomas, Massimo Caputi, Waseem Asghar
      First page: 298
      Abstract: Hepatitis C virus (HCV) infections occur in approximately 3% of the world population. The development of an enhanced and extensive-scale screening is required to accomplish the World Health Organization’s (WHO) goal of eliminating HCV as a public health problem by 2030. However, standard testing methods are time-consuming, expensive, and challenging to deploy in remote and underdeveloped areas. Therefore, a cost-effective, rapid, and accurate point-of-care (POC) diagnostic test is needed to properly manage the disease and reduce the economic burden caused by high case numbers. Herein, we present a fully automated reverse-transcription loop-mediated isothermal amplification (RT-LAMP)-based molecular diagnostic set-up for rapid HCV detection. The set-up consists of an automated disposable microfluidic chip, a small surface heater, and a reusable magnetic actuation platform. The microfluidic chip contains multiple chambers in which the plasma sample is processed. The system utilizes SYBR green dye to detect the amplification product with the naked eye. The efficiency of the microfluidic chip was tested with human plasma samples spiked with HCV virions, and the limit of detection observed was 500 virions/mL within 45 min. The entire virus detection process was executed inside a uniquely designed, inexpensive, disposable, and self-driven microfluidic chip with high sensitivity and specificity.
      Citation: Biosensors
      PubDate: 2022-05-05
      DOI: 10.3390/bios12050298
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 299: An Intelligent ECG-Based Tool for
           Diagnosing COVID-19 via Ensemble Deep Learning Techniques

    • Authors: Attallah
      First page: 299
      Abstract: Diagnosing COVID-19 accurately and rapidly is vital to control its quick spread, lessen lockdown restrictions, and decrease the workload on healthcare structures. The present tools to detect COVID-19 experience numerous shortcomings. Therefore, novel diagnostic tools are to be examined to enhance diagnostic accuracy and avoid the limitations of these tools. Earlier studies indicated multiple structures of cardiovascular alterations in COVID-19 cases which motivated the realization of using ECG data as a tool for diagnosing the novel coronavirus. This study introduced a novel automated diagnostic tool based on ECG data to diagnose COVID-19. The introduced tool utilizes ten deep learning (DL) models of various architectures. It obtains significant features from the last fully connected layer of each DL model and then combines them. Afterward, the tool presents a hybrid feature selection based on the chi-square test and sequential search to select significant features. Finally, it employs several machine learning classifiers to perform two classification levels. A binary level to differentiate between normal and COVID-19 cases, and a multiclass to discriminate COVID-19 cases from normal and other cardiac complications. The proposed tool reached an accuracy of 98.2% and 91.6% for binary and multiclass levels, respectively. This performance indicates that the ECG could be used as an alternative means of diagnosis of COVID-19.
      Citation: Biosensors
      PubDate: 2022-05-05
      DOI: 10.3390/bios12050299
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 300: Label-Free Detection of the
           Receptor-Binding Domain of the SARS-CoV-2 Spike Glycoprotein at
           Physiologically Relevant Concentrations Using Surface-Enhanced Raman

    • Authors: Sarychev, Sukhanova, Ivanov, Bykov, Bakholdin, Vasina, Gushchin, Tkachuk, Nifontova, Samokhvalov, Karaulov, Nabiev
      First page: 300
      Abstract: Surface-enhanced Raman scattering (SERS) spectroscopy is a surface- or cavity-enhanced variant of Raman scattering spectroscopy that allows the detection of analytes with a sensitivity down to single molecules. This method involves the use of SERS-active surfaces or cavities capable of concentrating incident radiation into small mode volumes containing the analyte. Here, we have engineered an ultranarrow metal–dielectric nano-cavity out of a film of the receptor-binding domain (RBD) of SARS-CoV-2 spike (S) glycoprotein and a silver surface, held together by interaction between reduced protein sulfhydryl groups and silver. The concentration of light in this nano-cavity allows the label-free recording of the characteristic Raman spectra of protein samples smaller than 1 pg. This is sufficient for the ultrasensitive detection of viral protein antigens at physiologically relevant levels. Moreover, the protein SERS signal can be increased by several orders of magnitude by coating the RBD film with a nanometer-thick silver shell, thereby raising the cavity Q-factor. This ensures a sub-femtogram sensitivity of the viral antigen detection. A simple theoretical model explaining the observed additional enhancement of the SERS signal from the silver-coated protein is proposed. Our study is the first to obtain the characteristic Raman and SERS spectra of the RBD of S glycoprotein, the key SARS-CoV-2 viral antigen, directly, without the use of Raman-reporter molecules. Thus, our approach allows label-free recording of the characteristic spectra of viral antigens at concentrations orders of magnitude lower than those required for detecting the whole virus in biological media. This makes it possible to develop a high-performance optical detection method and conformational analysis of the pathogen and its variants.
      Citation: Biosensors
      PubDate: 2022-05-05
      DOI: 10.3390/bios12050300
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 301: Nano-Scaled Materials and Polymer
           Integration in Biosensing Tools

    • Authors: Hichem Moulahoum, Faezeh Ghorbanizamani, Emine Guler Celik, Suna Timur
      First page: 301
      Abstract: The evolution of biosensors and diagnostic devices has been thriving in its ability to provide reliable tools with simplified operation steps. These evolutions have paved the way for further advances in sensing materials, strategies, and device structures. Polymeric composite materials can be formed into nanostructures and networks of different types, including hydrogels, vesicles, dendrimers, molecularly imprinted polymers (MIP), etc. Due to their biocompatibility, flexibility, and low prices, they are promising tools for future lab-on-chip devices as both manufacturing materials and immobilization surfaces. Polymers can also allow the construction of scaffold materials and 3D structures that further elevate the sensing capabilities of traditional 2D biosensors. This review discusses the latest developments in nano-scaled materials and synthesis techniques for polymer structures and their integration into sensing applications by highlighting their various structural advantages in producing highly sensitive tools that rival bench-top instruments. The developments in material design open a new door for decentralized medicine and public protection that allows effective onsite and point-of-care diagnostics.
      Citation: Biosensors
      PubDate: 2022-05-05
      DOI: 10.3390/bios12050301
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 302: Investigation of the Therapeutic Potential
           of New Antidiabetic Compounds Using Islet-on-a-Chip Microfluidic Model

    • Authors: Sokolowska, Jastrzebska, Dobrzyn, Brzozka
      First page: 302
      Abstract: Nowadays, diabetes mellitus is one of the most common chronic diseases in the world. Current research on the treatment of diabetes combines many fields of science, such as biotechnology, transplantology or engineering. Therefore, it is necessary to develop new therapeutic strategies and preventive methods. A newly discovered class of lipids—Palmitic Acid Hydroxy Stearic Acid (PAHSA) has recently been proposed as an agent with potential therapeutic properties. In this research, we used an islet-on-a-chip microfluidic 3D model of pancreatic islets (pseudoislets) to study two isomers of PAHSA: 5-PAHSA and 9-PAHSA as potential regulators of proliferation, viability, insulin and glucagon expression, and glucose-stimulated insulin and glucagon secretion. Due to the use of the Lab-on-a-chip systems and flow conditions, we were able to reflect conditions similar to in vivo. In addition, we significantly shortened the time of pseudoislet production, and we were able to carry out cell culture, microscopic analysis and measurements using a multi-well plate reader at the same time on one device. In this report we showed that under microfluidic conditions PAHSA, especially 5-PAHSA, has a positive effect on pseudoislet proliferation, increase in cell number and mass, and glucose-stimulated insulin secretion, which may qualify it as a compound with potential therapeutic properties.
      Citation: Biosensors
      PubDate: 2022-05-05
      DOI: 10.3390/bios12050302
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 303: Ultrafast DNA Amplification Using
           Microchannel Flow-Through PCR Device

    • Authors: Yen-Heng Lin, Xiang-Jun Liao, Wei Chang, Chiuan-Chian Chiou
      First page: 303
      Abstract: Polymerase chain reaction (PCR) is limited by the long reaction time for point-of-care. Currently, commercial benchtop rapid PCR requires 30–40 min, and this time is limited by the absence of rapid and stable heating and cooling platforms rather than the biochemical reaction kinetics. This study develops an ultrafast PCR (<3 min) platform using flow-through microchannel chips. An actin gene amplicon with a length of 151 base-pairs in the whole genome was used to verify the ultrafast PCR microfluidic chip. The results demonstrated that the channel of 56 μm height can provide fast heat conduction and the channel length should not be short. Under certain denaturation and annealing/extension times, a short channel design will cause the sample to drive slowly in the microchannel with insufficient pressure in the channel, causing the fluid to generate bubbles in the high-temperature zone and subsequently destabilizing the flow. The chips used in the experiment can complete 40 thermal cycles within 160 s through a design with the 56 µm channel height and with each thermal circle measuring 4 cm long. The calculation shows that the DNA extension speed is ~60 base-pairs/s, which is consistent with the theoretical speed of the Klen Taq extension used, and the detection limit can reach 67 copies. The heat transfer time of the reagent on this platform is very short. The simple chip design and fabrication are suitable for the development of commercial ultrafast PCR chips.
      Citation: Biosensors
      PubDate: 2022-05-06
      DOI: 10.3390/bios12050303
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 304: Real-Time Monitoring the Cytotoxic Effect
           of Andrographolide on Human Oral Epidermoid Carcinoma Cells

    • Authors: Heng-Yi Liao, Chun-Chung Huang, Shih-Chi Chao, Chien-Ping Chiang, Bo-Hsuan Tang, Shiao-Pieng Lee, Jehng-Kang Wang
      First page: 304
      Abstract: Andrographolide is an active diterpenoid compound extracted from Andrographis paniculata. It exhibits antiinflammatory and anticancer effects. Previous studies show that it is non-toxic to experimental animals. The leading causes of cancer are chronic inflammation and high blood glucose. This study determines the cytotoxic effect of andrographolide on cellular morphology, viability, and migration for human oral epidermoid carcinoma cell Meng-1 (OEC-M1). We use electric cell-substrate impedance sensing (ECIS) to measure the subsequent overall impedance changes of the cell monolayer in response to different concentrations of andrographolide for 24 h (10–100 µM). The results for exposure of OEC-M1 cells to andrographolide (10–100 µM) for 24 h show a concentration-dependent decrease in the overall measured resistance at 4 kHz. AlamarBlue cell viability assay and annexin V also show the apoptotic effect of andrographolide on OEC-M1 cells. A reduction in wound-healing recovery rate is observed for cells treated with 30 μM andrographolide. This study demonstrates that ECIS can be used for the in vitro screening of anticancer drugs. ECIS detects the cytotoxic effect of drugs earlier than traditional biochemical assays, and it is more sensitive and shows more detail.
      Citation: Biosensors
      PubDate: 2022-05-06
      DOI: 10.3390/bios12050304
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 305: Interdigitated Organic Sensor in
           Multimodal Facemask’s Barrier Integrity and Wearer’s
           Respiration Monitoring

    • Authors: Marina Galliani, Laura M. Ferrari, Esma Ismailova
      First page: 305
      Abstract: Facemasks are used as a personal protective equipment in medical services. They became compulsory during the recent COVID-19 pandemic at large. Their barrier effectiveness during various daily activities over time has been the subject of much debate. We propose the fabrication of an organic sensor to monitor the integrity of surgical masks to ensure individuals’ health and safety during their use. Inkjet printing of an interdigitated conducting polymer-based sensor on the inner layer of the mask proved to be an efficient and direct fabrication process to rapidly reach the end user. The sensor’s integration happens without hampering the mask functionality and preserving its original air permeability. Its resistive response to humidity accumulation allows it to monitor the mask’s wetting in use, providing a quantified way to track its barrier integrity and assist in its management. Additionally, it detects the user’s respiration rate as a capacitive response to the exhaled humidity, essential in identifying breathing difficulties or a sign of an infection. Respiration evaluations during daily activities show outstanding performance in relation to unspecific motion artifacts and breathing resolution. This e-mask yields an integrated solution for home-based individual monitoring and an advanced protective equipment for healthcare professionals.
      Citation: Biosensors
      PubDate: 2022-05-06
      DOI: 10.3390/bios12050305
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 306: Multimode Fano Resonances Sensing Based on
           a Non-Through MIM Waveguide with a Square Split-Ring Resonance Cavity

    • Authors: Jianfeng Chen, Xinyu Lian, Ming Zhao, Chenbo Xie
      First page: 306
      Abstract: In this article, a non-through metal–insulator–metal (MIM) waveguide that can excite fivefold Fano resonances is reported. The Fano resonances are obtained by the interaction between the modes excited by the square split-ring resonator (SSRC) and the bus waveguide. After a detailed analysis of the transmission characteristics and magnetic field strength of the structure using the finite element method (FEM), it was found that the independent tuning of Fano resonance wavelength and transmittance can be achieved by adjusting the geometric parameters of SSRC. In addition, after optimizing the geometric parameters, the refractive index sensing sensitivity (S) and figure of merit (FOM) of the structure can be optimal, which are 1290.2 nm/RIU and 3.6 × 104, respectively. Additionally, the annular cavity of the MIM waveguide structure can also be filled with biomass solution to act as a biosensor. On this basis, the structure can be produced for optical refractive index sensing in the biological, micro and nano fields.
      Citation: Biosensors
      PubDate: 2022-05-06
      DOI: 10.3390/bios12050306
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 307: Multi-Color Two-Photon Microscopic Imaging
           Based on a Single-Wavelength Excitation

    • Authors: Wei Yan, Yangrui Huang, Luwei Wang, Jin Li, Yong Guo, Zhigang Yang, Junle Qu
      First page: 307
      Abstract: Two-photon probes with broad absorption spectra are beneficial for multi-color two-photon microscopy imaging, which is one of the most powerful tools to study the dynamic processes of living cells. To achieve multi-color two-photon imaging, multiple lasers and detectors are usually required for excitation and signal collection, respectively. However, one makes the imaging system more complicated and costly. Here, we demonstrate a multi-color two-photon imaging method with a single-wavelength excitation by using a signal separation strategy. The method can effectively solve the problem of spectral crosstalk by selecting a suitable filter combination and applying image subtraction. The experimental results show that the two-color and three-color two-photon imaging are achieved with a single femtosecond laser. Furthermore, this method can also be combined with multi-photon imaging technology to reveal more information and interaction in thick biological tissues.
      Citation: Biosensors
      PubDate: 2022-05-06
      DOI: 10.3390/bios12050307
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 308: Applicability of Selected 3D Printing
           Materials in Electrochemistry

    • Authors: Marta Choińska, Vojtěch Hrdlička, Hana Dejmková, Jan Fischer, Luděk Míka, Eva Vaněčková, Viliam Kolivoška, Tomáš Navrátil
      First page: 308
      Abstract: This manuscript investigates the chemical and structural stability of 3D printing materials (3DPMs) frequently used in electrochemistry. Four 3D printing materials were studied: Clear photopolymer, Elastic photopolymer, PET filament, and PLA filament. Their stability, solubility, structural changes, flexibility, hardness, and color changes were investigated after exposure to selected organic solvents and supporting electrolytes. Furthermore, the available potential windows and behavior of redox probes in selected supporting electrolytes were investigated before and after the exposure of the 3D-printed objects to the electrolytes at various working electrodes. Possible electrochemically active interferences with an origin from the 3DPMs were also monitored to provide a comprehensive outline for the use of 3DPMs in electrochemical platform manufacturing.
      Citation: Biosensors
      PubDate: 2022-05-07
      DOI: 10.3390/bios12050308
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 309: Development and Assessment of Regeneration
           Methods for Peptide-Based QCM Biosensors in VOCs Analysis Applications

    • Authors: Tomasz Wasilewski, Bartosz Szulczyński, Dominik Dobrzyniewski, Weronika Jakubaszek, Jacek Gębicki, Wojciech Kamysz
      First page: 309
      Abstract: Cleaning a quartz crystal microbalance (QCM) plays a crucial role in the regeneration of its biosensors for reuse. Imprecise removal of a receptor layer from a transducer’s surface can lead to unsteady operation during measurements. This article compares three approaches to regeneration of the piezoelectric transducers using the electrochemical, oxygen plasma and Piranha solution methods. Optimization of the cleaning method allowed for evaluation of the influence of cleaning on the surface of regenerated biosensors. The effectiveness of cleaning the QCM transducers with a receptor layer in the form of a peptide with the KLLFDSLTDLKKKMSEC-NH2 sequence was described. Preliminary cleaning was tested for new electrodes to check the potential impact of the cleaning on deposition and the transducer’s operation parameters. The effectiveness of the cleaning was assessed via the measurement of a resonant frequency of the QCM transducers. Based on changes in the resonant frequency and the Sauerbrey equation, it was possible to evaluate the changes in mass adsorption on the transducer’s surface. Moreover, the morphology of the QCM transducer’s surface subjected to the selected cleaning techniques was presented with AFM imaging. The presented results confirm that each method is suitable for peptide-based biosensors cleaning. However, the most invasive seems to be the Piranha method, with the greatest decrease in performance after regeneration cycles (25% after three cycles). The presented techniques were evaluated for their efficiency with respect to a selected volatile compound, which in the future should allow reuse of the biosensors in particular applications, contributing to cost reduction and extension of the sensors’ lifetime.
      Citation: Biosensors
      PubDate: 2022-05-07
      DOI: 10.3390/bios12050309
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 310: An Ultrasensitive and Selective
           Determination of Cadmium Ions at Ppt Level Using an Enzymic Membrane with
           Colorimetric and Electrochemical Detection

    • Authors: Raouia Attaallah, Aziz Amine
      First page: 310
      Abstract: Cadmium ions (Cd2+) are extremely toxic heavy metal pollutants found in the environment, and which endanger human health. Therefore, it is critical to develop a sensitive and simple method for rapidly detecting Cd2+ in water samples. Herein, an enzymic membrane was developed based on an easy and rapid immobilization method of horseradish peroxidase (HRP), for determination of Cd2+ in drinking water. Hence, for the first time, an enzymic membrane was applied for the detection of Cd2+ without being pretreated. In the first format, the inhibition of horseradish peroxidase was performed using a colorimetric microplate reader. Under optimal conditions, the achieved limit of detection was 20 ppt. In addition, an electrochemical biosensor was developed, by combining the enzymic membrane with screen printed electrodes, which showed a linear calibration range between 0.02–100 ppb (R2 = 0.990) and a detection limit of 50 ppt. The use of this enzymic membrane proved to be advantageous when reversible inhibitors such as the copper ion (Cu2+) were present in water samples, as Cu2+ can interfere with Cd2+ and cause erroneous results. In order to alleviate this problem, a medium exchange procedure was used to eliminate Cu2+, by washing and leaving only cadmium ions as an irreversible inhibitor for identification. The use of this membrane proved to be a simple and rapid method of immobilizing HRP with a covalent bond.
      Citation: Biosensors
      PubDate: 2022-05-07
      DOI: 10.3390/bios12050310
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 311: Cell-Membrane Biomimetic Indocyanine Green
           Liposomes for Phototheranostics of Echinococcosis

    • Authors: Xinxin Xiong, Jun Li, Duyang Gao, Zonghai Sheng, Hairong Zheng, Wenya Liu
      First page: 311
      Abstract: Echinococcosis is an important zoonotic infectious disease that seriously affects human health. Conventional diagnosis of echinococcosis relies on the application of large-scale imaging equipment, which is difficult to promote in remote areas. Meanwhile, surgery and chemotherapy for echinococcosis can cause serious trauma and side effects. Thus, the development of simple and effective treatment strategies is of great significance for the diagnosis and treatment of echinococcosis. Herein, we designed a phototheranostic system utilizing neutrophil-membrane-camouflaged indocyanine green liposomes (Lipo-ICG) for active targeting the near-infrared fluorescence diagnosis and photothermal therapy of echinococcosis. The biomimetic Lipo-ICG exhibits a remarkable photo-to-heat converting performance and desirable active-targeting features by the inflammatory chemotaxis of the neutrophil membrane. In-vitro and in-vivo studies reveal that biomimetic Lipo-ICG with high biocompatibility can achieve in-vivo near-infrared fluorescence imaging and phototherapy of echinococcosis in mouse models. Our research is the first to apply bionanomaterials to the phototherapy of echinococcosis, which provides a new standard for the convenient and noninvasive detection and treatment of zoonotic diseases.
      Citation: Biosensors
      PubDate: 2022-05-09
      DOI: 10.3390/bios12050311
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 312: A Differentiable Dynamic Model for
           Musculoskeletal Simulation and Exoskeleton Control

    • Authors: Chao-Hung Kuo, Jia-Wei Chen, Yi Yang, Yu-Hao Lan, Shao-Wei Lu, Ching-Fu Wang, Yu-Chun Lo, Chien-Lin Lin, Sheng-Huang Lin, Po-Chuan Chen, You-Yin Chen
      First page: 312
      Abstract: An exoskeleton, a wearable device, was designed based on the user’s physical and cognitive interactions. The control of the exoskeleton uses biomedical signals reflecting the user intention as input, and its algorithm is calculated as an output to make the movement smooth. However, the process of transforming the input of biomedical signals, such as electromyography (EMG), into the output of adjusting the torque and angle of the exoskeleton is limited by a finite time lag and precision of trajectory prediction, which result in a mismatch between the subject and exoskeleton. Here, we propose an EMG-based single-joint exoskeleton system by merging a differentiable continuous system with a dynamic musculoskeletal model. The parameters of each muscle contraction were calculated and applied to the rigid exoskeleton system to predict the precise trajectory. The results revealed accurate torque and angle prediction for the knee exoskeleton and good performance of assistance during movement. Our method outperformed other models regarding the rate of convergence and execution time. In conclusion, a differentiable continuous system merged with a dynamic musculoskeletal model supported the effective and accurate performance of an exoskeleton controlled by EMG signals.
      Citation: Biosensors
      PubDate: 2022-05-09
      DOI: 10.3390/bios12050312
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 313: Chiral Liquid Crystal Microdroplets for
           Sensing Phospholipid Amphiphiles

    • Authors: Sepideh Norouzi, Jose A. Martinez Gonzalez, Monirosadat Sadati
      First page: 313
      Abstract: Designing simple, sensitive, fast, and inexpensive readout devices to detect biological molecules and biomarkers is crucial for early diagnosis and treatments. Here, we have studied the interaction of the chiral liquid crystal (CLC) and biomolecules at the liquid crystal (LC)-droplet interface. CLC droplets with high and low chirality were prepared using a microfluidic device. We explored the reconfiguration of the CLC molecules confined in droplets in the presence of 1,2-diauroyl-sn-glycero3-phosphatidylcholine (DLPC) phospholipid. Cross-polarized optical microscopy and spectrometry techniques were employed to monitor the effect of droplet size and DLPC concentration on the structural reorganization of the CLC molecules. Our results showed that in the presence of DLPC, the chiral LC droplets transition from planar to homeotropic ordering through a multistage molecular reorientation. However, this reconfiguration process in the low-chirality droplets happened three times faster than in high-chirality ones. Applying spectrometry and image analysis, we found that the change in the chiral droplets’ Bragg reflection can be correlated with the CLC–DLPC interactions.
      Citation: Biosensors
      PubDate: 2022-05-09
      DOI: 10.3390/bios12050313
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 314: Two-Dimensional Material-Based
           Electrochemical Sensors/Biosensors for Food Safety and Biomolecular

    • Authors: Tao Li, Dawei Shang, Shouwu Gao, Bo Wang, Hao Kong, Guozheng Yang, Weidong Shu, Peilong Xu, Gang Wei
      First page: 314
      Abstract: Two-dimensional materials (2DMs) exhibited great potential for applications in materials science, energy storage, environmental science, biomedicine, sensors/biosensors, and others due to their unique physical, chemical, and biological properties. In this review, we present recent advances in the fabrication of 2DM-based electrochemical sensors and biosensors for applications in food safety and biomolecular detection that are related to human health. For this aim, firstly, we introduced the bottom-up and top-down synthesis methods of various 2DMs, such as graphene, transition metal oxides, transition metal dichalcogenides, MXenes, and several other graphene-like materials, and then we demonstrated the structure and surface chemistry of these 2DMs, which play a crucial role in the functionalization of 2DMs and subsequent composition with other nanoscale building blocks such as nanoparticles, biomolecules, and polymers. Then, the 2DM-based electrochemical sensors/biosensors for the detection of nitrite, heavy metal ions, antibiotics, and pesticides in foods and drinks are introduced. Meanwhile, the 2DM-based sensors for the determination and monitoring of key small molecules that are related to diseases and human health are presented and commented on. We believe that this review will be helpful for promoting 2DMs to construct novel electronic sensors and nanodevices for food safety and health monitoring.
      Citation: Biosensors
      PubDate: 2022-05-09
      DOI: 10.3390/bios12050314
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 315: Lowering the Sampling Rate: Heart Rate
           Response during Cognitive Fatigue

    • Authors: Kar Fye Alvin Lee, Elliot Chan, Josip Car, Woon-Seng Gan, Georgios Christopoulos
      First page: 315
      Abstract: Cognitive fatigue is a mental state characterised by feelings of tiredness and impaired cognitive functioning due to sustained cognitive demands. Frequency-domain heart rate variability (HRV) features have been found to vary as a function of cognitive fatigue. However, it has yet to be determined whether HRV features derived from electrocardiogram data with a low sampling rate would remain sensitive to cognitive fatigue. Bridging this research gap is important as it has substantial implications for designing more energy-efficient and less memory-hungry wearables to monitor cognitive fatigue. This study aimed to examine (1) the level of agreement between frequency-domain HRV features derived from lower and higher sampling rates, and (2) whether frequency-domain HRV features derived from lower sampling rates could predict cognitive fatigue. Participants (N = 53) were put through a cognitively fatiguing 2-back task for 20 min whilst their electrocardiograms were recorded. Results revealed that frequency-domain HRV features derived from sampling rate as low as 125 Hz remained almost perfectly in agreement with features derived from the original sampling rate at 2000 Hz. Furthermore, frequency domain features, such as normalised low-frequency power, normalised high-frequency power, and the ratio of low- to high-frequency power varied as a function of increasing cognitive fatigue during the task across all sampling rates. In conclusion, it appears that sampling at 125 Hz is more than adequate for frequency-domain feature extraction to index cognitive fatigue. These findings have significant implications for the design of low-cost wearables for detecting cognitive fatigue.
      Citation: Biosensors
      PubDate: 2022-05-10
      DOI: 10.3390/bios12050315
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 316: Quantitative Determination of Ethylene
           Using a Smartphone-Based Optical Fiber Sensor (SOFS) Coupled with
           Pyrene-Tagged Grubbs Catalyst

    • Authors: Xin Yang, Justin Lee Kee Leong, Mingtai Sun, Linzhi Jing, Yuannian Zhang, Tian Wang, Suhua Wang, Dejian Huang
      First page: 316
      Abstract: For rapid and portable detection of ethylene in commercial fruit ripening storage rooms, we designed a smartphone-based optical fiber sensor (SOFS), which is composed of a 15 mW 365 nm laser for fluorescence signal excitation and a bifurcated fiber system for signal flow direction from probe to smartphone. Paired with a pyrene-tagged Grubbs catalyst (PYG) probe, our SOFS showed a wide linearity range up to 350 ppm with a detection limit of 0.6 ppm. The common gases in the warehouse had no significant interference with the results. The device is portable (18 cm × 8 cm × 6 cm) with an inbuilt power supply and replaceable optical fiber sensor tip. The images are processed with a dedicated smartphone application for RGB analysis and ethylene concentration. The device was applied in detection of ethylene generated from apples, avocados, and bananas. The linear correlation data showed agreement with data generated from a fluorometer. The SOFS provides a rapid, compact, cost-effective solution for determination of the fruit ethylene concentration dynamic during ripening for better fruit harvest timing and postharvest management to minimize wastage.
      Citation: Biosensors
      PubDate: 2022-05-10
      DOI: 10.3390/bios12050316
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 317: Development of a Linear Immobilization
           Carrier-Based Immunoassay for Aflatoxin

    • Authors: Honglin Yan, Xiaoqian Tang, Xiaohan Liu, Yating Zheng, Minhui Zhang, Yueju Zhao, Qi Zhang
      First page: 317
      Abstract: We explored the feasibility of developing immunoassay technology with a linear carrier, to develop a simpler and cheaper rapid immunoassay technology. We selected aflatoxins as an example for research, as they are a group of highly toxic and carcinogenic compounds representing a worldwide threat to human health and life. With a non-competitive immunoassay, we detected and evaluated the effect of 28 different linear materials on antibody immobilization. Mercerized cotton and Dyneema line were chosen from the linear materials for further comparison using a competitive immunoassay, because both showed high-signal values and relatively low background noise. The results showed the sensitive IC50 of mercerized cotton as the reaction carrier was 0.33 ng/mL, and the linear range was 0.16~3.25 ng/mL. The sensitivity using Dyneema line as the reaction carrier was 1.16 ng/mL. The competitive curves of four sample matrices were established to evaluate the stability of the detection system; these were basically consistent with those without sample matrices. In conclusion, both mercerized cotton and Dyneema, will be suggested for the novel development of linear immobilization carrier-based immunoassays for other analytes, and especially to construct inexpensive and easy-to-obtain biological and environmental analytical technologies and biosensors.
      Citation: Biosensors
      PubDate: 2022-05-10
      DOI: 10.3390/bios12050317
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 318: Advances, Challenges and Future Trends of
           Cell-Free Transcription-Translation Biosensors

    • Authors: Ting Wang, Yuan Lu
      First page: 318
      Abstract: In recent years, the application of cell-free protein synthesis systems in biosensing has been developing rapidly. Cell-free synthetic biology, with its advantages of high biosafety, fast material transport, and high sensitivity, has overcome many defects of cell-based biosensors and provided an abiotic substitute for biosensors. In addition, the application of freeze-drying technology has improved the stability of such systems, making it possible to realize point-of-care application of field detection and broadening the application prospects of cell-free biosensors. However, despite these advancements, challenges such as the risk of sample interference due to the lack of physical barriers, maintenance of activity during storage, and poor robustness still need to be addressed before the full potential of cell-free biosensors can be realized on a larger scale. In this review, current strategies and research results for improving the performance of cell-free biosensors are summarized, including a comprehensive discussion of the existing challenges, future trends, and potential investments needed for improvement.
      Citation: Biosensors
      PubDate: 2022-05-10
      DOI: 10.3390/bios12050318
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 319: SERS Determination of Trace Phosphate in
           Aquaculture Water Based on a Rhodamine 6G Molecular Probe Association

    • Authors: Ye Jiang, Xiaochan Wang, Guo Zhao, Yinyan Shi, Nguyen Thi Dieu Thuy, Haolin Yang
      First page: 319
      Abstract: Although phosphate (Pi) is a necessary nutrient for the growth of aquatic organisms, the presence of excess Pi leads to water eutrophication; thus, it is necessary to accurately determine the content of Pi in water. A method for the determination of trace Pi in aquaculture water was developed based on surface-enhanced Raman spectroscopy (SERS) combined with rhodamine 6G (R6G)-modified silver nanoparticles (AgNPs) as the active substrate. The adsorption of R6G on the AgNP surfaces led to a strong SERS signal. However, in the presence of Pi and ammonium molybdate, phosphomolybdic acid formed, which further associated with R6G to form a stable R6G-PMo12O403− association complex, thereby hindering the adsorption of R6G on the AgNPs, and reducing the SERS intensity; this sequence formed the basis of Pi detection. The decrease in the SERS intensity was linear with respect to the Pi concentration (0.2–20 μM), and the limit of detection was 29.3 nM. Upon the application of this method to the determination of Pi in aquaculture water, a recovery of 94.4–107.2% was obtained (RSD 1.77–6.18%). This study provides an accurate, rapid, and sensitive method for the trace determination of Pi in aquaculture water, which is suitable for on-site detection.
      Citation: Biosensors
      PubDate: 2022-05-10
      DOI: 10.3390/bios12050319
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 320: The Impact of Glucose Oxidase
           Immobilization on Dendritic Gold Nanostructures on the Performance of
           Glucose Biosensors

    • Authors: Laura Sakalauskiene, Anton Popov, Asta Kausaite-Minkstimiene, Arunas Ramanavicius, Almira Ramanaviciene
      First page: 320
      Abstract: In recent years, many efforts have been made to develop rapid, sensitive and user-friendly glucose biosensors for monitoring blood glucose concentration in patients. In this study, the electrochemical glucose biosensors based on graphite rod (GR) electrode electrochemically modified with dendritic gold nanostructures (DGNs) and glucose oxidase (GOx) were developed. Phenazine methosulfate was used as a soluble redox mediator. Three GOx immobilization methods: adsorption on DGNs and cross-linking with glutaraldehyde (GA) vapour (GA-GOx/DGNs/GR), covalent immobilization on DGNs modified with 11-mercaptoundecanoic acid self-assembled monolayer (SAM) (GOx-SAM/DGNs/GR) and covalent immobilization on SAM with additional cross-linking with GA vapour (GA-GOx-SAM/DGNs/GR), were used. It was determined that GA significantly improved the stability of the enzyme layer. The difference of maximal current generated during the enzymatic reaction (ΔImax) equal to 272.06 ± 8.69 µA was obtained using a biosensor based on GA-GOx/DGNs/GR electrodes. However, the highest ΔImax equal to 384.20 ± 16.06 µA was obtained using GA-GOx-SAM/DGNs/GR electrode. ΔImax for biosensors based on the GA-GOx-SAM/DGNs/GR electrode was 1.41 times higher than for the GA-GOx/DGNs/GR, whereas the linear dynamic range from 0.1 to 10 mM was the same using all three GOx immobilization methods. The limit of detection using GA-GOx-SAM/DGNs/GR and GA-GOx/DGNs/GR electrodes was 0.019 and 0.022 mM, respectively. The ability to detect glucose in the serum by developed biosensors was evaluated.
      Citation: Biosensors
      PubDate: 2022-05-10
      DOI: 10.3390/bios12050320
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 321: Rapidly Measuring Scattered Polarization
           Parameters of the Individual Suspended Particle with Continuously Large
           Angular Range

    • Authors: Yan Chen, Hongjian Wang, Ran Liao, Hening Li, Yihao Wang, Hu Zhou, Jiajin Li, Tongyu Huang, Xu Zhang, Hui Ma
      First page: 321
      Abstract: Suspended particles play a vital role in aquatic environments. We propose a method to rapidly measure the scattered polarization parameters of individual suspended particles with continuously large angular range (PCLAR), from 60° to 120° in one shot. A conceptual setup is built to measure PCLAR with 20 kHz; to verify the setup, 10 μm-diameter silica microspheres suspended in water, whose PCLAR are consistent with those simulated by Mie theory, are measured. PCLAR of 6 categories of particles are measured, which enables high-accuracy classification with the help of a convolutional neural network algorithm. PCLAR of different mixtures of Cyclotella stelligera and silica microspheres are measured to successfully identify particulate components. Furthermore, classification ability comparisons of different angular-selection strategies show that PCLAR enables the best classification beyond the single angle, discrete angles and small-ranged angles. Simulated PCLAR of particles with different size, refractive index, and structure show explicit discriminations between them. Inversely, the measured PCLAR are able to estimate the effective size and refractive index of individual Cyclotella cells. Results demonstrate the method’s power, which intrinsically takes the advantage of the optical polarization and the angular coverage. Future prototypes based on this concept would be a promising biosensor for particles in environmental monitoring.
      Citation: Biosensors
      PubDate: 2022-05-10
      DOI: 10.3390/bios12050321
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 322: Towards Wearable Health Monitoring Devices

    • Authors: Vladimir A. Pozdin, James Dieffenderfer
      First page: 322
      Abstract: Humans have searched far beyond our planet to understand the fundamental principles and mechanisms of life [...]
      Citation: Biosensors
      PubDate: 2022-05-11
      DOI: 10.3390/bios12050322
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 323: From Triboelectric Nanogenerator to
           Polymer-Based Biosensor: A Review

    • Authors: Yin Lu, Yajun Mi, Tong Wu, Xia Cao, Ning Wang
      First page: 323
      Abstract: Nowadays, self-powered wearable biosensors that are based on triboelectric nanogenerators (TENGs) are playing an important role in the continuous efforts towards the miniaturization, energy saving, and intelligence of healthcare devices and Internets of Things (IoTs). In this review, we cover the remarkable developments in TENG−based biosensors developed from various polymer materials and their functionalities, with a focus on wearable and implantable self-powered sensors for health monitoring and therapeutic devices. The functions of TENGs as power sources for third-party biosensors are also discussed, and their applications in a number of related fields are concisely illustrated. Finally, we conclude the review with a discussion of the challenges and problems of leveraging TENG−based intelligent biosensors.
      Citation: Biosensors
      PubDate: 2022-05-11
      DOI: 10.3390/bios12050323
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 324: All-in-One Digital Microfluidics System
           for Molecular Diagnosis with Loop-Mediated Isothermal Amplification

    • Authors: Siyi Hu, Yuhan Jie, Kai Jin, Yifan Zhang, Tianjie Guo, Qi Huang, Qian Mei, Fuqiang Ma, Hanbin Ma
      First page: 324
      Abstract: In this study, an “all-in-one” digital microfluidics (DMF) system was developed for automatic and rapid molecular diagnosis and integrated with magnetic bead-based nucleic acid extraction, loop-mediated isothermal amplification (LAMP), and real-time optical signal monitoring. First, we performed on- and off-chip comparison experiments for the magnetic bead nucleic acid extraction module and LAMP amplification function. The extraction efficiency for the on-chip test was comparable to that of conventional off-chip methods. The processing time for the automatic on-chip workflow was only 23 min, which was less than that of the conventional methods of 28 min 45 s. Meanwhile, the number of samples used in on-chip experiments was significantly smaller than that used in off-chip experiments; only 5 µL of E. coli samples was required for nucleic acid extraction, and 1 µL of the nucleic acid template was needed for the amplification reaction. In addition, we selected SARS-CoV-2 nucleic acid reference materials for the nucleic acid detection experiment, demonstrating a limit of detection of 10 copies/µL. The proposed “all-in-one” DMF system provides an on-site “sample to answer” time of approximately 60 min, which can be a powerful tool for point-of-care molecular diagnostics.
      Citation: Biosensors
      PubDate: 2022-05-11
      DOI: 10.3390/bios12050324
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 325: A Novel Perturbed Spiral Sheathless Chip
           for Particle Separation Based on Traveling Surface Acoustic Waves (TSAW)

    • Authors: Miaomiao Ji, Yukai Liu, Junping Duan, Wenxuan Zang, Yongsheng Wang, Zeng Qu, Binzhen Zhang
      First page: 325
      Abstract: The combination of the new perturbed spiral channel and a slanted gold interfingered transducer (IDT) is designed to achieve precise dynamic separation of target particles (20 μm). The offset micropillar array solves the defect that the high-width flow (avoiding the occurrence of channel blockage) channel cannot realize the focusing of small particles (5 μm, 10 μm). The relationship between the maximum design gap of the micropillar (Smax) and the particle radius (a) is given: Smax = 4a, which not only ensures that small particles will not pass through the micropillar gap, but also is compatible with the appropriate flow rates. A non-offset micropillar array was used to remove 20 μm particles in the corner area. The innovation of a spiral channel structure greatly improves the separation efficiency and purity of the separation chip. The separation chip designed by us achieves deflection separation of 20 μm particles at 24.95–41.58 MHz (κ = 1.09–1.81), at a flow rate of 1.2 mL per hour. When f = 33.7 MHz (κ = 1.47), the transverse migration distance of 20 μm particles is the smallest, and the separation purity and efficiency are as high as 92% and 100%, respectively.
      Citation: Biosensors
      PubDate: 2022-05-11
      DOI: 10.3390/bios12050325
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 326: Specific and Sensitive Detection of
           Tartrazine on the Electrochemical Interface of a Molecularly Imprinted
           Polydopamine-Coated PtCo Nanoalloy on Graphene Oxide

    • Authors: Shuwen Cheng, Danyao Tang, Yi Zhang, Libin Xu, Kunping Liu, Kejing Huang, Zhengzhi Yin
      First page: 326
      Abstract: A novel electrochemical sensor designed to recognize and detect tartrazine (TZ) was constructed based on a molecularly imprinted polydopamine (MIPDA)-coated nanocomposite of platinum cobalt (PtCo) nanoalloy-functionalized graphene oxide (GO). The nanocomposites were characterized and the TZ electrochemical detection performance of the sensor and various reference electrodes was investigated. Interestingly, the synergistic effect of the strong electrocatalytic activity of the PtCo nanoalloy-decorated GO and the high TZ recognition ability of the imprinted cavities of the MIPDA coating resulted in a large and specific response to TZ. Under the optimized conditions, the sensor displayed linear response ranges of 0.003–0.180 and 0.180–3.950 µM, and its detection limit was 1.1 nM (S/N = 3). The electrochemical sensor displayed high anti-interference ability, good stability, and adequate reproducibility, and was successfully used to detect TZ in spiked food samples. Comparison of important indexes of this sensor with those of previous electrochemical sensors for TZ revealed that this sensor showed improved performance. This surface-imprinted sensor provides an ultrasensitive, highly specific, effective, and low-cost method for TZ determination in foodstuffs.
      Citation: Biosensors
      PubDate: 2022-05-11
      DOI: 10.3390/bios12050326
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 327: Exploiting Catabolite Repression and
           Stringent Response to Control Delay and Multimodality of Bioluminescence
           Signal by Metal Whole-Cell Biosensors: Interplay between Metal
           Bioavailability and Nutritional Medium Conditions

    • Authors: Eva Delatour, Christophe Pagnout, Marie Zaffino, Jérôme F. L. Duval
      First page: 327
      Abstract: The time-dependent response of metal-detecting whole-cell luminescent bacterial sensors is impacted by metal speciation/bioavailability in solution. The comprehensive understanding of such connections requires the consideration of the bacterial energy metabolism at stake and the effects of supplied food on cells’ capability to convert bioaccumulated metals into light. Accordingly, we investigated the time response (48 h assay) of PzntA-luxCDABE Escherichia coli Cd biosensors in media differing with respect to sources of amino acids (tryptone or Lysogeny Broth) and carbon (glucose, xylose and mixtures thereof). We show that the resulting coupling between the stringent cell response and glucose/xylose-mediated catabolite repressions lead to well-defined multimodalities and shapes of the bioluminescence signal over time. Based on a recent theory for the time–response of metal-sensing luminescent bacteria, successful theoretical reconstructions of the bioluminescence signals are reported under all Cd concentrations (0–20 nM) and nutritive conditions examined. This analysis leads to the evaluation of time-dependent cell photoactivity and qualitative information on metal speciation/bioavailability in solution. Biosensor performance and the position, shape, number, and magnitude of detected peaks are discussed in relation to the metabolic pathways operative during the successive light emission modes identified here over time. Altogether, the results clarify the contributions of metal/nutrient bio-availabilities and food quality to cell response typology.
      Citation: Biosensors
      PubDate: 2022-05-11
      DOI: 10.3390/bios12050327
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 328: Label-Free miRNA-21 Analysis Based on
           Strand Displacement and Terminal Deoxynucleotidyl Transferase-Assisted
           Amplification Strategy

    • Authors: Ying Yan, Han Zhao, Yukang Fang, Changbei Ma, Junxiang Chen
      First page: 328
      Abstract: MicroRNAs (miRNAs) are regarded as a rising star in the biomedical industry. By monitoring slight increases in miRNA-21 levels, the possibilities of multi-type malignancy can be evaluated more precisely and earlier. However, the inconvenience and insensitivity of traditional methods for detecting miRNA-21 levels remains challenging. In this study, a partially complementary cDNA probe was designed to detect miRNA-21 with target-triggered dual amplification based on strand displacement amplification (SDA) and terminal deoxynucleotidyl transferase (TdT)-assisted amplification. In this system, the presence of miRNA-21 can hybridize with template DNA to initiate SDA, generating a large number of trigger molecules. With the assistance of TdT and dGTP, the released trigger DNA with 3′-OH terminal can be elongated to a superlong poly(guanine) sequence, and a notable fluorescence signal was observed in the presence of thioflavin T. By means of dual amplification strategy, the sensing platform showed a good response tomiRNA-21 with a detection limit of 1.7 pM (S/N = 3). Moreover, the specificity of this method was verified using a set of miRNA with sequence homologous to miRNA-21. In order to further explore its practical application capabilities, the expression of miRNA in different cell lines was quantitatively analyzed and compared with the qRT-PCR. The considerable results of this study suggest great potential for the application of the proposed approach in clinical diagnosis.
      Citation: Biosensors
      PubDate: 2022-05-12
      DOI: 10.3390/bios12050328
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 329: Electrochemical DNA Sensor Based on Carbon
           Black—Poly(Methylene Blue)—Poly(Neutral Red) Composite

    • Authors: Dominica Kappo, Dmitry Shurpik, Pavel Padnya, Ivan Stoikov, Alexey Rogov, Gennady Evtugyn
      First page: 329
      Abstract: The detection of small molecules interacting with DNA is important for the assessment of potential hazards related to the application of rather toxic antitumor drugs, and for distinguishing the factors related to thermal and oxidative DNA damage. In this work, a novel electrochemical DNA sensor has been proposed for the determination of antitumor drugs. For DNA sensor assembling, a glassy carbon electrode was modified with carbon black dispersed in DMF. After that, pillar [5]arene was adsorbed and Methylene blue and Neutral red were consecutively electropolymerized onto the carbon black layer. To increase sensitivity of intercalator detection, DNA was first mixed with water-soluble thiacalixarene bearing quaternary ammonium groups in the substituents at the lower rim. The deposition of the mixture on the electropolymerized dyes made it possible to detect doxorubicin as model intercalator by suppression of the redox activity of the polymerization products. The DNA sensor made it possible to determine 0.5 pM–1.0 nM doxorubicin (limit of detection 0.13 pM) with 20 min of incubation. The DNA sensor was successfully tested on spiked samples of human plasma and doxorubicin medication.
      Citation: Biosensors
      PubDate: 2022-05-12
      DOI: 10.3390/bios12050329
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 330: A Digital Microfluidic Device Integrated
           with Electrochemical Impedance Spectroscopy for Cell-Based Immunoassay

    • Authors: Yuqian Zhang, Yuguang Liu
      First page: 330
      Abstract: The dynamic immune response to various diseases and therapies has been considered a promising indicator of disease status and therapeutic effectiveness. For instance, the human peripheral blood mononuclear cell (PBMC), as a major player in the immune system, is an important index to indicate a patient’s immune function. Therefore, establishing a simple yet sensitive tool that can frequently assess the immune system during the course of disease and treatment is of great importance. This study introduced an integrated system that includes an electrochemical impedance spectroscope (EIS)-based biosensor in a digital microfluidic (DMF) device, to quantify the PBMC abundance with minimally trained hands. Moreover, we exploited the unique droplet manipulation feature of the DMF platform and conducted a dynamic cell capture assay, which enhanced the detection signal by 2.4-fold. This integrated system was able to detect as few as 104 PBMCs per mL, presenting suitable sensitivity to quantify PBMCs. This integrated system is easy-to-operate and sensitive, and therefore holds great potential as a powerful tool to profile immune-mediated therapeutic responses in a timely manner, which can be further evolved as a point-of-care diagnostic device to conduct near-patient tests from blood samples.
      Citation: Biosensors
      PubDate: 2022-05-12
      DOI: 10.3390/bios12050330
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 331: Electrochemical Biosensor Using
           Nitrogen-Doped Graphene/Au Nanoparticles/DNAzyme for Ca2+ Determination

    • Authors: Zhixue Yu, Hui Wang, Yiguang Zhao, Fan Zhang, Xiangfang Tang, Benhai Xiong
      First page: 331
      Abstract: An electrochemical biosensor for detecting Ca2+ concentration was proposed using glass carbon electrodes (GCEs) modified with nitrogen-doped graphene (NGR), gold nanoparticles (AuNPs) and DNAzyme. The resistance signal was amplified through two methods: electrochemical reduction of AuNPs on the NGR surface to increase the specific surface area of the electrode and strengthen the adsorption of DNAzyme; and increasement of the DNAzyme base sequence. The process of electrode modification was characterized by scanning electron microscopy, Raman spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Experimental parameters’ influence, such as the deposition time of gold nanoparticles and the detection time, were assessed by electrochemical methods. The linear ranges of the electrochemical biosensor were in the range from 5 × 10−6 to 5 × 10−5 and 5 × 10−5 to 4 × 10−4 M, with a detection limit of 3.8 × 10−6 M. The concentration of Ca2+ in the serum of dairy cows was determined by the biosensor with satisfactory results, which could be potentially used to diagnose subclinical hypocalcemia.
      Citation: Biosensors
      PubDate: 2022-05-12
      DOI: 10.3390/bios12050331
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 332: Two-Dimensional Ti3C2 MXene-Based Novel
           Nanocomposites for Breath Sensors for Early Detection of Diabetes Mellitus

    • Authors: Anna Rudie, Anna Marie Schornack, Qiang Wu, Qifeng Zhang, Danling Wang
      First page: 332
      Abstract: The rates of diabetes throughout the world are rising rapidly, impacting nearly every country. New research is focused on better ways to monitor and treat this disease. Breath acetone levels have been defined as a biomarker for diabetes. The development of a method to monitor and diagnose diabetes utilizing breath acetone levels would provide a fast, easy, and non-invasive treatment option. An ideal material for point-of-care diabetes management would need to have a high response to acetone, high acetone selectivity, low interference from humidity, and be able to operate at room temperature. Chemiresistive gas sensors are a promising method for sensing breath acetone due to their simple fabrication and easy operation. Certain semiconductor materials in chemiresistive sensors can react to acetone in the air and produce changes in resistance that can be correlated with acetone levels. While these materials have been developed and show strong responses to acetone with good selectivity, most of them must operate at high temperatures (compared to RT), causing high power consumption, unstable device operation, and complex device design. In this paper, we systematically studied a series of 2-dimensional MXene-based nanocomposites as the sensing materials in chemiresistive sensors to detect 2.86 ppm of acetone at room temperature. Most of them showed great sensitivity and selectivity for acetone. In particular, the 1D/2D CrWO/Ti3C2 nanocomposite showed the best sensing response to acetone: nine times higher sensitivity than 1D KWO nanowires. To determine the sensing selectivity, a CrWO/Ti3C2 nanocomposite-based sensor was exposed to various common vapors in human breath. The result revealed that it has excellent selectivity for acetone, and far lower responses to other vapors. All these preliminary results indicate that this material is a promising candidate for the creation of a point-of-care diabetes management device.
      Citation: Biosensors
      PubDate: 2022-05-13
      DOI: 10.3390/bios12050332
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 333: A Patient-Ready Wearable Transcutaneous
           CO2 Sensor

    • Authors: Juan Pedro Cascales, Xiaolei Li, Emmanuel Roussakis, Conor L. Evans
      First page: 333
      Abstract: Continuously monitoring transcutaneous CO2 partial pressure is of crucial importance in the diagnosis and treatment of respiratory and cardiac diseases. Despite significant progress in the development of CO2 sensors, their implementation as portable or wearable devices for real-time monitoring remains under-explored. Here, we report on the creation of a wearable prototype device for transcutaneous CO2 monitoring based on quantifying the fluorescence of a highly breathable CO2-sensing film. The developed materials are based on a fluorescent pH indicator (8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt or HPTS) embedded into hydrophobic polymer matrices. The film’s fluorescence is highly sensitive to changes in CO2 partial pressure in the physiological range, as well as photostable and insensitive to humidity. The device and medical-grade films are based on our prior work on transcutaneous oxygen-sensing technology, which has been extensively validated clinically.
      Citation: Biosensors
      PubDate: 2022-05-13
      DOI: 10.3390/bios12050333
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 334: Field-Effect Capacitors Decorated with
           Ligand-Stabilized Gold Nanoparticles: Modeling and Experiments

    • Authors: Arshak Poghossian, Tobias Karschuck, Patrick Wagner, Michael J. Schöning
      First page: 334
      Abstract: Nanoparticles are recognized as highly attractive tunable materials for designing field-effect biosensors with enhanced performance. In this work, we present a theoretical model for electrolyte-insulator-semiconductor capacitors (EISCAP) decorated with ligand-stabilized charged gold nanoparticles. The charged AuNPs are taken into account as additional, nanometer-sized local gates. The capacitance-voltage (C–V) curves and constant-capacitance (ConCap) signals of the AuNP-decorated EISCAPs have been simulated. The impact of the AuNP coverage on the shift of the C–V curves and the ConCap signals was also studied experimentally on Al–p-Si–SiO2 EISCAPs decorated with positively charged aminooctanethiol-capped AuNPs. In addition, the surface of the EISCAPs, modified with AuNPs, was characterized by scanning electron microscopy for different immobilization times of the nanoparticles.
      Citation: Biosensors
      PubDate: 2022-05-13
      DOI: 10.3390/bios12050334
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 335: Functionalization of Glucose Oxidase in
           Organic Solvent: Towards Direct Electrical Communication across
           Enzyme-Electrode Interface

    • Authors: Vygailė Dudkaitė, Gintautas Bagdžiūnas
      First page: 335
      Abstract: Enzymatic biosensors based on glucose oxidase has been proven to be one of the effective strategies for the detection of glucose and contributed to health improvements. Therefore, research and debates to date are ongoing in an attempt to find the most effective way to detect this analyte using this enzyme as the recognition center. The 3rd generation biosensors using direct electron transfer (DET) type enzymes are a great way towards practical devices. In this work, we developed a simple method for the functionalization of glucose oxidase with redoxable ferrocene groups in chloroform. The enzyme retained its activity after storage in this organic solvent and after the functionalization procedures. This enzyme functionalization strategy was employed to develop the biosensing monolayer-based platforms for the detection of glucose utilizing the quasi-DET mechanism. As a result of an electrochemical regeneration of the catalytic center, the formation of harmful H2O2 is minimized during enzymatic electrocatalysis.
      Citation: Biosensors
      PubDate: 2022-05-13
      DOI: 10.3390/bios12050335
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 336: Assessment of Nanoparticle-Mediated Tumor
           Oxygen Modulation by Photoacoustic Imaging

    • Authors: Sivasubramanian, Lo
      First page: 336
      Abstract: Photoacoustic imaging (PAI) is an invaluable tool in biomedical imaging, as it provides anatomical and functional information in real time. Its ability to image at clinically relevant depths with high spatial resolution using endogenous tissues as contrast agents constitutes its major advantage. One of the most important applications of PAI is to quantify tissue oxygen saturation by measuring the differential absorption characteristics of oxy and deoxy Hb. Consequently, PAI can be utilized to monitor tumor-related hypoxia, which is a crucial factor in tumor microenvironments that has a strong influence on tumor invasiveness. Reactive oxygen species (ROS)-based therapies, such as photodynamic therapy, radiotherapy, and sonodynamic therapy, are oxygen-consuming, and tumor hypoxia is detrimental to their efficacy. Therefore, a persistent demand exists for agents that can supply oxygen to tumors for better ROS-based therapeutic outcomes. Among the various strategies, NP-mediated supplemental tumor oxygenation is especially encouraging due to its physio-chemical, tumor targeting, and theranostic properties. Here, we focus on NP-based tumor oxygenation, which includes NP as oxygen carriers and oxygen-generating strategies to alleviate hypoxia monitored by PAI. The information obtained from quantitative tumor oxygenation by PAI not only supports optimal therapeutic design but also serves as a highly effective tool to predict therapeutic outcomes.
      Citation: Biosensors
      PubDate: 2022-05-13
      DOI: 10.3390/bios12050336
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 337: Multilayered Mesoporous Composite
           Nanostructures for Highly Sensitive Label-Free Quantification of Cardiac

    • Authors: Mohsen Saeidi, Mohammad Ali Amidian, Sana Sheybanikashani, Hossein Mahdavi, Homayoon Alimohammadi, Leila Syedmoradi, Fatemeh Mohandes, Ali Zarrabi, Elnaz Tamjid, Kobra Omidfar, Abdolreza Simchi
      First page: 337
      Abstract: Cardiac troponin-I (cTnI) is a well-known biomarker for the diagnosis and control of acute myocardial infarction in clinical practice. To improve the accuracy and reliability of cTnI electrochemical immunosensors, we propose a multilayer nanostructure consisting of Fe3O4-COOH labeled anti-cTnI monoclonal antibody (Fe3O4-COOH-Ab1) and anti-cTnI polyclonal antibody (Ab2) conjugated on Au-Ag nanoparticles (NPs) decorated on a metal–organic framework (Au-Ag@ZIF-67-Ab2). In this design, Fe3O4-COOH was used for separation of cTnI in specimens and signal amplification, hierarchical porous ZIF-67 extremely enhanced the specific surface area, and Au-Ag NPs synergically promoted the conductivity and sensitivity. They were additionally employed as an immobilization platform to enhance antibody loading. Electron microscopy images indicated that Ag-Au NPs with an average diameter of 1.9 ± 0.5 nm were uniformly decorated on plate-like ZIF-67 particles (with average size of 690 nm) without any agglomeration. Several electrochemical assays were implemented to precisely evaluate the immunosensor performance. The square wave voltammetry technique exhibited the best performance with a sensitivity of 0.98 mA mL cm−2 ng−1 and a detection limit of 0.047 pg mL−1 in the linear range of 0.04 to 8 ng mL−1.
      Citation: Biosensors
      PubDate: 2022-05-14
      DOI: 10.3390/bios12050337
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 338: Establishment and Comparative Analysis of
           Enzyme-Linked Immunoassay and Time-Resolved Fluoroimmunoassay for the
           Determination of Trace Quinclorac in Environment

    • Authors: Xue Liu, Xiuzhai Chen, Xu Zhu, Qing Lin, Xi Pan, Xiaolei Tan, Yongfeng Guo, Jun Qiu, Song Fang
      First page: 338
      Abstract: As a common herbicide in farmland, there has been wide concern over quinclorac residue because of its potential risks to the environment and human health. For the detection and monitoring of quinclorac residue in the environment, enzyme-linked immunoassay (ELISA) and time-resolved fluoroimmunoassay (TRFIA) were established. The half-maximal inhibition concentrations (IC50) of ELISA and TRFIA were 0.169 mg/L and 0.087 mg/L with a linear range (IC20-IC80) of 0.020–1.389 mg/L and 0.004–1.861 mg/L, respectively. Compared with ELISA, the limit of detection (LOD, IC20) and IC50 of TRFIA improved approximately 5-fold and 2-fold. The cross-reaction rates for the quinclorac analogs were less than 2%. The average recoveries of quinclorac in river water, paddy water, paddy soil, and brown rice samples were 77.3–106.1%, with RSDs of 1.7–12.5%. More importantly, the results of the two methods were consistent with that of the referenced method of UPLC-MS/MS (R2 > 0.98). ELISA and TRFIA both showed good detection performance and could meet the requirements of the quantitative determination of quinclorac. Therefore, the proposed ELISA and TRFIA could be applied to the rapid and sensitive detection and monitoring of quinclorac residue in the environment.
      Citation: Biosensors
      PubDate: 2022-05-14
      DOI: 10.3390/bios12050338
      Issue No: Vol. 12, No. 5 (2022)
  • Biosensors, Vol. 12, Pages 239: Emerging Methods of Monitoring Volatile
           Organic Compounds for Detection of Plant Pests and Disease

    • Authors: Samantha MacDougall, Fatih Bayansal, Ali Ahmadi
      First page: 239
      Abstract: Each year, unwanted plant pests and diseases, such as Hendel or potato soft rot, cause damage to crops and ecosystems all over the world. To continue to feed the growing population and protect the global ecosystems, the surveillance and management of the spread of these pests and diseases are crucial. Traditional methods of detection are often expensive, bulky and require expertise and training. Therefore, inexpensive, portable, and user-friendly methods are required. These include the use of different gas-sensing technologies to exploit volatile organic compounds released by plants under stress. These methods often meet these requirements, although they come with their own set of advantages and disadvantages, including the sheer number of variables that affect the profile of volatile organic compounds released, such as sensitivity to environmental factors and availability of soil nutrients or water, and sensor drift. Furthermore, most of these methods lack research on their use under field conditions. More research is needed to overcome these disadvantages and further understand the feasibility of the use of these methods under field conditions. This paper focuses on applications of different gas-sensing technologies from over the past decade to detect plant pests and diseases more efficiently.
      Citation: Biosensors
      PubDate: 2022-04-13
      DOI: 10.3390/bios12040239
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 240: Rapid Detection of Deoxynivalenol in Dry
           Pasta Using a Label-Free Immunosensor

    • Authors: Francesca Malvano, Roberto Pilloton, Alfredo Rubino, Donatella Albanese
      First page: 240
      Abstract: This work focused on the development and optimization of an impedimetric label-free immunosensor for detecting deoxynivalenol (DON). A monoclonal antibody for DON detection was immobilized on a modified gold electrode with a cysteamine layer and polyamidoamine (PAMAM) dendrimers. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to monitor the layer-by-layer development of the immunosensor design, while electrochemical impedance spectroscopy and differential pulse voltammetry were employed to investigate the antigen/antibody interaction. The PAMAM dendrimers, allowing to immobilize a large number of monoclonal antibodies, permitted reaching, through the DPV technique, a high sensitivity and a low limit of detection equal to 1 ppb. The evaluation of the possible reuse of the immunosensors highlighted a decrease in the analytical performances of the regenerated immunosensors. After evaluating the matrix effect, the developed immunosensor was used to quantify DON in pasta samples spiked with a known mycotoxin concentration. Taking into consideration the DON extraction procedure used for the pasta samples and the matrix effect related to the sample, the proposed immunosensor showed a limit of detection of 50 ppb, which is lower than the maximum residual limit imposed by European Regulation for DON in dry pasta (750 ppb).
      Citation: Biosensors
      PubDate: 2022-04-13
      DOI: 10.3390/bios12040240
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 241: Novel Screen-Printed Sensor with
           Chemically Deposited Boron-Doped Diamond Electrode: Preparation,
           Characterization, and Application

    • Authors: Oleksandr Matvieiev, Renáta Šelešovská, Marian Vojs, Marián Marton, Pavol Michniak, Vojtěch Hrdlička, Michal Hatala, Lenka Janíková, Jaromíra Chýlková, Jana Skopalová, Petr Cankař, Tomáš Navrátil
      First page: 241
      Abstract: New screen-printed sensor with a boron-doped diamond working electrode (SP/BDDE) was fabricated using a large-area linear antenna microwave chemical deposition vapor system (LA-MWCVD) with a novel precursor composition. It combines the advantages of disposable printed sensors, such as tailored design, low cost, and easy mass production, with excellent electrochemical properties of BDDE, including a wide available potential window, low background currents, chemical resistance, and resistance to passivation. The newly prepared SP/BDDEs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. Their electrochemical properties were investigated by cyclic voltammetry and electrochemical impedance spectroscopy using inner sphere ([Fe(CN)6]4−/3−) and outer sphere ([Ru(NH3)6]2+/3+) redox probes. Moreover, the applicability of these new sensors was verified by analysis of the anti-inflammatory drug lornoxicam in model and pharmaceutical samples. Using optimized differential pulse voltammetry in Britton–Robinson buffer of pH 3, detection limits for lornoxicam were 9 × 10−8 mol L−1. The oxidation mechanism of lornoxicam was investigated using bulk electrolysis and online electrochemical cell with mass spectrometry; nine distinct reaction steps and corresponding products and intermediates were identified.
      Citation: Biosensors
      PubDate: 2022-04-13
      DOI: 10.3390/bios12040241
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 242: Based on Unmodified Aptamer-Gold
           Nanoparticles Colorimetric Detection of Dexamethasone in Food

    • Authors: Yadi Qin, Hayilati Bubiajiaer, Jun Yao, Minwei Zhang
      First page: 242
      Abstract: Residue and illegal addition of Dexamethasone (DEX) in food has received widespread attention over the past few decades. Long-term intake of DEX will have a strong endocrine-disrupting effect, and there is an urgent need to develop highly sensitive and rapid on-site detection methods. In this work, a colorimetric sensor based on an unmodified aptamer and gold nanoparticles (Au NPs) was designed to detect DEX in milk and glucosamine. Under optimized conditions, the absorbance ratio of Au NPs increased linearly with DEX concentration over the range of 10–350 nmol/mL (r2 = 0.997), with a limit of detection (LOD) of 0.5 nmol/mL, and the recoveries ranged from 93.6 to 117%. To explore the interaction mechanism between aptamer and DEX, molecular docking and molecular dynamics simulations were applied to probe intermolecular interactions and structures of the complex. The establishment of aptamer-based sensors effectively avoids the antibody screening response, with a cost-efficient, excellent selective and great potential in DEX determination.
      Citation: Biosensors
      PubDate: 2022-04-14
      DOI: 10.3390/bios12040242
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 243: Fiber-Enhanced Stimulated Raman Scattering
           and Sensitive Detection of Dilute Solutions

    • Authors: Li Guo, Jing Huang, Yaxin Chen, Bohan Zhang, Minbiao Ji
      First page: 243
      Abstract: Stimulated Raman scattering (SRS) is known to gain coherent amplification of molecular vibrations that allow for rapid and label-free chemical imaging in the microscopy setting. However, the tightly focused laser spot has limited the detection sensitivity, partly due to the tiny interaction volume. Here, we report the use of metal-lined hollow-core fiber (MLHCF) to improve the sensitivity of SRS in sensing dilute solutions by extending the light–matter interaction volume through the fiber waveguide. With a focusing lens (100 mm FL) and 320 μm diameter fiber, we demonstrated an optimum enhancement factor of ~20 at a fiber length of 8.3 cm. More importantly, the MLHCF exhibited a significantly suppressed cross-phase modulation (XPM) background, enabling the detection of ~0.7 mM DMSO in water. Furthermore, the relationship between fiber length and SRS signal could be well explained theoretically. The fiber-enhanced SRS (FE-SRS) method may be further optimized and bears potential in the sensitive detection of molecules in the solution and gas phases.
      Citation: Biosensors
      PubDate: 2022-04-14
      DOI: 10.3390/bios12040243
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 244: Graphene-Based Biosensors for Molecular
           Chronic Inflammatory Disease Biomarker Detection

    • Authors: Isidro Badillo-Ramírez, Yojana J. P. Carreón, Claudia Rodríguez-Almazán, Claudia M. Medina-Durán, Selene R. Islas, José M. Saniger
      First page: 244
      Abstract: Chronic inflammatory diseases, such as cancer, diabetes mellitus, stroke, ischemic heart diseases, neurodegenerative conditions, and COVID-19 have had a high number of deaths worldwide in recent years. The accurate detection of the biomarkers for chronic inflammatory diseases can significantly improve diagnosis, as well as therapy and clinical care in patients. Graphene derivative materials (GDMs), such as pristine graphene (G), graphene oxide (GO), and reduced graphene oxide (rGO), have shown tremendous benefits for biosensing and in the development of novel biosensor devices. GDMs exhibit excellent chemical, electrical and mechanical properties, good biocompatibility, and the facility of surface modification for biomolecular recognition, opening new opportunities for simple, accurate, and sensitive detection of biomarkers. This review shows the recent advances, properties, and potentialities of GDMs for developing robust biosensors. We show the main electrochemical and optical-sensing methods based on GDMs, as well as their design and manufacture in order to integrate them into robust, wearable, remote, and smart biosensors devices. We also describe the current application of such methods and technologies for the biosensing of chronic disease biomarkers. We also describe the current application of such methods and technologies for the biosensing of chronic disease biomarkers with improved sensitivity, reaching limits of detection from the nano to atto range concentration.
      Citation: Biosensors
      PubDate: 2022-04-14
      DOI: 10.3390/bios12040244
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 245: Optimization Strategies Used for Boosting
           Piezoelectric Response of Biosensor Based on Flexible Micro-ZnO Composites

    • Authors: Zhang, Villafuerte, Consonni, Sarigiannidou, Capsal, Bruhat, Grinberg, Petit, Cottinet, Le
      First page: 245
      Abstract: Piezoelectric ZnO-based composites have been explored as a flexible and compact sensor for the implantable biomedical systems used in cardio surgery. In this work, a progressive development route was investigated to enhance the performance of piezoelectric composites incorporated with different shape, concentration and connectivity of ZnO fillers. ZnO microrods (MRs) have been successfully synthesized homogeneously in aqueous solution using a novel process-based on chemical bath deposition (CBD) method. The morphological analysis along with Raman scattering and cathodoluminescence spectroscopy of ZnO MRs confirm their high crystalline quality, their orientation along the polar c-axis and the presence of hydrogen-related defects acting as shallow donors in their center. The experimental characterizations highlight that ZnO MR-based composites, with a higher aspect ratio (AR), lead to a significant improvement in the mechanical, dielectric and piezoelectric properties as opposed to the ZnO microparticles (MP) counterparts. The dielectrophoretic (DEP) process is then subjected to both ZnO MP- and MR-based composites, whose performance is expected to be improved as compared to the randomly dispersed composites, thanks to the creation of chain-like structures along the electric field direction. Furthermore, a numerical simulation using COMSOL software is developed to evaluate the influence of the material structuration as well as the filler’s shape on the electric field distribution within different phases (filler, matrix and interface) of the composites. Finally, the aligned MR piezoelectric composites are revealed to be high potential in the development of innovative compact and biocompatible force-sensing devices. Such a technological breakthrough allows the achievement of a real-time precise characterization of mitral valve (MV) coaptation to assist surgeons during MV repair surgery.
      Citation: Biosensors
      PubDate: 2022-04-14
      DOI: 10.3390/bios12040245
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 246: Preparation of Graphene Quantum Dots by
           Visible-Fenton Reaction and Ultrasensitive Label-Free Immunosensor for
           Detecting Lipovitellin of Paralichthys Olivaceus

    • Authors: Ailing Yang, Yue Su, Zhenzhong Zhang, Huaidong Wang, Chong Qi, Shaoguo Ru, Jun Wang
      First page: 246
      Abstract: The increasing levels of environmental estrogens are causing negative effects on water, soil, wildlife, and human beings; label-free immunosensors with high specificities and sensitivities are being developed to test estrogeneous chemicals in complex environmental conditions. For the first time, highly fluorescent graphene quantum dots (GQDs) were prepared using a visible-Fenton catalysis reaction with graphene oxide (GO) as a precursor. Different microscopy and spectroscopy techniques were employed to characterize the physical and chemical properties of the GQDs. Based on the fluorescence resonance energy transfer (FRET) between amino-functionalized GQDs conjugated with anti-lipovitellin monoclonal antibodies (Anti-Lv-mAb) and reduced graphene oxide (rGO), an ultrasensitive fluorescent “ON-OFF” label-free immunosensor for the detection of lipovitellin (Lv), a sensitive biomarker derived from Paralichthys olivaceus for environmental estrogen, has been established. The immunosensor has a wide linear test range (0.001–1500 ng/mL), a lower limit of detection (LOD, 0.9 pg/mL), excellent sensitivity (26,407.8 CPS/(ng/mL)), and high selectivity and reproducibility for Lv quantification. The results demonstrated that the visible-Fenton is a simple, mild, green, efficient, and general approach to fabricating GQDs, and the fluorescent “ON-OFF” immunosensor is an easy-to-use, time-saving, ultrasensitive, and accurate detection method for weak estrogenic activity.
      Citation: Biosensors
      PubDate: 2022-04-15
      DOI: 10.3390/bios12040246
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 247: An iEEG Recording and Adjustable
           Shunt-Current Conduction Platform for Epilepsy Treatment

    • Authors: Changhua You, Lei Yao, Pan Yao, Li Li, Ping Ding, Shuli Liang, Chunxiu Liu, Ning Xue
      First page: 247
      Abstract: This paper proposes a compact bioelectronics sensing platform, including a multi-channel electrode, intracranial electroencephalogram (iEEG) recorder, adjustable galvanometer, and shunt-current conduction circuit pathway. The developed implantable electrode made of polyurethane-insulated stainless-steel materials is capable of recording iEEG signals and shunt-current conduction. The electrochemical impedance of the conduction, ground/reference, and working electrode were characterized in phosphate buffer saline solution, revealing in vitro results of 517.2 Ω@1 kHz (length of 0.1 mm, diameter of 0.8 mm), 1.374 kΩ@1 kHz (length of 0.3 mm, diameter of 0.1 mm), and 3.188 kΩ@1 kHz (length of 0.1 mm, diameter of 0.1 mm), respectively. On-bench measurement of the system revealed that the input noise of the system is less than 2 μVrms, the signal frequency bandwidth range is 1 Hz~10 kHz, and the shunt-current detection range is 0.1~3000 μA with an accuracy of above 99.985%. The electrode was implanted in the CA1 region of the right hippocampus of rats for the in vivo experiments. Kainic acid (KA)-induced seizures were detected through iEEG monitoring, and the induced shunt-current was successfully measured and conducted out of the brain through the designed circuit-body path, which verifies the potential of current conduction for the treatment of epilepsy.
      Citation: Biosensors
      PubDate: 2022-04-15
      DOI: 10.3390/bios12040247
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 248: Colorimetric Sensing of Lactate in Human
           Sweat Using Polyaniline Nanoparticles-Based Sensor Platform and

    • Authors: Hyunjung Kim, Insu Park, Seungpil Pack, Gyudo Lee, Yoochan Hong
      First page: 248
      Abstract: In emergency medicine, the lactate level is commonly used as an indicator of the severity and response to the treatment of hypoperfusion-related diseases. Clinical lactate measurements generally require 3 h for clinical determination. To improve the current gold standard methods, the development of sensor devices that can reduce detection time while maintaining sensitivity and providing portability is gaining great attention. This study aimed to develop a polyaniline (PAni)-based single-sensor platform for sensing lactate in human sweat using a CIELAB color system-based colorimetric device. To establish a lactate sensing platform, PAni nanoparticles were synthesized and adsorbed on the filter paper surface using solvent shift and dip-coating methods, respectively. PAni is characterized by a chemical change accompanied by a color change according to the surrounding environment. To quantify the color change of PAni, a CIELAB color system-based colorimetric device was fabricated. The color change of PAni was measured according to the chemical state using a combination of a PAni-based filter paper sensor platform and a colorimetric device, based on the lactate concentration in deionized water. Finally, human sweat was spiked with lactate to measure the color change of the PAni-based filter paper sensor platform. Under these conditions, the combination of polyaniline-based sensor platforms and colorimetric systems has a limit of detection (LOD) and limit of quantitation (LOQ) of 1 mM, linearity of 0.9684, and stability of 14%. Tbe confirmed that the color of the substrate changes after about 30 s, and through this, the physical fatigue of the individual can be determined. In conclusion, it was confirmed through this study that a combination of the PAni paper sensor platform and colorimeter can detect clinically meaningful lactate concentration.
      Citation: Biosensors
      PubDate: 2022-04-15
      DOI: 10.3390/bios12040248
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 249: A Simple and Universal Nucleic Acid Assay
           Platform Based on Personal Glucose Meter Using SARS-CoV-2 N Gene as the

    • Authors: Tian Li, Rui Pan, Yuhan Wen, Jiaqi Xu, Liping Zhang, Suna He, Gaofeng Liang
      First page: 249
      Abstract: A simple, selective, and quantitative platform for point-of-care diagnostic of COVID-19 is urgently needed as a complement in areas where resources are currently relatively scarce. To meet the needs of early diagnosis and intervention, a proof-of-concept demonstration of a universal personal glucose meter-based nucleic acid assay platform (PGM-NAAP) is presented, which converts to SARS-CoV-2 detection from glucose detection. By using magnetic bead separation together with the hand-held PGM for quantitative readout, PGM-NAAP achieves the 98 pM limit of detection for a sequence related to SARS-CoV-2. The ability to discriminate target nucleic acid from genomic DNA, the satisfactory spike recoveries of saliva and serum samples, as well as the good stability all together suggest the potential of the PGM-NAAP for the screening and diagnosis of suspected patients during the outbreaks of COVID-19 in resource-limited settings without sophisticated instruments. On the basis of these findings, PGM-NAAP can be expected to provide an accurate and convenient path for diagnosis of disease-associated nucleic acid.
      Citation: Biosensors
      PubDate: 2022-04-15
      DOI: 10.3390/bios12040249
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 250: Label-Free Differentiation of Cancer and
           Non-Cancer Cells Based on Machine-Learning-Algorithm-Assisted Fast Raman

    • Authors: Qing He, Wen Yang, Weiquan Luo, Stefan Wilhelm, Binbin Weng
      First page: 250
      Abstract: This paper proposes a rapid, label-free, and non-invasive approach for identifying murine cancer cells (B16F10 melanoma cancer cells) from non-cancer cells (C2C12 muscle cells) using machine-learning-assisted Raman spectroscopic imaging. Through quick Raman spectroscopic imaging, a hyperspectral data processing approach based on machine learning methods proved capable of presenting the cell structure and distinguishing cancer cells from non-cancer muscle cells without compromising full-spectrum information. This study discovered that biomolecular information–nucleic acids, proteins, and lipids—from cells could be retrieved efficiently from low-quality hyperspectral Raman datasets and then employed for cell line differentiation.
      Citation: Biosensors
      PubDate: 2022-04-15
      DOI: 10.3390/bios12040250
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 251: Nanozymes with Multiple Activities:
           Prospects in Analytical Sensing

    • Authors: Xiangheng Niu, Bangxiang Liu, Panwang Hu, Hengjia Zhu, Mengzhu Wang
      First page: 251
      Abstract: Given the superiorities in catalytic stability, production cost and performance tunability over natural bio-enzymes, artificial nanomaterials featuring enzyme-like characteristics (nanozymes) have drawn extensive attention from the academic community in the past decade. With these merits, they are intensively tested for sensing, biomedicine and environmental engineering. Especially in the analytical sensing field, enzyme mimics have found wide use for biochemical detection, environmental monitoring and food analysis. More fascinatingly, rational design enables one fabrication of enzyme-like materials with versatile activities, which show great promise for further advancement of the nanozyme-involved biochemical sensing field. To understand the progress in such an exciting field, here we offer a review of nanozymes with multiple catalytic activities and their analytical application prospects. The main types of enzyme-mimetic activities are first introduced, followed by a summary of current strategies that can be employed to design multi-activity nanozymes. In particular, typical materials with at least two enzyme-like activities are reviewed. Finally, opportunities for multi-activity nanozymes applied in the sensing field are discussed, and potential challenges are also presented, to better guide the development of analytical methods and sensors using nanozymes with different catalytic features.
      Citation: Biosensors
      PubDate: 2022-04-16
      DOI: 10.3390/bios12040251
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 252: A Review on Flexible Electrochemical
           Biosensors to Monitor Alcohol in Sweat

    • Authors: Nuna G. Costa, Joana C. Antunes, Antonio J. Paleo, Ana M. Rocha
      First page: 252
      Abstract: The continued focus on improving the quality of human life has encouraged the development of increasingly efficient, durable, and cost-effective products in healthcare. Over the last decade, there has been substantial development in the field of technical and interactive textiles that combine expertise in electronics, biology, chemistry, and physics. Most recently, the creation of textile biosensors capable of quantifying biometric data in biological fluids is being studied, to detect a specific disease or the physical condition of an individual. The ultimate goal is to provide access to medical diagnosis anytime and anywhere. Presently, alcohol is considered the most commonly used addictive substance worldwide, being one of the main causes of death in road accidents. Thus, it is important to think of solutions capable of minimizing this public health problem. Alcohol biosensors constitute an excellent tool to aid at improving road safety. Hence, this review explores concepts about alcohol biomarkers, the composition of human sweat and the correlation between alcohol and blood. Different components and requirements of a biosensor are reviewed, along with the electrochemical techniques to evaluate its performance, in addition to construction techniques of textile-based biosensors. Special attention is given to the determination of biomarkers that must be low cost and fast, so the use of biomimetic materials to recognize and detect the target analyte is turning into an attractive option to improve electrochemical behavior.
      Citation: Biosensors
      PubDate: 2022-04-16
      DOI: 10.3390/bios12040252
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 253: Nanomaterial-Based Label-Free
           Electrochemical Aptasensors for the Detection of Thrombin

    • Authors: Hibba Yousef, Yang Liu, Lianxi Zheng
      First page: 253
      Abstract: Thrombin plays a central role in hemostasis and its imbalances in coagulation can lead to various pathologies. It is of clinical significance to develop a fast and accurate method for the quantitative detection of thrombin. Electrochemical aptasensors have the capability of combining the specific selectivity from aptamers with the extraordinary sensitivity from electrochemical techniques and thus have attracted considerable attention for the trace-level detection of thrombin. Nanomaterials and nanostructures can further enhance the performance of thrombin aptasensors to achieve high sensitivity, selectivity, and antifouling functions. In highlighting these material merits and their impacts on sensor performance, this paper reviews the most recent advances in label-free electrochemical aptasensors for thrombin detection, with an emphasis on nanomaterials and nanostructures utilized in sensor design and fabrication. The performance, advantages, and limitations of those aptasensors are summarized and compared according to their material structures and compositions.
      Citation: Biosensors
      PubDate: 2022-04-16
      DOI: 10.3390/bios12040253
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 254: Two-Dimensional Quantum Dot-Based
           Electrochemical Biosensors

    • Authors: Jian Zhang, Xiaoyue Zhang, Sai Bi
      First page: 254
      Abstract: Two-dimensional quantum dots (2D-QDs) derived from two-dimensional sheets have received increasing interest owing to their unique properties, such as large specific surface areas, abundant active sites, good aqueous dispersibility, excellent electrical property, easy functionalization, and so on. A variety of 2D-QDs have been developed based on different materials including graphene, black phosphorus, nitrides, transition metal dichalcogenides, transition metal oxides, and MXenes. These 2D-QDs share some common features due to the quantum confinement effects and they also possess unique properties owing to their structural differences. In this review, we discuss the categories, properties, and synthetic routes of these 2D-QDs and emphasize their applications in electrochemical biosensors. We deeply hope that this review not only stimulates more interest in 2D-QDs, but also promotes further development and applications of 2D-QDs in various research fields.
      Citation: Biosensors
      PubDate: 2022-04-17
      DOI: 10.3390/bios12040254
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 255: Application of Self-Assembly Nanoparticles
           Based on DVDMS for Fenton-Like Ion Delivery and Enhanced Sonodynamic

    • Authors: Jinqiang Liu, Shiying Fu, Jiaxuan Xie, Jianzhong Zhang, Jintao Pan, Chengchao Chu, Gang Liu, Shenghong Ju
      First page: 255
      Abstract: Upon harnessing low-intensity ultrasound to activate sonosensitizers, sonodynamic therapy (SDT) induces cancer cell death through the reactive oxygen species (ROS) mediated pathway. Compared with photodynamic therapy (PDT), SDT possesses numerous advantages, including deeper tissue penetration, higher accuracy, fewer side effects, and better patient compliance. Sinoporphyrin sodium (DVDMS), a sonosensitizer approved by the FDA, has drawn abundant attention in clinical research, but there are some deficiencies. In order to further improve the efficiency of DVDMS, many studies have applied self-assembly nanotechnology to modify it. Furthermore, the combined applications of SDT/chemodynamic therapy (CDT) have become a research hotspot in tumor therapy. Therefore, we explored the self-assembly of nanoparticles based on DVDMS and copper to combine SDT and CDT. A cost-effective sonosensitizer was synthesized by dropping CuCl2 into the DVDMS solution with the assistance of PVP. The results revealed that the nanostructures could exert excellent treatment effects on tumor therapy and perform well for PET imaging, indicating the potential for cancer theranostics. In vitro and in vivo experiments showed that the nanoparticles have outstanding biocompatibility, higher ROS production efficiency, and antitumor efficacy. We believe this design can represent a simple approach to combining SDT and CDT with potential applications in clinical treatment and PET imaging.
      Citation: Biosensors
      PubDate: 2022-04-18
      DOI: 10.3390/bios12040255
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 256: Nanomechanical Sensors for Gas Detection
           towards Artificial Olfaction

    • Authors: Kosuke Minami
      First page: 256
      Abstract: Humans, as well as other organisms, tend to recognize their surroundings by smells/odors [...]
      Citation: Biosensors
      PubDate: 2022-04-18
      DOI: 10.3390/bios12040256
      Issue No: Vol. 12, No. 4 (2022)
  • Biosensors, Vol. 12, Pages 257: Target-Specific Exosome Isolation through
           Aptamer-Based Microfluidics

    • Authors: Zixuan Zhou, Yan Chen, Xiang Qian
      First page: 257
      Abstract: Exosomes (30–100 nm in diameter) are a group of cell-derived membrane vesicles, packaged as valuable cargo with lipid, proteins, and genetic materials from their parent cells. With the increasing interest in exosomes for diagnostic and therapeutic applications, the rapid isolation of pure exosome populations has become a hot topic. In this paper, we propose modified microchannels with aptamer in a microfluidics system for rapid and efficient isolation of exosomes by targeting exosome-carrying CD63 and PTK 7. The capture efficiency in surface-modified channels reaches around 107–108 particles/mL in 20 min, and purified exosomes with reliable size can be achieved.
      Citation: Biosensors
      PubDate: 2022-04-18
      DOI: 10.3390/bios12040257
      Issue No: Vol. 12, No. 4 (2022)
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