Subjects -> CHEMISTRY (Total: 1001 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (726 journals)
    - CRYSTALLOGRAPHY (23 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
    - ORGANIC CHEMISTRY (49 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (726 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: 36)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 14)
ACS Catalysis     Hybrid Journal   (Followers: 77)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 25)
ACS Combinatorial Science     Hybrid Journal   (Followers: 25)
ACS Macro Letters     Hybrid Journal   (Followers: 34)
ACS Materials Letters     Open Access   (Followers: 3)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 49)
ACS Nano     Hybrid Journal   (Followers: 448)
ACS Photonics     Hybrid Journal   (Followers: 19)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 40)
Acta Chemica Iasi     Open Access   (Followers: 8)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 4)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 10)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 10)
Adsorption Science & Technology     Open Access   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 81)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 15)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 14)
Advanced Science Focus     Free   (Followers: 7)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 108)
Advances in Chemical Science     Open Access   (Followers: 50)
Advances in Chemistry     Open Access   (Followers: 39)
Advances in Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21)
Advances in Drug Research     Full-text available via subscription   (Followers: 27)
Advances in Environmental Chemistry     Open Access   (Followers: 11)
Advances in Enzyme Research     Open Access   (Followers: 13)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 20)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 35)
Advances in Nanoparticles     Open Access   (Followers: 20)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 20)
Advances in Polymer Science     Hybrid Journal   (Followers: 53)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 22)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7)
Advances in Science and Technology     Full-text available via subscription   (Followers: 17)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 6)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Aggregate     Open Access   (Followers: 3)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 3)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 5)
Alchemy : Jurnal Penelitian Kimia     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 71)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 24)
American Journal of Chemistry     Open Access   (Followers: 41)
American Journal of Plant Physiology     Open Access   (Followers: 13)
Analyst     Full-text available via subscription   (Followers: 40)
Analytical Science Advances     Open Access   (Followers: 2)
Angewandte Chemie     Hybrid Journal   (Followers: 235)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 353)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 8)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 6)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 13)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 12)
Applied Spectroscopy     Full-text available via subscription   (Followers: 27)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 3)
Atomization and Sprays     Full-text available via subscription   (Followers: 8)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 7)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 483)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 3)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 4)
Biomacromolecules     Hybrid Journal   (Followers: 27)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 4)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 214)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 88)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 4)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
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: 26)
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: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 13)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Polymer Technologies and Applications     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 13)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 76)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 13)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 14)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 17)
Cereal Chemistry     Full-text available via subscription   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 11)
Chemical and Engineering News     Free   (Followers: 25)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 88)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 28)
Chemical Physics Letters : X     Open Access   (Followers: 4)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 25)
Chemical Reviews     Hybrid Journal   (Followers: 265)
Chemical Science     Open Access   (Followers: 44)
Chemical Science International Journal     Open Access   (Followers: 1)
Chemical Technology     Open Access   (Followers: 71)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 23)
ChemInform     Hybrid Journal   (Followers: 9)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 224)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 20)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 24)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry Education Research and Practice     Free   (Followers: 8)
Chemistry Education Review     Open Access   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry Letters     Full-text available via subscription   (Followers: 49)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 335)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal  
Chemistry–Methods     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 14)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access   (Followers: 1)
ChemSystemsChem     Hybrid Journal   (Followers: 2)
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: 13)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Ciencia     Open Access   (Followers: 1)
Clay Minerals     Hybrid Journal   (Followers: 9)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 12)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 24)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)

        1 2 3 4 | Last

Similar Journals
Journal Cover
Chemosensors
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2227-9040
Published by MDPI Homepage  [238 journals]
  • Chemosensors, Vol. 9, Pages 86: Construction of a Highly Selective
           Membrane Sensor for the Determination of Cobalt (II) Ions

    • Authors: Sabry Khalil, Mohamed El-Sharnouby
      First page: 86
      Abstract: A highly Co (II) liquid ion-selective electrode depending on the reaction of cobalt ions with the reagent 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl) amino] aniline is successfully fabricated. The characteristic slope (56.66 mV), the linear range response from 3.4 × 10−8 to 2.4 × 10−2 molar, the detection limit (2.7 × 10−8) molar, the selectivity coefficient toward some metal ions, the time of response (10 s), lifetime (seven months), the pH effect on the sensor potential and the basic analytical parameters were studied. The sensor was used to estimate the concentration of cobalt ions in food products and pharmaceutical formulations. The obtained results of the developed sensor were statistically analyzed and compared with those of other different reported electrodes.
      Citation: Chemosensors
      PubDate: 2021-04-21
      DOI: 10.3390/chemosensors9050086
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 87: Thiol-Amine Functionalized Decorated
           Carbon Nanotubes for Biomarker Gases Detection

    • Authors: Atef Thamri, Hamdi Baccar, Juan Casanova-Chafer, Moataz Billeh Mejri, Eduard Llobet, Adnane Abdelghani
      First page: 87
      Abstract: Thousands of gas molecules are expelled in exhaled breath, and some of them can reveal diseases and metabolomic disorders. For that reason, the development of fast, inexpensive, and reliable sensing devices has been attracting growing interest. Here, we present the development of different chemoresistors based on multi-walled carbon nanotubes (MWCNTs) decorated with platinum (MWCNT/Pt) and palladium (MWCNT/Pt) nanoparticles and also functionalized with a self-assembled monolayer (SAM) of 11-amino-1-undecanethiol (Thiol-amine). The nanocomposites developed are a proof-of-concept to detect some biomarker molecules. Specifically, the capability to identify and measure different concentrations of volatile organic compounds (VOCs), either aromatic (toluene and benzene) and non-aromatic (ethanol and methanol) was assessed. As a result, this paper reports the significant differences in sensing performance achieved according to the metal nanoparticle used, and the high sensitivity obtained when SAMs are grown on the sensitive film, acting as a receptor for biomarker vapours.
      Citation: Chemosensors
      PubDate: 2021-04-23
      DOI: 10.3390/chemosensors9050087
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 88: Glassy Carbon Electrode Modified with C/Au
           Nanostructured Materials for Simultaneous Determination of Hydroquinone
           and Catechol in Water Matrices

    • Authors: Samuel Piña, Christian Candia-Onfray, Natalia Hassan, Paola Jara-Ulloa, David Contreras, Ricardo Salazar
      First page: 88
      Abstract: The simultaneous determination of hydroquinone and catechol was conducted in aqueous and real samples by means of differential pulse voltammetry (DPV) using a glassy carbon electrode modified with Gold Nanoparticles (AuNP) and functionalized multiwalled carbon nanotubes by drop coating. A good response was obtained in the simultaneous determination of both isomers through standard addition to samples prepared with analytical grade water and multivariate calibration by partial least squares (PLS) in winery wastewater fortified with HQ and CT from 4.0 to 150.00 µM. A sensitivity of 0.154 µA µM−1 and 0.107 µA µM−1, and detection limits of 4.3 and 3.9 µM were found for hydroquinone and catechol, respectively. We verified the reliability of the developed method by simultaneously screening analytes in spiked tap water and industrial wastewater, achieving recoveries over 80%. In addition, this paper demonstrates the applicability of chemometric tools for the simultaneous quantification of both isomers in real matrices, obtaining prediction errors of lower than 10% in fortified wastewater.
      Citation: Chemosensors
      PubDate: 2021-04-24
      DOI: 10.3390/chemosensors9050088
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 89: Oxidative Free Radicals and Other Species:
           Selective Messengers with a Reactive Capacity for Unselective Tissue
           Damage

    • Authors: Pankaj Vadgama
      First page: 89
      Abstract: Oxygen and nitrogen free radicals (RONS) form an exceptionally reactive molecular assembly within eukaryote cells. This perspective article gives a combined overview of different facets of research covering molecular reactivity, resultant tissue damage and final tissue outcomes as they relate to major disease. There is an emphasis on cardiovascular disease, as the damage processes are best liked to the pathology. The overriding importance of inflammation in driving damage across all tissues is highlighted. Brief coverage is also provided of measurement approaches, respectively for antioxidant status, using potentiometry, and voltammetry for selected target species. Whilst damage due to RONS is a common focus, the fundamental importance of RONS to biological signalling is also covered here as an indispensable basis for life. The article thus provides a global overview of this topic for anyone wishing to understand the current status across multiple fronts.
      Citation: Chemosensors
      PubDate: 2021-04-24
      DOI: 10.3390/chemosensors9050089
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 90: Metallo-Liposomes Derived from the
           [Ru(bpy)3]2+ Complex as Nanocarriers of Therapeutic Agents

    • Authors: Maria Luisa Moyá, Francisco José Ostos, Izamar Moreno, Diandra García, Paula Moreno-Gordillo, Ivan V. Rosado, Pilar López-Cornejo, José Antonio Lebrón, Manuel López-López
      First page: 90
      Abstract: The obtaining of nanocarriers of gene material and small drugs is still an interesting research line. Side-effects produced by the toxicity of several pharmaceutics, the high concentrations needed to get therapeutic effects, or their excessive use by patients have motivated the search for new nanostructures. For these reasons, cationic metallo-liposomes composed by phosphatidylcholine (PC), cholesterol (CHO) and RuC1C19 (a surfactant derived from the metallic complex [Ru(bpy)3]2+) were prepared and characterized by using diverse techniques (zeta potential, dynamic light scattering and electronic transmission microscopy –TEM-). Unimodal or bimodal populations of spherical aggregates with small sizes were obtained depending on the composition of the liposomes. The presence of cholesterol favored the formation of small aggregates. ct-DNA was condensed in the presence of the liposomes investigated. In-vitro assays demonstrated the ability of these nanoaggregates to internalize into different cell lines. A positive gene transfection into human bone osteosarcoma epithelial cells (U2OS) was also observed. The RuC1C19 surfactant was used as sensor to quantify the binding of DNA to the liposomes. Doxorubicin was encapsulated into the metallo-liposomes, demonstrating their ability to be also used as nanocarriers of drugs. A relationship between then encapsulation percentage of the antibiotic and the composition of the aggregates has been established.
      Citation: Chemosensors
      PubDate: 2021-04-25
      DOI: 10.3390/chemosensors9050090
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 91: Analytical Capabilities of Coulometric
           Sensor Systems in the Antioxidants Analysis

    • Authors: Guzel Ziyatdinova, Herman Budnikov
      First page: 91
      Abstract: The definition of antioxidants (AOs), their classification and properties as well as electrochemical sensor systems for AOs analysis are briefly discussed. The analytical capabilities of coulometric titration with electrogenerated titrants as sensor systems for AOs determination have been considered in detail. The attention focused on the individual AO quantification that was mainly used in the pharmaceutical analysis and estimation of total antioxidant parameters (total antioxidant capacity (TAC), ferric reducing power (FRP) and ceric reducing/antioxidant capacity (CRAC)) allowing the fast screening of the target samples including their quality control. The main advantages of coulometric sensor systems are pointed out. The selective quantification of individual AO in a complex matrix using a combination of chromatography with coulometric or coulometric array detection under potentiostatic mode is discussed. The future development of coulometric sensor systems for AOs analysis is focused on the application of novel coulometric titrants and the application of coulometric detection in flow injection analysis.
      Citation: Chemosensors
      PubDate: 2021-04-25
      DOI: 10.3390/chemosensors9050091
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 92: Development of a Tri-Functional Nanoprobe
           for Background-Free SERS Detection of Sialic Acid on the Cell Surface

    • Authors: Septila Renata, Nitish Verma, Zhijay Tu, Rong-Long Pan, Mario Hofmann, Chun-Hung Lin
      First page: 92
      Abstract: Sialic acid (SA) on the surface of cells is indispensable in numerous physiological and pathological processes, and sensitive and reproducible detection of SA is crucial for diagnosis and therapy in many diseases. Here, we developed a tri-functional nanoprobe as a sensitive and straightforward surface-enhanced Raman spectroscopy (SERS) nanoprobe for sialoglycan detection on cell surfaces. The reporter was designed to provide three key functionalities that make it ideal for SA detection. First, we employed two recognition groups, phenylboronic acid and an ammonium group, that enhance SA recognition and capture efficiency. Second, we used cyano as the Raman reporter because it emits in the cellular Raman silent region. Finally, thiol acted as an anchoring agent to conjugate the reporter to silver nanocubes to provide SERS enhancement. Our molecular nanoprobe design demonstrated the ability to detect SA on the cell surface with high sensitivity and spatial resolution, opening up new routes to cellular diagnostics.
      Citation: Chemosensors
      PubDate: 2021-04-26
      DOI: 10.3390/chemosensors9050092
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 93: Helix-Like Receptors for Perrhenate
           Recognition Forming Hydrogen Bonds with All Four Oxygen Atoms

    • Authors: Boris S. Morozov, Anil Ravi, Aleksandr S. Oshchepkov, Tobias Rüffer, Heinrich Lang, Evgeny A. Kataev
      First page: 93
      Abstract: Supramolecular recognition of perrhenate is a challenging task due to therelatively large size and low charge density of this anion. In this work, we design and synthesize a family of helix-like synthetic receptors that can bind perrhenate by forming hydrogen bonds with all four oxygen atoms of the anion. Among the investigated rigid helix-forming subunit derived from 1,1′-ferrocenedicarboxylic acid, 1,3-phenylenediacetic acid and 2,2′-(ethyne-1,2-diyl)dibenzoic acid, the latter one shows the best selectivity for perrhenate recognition. However, the receptor based on 1,1′-ferrocenedicarboxylic acid demonstrates selectivity to bind chloride in a 1:2 fashion. The properties of the receptors are investigated in the acetonitrile solution by using NMR, UV–Vis, and in the solid state by single crystal X-ray analysis.
      Citation: Chemosensors
      PubDate: 2021-04-26
      DOI: 10.3390/chemosensors9050093
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 94: Determination of Trace Levels of
           Nickel(II) by Adsorptive Stripping Voltammetry Using a Disposable and
           Low-Cost Carbon Screen-Printed Electrode

    • Authors: Víctor Padilla, Núria Serrano, José Manuel Díaz-Cruz
      First page: 94
      Abstract: A commercial and disposable screen-printed carbon electrode (SPCE) has been proposed for a fast, simple and low-cost determination of Ni(II) at very low concentration levels by differential pulse adsorptive stripping voltammetry (DPAdSV) in the presence of dimethylglyoxime (DMG) as complexing agent. In contrast with previously proposed methods, the Ni(II)-DMG complex adsorbs directly on the screen-printed carbon surface, with no need of mercury, bismuth or antimony coatings. Well-defined stripping peaks and a linear dependence of the peak area on the concentration of Ni(II) was achieved in the range from 1.7 to 150 µg L−1, with a limit of detection of 0.5 µg L−1 using a deposition time of 120 s. An excellent reproducibility and repeatability with 0.3% (n = 3) and 1.5% (n = 15) relative standard deviation, respectively, were obtained. In addition, the suitability of the SPCE as sensing unit has been successfully assessed in a wastewater certificated reference material with remarkable trueness and very good reproducibility.
      Citation: Chemosensors
      PubDate: 2021-04-26
      DOI: 10.3390/chemosensors9050094
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 95: Low-Cost Inkjet-Printed Temperature
           Sensors on Paper Substrate for the Integration into Natural
           Fiber-Reinforced Lightweight Components

    • Authors: Johanna Zikulnig, Mohammed Khalifa, Lukas Rauter, Herfried Lammer, Jürgen Kosel
      First page: 95
      Abstract: In a unique approach to develop a “green” solution for in-situ monitoring, low-cost inkjet-printed temperature sensors on paper substrate were fully integrated into natural fiber-reinforced lightweight components for which structural health monitoring is becoming increasingly important. The results showed that the sensors remained functional after the vacuum infusion process; furthermore, the integration of the sensors improved the mechanical integrity and stability of the lightweight parts, as demonstrated by tensile testing. To verify the qualification of the printed sensors for the target application, the samples were exposed to varying temperature and humidity conditions inside of a climate chamber. The sensors showed linear temperature dependence in the temperature range of interest (−20 to 60 °C) with a TCR ranging from 1.576 × 10−3 K−1 to 1.713 × 10−3 K−1. Furthermore, the results from the tests in humid environments indicated that the used paper-based sensors could be made almost insensitive to changes in ambient humidity by embedding them into fiber-reinforced lightweight materials. This study demonstrates the feasibility of fully integrating paper-based printed sensors into lightweight components, which paves the way towards integration of other highly relevant sensing devices, such as strain and humidity sensors, for structural health monitoring of smart, sustainable, and environmentally compatible lightweight composite materials.
      Citation: Chemosensors
      PubDate: 2021-04-27
      DOI: 10.3390/chemosensors9050095
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 96: A Paper-Based Potentiometric Platform for
           Determination of Water Hardness

    • Authors: Mohammed L. Bouhoun, Pascal Blondeau, Yamina Louafi, Francisco J. Andrade
      First page: 96
      Abstract: A novel paper-based potentiometric platform for the simple and fast monitoring of water hardness is presented. First, potentiometric ion-selective electrodes for calcium and magnesium printed on a paper substrate were built and optimized. These sensors, which display near-Nernstian sensitivity, were used for the determination of the concentration of these cations and the calculation of the water hardness. Second, the incorporation of a solid-state reference electrode allowed building an integrated paper-based potentiometric cell for the determination of the hardness of artificial and real samples (mineral waters). The validation of the results shows good ability to predict hardness in the conventional scale. Truly decentralized measurements were demonstrated by integration of a miniaturized instrument and dedicated software in a portable device. The measurements were able to be performed in just under two minutes, including a two-point calibration. Since the method is simple to use and cost-effective, it can be implemented in domestic and industrial settings.
      Citation: Chemosensors
      PubDate: 2021-04-28
      DOI: 10.3390/chemosensors9050096
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 97: Rapid and Sensitive Point of Care
           Detection of MRSA Genomic DNA by Nanoelectrokinetic Sensors

    • Authors: Rania Oueslati, Yu Jiang, Jiangang Chen, Jayne Wu
      First page: 97
      Abstract: Biosensors have shown great potential in realizing rapid, low cost, and portable on-site detection for diseases. This work reports the development of a new bioelectronic sensor called AC electrokinetics-based capacitive (ABC) biosensor, for the detection of genomic DNA (gDNA) of methicillin-resistant Staphylococcus aureus (MRSA). The ABC sensor is based on interdigitated microelectrodes biofunctionalized with oligonucleotide probes. It uses a special AC signal for direct capacitive monitoring of topological change on nanostructured sensor surface, which simultaneously induces dielectrophoretic enrichment of target gDNAs. As a result, rapid and specific detection of gDNA/probe hybridization can be realized with high sensitivity. It requires no signal amplification such as labeling, hybridization chain reaction, or nucleic acid sequence-based amplification. This method involves only simple sample preparation. After optimization of nanostructured sensor surface and signal processing, the ABC sensor demonstrated fast turnaround of results (~10 s detection), excellent sensitivity (a detection limit of 4.7 DNA copies/µL MRSA gDNA), and high specificity, suitable for point of care diagnosis. As a bioelectronic sensor, the developed ABC sensors can be easily adapted for detections of other infectious agents.
      Citation: Chemosensors
      PubDate: 2021-04-29
      DOI: 10.3390/chemosensors9050097
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 98: Recent Development in Nanomaterial-Based
           Electrochemical Sensors for Cholesterol Detection

    • Authors: Hemraj Mahipati Yadav, Jong-Deok Park, Hyeong-Cheol Kang, Jae-Joon Lee
      First page: 98
      Abstract: Functional nanomaterials have attracted significant attention in a variety of research fields (in particular, in the healthcare system) because of the easily controllable morphology, their high chemical and environmental stability, biocompatibility, and unique optoelectronic and sensing properties. The sensing properties of nanomaterials can be used to detect biomolecules such as cholesterol. Over the past few decades, remarkable progress has been made in the production of cholesterol biosensors that contain nanomaterials as the key component. In this article, various nanomaterials for the electrochemical sensing of cholesterol were reviewed. Cholesterol biosensors are recognized tools in the clinical diagnosis of cardiovascular diseases (CVDs). The function of nanomaterials in cholesterol biosensors were thoroughly discussed. In this study, different pathways for the sensing of cholesterol with functional nanomaterials were investigated.
      Citation: Chemosensors
      PubDate: 2021-04-29
      DOI: 10.3390/chemosensors9050098
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 99: Advances in Wearable Chemosensors

    • Authors: Panagiota Koralli, Dionysios E. Mouzakis
      First page: 99
      Abstract: In this review, the latest research on wearable chemosensors is presented. In focus are the results from open literature, mainly from the last three years. The progress in wearable chemosensors is presented with attention drawn to the measuring technologies, their ability to provide robust data, the manufacturing techniques, as well their autonomy and ability to produce power. However, from statistical studies, the issue of patients’ trust in these technologies has arisen. People do not trust their personal data be transferred, stored, and processed through the vastness of the internet, which allows for timely diagnosis and treatment. The issue of power consumption and autonomy of chemosensor-integrated devices is also studied and the most recent solutions to this problem thoroughly presented.
      Citation: Chemosensors
      PubDate: 2021-04-29
      DOI: 10.3390/chemosensors9050099
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 100: Electronic Surveillance and Security
           Applications of Magnetic Microwires

    • Authors: Zhukova, Corte-Leon, Blanco, Ipatov, Gonzalez, Zhukov
      First page: 100
      Abstract: Applications in security and electronic surveillance require a combination of excellent magnetic softness with good mechanical and anticorrosive properties and low dimensionality. We overviewed the feasibility of using glass-coated microwires for electronic article surveillance and security applications, as well as different routes of tuning the magnetic properties of individual microwires or microwire arrays, making them quite attractive for electronic article surveillance and security applications. We provide the routes for tuning the hysteresis loops’ nonlinearity by the magnetostatic interaction between the microwires in the arrays of different types of amorphous microwires. The presence of neighboring microwire (either Fe- or Co-based) significantly affects the hysteresis loop of the whole microwires array. In a microwires array containing magnetically bistable microwires, we observed splitting of the initially rectangular hysteresis loop with a number of Barkhausen jumps correlated with the number of magnetically bistable microwires. Essentially, nonlinear and irregular hysteresis loops have been observed in mixed arrays containing Fe- and Co-rich microwires. The obtained nonlinearity in hysteresis loops allowed to increase the harmonics and tune their magnetic field dependencies. On the other hand, several routes allowing to tune the switching field by either postprocessing or modifying the magnetoelastic anisotropy have been reviewed. Nonlinear hysteresis loops have been also observed upon devitrification of amorphous microwires. Semihard magnetic microwires have been obtained by annealing of Fe–Pt–Si microwires. The observed unique combination of magnetic properties together with thin dimensions and excellent mechanical and anticorrosive properties provide excellent perspectives for the use of glass-coated microwires for security and electronic surveillance applications.
      Citation: Chemosensors
      PubDate: 2021-04-30
      DOI: 10.3390/chemosensors9050100
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 101: Progress in Metal-Organic Frameworks
           Facilitated Mercury Detection and Removal

    • Authors: Muthaiah Shellaiah, Kien-Wen Sun
      First page: 101
      Abstract: Metal Organic Frameworks (MOFs) are noted as exceptional candidates towards the detection and removal of specific analytes. MOFs were reported in particular for the detection/removal of environmental contaminants, such as heavy metal ions, toxic anions, hazardous gases, explosives, etc. Among heavy metal ions, mercury has been noted as a global hazard because of its high toxicity in the elemental (Hg0), divalent cationic (Hg2+), and methyl mercury (CH3Hg+) forms. To secure the environment and living organisms, many countries have imposed stringent regulations to monitor mercury at all costs. Regarding the detection/removal requirements of mercury, researchers have proposed and reported all kinds of MOFs-based luminescent/non-luminescent probes towards mercury. This review provides valuable information about the MOFs which have been engaged in detection and removal of elemental mercury and Hg2+ ions. Moreover, the involved mechanisms or adsorption isotherms related to sensors or removal studies are clarified for the readers. Finally, advantages and limitations of MOFs in mercury detection/removal are described together with future scopes.
      Citation: Chemosensors
      PubDate: 2021-05-04
      DOI: 10.3390/chemosensors9050101
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 102: Dual Transduction of H2O2 Detection Using
           ZnO/Laser-Induced Graphene Composites

    • Authors: Julia Zanoni, Jorge P. Moura, Nuno F. Santos, Alexandre F. Carvalho, António J. S. Fernandes, Teresa Monteiro, Florinda M. Costa, Sónia O. Pereira, Joana Rodrigues
      First page: 102
      Abstract: Zinc oxide (ZnO)/laser-induced graphene (LIG) composites were prepared by mixing ZnO, grown by laser-assisted flow deposition, with LIG produced by laser irradiation of a polyimide, both in ambient conditions. Different ZnO:LIG ratios were used to infer the effect of this combination on the overall composite behavior. The optical properties, assessed by photoluminescence (PL), showed an intensity increase of the excitonic-related recombination with increasing LIG amounts, along with a reduction in the visible emission band. Charge-transfer processes between the two materials are proposed to justify these variations. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy evidenced increased electron transfer kinetics and an electrochemically active area with the amount of LIG incorporated in the composites. As the composites were designed to be used as transducer platforms in biosensing devices, their ability to detect and quantify hydrogen peroxide (H2O2) was assessed by both PL and CV analysis. The results demonstrated that both methods can be employed for sensing, displaying slightly distinct operation ranges that allow extending the detection range by combining both transduction approaches. Moreover, limits of detection as low as 0.11 mM were calculated in a tested concentration range from 0.8 to 32.7 mM, in line with the values required for their potential application in biosensors.
      Citation: Chemosensors
      PubDate: 2021-05-05
      DOI: 10.3390/chemosensors9050102
      Issue No: Vol. 9, No. 5 (2021)
       
  • Chemosensors, Vol. 9, Pages 59: Electrochemical Detection of Prostate
           Cancer Biomarker PCA3 Using Specific RNA-Based Aptamer Labelled with
           Ferrocene

    • Authors: Alexei Nabok, Hisham Abu-Ali, Sarra Takita, David P. Smith
      First page: 59
      Abstract: This paper reports on a feasibility study of electrochemical in-vitro detection of prostate cancer biomarker PCA3 (prostate cancer antigen 3) in direct assay with specific RNA aptamer labelled with a redox group (ferrocene) and immobilized on a screen-printed gold electrode surface. The cyclic voltammograms and electrochemical impedance spectroscopy methods yield encouraging results on the detection of PCA3 in a range of concentrations from 1 μg/mL down to 0.1 ng/mL in buffer solutions. Both anodic and cathodic current values in cyclic voltammograms measurements and charge transfer resistance values in electrochemical impedance spectroscopy experiments correlate with the PCA3 concentration in the sample. Kinetics studies of the binding of the PCA3 to our aptamer demonstrated high specificity of the reaction with a characteristic affinity constant of approximately 4·10−10 molar. The results of this work provide a background for the future development of novel, highly sensitive and cost-effective diagnostic methodologies for prostate cancer detection.
      Citation: Chemosensors
      PubDate: 2021-03-24
      DOI: 10.3390/chemosensors9040059
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 60: A Review of Microfluidic Detection
           Strategies for Heavy Metals in Water

    • Authors: Annija Lace, John Cleary
      First page: 60
      Abstract: Heavy metal pollution of water has become a global issue and is especially problematic in some developing countries. Heavy metals are toxic to living organisms, even at very low concentrations. Therefore, effective and reliable heavy metal detection in environmental water is very important. Current laboratory-based methods used for analysis of heavy metals in water require sophisticated instrumentation and highly trained technicians, making them unsuitable for routine heavy metal monitoring in the environment. Consequently, there is a growing demand for autonomous detection systems that could perform in situ or point-of-use measurements. Microfluidic detection systems, which are defined by their small size, have many characteristics that make them suitable for environmental analysis. Some of these advantages include portability, high sample throughput, reduced reagent consumption and waste generation, and reduced production cost. This review focusses on developments in the application of microfluidic detection systems to heavy metal detection in water. Microfluidic detection strategies based on optical techniques, electrochemical techniques, and quartz crystal microbalance are discussed.
      Citation: Chemosensors
      PubDate: 2021-03-24
      DOI: 10.3390/chemosensors9040060
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 61: Silver Inkjet-Printed Electrode on Paper
           for Electrochemical Sensing of Paraquat

    • Authors: Patricia Batista Deroco, Dagwin Wachholz Junior, Lauro Tatsuo Kubota
      First page: 61
      Abstract: The use of fully printed electrochemical devices has gained more attention for the monitoring of clinical, food, and environmental analytes due to their low cost, great reproducibility, and versatility characteristics, serving as an important technology for commercial application. Therefore, a paper-based inkjet-printed electrochemical system is proposed as a cost-effective analytical detection tool for paraquat. Chromatographic paper was used as the printing substrate due its sustainable and disposable characteristics, and an inkjet-printing system deposited the conductive silver ink with no further modification on the paper surface, providing a three-electrode system. The printed electrodes were characterized with scanning electron microscopy, cyclic voltammetry, and chronopotentiometry. The proposed sensor exhibited a large surface area, providing a powerful tool for paraquat detection due to its higher analytical signal. For the detection of paraquat, square-wave voltammetry was used, and the results showed a linear response range of 3.0–100 μM and a detection limit of 0.80 µM, along with the high repeatability and disposability of the sensor. The prepared sensors were also sufficiently selective against interference, and high accuracy (recovery range = 96.7–113%) was obtained when applied to samples (water, human serum, and orange juice), showing the promising applicability of fully printed electrodes for electrochemical monitoring.
      Citation: Chemosensors
      PubDate: 2021-03-25
      DOI: 10.3390/chemosensors9040061
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 62: Bioanalytical Detection of Steroid Abuse
           in Sports Based on the Androgenic Activity Measurement

    • Authors: Pilar Martín-Escudero, Jesus A. Muñoz-Guerra, Soledad Vargas García-Tenorio, Ester Serrano-Garde, Ana Belén Soldevilla-Navarro, Nuria Cortes-Carrillo, Mercedes Galindo-Canales, Nayade del Prado, Manuel Fuentes-Ferrer, Cristina Fernández-Pérez, Peter Alexander Behnisch, Abraham Brouwer
      First page: 62
      Abstract: The anabolic androgenic steroids (AAS) are the most frequently consumed performance enhancing drugs (PED) in sports. In the anti-doping field, the detection of AAS is carried out by the analysis of the athlete’s urine using methodologies based on liquid/gas chromatography-mass spectrometry. Unfortunately, the detection of unknown compounds is not possible. BDS’s AR CALUX® bio detection technology was studied as an indirect method to detect the administration of a single dose of testosterone (T). Twelve T and placebo single dose administered men volunteers underwent a triple-blind crossover clinical trial. The UGT2B17 deletion was present among the volunteers and evenly distributed in heterozygous (ins/del), wild-type homozygous (ins/ins), and mutated homozygous (del/del) groups. A significant statistical difference in terms of bioluminescence was observed after the testosterone (T) administration for the three types of polymorphic groups. The ratio of means between the pre- and post-T administration periods, depending on the type of polymorphism, was in group ins/ins 3.31 (CI. 95%: 2.07–5.29), group ins/del 4.15 (CI 95%: 3.05–5.67), and group del/del 2.89 (CI 95%: 2.42–3.46). The results of the study are very promising, as they may offer us the possibility of designing a detection approach that, based on intra-individual monitoring of androgenic values, in the UGT2B17 deletion type.
      Citation: Chemosensors
      PubDate: 2021-03-26
      DOI: 10.3390/chemosensors9040062
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 63: A Sensitive and Portable Deep-UV
           Absorbance Detector with a Microliter Gas Cell Compatible with Micro GC

    • Authors: Sulaiman Khan, David Newport, Stéphane Le Calvé
      First page: 63
      Abstract: Deep-UV absorption spectrometry for detection of toxic airborne gases, for instance, Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) has drawn considerable attention owing to its high sensitivity and reliability. However, the development of a deep-UV absorbance detector having good sensitivity, portability, and a low-volume gas cell with applicability for a micro Gas Chromatography (μGC) is challenging. Herein we present a novel, self-referenced, and portable deep-UV absorbance detector with a microliter (275 μL) gas cell having minimal dead volume. It has excellent compatibility with μGC for detection of individual BTEX components in a mixed sample at a sub-ppm level. The design consists of the latest, portable, and cost-effective optical and electronic components, i.e., deep-UV LED, hollow-core waveguide, and photodiodes. The detector directly measures the absorbance values in volts using an integrated circuit with a log-ratio amplifier. The prototype was tested with direct injection of toluene-N2 (1.5 ppm to 50 ppm) and good linearity (R2 = 0.99) with a limit of detection of 196 ppb was obtained. The absorbance detector with μGC setup was tested with a BTEX mixture in N2 at different GC column temperatures. All the BTEX species were sequentially separated and detected with an individual peak for a concentration range of 2.5 ppm to 10 ppm.
      Citation: Chemosensors
      PubDate: 2021-03-27
      DOI: 10.3390/chemosensors9040063
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 64: Trends in the Implementation of Advanced
           Plasmonic Materials in Optical Fiber Sensors (2010–2020)

    • Authors: María Elena Martínez-Hernández, Pedro J. Rivero, Javier Goicoechea, Francisco J. Arregui
      First page: 64
      Abstract: In recent years, the interaction between light and metallic films have been proven to be a highly powerful tool for optical sensing applications. We have witnessed the development of highly sensitive commercial devices based on Surface Plasmon Resonances. There has been continuous effort to integrate this plasmonic sensing technology using micro and nanofabrication techniques with the optical fiber sensor world, trying to get better, smaller and cost-effective high performance sensing solutions. In this work, we present a review of the latest and more relevant scientific contributions to the optical fiber sensors field using plasmonic materials over the last decade. The combination of optical fiber technology with metallic micro and nanostructures that allow plasmonic interactions have opened a complete new and promising field of study. We review the main advances in the integration of such metallic micro/nanostructures onto the optical fibers, discuss the most promising fabrication techniques and show the new trends in physical, chemical and biological sensing applications.
      Citation: Chemosensors
      PubDate: 2021-03-27
      DOI: 10.3390/chemosensors9040064
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 65: A Novel Thiosemicarbazide-Based
           Fluorescent Chemosensor for Hypochlorite in Near-Perfect Aqueous Solution
           and Zebrafish

    • Authors: Minji Lee, Donghwan Choe, Soyoung Park, Hyeongjin Kim, Soomin Jeong, Ki-Tae Kim, Cheal Kim
      First page: 65
      Abstract: A novel thiosemicarbazide-based fluorescent sensor (AFC) was developed. It was successfully applied to detect hypochlorite (ClO−) with fluorescence quenching in bis-tris buffer. The limit of detection of AFC for ClO− was analyzed to be 58.7 μM. Importantly, AFC could be employed as an efficient and practical fluorescent sensor for ClO− in water sample and zebrafish. Moreover, AFC showed a marked selectivity to ClO− over varied competitive analytes with reactive oxygen species. The detection process of AFC to ClO− was illustrated by UV–visible and fluorescent spectroscopy and electrospray ionization–mass spectrometry (ESI–MS).
      Citation: Chemosensors
      PubDate: 2021-03-28
      DOI: 10.3390/chemosensors9040065
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 66: Boosting Selectivity and Sensitivity to
           Biomarkers of Quantum Resistive Vapour Sensors Used for Volatolomics with
           Nanoarchitectured Carbon Nanotubes or Graphene Platelets Connected by
           Fullerene Junctions

    • Authors: Sananda Nag, Mickaël Castro, Veena Choudhary, Jean-Francois Feller
      First page: 66
      Abstract: Nanocarbon-based vapour sensors are increasingly used to make anticipated diagnosis of diseases by the analysis of volatile organic compound (VOC) biomarkers from the breath, i.e., volatolomics. However, given the tiny number of molecules to detect, usually only tens of parts per billion (ppb), increasing the sensitivity of polymer nanocomposite chemoresistive transducers is still a challenge. As the ability of these nanosensors to convert the interactions with chemical compounds into changes of resistance, depends on the variations of electronic transport through the percolated network of the conducting nanofillers, it is a key parameter to control. Actually, in this conducting architecture, the bottlenecks for electrons’ circulation are the interparticular junctions giving either ohmic conduction in the case of close contacts or quantum tunnelling when jumps though gaps are necessary. This in turn depends on a number of nanometric parameters such as the size and geometry of the nanofillers (spherical, cylindrical, lamellar), the method of structuring of the conductive architecture in the sensory system, etc. The present study focuses on the control of the interparticular junctions in quantum-resistive vapour sensors (vQRS) by nanoassembling pristine CNT or graphene covalently or noncovalently functionalized with spherical Buckminster fullerene (C60) into a percolated network with a hybrid structure. It is found that this strategy allows us to significantly boost, both selectivity and sensitivity of pristine CNT or graphene-based transducers exposed to a set of seven biomarkers, ethanol, methanol, acetone, chloroform, benzene, toluene, cyclohexane and water. This is assumed to result from the spherical fullerene acting on the electronic transport properties at the nanojunctions between the CNT or graphene nanofillers.
      Citation: Chemosensors
      PubDate: 2021-03-28
      DOI: 10.3390/chemosensors9040066
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 67: Nanodiagnosis and Nanotreatment of
           Cardiovascular Diseases: An Overview

    • Authors: Fakhara Sabir, Mahmood Barani, Mahwash Mukhtar, Abbas Rahdar, Magali Cucchiarini, Muhammad Nadeem Zafar, Tapan Behl, Simona Bungau
      First page: 67
      Abstract: Cardiovascular diseases (CVDs) are the world’s leading cause of mortality and represent a large contributor to the costs of medical care. Although tremendous progress has been made for the diagnosis of CVDs, there is an important need for more effective early diagnosis and the design of novel diagnostic methods. The diagnosis of CVDs generally relies on signs and symptoms depending on molecular imaging (MI) or on CVD-associated biomarkers. For early-stage CVDs, however, the reliability, specificity, and accuracy of the analysis is still problematic. Because of their unique chemical and physical properties, nanomaterial systems have been recognized as potential candidates to enhance the functional use of diagnostic instruments. Nanomaterials such as gold nanoparticles, carbon nanotubes, quantum dots, lipids, and polymeric nanoparticles represent novel sources to target CVDs. The special properties of nanomaterials including surface energy and topographies actively enhance the cellular response within CVDs. The availability of newly advanced techniques in nanomaterial science opens new avenues for the targeting of CVDs. The successful application of nanomaterials for CVDs needs a detailed understanding of both the disease and targeting moieties.
      Citation: Chemosensors
      PubDate: 2021-03-30
      DOI: 10.3390/chemosensors9040067
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 68: A Deferasirox Derivative That Acts as a
           Multifaceted Platform for the Detection and Quantification of Fe3+

    • Authors: Axel Steinbrueck, Adam C. Sedgwick, Suh-Mi Hwang, Sajal Sen, Michael Y. Zhao, Dan-Ying Huang, Daniel M. Knoll, Yu-Ying Wang, Jonathan L. Sessler
      First page: 68
      Abstract: Here, we report that ExSO3H, a synthetically accessible, water-soluble, non-toxic derivative of the clinical iron chelator deferasirox, acts as a colorimetric chemosensor that permits the detection and quantification of Fe3+ in aqueous samples at pH 2–5. In addition, we observed that a fluorescent turn-on response was produced when this chelator was allowed to interact with human serum albumin (HSA). This fluorescence was quenched in the presence of Fe3+, thus allowing us to monitor the presence of this biologically important metal cation via two independent methods.
      Citation: Chemosensors
      PubDate: 2021-03-30
      DOI: 10.3390/chemosensors9040068
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 69: Contribution of Nanomaterials to the
           Development of Electrochemical Aptasensors for the Detection of
           Antimicrobial Residues in Food Products

    • Authors: Valérie Gaudin
      First page: 69
      Abstract: The detection of antimicrobial residues in food products of animal origin is of utmost importance. Indeed antimicrobial residues could be present in animal derived food products because of animal treatments for curative purposes or from illegal use. The usual screening methods to detect antimicrobial residues in food are microbiological, immunological or physico-chemical methods. The development of biosensors to propose sensitive, cheap and quick alternatives to classical methods is constantly increasing. Aptasensors are one of the major trends proposed in the literature, in parallel with the development of immunosensors based on antibodies. The characteristics of electrochemical sensors (i.e., low cost, miniaturization, and portable instrumentation) make them very good candidates to develop screening methods for antimicrobial residues in food products. This review will focus on the recent advances in the development of electrochemical aptasensors for the detection of antimicrobial residues in food products. The contribution of nanomaterials to improve the performance characteristics of electrochemical aptasensors (e.g., Sensitivity, easiness, stability) in the last ten years, as well as signal amplification techniques will be highlighted.
      Citation: Chemosensors
      PubDate: 2021-03-30
      DOI: 10.3390/chemosensors9040069
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 70: Electrospun Fibres of Chitosan/PVP for the
           Effective Chemotherapeutic Drug Delivery of 5-Fluorouracil

    • Authors: Jamie J. Grant, Suresh C. Pillai, Tatiana S. Perova, Sarah Hehir, Steven J. Hinder, Marion McAfee, Ailish Breen
      First page: 70
      Abstract: Electrospun nanofibrous mats consisting of chitosan (CS) and polyvinylpyrrolidone (PVP) were constructed. Tuning of solution and process parameters was performed and resulted in an electrospun system containing a 6:4 ratio of PVP:CS. This is a significant increase in the proportion of spun CS on the previously reported highest ratio PVP:CS blend. SEM analysis showed that the nanofibrous mats with 4 wt% CS/6 wt% PVP (sample E) comprised homogenous, uniform fibres with an average diameter of 0.569 μm. XPS analysis showed that the surface of the samples consisted of PVP. Raman and FTIR analysis revealed intermolecular interactions (via H-bonding) between PVP and CS. In FTIR spectra, the contribution of chitosan to CS/PVP complexes was shown by the downshift of the C=O band and by the linear increase in intensity of C-O stretching in CS. XPS analysis showed a smaller shift at the binding energy 531 eV, which relates to the amide of the acetylated functional groups. The obtained results demonstrate a sensitivity of Raman and FTIR tests to the presence of chitosan in PVP:CS blend. The chemotherapy drug 5-Fu was incorporated into the constructs and cell viability studies were performed. WST-8 viability assay showed that exposure of A549 human alveolar basal epithelial cells to 10 mg/mL 5-Fu loaded fibres was most effective at killing cells over 24 h. On the other hand, the constructs with loading of 1 mg/mL of drug were not efficient at killing A549 human alveolar basal epithelial cells. This study showed that CS/PVP/5-Fu constructs have potential in chemotherapeutic drug delivery systems.
      Citation: Chemosensors
      PubDate: 2021-03-31
      DOI: 10.3390/chemosensors9040070
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 71: Hyperspectral Imaging to Characterize
           Table Grapes

    • Authors: Mario Gabrielli, Vanessa Lançon-Verdier, Pierre Picouet, Chantal Maury
      First page: 71
      Abstract: Table grape quality is of importance for consumers and thus for producers. Its objective quality is usually determined by destructive methods mainly based on sugar content. This study proposed to evaluate the possibility of hyperspectral imaging to characterize table grapes quality through its sugar (TSS), total flavonoid (TF), and total anthocyanin (TA) contents. Different data pre-treatments (WD, SNV, and 1st and 2nd derivative) and different methods were tested to get the best prediction models: PLS with full spectra and then Multiple Linear Regression (MLR) were realized after selecting the optimal wavelengths thanks to the regression coefficients (β-coefficients) and the Variable Importance in Projection (VIP) scores. All models were good at showing that hyperspectral imaging is a relevant method to predict sugar, total flavonoid, and total anthocyanin contents. The best predictions were obtained from optimal wavelength selection based on β-coefficients for TSS and from VIPs optimal wavelength windows using SNV pre-treatment for total flavonoid and total anthocyanin content. Thus, good prediction models were proposed in order to characterize grapes while reducing the data sets and limit the data storage to enable an industrial use.
      Citation: Chemosensors
      PubDate: 2021-04-01
      DOI: 10.3390/chemosensors9040071
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 72: Antioxidant Determination with the Use of
           Carbon-Based Electrodes

    • Authors: Aurelia Magdalena Pisoschi, Aneta Pop, Florin Iordache, Loredana Stanca, Liviu Bilteanu, Andreea Iren Serban
      First page: 72
      Abstract: Antioxidants are compounds that prevent or delay the oxidation process, acting at a much smaller concentration, in comparison to that of the preserved substrate. Primary antioxidants act as scavenging or chain breaking antioxidants, delaying initiation or interrupting propagation step. Secondary antioxidants quench singlet oxygen, decompose peroxides in non-radical species, chelate prooxidative metal ions, inhibit oxidative enzymes. Based on antioxidants’ reactivity, four lines of defense have been described: Preventative antioxidants, radical scavengers, repair antioxidants, and antioxidants relying on adaptation mechanisms. Carbon-based electrodes are largely employed in electroanalysis given their special features, that encompass large surface area, high electroconductivity, chemical stability, nanostructuring possibilities, facility of manufacturing at low cost, and easiness of surface modification. Largely employed methods encompass voltammetry, amperometry, biamperometry and potentiometry. Determination of key endogenous and exogenous individual antioxidants, as well as of antioxidant activity and its main contributors relied on unmodified or modified carbon electrodes, whose analytical parameters are detailed. Recent advances based on modifications with carbon-nanotubes or the use of hybrid nanocomposite materials are described. Large effective surface area, increased mass transport, electrocatalytical effects, improved sensitivity, and low detection limits in the nanomolar range were reported, with applications validated in complex media such as foodstuffs and biological samples.
      Citation: Chemosensors
      PubDate: 2021-04-01
      DOI: 10.3390/chemosensors9040072
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 73: Determination of Uric Acid in Artificial
           Saliva with Compact AMP3291 Reader and Au Nanoparticles Modified Electrode
           

    • Authors: Jessica Piedras, Rocio B. Dominguez, Juan Manuel Gutiérrez
      First page: 73
      Abstract: Uric acid (UA) is a residual product of purines in the body and has been proposed as a valuable biomarker for Diabetes Mellitus, renal disorder, hypertension and preeclampsia. This work presents a sensing platform for nonenzymatic UA detection using a screen-printed electrode modified with gold nanoparticles (SPE-AuNps) operated with the compact and low-cost amperometric reader AMP3291. This laboratory-made instrument was designed using the analog front end LMP91000 and the microcontroller ESP32; the operational parameters like working potential, acquisition time and dynamic measuring range were configured for UA detection. The whole sensing system (AMP3291+ SPE-AuNps) was evaluated for nonenzymatic sensing of UA, showing a fast response time of 3.5 s, a sensitivity of 0.022 μA·μM−1, a linear range from 20 to 200 μM (R2 = 0.993) and a limit of detection of 11.91 μM. Throughout, a piece of commercial equipment was used for validation and noticeably the measurements with the AMP3291-based platform showed improved performance, indicating the feasibility of the developed instrument for UA monitoring and potentially for in situ decentralized applications. Finally, artificial saliva was used as model medium exhibiting interesting analytical parameters, encouraging to consider the reported system as a potentially valuable tool for monitoring UA for clinical applications in resource-limited settings.
      Citation: Chemosensors
      PubDate: 2021-04-07
      DOI: 10.3390/chemosensors9040073
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 74: Amperometric L-Lactate Biosensor Based
           upon a Gold Nanoparticles/Reduced Graphene Oxide/Polyallylamine
           Hydrochloride Modified Screen-Printed Graphite Electrode

    • Authors: Oana-Maria Istrate, Lucian Rotariu, Camelia Bala
      First page: 74
      Abstract: This work describes a novel L-lactate biosensor based on the immobilization of L-lactate dehydrogenase enzyme on the screen-printed electrode modified with a ternary composite based on gold nanoparticles, electrochemically-reduced graphene oxide, and poly (allylamine hydrochloride). The enzyme was stabilized by crosslinking with glutaraldehyde. Applied working potential, pH and NAD+ concentration were optimized. The biosensor reports a specific sensitivity of 1.08 µA/mM·cm2 in a range up to 3 mM L-lactic acid with a detection limit of 1 µM. The operational and long-term stability as well as good selectivity allowed the L-lactic acid measurement in dairy products and wine samples.
      Citation: Chemosensors
      PubDate: 2021-04-08
      DOI: 10.3390/chemosensors9040074
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 75: Visible and Near-Infrared Image
           Acquisition and Fusion for Night Surveillance

    • Authors: Hyuk-Ju Kwon, Sung-Hak Lee
      First page: 75
      Abstract: Image fusion combines images with different information to create a single, information-rich image. The process may either involve synthesizing images using multiple exposures of the same scene, such as exposure fusion, or synthesizing images of different wavelength bands, such as visible and near-infrared (NIR) image fusion. NIR images are frequently used in surveillance systems because they are beyond the narrow perceptual range of human vision. In this paper, we propose an infrared image fusion method that combines high and low intensities for use in surveillance systems under low-light conditions. The proposed method utilizes a depth-weighted radiance map based on intensities and details to enhance local contrast and reduce noise and color distortion. The proposed method involves luminance blending, local tone mapping, and color scaling and correction. Each of these stages is processed in the LAB color space to preserve the color attributes of a visible image. The results confirm that the proposed method outperforms conventional methods.
      Citation: Chemosensors
      PubDate: 2021-04-08
      DOI: 10.3390/chemosensors9040075
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 76: Flexible Potentiometric Sensor System for
           Non-Invasive Determination of Antioxidant Activity of Human Skin:
           Application for Evaluating the Effectiveness of Phytocosmetic Products

    • Authors: Aleksey V. Tarasov, Ekaterina I. Khamzina, Maria A. Bukharinova, Natalia Yu. Stozhko
      First page: 76
      Abstract: In contemporary bioanalysis, monitoring the antioxidant activity (AOA) of the human skin is used to assess stresses, nutrition, cosmetics, and certain skin diseases. Non-invasive methods for skin AOA monitoring have certain advantages over invasive methods, namely cost-effectiveness, lower labor intensity, reduced risk of infection, and obtaining results in the real-time mode. This study presents a new flexible potentiometric sensor system (FPSS) for non-invasive determination of the human skin AOA, which is based on flexible film electrodes (FFEs) and membrane containing a mediator ([Fe(CN)6]3–/4–). Low-cost available materials and scalable technologies were used for FFEs manufacturing. The indicator FFE was fabricated based on polyethylene terephthalate (PET) film and carbon veil (CV) by single-sided hot lamination. The reference FFE was fabricated based on PET film and silver paint by using screen printing, which was followed by the electrodeposition of precipitate containing a mixture of silver chloride and silver ferricyanide (SCSF). The three-electrode configuration of the FPSS, including two indicator FFEs (CV/PET) and one reference FFE (SCSF/Ag/PET), has been successfully used for measuring the skin AOA and evaluating the impact of phytocosmetic products. FPSS provides reproducible (RSD ≤ 7%) and accurate (recovery of antioxidants is almost 100%) results, which allows forecasting its broad applicability in human skin AOA monitoring as well as for evaluating the effectiveness of topically and orally applied antioxidants.
      Citation: Chemosensors
      PubDate: 2021-04-09
      DOI: 10.3390/chemosensors9040076
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 77: Quantitative Determination of the Surface
           Distribution of Supported Metal Nanoparticles: A Laser Ablation–ICP–MS
           Based Approach

    • Authors: Davide Spanu, Gilberto Binda, Marcello Marelli, Laura Rampazzi, Sandro Recchia, Damiano Monticelli
      First page: 77
      Abstract: A laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) based method is proposed for the quantitative determination of the spatial distribution of metal nanoparticles (NPs) supported on planar substrates. The surface is sampled using tailored ablation patterns and the data are used to define three-dimensional functions describing the spatial distribution of NPs. The volume integrals of such interpolated surfaces are calibrated to obtain the mass distribution of Ag NPs by correlation with the total mass of metal as determined by metal extraction and ICP–MS analysis. Once this mass calibration is carried out on a sacrificial sample, quantifications can be performed over multiple samples by a simple micro-destructive LA–ICP–MS analysis without requiring the extraction/dissolution of metal NPs. The proposed approach is here tested using a model sample consisting of a low-density polyethylene (LDPE) disk decorated with silver NPs, achieving high spatial resolution over cm2-sized samples and very high sensitivity. The developed method is accordingly a useful analytical tool for applications requiring both the total mass and the spatial distribution of metal NPs to be determined without damaging the sample surface (e.g., composite functional materials and NPs, decorated catalysts or electrodic materials).
      Citation: Chemosensors
      PubDate: 2021-04-10
      DOI: 10.3390/chemosensors9040077
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 78: Drift Compensation on Massive Online
           Electronic-Nose Responses

    • Authors: Jianhua Cao, Tao Liu, Jianjun Chen, Tao Yang, Xiuxiu Zhu, Hongjin Wang
      First page: 78
      Abstract: Gas sensor drift is an important issue of electronic nose (E-nose) systems. This study follows this concern under the condition that requires an instant drift compensation with massive online E-nose responses. Recently, an active learning paradigm has been introduced to such condition. However, it does not consider the “noisy label” problem caused by the unreliability of its labeling process in real applications. Thus, we have proposed a class-label appraisal methodology and associated active learning framework to assess and correct the noisy labels. To evaluate the performance of the proposed methodologies, we used the datasets from two E-nose systems. The experimental results show that the proposed methodology helps the E-noses achieve higher accuracy with lower computation than the reference methods do. Finally, we can conclude that the proposed class-label appraisal mechanism is an effective means of enhancing the robustness of active learning-based E-nose drift compensation.
      Citation: Chemosensors
      PubDate: 2021-04-11
      DOI: 10.3390/chemosensors9040078
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 79: Application of PEDOT:PSS and Its
           Composites in Electrochemical and Electronic Chemosensors

    • Authors: Nan Gao, Jiarui Yu, Qingyun Tian, Jiangfan Shi, Miao Zhang, Shuai Chen, Ling Zang
      First page: 79
      Abstract: Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a highly important and attractive conducting polymer as well as commercially available in organic electronics, including electrochemical and electronic chemosensors, due to its unique features such as excellent solution-fabrication capability and miscibility, high and controllable conductivity, excellent chemical and electrochemical stability, good optical transparency and biocompatibility. In this review, we present a comprehensive overview of the recent research progress of PEDOT:PSS and its composites, and the application in electrochemical and electronic sensors for detecting liquid-phase or gaseous chemical analytes, including inorganic or organic ions, pH, humidity, hydrogen peroxide (H2O2), ammonia (NH3), CO, CO2, NO2, and organic solvent vapors like methanol, acetone, etc. We will discuss in detail the structural, architectural and morphological optimization of PEDOT:PSS and its composites with other additives, as well as the fabrication technology of diverse sensor systems in response to a wide range of analytes in varying environments. At the end of the review will be given a perspective summary covering both the key challenges and potential solutions in the future research of PEDOT:PSS-based chemosensors, especially those in a flexible or wearable format.
      Citation: Chemosensors
      PubDate: 2021-04-13
      DOI: 10.3390/chemosensors9040079
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 80: Quartz Crystal Microbalance (QCM) Based
           Biosensor Functionalized by HER2/neu Antibody for Breast Cancer Cell
           Detection

    • Authors: Merve Yılmaz, Monireh Bakhshpour, Ilgım Göktürk, Ayşe Kevser Pişkin, Adil Denizli
      First page: 80
      Abstract: The heterogeneity and metastatic features of cancer cells lead to a great number of casualties in the world. Additionally, its diagnosis as well as its treatment is highly expensive. Therefore, development of simple but effective diagnostic systems which detect the molecular markers of cancer is of great importance. The molecular changes on cancer cell membranes serve as targets, such as HER2/neu receptor which is detected on the surface of highly metastatic breast cancer cells. We have aimed to develop a specific and simple quartz crystal microbalance (QCM)-based system to identify HER2/neu expressing breast cancer cells via a receptor-specific monoclonal antibody. First, the QCM chip was coated with polymeric nanoparticles composed of hydroxyethylmethacrylate (HEMA) and ethylene glycol dimethacrylate (EDMA). The nanoparticle coated QCM chip was then functionalized by binding of HER2/neu antibody. The breast cancer cells with/without HER2/neu receptor expression, namely, SKBR3, MDA-MB 231 and also mouse fibroblasts were passed over the chip at a rate of 10–500 cells/mL and the mass changes (Δm) on cell/cm2 unit surface of sensor were detected in real-time. The detection limit of the system was 10 cells/mL. Thus, this QCM-based HER2/neu receptor antibody functionalized system might be used effectively in the detection of HER2/neu expressing SKBR3 breast cancer cells.
      Citation: Chemosensors
      PubDate: 2021-04-14
      DOI: 10.3390/chemosensors9040080
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 81: Efficient Oxidase Biosensors Based on
           Bioelectrocatalytic Surfaces of Electrodeposited Ferrocenyl
           Polycyclosiloxanes—Pt Nanoparticles

    • Authors: Alvaro Boluda, Carmen Casado, Beatriz Alonso, M. García Armada
      First page: 81
      Abstract: The in-situ synthesis of catalytic surfaces with metallic nanoparticles must overcome the issues related to particle aggregation and polydispersity in the particle size. This work achieves it by using two electrodeposited ferrocenyl polycyclosiloxane polymers (MFPP and FPP) as templates for electro-synthesize Pt nanoparticles (PtNPS). In addition, this new electrode surface combines two efficient electrocatalysts: Ferrocene and Pt nanoparticles, with synergistic biocatalytic properties that constitute an electrocatalytic framework for the covalent immobilization of xanthine oxidase. In this work, we present the results of the kinetic, electrochemical and analytical studies of the prepared electrodes. These results showed that the PtNPs/FPP system is the best bioelectrocatalytic surface and improves other more complex xanthine oxidase devices based on the hydrogen peroxide oxidation, allowing the use of lower measuring potential with good sensitivity, wider linear ranges and low detection limits. In addition, this electrode provides the novelty of allowing the measurement of xanthine through the enzymatic consumption of oxygen at potential −0.1 V with a sensitivity of 1.10 A M−1 cm−2, linear ranges of 0.01–0.1 and 0.1–1.4 mM, low detection limit (48 nM) and long-term stability. The new device has been successfully applied to the determination of xanthine in fish meat.
      Citation: Chemosensors
      PubDate: 2021-04-15
      DOI: 10.3390/chemosensors9040081
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 82: Electrochemical Approach to Detection of
           Chlorophene in Water Catalyzed by a Laccase Modified Gold Electrode

    • Authors: Gabriela Elizabeth Quintanilla-Villanueva, Donato Luna-Moreno, Araceli Sánchez-Álvarez, Juan Francisco Villarreal-Chiu, José Manuel Rodríguez-Delgado, Melissa Marlene Rodríguez-Delgado
      First page: 82
      Abstract: Despite the increasing number of reports that relate antimicrobial chlorophene (CP) with health and environmental effects, few studies have addressed biosensing technologies to detect this threat. This work proposed an electrochemical approach for the detection of CP using laccase enzymes as an alternative recognition element immobilized onto thin-film gold electrodes. The electrochemical parameters of the detection method, under controlled conditions, resulted in a limit of detection (0.14 ± 0.06 mg L−1) and quantification (0.48 ± 0.04 mg L−1) that agreed with concentrations of CP that already had been measured in natural water samples. Nevertheless, during the analysis of natural river water samples, the provided method suffered a drawback due to matrix effects reflected in the obtained recovery percentage, the value of which was 62.0 ± 2.4% compared to the 101.3 ± 3.5% obtained by the HPLC reference method. These detrimental effects were mainly attributed to organic matter, SO4-2, and Cl- present in river samples.
      Citation: Chemosensors
      PubDate: 2021-04-16
      DOI: 10.3390/chemosensors9040082
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 83: Microneedle Arrays for Sampling and
           Sensing Skin Interstitial Fluid

    • Authors: Navid Kashaninejad, Ahmed Munaz, Hajar Moghadas, Sharda Yadav, Muhammad Umer, Nam-Trung Nguyen
      First page: 83
      Abstract: Dermal interstitial fluid (ISF) is a novel source of biomarkers that can be considered as an alternative to blood sampling for disease diagnosis and treatment. Nevertheless, in vivo extraction and analysis of ISF are challenging. On the other hand, microneedle (MN) technology can address most of the challenges associated with dermal ISF extraction and is well suited for long-term, continuous ISF monitoring as well as in situ detection. In this review, we first briefly summarise the different dermal ISF collection methods and compare them with MN methods. Next, we elaborate on the design considerations and biocompatibility of MNs. Subsequently, the fabrication technologies of various MNs used for dermal ISF extraction, including solid MNs, hollow MNs, porous MNs, and hydrogel MNs, are thoroughly explained. In addition, different sensing mechanisms of ISF detection are discussed in detail. Subsequently, we identify the challenges and propose the possible solutions associated with ISF extraction. A detailed investigation is provided for the transport and sampling mechanism of ISF in vivo. Also, the current in vitro skin model integrated with the MN arrays is discussed. Finally, future directions to develop a point-of-care (POC) device to sample ISF are proposed.
      Citation: Chemosensors
      PubDate: 2021-04-16
      DOI: 10.3390/chemosensors9040083
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 84: Carboxylated Graphene Nanoribbons for
           Highly-Selective Ammonia Gas Sensors: Ab Initio Study

    • Authors: Pavel V. Barkov, Olga E. Glukhova
      First page: 84
      Abstract: The character and degree of influence of carboxylic acid groups (COOH) on the sensory properties (particularly on the chemoresistive response) of a gas sensor based on zigzag and armchair graphene nanoribbons are shown. Using density functional theory (DFT) calculations, it is found that it is more promising to use a carboxylated zigzag nanoribbon as a sensor element. The chemoresistive response of these nanoribbons is higher than uncarboxylated and carboxylated nanoribbons. It is also revealed that the wet nanoribbon reacts more noticeably to the adsorption of ammonia. In this case, carboxyl groups primarily attract water molecules, which are energetically favorable to land precisely on these regions and then on the nanoribbon’s basal surface. Moreover, the COOH groups with water are adsorption centers for ammonia molecules. That is, the carboxylated zigzag nanoribbon can be the most promising.
      Citation: Chemosensors
      PubDate: 2021-04-18
      DOI: 10.3390/chemosensors9040084
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 85: Metal Nanoparticle and Quantum Dot Tags
           for Signal Amplification in Electrochemical Immunosensors for Biomarker
           Detection

    • Authors: Anton Popov, Benediktas Brasiunas, Asta Kausaite-Minkstimiene, Almira Ramanaviciene
      First page: 85
      Abstract: With the increasing importance of healthcare and clinical diagnosis, as well as the growing demand for highly sensitive analytical instruments, immunosensors have received considerable attention. In this review, electrochemical immunosensor signal amplification strategies using metal nanoparticles (MNPs) and quantum dots (Qdots) as tags are overviewed, focusing on recent developments in the ultrasensitive detection of biomarkers. MNPs and Qdots can be used separately or in combination with other nanostructures, while performing the function of nanocarriers, electroactive labels, or catalysts. Thus, different functions of MNPs and Qdots as well as recent advances in electrochemical signal amplification are discussed. Additionally, the methods most often used for antibody immobilization on nanoparticles, immunoassay formats, and electrochemical methods for indirect biomarker detection are overviewed.
      Citation: Chemosensors
      PubDate: 2021-04-18
      DOI: 10.3390/chemosensors9040085
      Issue No: Vol. 9, No. 4 (2021)
       
  • Chemosensors, Vol. 9, Pages 42: High-Sensitivity pH Sensor Based on
           Coplanar Gate AlGaN/GaN Metal-Oxide-Semiconductor High Electron Mobility
           Transistor

    • Authors: Seong-Kun Cho, Won-Ju Cho
      First page: 42
      Abstract: The sensitivity of conventional ion-sensitive field-effect transistors is limited to the Nernst limit (59.14 mV/pH). In this study, we developed a pH sensor platform based on a coplanar gate AlGaN/GaN metal-oxide-semiconductor (MOS) high electron mobility transistor (HEMT) using the resistive coupling effect to overcome the Nernst limit. For resistive coupling, a coplanar gate comprising a control gate (CG) and a sensing gate (SG) was designed. We investigated the amplification of the pH sensitivity with the change in the magnitude of a resistance connected in series to each CG and SG via Silvaco TCAD simulations. In addition, a disposable extended gate was applied as a cost-effective sensor platform that helped prevent damages due to direct exposure of the AlGaN/GaN MOS HEMT to chemical solutions. The pH sensor based on the coplanar gate AlGaN/GaN MOS HEMT exhibited a pH sensitivity considerably higher than the Nernst limit, dependent on the ratio of the series resistance connected to the CG and SG, as well as excellent reliability and stability with non-ideal behavior. The pH sensor developed in this study is expected to be readily integrated with wide transmission bandwidth, high temperature, and high-power electronics as a highly sensitive biosensor platform.
      Citation: Chemosensors
      PubDate: 2021-02-25
      DOI: 10.3390/chemosensors9030042
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 43: Improving Surface Imprinting Effect by
           Reducing Nonspecific Adsorption on Non-Imprinted Polymer Films for 2,4-D
           Herbicide Sensors

    • Authors: Jin Chul Yang, Suck Won Hong, Jinyoung Park
      First page: 43
      Abstract: Surface imprinting used for template recognition in nanocavities can be controlled and improved by surface morphological changes. Generally, the lithographic technique is used for surface patterning concerning sensing signal amplification in molecularly imprinted polymer (MIP) thin films. In this paper, we describe the effects of silanized silica molds on sensing the properties of MIP films. Porous imprinted poly(MAA–co–EGDMA) films were lithographically fabricated using silanized or non-treated normal silica replica molds to detect 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide as the standard template. The silanized mold MIP film (st-MIP) (Δf = −1021 Hz) exhibited a better sensing response than the non-treated normal MIP (n-MIP) (Δf = −978 Hz) because the imprinting effects, which occurred via functional groups on the silica surface, could be reduced through silane modification. Particularly, two non-imprinted (NIP) films (st-NIP and n-NIP) exhibited significantly different sensing responses. The st-NIP (Δfst-NIP = −332 Hz) films exhibited lower Δf values than the n-NIP film (Δfn-NIP = −610 Hz) owing to the remarkably reduced functionality against nonspecific adsorption. This phenomenon led to different imprinting factor (IF) values for the two MIP films (IFst-MIP = 3.38 and IFn-MIP = 1.86), which was calculated from the adsorbed 2,4-D mass per poly(MAA–co–EGDMA) unit weight (i.e., QMIP/QNIP). Moreover, it was found that the st-MIP film had better selectivity than the n-MIP film based on the sensing response of analogous herbicide solutions. As a result, it was revealed that the patterned molds’ chemical surface modification, which controls the surface functionality of imprinted films during photopolymerization, plays a role in fabricating enhanced sensing properties in patterned MIP films.
      Citation: Chemosensors
      PubDate: 2021-02-26
      DOI: 10.3390/chemosensors9030043
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 44: Diketopyrrolopyrrole Fluorescent Probes,
           Photophysical and Biological Applications

    • Authors: Muhammad Aminu Auwalu, Shanshan Cheng
      First page: 44
      Abstract: Biological applications of fluorescent probes are rapidly increasing in the supramolecular chemistry research field. Several organic dyes are being utilized currently in developing and advancing this attractive research area, of which diketopyrrolopyrrole (DPP) organic dyes show an exceptional photophysical features (high-fluorescence quantum yield (FQY), good photochemical and thermal stability) that are essential properties for biological applications. Great efforts have been made in recent years towards developing novel fluorescent DPPs by different chemists for such applications, and some positive results have been reported. As a result, this review article gives an account of the progress that has so far been made very recently, mainly within the last decade, in that we selectively focus on and discuss more from 2015 to present on some recent scholarly achievements of fluorescent DPPs: quantum yield, aggregation-induced emission (AIE), solid-state emission, bio-imaging, cancer/tumor therapy, mitochondria staining and some polymeric fluorescent DPPs. Finally, this review article highlights researchers working on luminescent DPPs and the future prospects in some key areas towards designing DPP-based fluorescent probes in order to boost their photophysical and biological applications more effectively.
      Citation: Chemosensors
      PubDate: 2021-02-26
      DOI: 10.3390/chemosensors9030044
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 45: Collision of a Positron with the Capture
           of an Electron from Lithium and the Effect of a Magnetic Field on the
           Particles Balance

    • Authors: Elena V. Orlenko, Alexandr V. Evstafev, Fedor E. Orlenko
      First page: 45
      Abstract: The processes of scattering slow positrons with the possible formation of positronium play an important role in the diagnosis of both composite materials, including semiconductor materials, and for the analysis of images obtained by positron tomography of living tissues. In this paper, we consider the processes of scattering positrons with the capture of an electron and the formation of positronium. When calculating the cross-section for the capture reaction, exchange effects caused by the rearrangement of electrons between colliding particles are taken into account. Comparison of the results of calculating the cross-section with a similar problem of electron capture by a proton showed that the mass effect is important in such a collision process. The loss of an electron by a lithium atom is more effective when it collides with a positron than with a proton or alpha particles. The dynamic equilibrium of the formation of positronium in the presence of a strong magnetic field is considered. It is shown that a strong magnetic field during tomography investigation shifts the dynamic equilibrium to the positronium concentration followed by positron annihilation with radiation of three gamma-quants.
      Citation: Chemosensors
      PubDate: 2021-02-27
      DOI: 10.3390/chemosensors9030045
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 46: Determination of Chemical Oxygen Demand
           (COD) Using Nanoparticle-Modified Voltammetric Sensors and Electronic
           Tongue Principles

    • Authors: Qing Wang, Manel del Valle
      First page: 46
      Abstract: This manuscript reports the use of nanoparticle-modified voltammetric sensors for the rapid and green determination of chemical oxygen demand in river waters and waters from agricultural waste. Four different variants of modified electrodes have been prepared: CuO nanoparticles electrogenerated over Cu and covered with Nafion film (CuO/Cu-Nf), and graphite–epoxy composites modified with Cu, CuO, and Cu–Ni alloy nanoparticles. The response features of these electrodes were assessed by calibrating them vs. glucose, glycine, ethyleneglycol, and hydrogenphtalate in alkaline media, as samples providing different difficulty in their (bio)degradation characteristics. The most sensitive electrode was demonstrated to be the (CuO/Cu-Nf) electrode, with an LOD of 12.3 mg O2·L−1. The joint information provided by the sensor array showed the ability of estimating both the organic load and the type of sample in terms of difficulty of degradation, in what can be named an intelligent sensor assembly.
      Citation: Chemosensors
      PubDate: 2021-02-27
      DOI: 10.3390/chemosensors9030046
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 47: A Sensor-Based Methodology to
           Differentiate Pure and Mixed White Tequilas Based on Fused Infrared
           Spectra and Multivariate Data Treatment

    • Authors: Christian Hazael Pérez-Beltrán, Víctor M. Zúñiga-Arroyo, José M. Andrade, Luis Cuadros-Rodríguez, Guadalupe Pérez-Caballero, Ana M. Jiménez-Carvelo
      First page: 47
      Abstract: Mexican Tequila is one of the most demanded import spirits in Europe. Its fast-raising worldwide request makes counterfeiting a profitable activity affecting both consumers and legal distillers. In this paper, a sensor-based methodology based on a combination of infrared measurements (IR) and multivariate data analysis (MVA) is presented. The case study is about differentiating two categories of white Tequila: pure Tequila (or ‘100% agave’) and mixed Tequila (or simply, Tequila). The IR spectra were treated and fused with a low-level approach. Exploratory data analysis was performed using PCA and partial least squares (PLS), whilst the authentication analyses were carried out with PLS-discriminant analysis (DA) and soft independent modeling for class analogy (SIMCA) models. Results demonstrated that data fusion of IR spectra enhanced the outcomes of the authentication models capable of differentiating pure from mixed Tequilas. In fact, PLS-DA presented the best results which correctly classified all fifteen commercial validation samples. The methodology thus presented is fast, cheap, and of simple application in the Tequila industry.
      Citation: Chemosensors
      PubDate: 2021-02-27
      DOI: 10.3390/chemosensors9030047
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 48: Highly Selective Recognition of
           Pyrophosphate by a Novel Coumarin-Iron (III) Complex and the Application
           in Living Cells

    • Authors: Wei Wang, Hongren Zhao, Bing Zhao, Huimin Liu, Qinglei Liu, Yan Gao
      First page: 48
      Abstract: In this paper, a novel NL-Fe3+ ensemble was designed as a fluorescent chemosensor for highly selective detection of pyrophosphate (PPi) in DMSO/H2O (2:8/v:v, pH = 7.2) solution and living cells. NL showed a strong affinity for Fe3+ and was accompanied by obvious fluorescence quenching. Upon the addition of PPi to the generated NL-Fe3+ ensemble, the fluorescence and absorption spectra were recovered completely. Spectroscopic investigation showed that the interference provoked by common anions such as adenosine-triphosphate (ATP), adenosine diphosphate (ADP), and phosphates (Pi) can be ignored. The detection limit of NL-Fe3+ to PPi was calculated to be 1.45 × 10−8 M. Intracellular imaging showed that NL-Fe3+ has good membrane permeability and could be used for the detection of PPi in living cells. A B3LYP/6-31G(d,p) basis set was used to optimize NL and NL-Fe3+ complex.
      Citation: Chemosensors
      PubDate: 2021-02-28
      DOI: 10.3390/chemosensors9030048
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 49: Label-Free Electrochemical Biosensor Based
           on Au@MoS₂–PANI for Escherichia coli Detection

    • Authors: Pushap Raj, Man Hwan Oh, Kyudong Han, Tae Yoon Lee
      First page: 49
      Abstract: Bacterial infections have become a significant challenge in terms of public health, the food industry, and the environment. Therefore, it is necessary to address these challenges by developing a rapid, cost-effective, and easy-to-use biosensor for early diagnosis of bacterial pathogens. Herein, we developed a simple, label-free, and highly sensitive immunosensor based on electrochemical detection using the Au@MoS₂–PANI nanocomposite. The conductivity of the glassy carbon electrode is greatly enhanced using the Au@MoS₂–PANI nanocomposite and a self-assembled monolayer of mercaptopropionic acid on the gold nanoparticle surface was employed for the covalent immobilization of antibodies to minimize the nonspecific adsorption of bacterial pathogens on the electrode surface. The biosensor established a high selectivity and sensitivity with a low limit of detection of 10 CFU/mL, and detected Escherichia coli within 30 min. Moreover, the developed biosensor demonstrated a good linear detection range, practical utility in urine samples, and electrode regenerative studies.
      Citation: Chemosensors
      PubDate: 2021-03-01
      DOI: 10.3390/chemosensors9030049
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 50: Mathematical Modelling of Biosensing
           Platforms Applied for Environmental Monitoring

    • Authors: Ahlem Teniou, Amina Rhouati, Jean-Louis Marty
      First page: 50
      Abstract: In recent years, mathematical modelling has known an overwhelming integration in different scientific fields. In general, modelling is used to obtain new insights and achieve more quantitative and qualitative information about systems by programming language, manipulating matrices, creating algorithms and tracing functions and data. Researchers have been inspired by these techniques to explore several methods to solve many problems with high precision. In this direction, simulation and modelling have been employed for the development of sensitive and selective detection tools in different fields including environmental control. Emerging pollutants such as pesticides, heavy metals and pharmaceuticals are contaminating water resources, thus threatening wildlife. As a consequence, various biosensors using modelling have been reported in the literature for efficient environmental monitoring. In this review paper, the recent biosensors inspired by modelling and applied for environmental monitoring will be overviewed. Moreover, the level of success and the analytical performances of each modelling-biosensor will be discussed. Finally, current challenges in this field will be highlighted.
      Citation: Chemosensors
      PubDate: 2021-03-03
      DOI: 10.3390/chemosensors9030050
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 51: Gas Sensors Based on Copper Oxide
           Nanomaterials: A Review

    • Authors: Stephan Steinhauer
      First page: 51
      Abstract: Metal oxide semiconductors have found widespread applications in chemical sensors based on electrical transduction principles, in particular for the detection of a large variety of gaseous analytes, including environmental pollutants and hazardous gases. This review recapitulates the progress in copper oxide nanomaterial-based devices, while discussing decisive factors influencing gas sensing properties and performance. Literature reports on the highly sensitive detection of several target molecules, including volatile organic compounds, hydrogen sulfide, carbon monoxide, carbon dioxide, hydrogen and nitrogen oxide from parts-per-million down to parts-per-billion concentrations are compared. Physico-chemical mechanisms for sensing and transduction are summarized and prospects for future developments are outlined.
      Citation: Chemosensors
      PubDate: 2021-03-05
      DOI: 10.3390/chemosensors9030051
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 52: Influence of Nitrogen-Doped Carbon Dot and
           Silver Nanoparticle Modified Carbon Paste Electrodes on the Potentiometric
           Determination of Tobramycin Sulfate: A Comparative Study

    • Authors: Nermine V. Fares, Passant M. Medhat, Christine M. El Maraghy, Sherif Okeil, Miriam F. Ayad
      First page: 52
      Abstract: Two inexpensive and simple methods for synthesis of carbon nanodots were applied and compared to each other, namely a hydrothermal and microwave-assisted method. The synthesized carbon nanodots were characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis), photoluminescence (PL), Fourier transform-infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The synthesized microwave carbon nanodots had smaller particle size and were thus chosen for better electrochemical performance. Therefore, they were used for our modification process. The proposed electrodes performance characteristics were evaluated according to the IUPAC guidelines, showing linear response in the concentration range 10−6–10−2, 10−7–10−2, and 10−8–10−2 M of tobramycin with a Nernstian slope of 52.60, 58.34, and 57.32 mV/decade for the bare, silver nanoparticle and carbon nanodots modified carbon paste electrodes, respectively. This developed potentiometric method was used for quantification of tobramycin in its co-formulated dosage form and spiked human plasma with good recovery percentages and without interference of the co-formulated drug loteprednol etabonate and excipients.
      Citation: Chemosensors
      PubDate: 2021-03-07
      DOI: 10.3390/chemosensors9030052
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 53: Preliminary Studies of Perovskite-Loaded
           Plastic Scintillator Prototypes for Radioactive Strontium Detection

    • Authors: Hara Kang, Sujung Min, Bumkyung Seo, Changhyun Roh, Sangbum Hong, Jae Hak Cheong
      First page: 53
      Abstract: Functional plastic scintillators have attracted much attention for their usefulness in on-site monitoring and detection in environments. In this study, we elucidated a highly reliable and functional plastic scintillator for detection of radioactive strontium, which means a potent perovskite-loaded polymeric scintillation material based on epoxy and 2,5-diphenyloxazole (PPO). Moreover, Monte Carlo N-Particle (MCNP) simulation was performed to optimize the thickness of a plastic scintillator for efficient strontium detection. A thickness of 2 mm was found to be the optimum thickness for strontium beta-ray detection. A newly developed plastic scintillator with 430 nm emission from perovskite loading could trigger scintillation enhancement employing potential indication of perovskite energy transfer into a photomultiplier (PMT) detector. Furthermore, the response to beta-ray emitter of 90Sr was compared to commercial scintillator of BC-400 by exhibiting detection efficiency in the energy spectrum with a fabricated perovskite-loaded plastic scintillator. We believe that this suggested functional plastic scintillator could be employed as a radiation detector for strontium detection in a wide range of applications including decommissioning sites in nuclear facilities, nuclear security and monitoring, nonproliferation, and safeguards.
      Citation: Chemosensors
      PubDate: 2021-03-08
      DOI: 10.3390/chemosensors9030053
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 54: Fluorogenic Aptasensors with Small
           Molecules

    • Authors: Eun-Song Lee, Jeong Min Lee, Hea-Jin Kim, Young-Pil Kim
      First page: 54
      Abstract: Aptamers are single-stranded DNA or RNA molecules that can be identified through an iterative in vitro selection–amplification process. Among them, fluorogenic aptamers in response to small molecules have been of great interest in biosensing and bioimaging due to their rapid fluorescence turn-on signals with high target specificity and low background noise. In this review, we report recent advances in fluorogenic aptasensors and their applications to in vitro diagnosis and cellular imaging. These aptasensors modulated by small molecules have been implemented in different modalities that include duplex or molecular beacon-type aptasensors, aptazymes, and fluorogen-activating aptamer reporters. We highlight the working principles, target molecules, modifications, and performance characteristics of fluorogenic aptasensors, and discuss their potential roles in the field of biosensor and bioimaging with future directions and challenges.
      Citation: Chemosensors
      PubDate: 2021-03-10
      DOI: 10.3390/chemosensors9030054
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 55: Integration of Spectral Reflectance
           Indices and Adaptive Neuro-Fuzzy Inference System for Assessing the Growth
           Performance and Yield of Potato under Different Drip Irrigation Regimes

    • Authors: Salah Elsayed, Salah El-Hendawy, Mosaad Khadr, Osama Elsherbiny, Nasser Al-Suhaibani, Yaser Hassan Dewir, Muhammad Usman Tahir, Muhammad Mubushar, Waleed Darwish
      First page: 55
      Abstract: Simultaneous and timely assessment of growth and water status-related plant traits is critical for precision irrigation management in arid regions. Here, we used proximal hyperspectral sensing tools to estimate biomass fresh weight (BFW), biomass dry weight (BDW), canopy water content (CWC), and total tuber yield (TTY) of two potato varieties irrigated with 100%, 75%, and 50% of the estimated crop evapotranspiration (ETc). Plant traits were assessed remotely using published and newly constructed vegetation and water spectral reflectance indices (SRIs). We integrated genetic algorithm (GA) and adaptive neuro-fuzzy inference system (ANFIS) models to predict the measured traits based on all SRIs. The different plant traits and SRIs varied significantly (p < 0.05) between the three irrigation regimes for the two varieties. The values of plant traits and majority SRIs showed a continuous decrease from the 100% ETc to the 50% ETc. Water-SRIs performed better than vegetation-SRIs for estimating the four plant traits. Almost all indices of the two SRI types had a weak relationship with the four plant traits (R2 = 0.00–0.37) under each irrigation regime. However, the majority of vegetation-SRIs and all water-SRIs showed strong relationships with BFW, CWC, and TTY (R2 ≥ 0.65) and moderate relationships with BDW (R2 ≥ 0.40) when the data of all irrigation regimes and varieties were analyzed together for each growing season or the data of all irrigation regimes, varieties, and seasons were combined together. The ANFIS-GA model predicted plant traits with satisfactory accuracy in both calibration (R2 = 1.0) and testing (R2 = 0.72–0.97) modes. The results indicate that SRI-based ANFIS models can improve plant trait estimation. This analysis also confirmed the benefits of applying GA to ANFIS to estimate plant responses to different growth conditions.
      Citation: Chemosensors
      PubDate: 2021-03-12
      DOI: 10.3390/chemosensors9030055
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 56: One-Pot Synthesis of Copper
           Iodide-Polypyrrole Nanocomposites

    • Authors: Artem O. Konakov, Nadejda N. Dremova, Igor I. Khodos, Marcus Koch, Ekaterina V. Zolotukhina, Yuliya E. Silina
      First page: 56
      Abstract: A novel one-pot chemical synthesis of functional copper iodide-polypyrrole composites, CuI-PPy, has been proposed. The fabrication process allows the formation of nanodimensional metal salt/polymer hybrid structures in a fully controlled time- and concentration-dependent manner. The impact of certain experimental conditions, viz., duration of synthesis, sequence of component addition and concentrations of the intact reagents on the structure, dimensionality and yield of the end-product was evaluated in detail. More specifically, the amount of marshite CuI within the hybrid composite can be ranged from 60 to 90 wt.%, depending on synthetic conditions (type and concentration of components, process duration). In addition, the conditions allowing the synthesis of nano-sized CuI distributed inside the polypyrrole matrix were found. A high morphological stability and reproducibility of the synthesized nanodimensional metal-polymer hybrid materials were approved. Finally, the electrochemical activity of the formed composites was verified by cyclic voltammetry studies. The stability of CuI-PPy composite deposited on the electrodes was strongly affected by the applied anodic limit. The proposed one-pot synthesis of the hybrid nanodimensional copper iodide-polypyrrole composites is highly innovative, meets the requirements of Green Chemistry and is potentially useful for future biosensor development. In addition, this study is expected to generally contribute to the knowledge on the hybrid nano-based composites with tailored properties.
      Citation: Chemosensors
      PubDate: 2021-03-16
      DOI: 10.3390/chemosensors9030056
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 57: Biochar from Spent Malt Rootlets and Its
           Application to an Energy Conversion and Storage Device

    • Authors: John Vakros, Ioannis D. Manariotis, Vassilios Dracopoulos, Dionissios Mantzavinos, Panagiotis Lianos
      First page: 57
      Abstract: Activated carbon obtained from biomass wastes was presently studied in order to evaluate its applicability in an energy storage device. Biochar was obtained by the carbonization of spent malt rootlets and was further processed by mild treatment in NaOH. The final product had a specific surface of 362 m2 g−1 and carried Na, P and a few mineral sites. This material was first characterized by several techniques. Then it was used to make a supercapacitor electrode, which reached a specific capacitance of 156 F g−1. The supercapacitor electrode was combined with a photocatalytic fuel cell, making a simple three-electrode device functioning with a single alkaline electrolyte. This device allows solar energy conversion and storage at the same time, promoting the use of biomass wastes for energy applications.
      Citation: Chemosensors
      PubDate: 2021-03-22
      DOI: 10.3390/chemosensors9030057
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 58: Advances in Electromagnetic Piezoelectric
           Acoustic Sensor Technology for Biosensor-Based Detection

    • Authors: Gábor Mészáros, Sanaz Akbarzadeh, Brian De La Franier, Zsófia Keresztes, Michael Thompson
      First page: 58
      Abstract: The ultra-high frequency EMPAS (electromagnetic piezoelectric acoustic sensor) device is composed of an electrode-less quartz disc in which shear oscillation is induced by an AC-powered magnetic coil located 30 μm below the substrate. This configuration allows the instigation of high acoustic harmonics (in the region of 49th–53rd), with the resulting enhanced analytical sensitivity for biosensor purposes compared to the conventional thickness-shear mode device. In this paper, we introduce significant improvements to the operation of the system with respect to sensing applications. This includes a new interface program and the capability to measure the acoustic quality factor not available in the prototype version. The enhanced configuration is subject to testing through biosensor detection of surface adsorption of biological macromolecules, which include β-casein, and a gelsolin-actin complex.
      Citation: Chemosensors
      PubDate: 2021-03-23
      DOI: 10.3390/chemosensors9030058
      Issue No: Vol. 9, No. 3 (2021)
       
  • Chemosensors, Vol. 9, Pages 19: Functionalized Surfaces as a Tool for
           Virus Sensing: A Demonstration of Human mastadenovirus Detection in
           Environmental Waters

    • Authors: Juliana Schons Gularte, Roana de Oliveira Hansen, Meriane Demoliner, Jacek Fiutowski, Ana Karolina Antunes Eisen, Fagner Henrique Heldt, Paula Rodrigues de Almeida, Daniela Müller de Quevedo, Horst-Günter Rubahn, Fernando Rosado Spilki
      First page: 19
      Abstract: The main goal of this study was to apply magnetic bead surface functionalization in the form of immunomagnetic separation (IMS) combined with real-time polymerase chain reaction (qPCR) (IMS-qPCR) to detect Human mastadenovirus species C (HAdV-C) and F (HAdV-F) in water samples. The technique efficiency was compared to a nonfunctionalized method (ultracentrifugation) followed by laboratory detection. Tests were carried out to standardize IMS parameters followed by tests on 15 water samples concentrated by IMS and ultracentrifugation. Microscopic analyses detected a successful beads–antibody attachment. HAdV was detected up to dilutions of 10−6 by IMS-qPCR, and samples concentrated by IMS were able to infect cell cultures. In water samples, HAdV-C was detected in 60% (monoclonal) and 47% (polyclonal) by IMS-qPCR, while 13% of samples concentrated by ultracentrifugation gave a positive result. HAdV-F was positive in 27% of samples by IMS-qPCR (polyclonal) and ultracentrifugation and 20% by IMS-qPCR (monoclonal). The rate of detection varied from 4.55 × 102 to 5.83 × 106 genomic copies/L for IMS-qPCR and from 2.00 × 102 to 2.11 × 103 GC/L for ultracentrifugation. IMS showed to be a more effective concentration technique for HAdV than ultracentrifugation, improving the assessment of infectious HAdV in water resources.
      Citation: Chemosensors
      PubDate: 2021-01-21
      DOI: 10.3390/chemosensors9020019
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 20: Combining Chemical Functionalization and
           FinFET Geometry for Field Effect Sensors as Accessible Technology to
           Optimize pH Sensing

    • Authors: Dipti Rani, Serena Rollo, Wouter Olthuis, Sivashankar Krishnamoorthy, César Pascual García
      First page: 20
      Abstract: Field Effect Transistors (FETs) have led the progress of applications measuring the acidity in aqueous solutions thanks to their accuracy, ease of miniaturization and capacity of multiplexing. The signal-to-noise ratio and linearity of the sensors are two of the most relevant figures of merit that can facilitate the improvements of these devices. In this work we present the functionalization with aminopropyltriethoxysilane (APTES) of a promising new FET design consisting of a high height-to-width aspect ratio with an efficient 2D gating architecture that improves both factors. We measured the transistor transfer and output characteristics before and after APTES functionalization, obtaining an improved sensitivity and linearity in both responses. We also compared the experimental results with a site-biding model of the surface buffering capacity of the APTES functionalized layers.
      Citation: Chemosensors
      PubDate: 2021-01-21
      DOI: 10.3390/chemosensors9020020
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 21: Fabrication of Zinc
           Protoporphyrin-Modified Gold Electrode for Sensitive and Fast Detection of
           Vascular Endothelial Growth Factor

    • Authors: Hung-Yu Lin, Chin-Cheng Liao, Mu-Yi Hua
      First page: 21
      Abstract: Vascular endothelial growth factor (VEGF) is directly related to cancer growth and its distant spread, and thus, it is considered a promising biomarker for diagnosis and post-treatment monitoring of patients with malignancies. Zinc protoporphyrin (ZnPP) is a zinc-centered raw purple compound (protoporphyrin) that has unique optical and electrochemical characteristics. In this study, we used a ZnPP-modified gold electrode to generate a chemical bond with Avastin by self-assembly and fabricate a Au/ZnPP/Avastin electrode. Bovine serum protein (BSA) was added to the electrode to prevent non-specific linkage with biomolecules. The prepared Au/ZnPP/Avastin/BSA electrodes were used for the detection of VEGF by cyclic voltammetry and amperometry. The optical properties of ZnPP were analyzed with an ultraviolet/visible/near-infrared spectrometer and a photoluminescence spectrometer. The structural and hydrophilic/hydrophobic properties of the ZnPP-modified gold electrodes were investigated by Fourier-transform infrared spectroscopy and contact angle gauge, respectively. VEGF was detected with the Au/ZnPP/Avastin/BSA electrodes prepared either with (w/LT) or without light treatment (w/o LT). The w/LT electrode showed a linear range and a sensitivity of 0.1 pg/mL–10 ng/mL and 6.52 μA/log(pg/mL)-cm2, respectively; the corresponding values for the w/o LT electrode were 10 pg/mL–10 ng/mL and 3.15 μA/log(pg/mL)-cm2, respectively. The w/LT electrode had good specificity for VEGF and was minimally influenced by other molecules. The excellent detection range, high sensitivity, and high selectivity for VEGF detection indicate that Au/ZnPP/Avastin electrodes have great potential for diagnostic and prognostic applications in patients with malignancies.
      Citation: Chemosensors
      PubDate: 2021-01-23
      DOI: 10.3390/chemosensors9020021
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 22: Chemosensors Comes of Age

    • Authors: Igor L. Medintz
      First page: 22
      Abstract: It has now been just over eight years since I had the pleasure of introducing Chemosensors to the world [...]
      Citation: Chemosensors
      PubDate: 2021-01-27
      DOI: 10.3390/chemosensors9020022
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 23: A Novel Multi-Ionophore Approach for
           Potentiometric Analysis of Lanthanide Mixtures

    • Authors: Julia Ashina, Vasily Babain, Dmitry Kirsanov, Andrey Legin
      First page: 23
      Abstract: This work aims to discuss quantification of rare earth metals in a complex mixture using the novel multi-ionophore approach based on potentiometric sensor arrays. Three compounds previously tested as extracting agents in reprocessing of spent nuclear fuel were applied as ionophores in polyvinyl chloride (PVC)-plasticized membranes of potentiometric sensors. Seven types of sensors containing these ionophores were prepared and assembled into a sensor array. The multi-ionophore array performance was evaluated in the analysis of Ln3+ mixtures and compared to that of conventional monoionophore sensors. It was demonstrated that a multi-ionophore array can yield RMSEP (root mean-squared error of prediction) values not exceeding 0.15 logC for quantification of individual lanthanides in binary mixtures in a concentration range 5 to 3 pLn3+.
      Citation: Chemosensors
      PubDate: 2021-01-27
      DOI: 10.3390/chemosensors9020023
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 24: Gold-Platinum Core-Shell Nanoparticles
           with Thiolated Polyaniline and Multi-Walled Carbon Nanotubes for the
           Simultaneous Voltammetric Determination of Six Drug Molecules

    • Authors: Shaopei Li, Jiayun Zhou, Meissam Noroozifar, Kagan Kerman
      First page: 24
      Abstract: In this proof-of-concept study, a novel nanocomposite of the thiolated polyaniline (tPANI), multi-walled carbon nanotubes (MWCNTs) and gold–platinum core-shell nanoparticles (Au@Pt) (tPANI-Au@Pt-MWCNT) was synthesized and utilized to modify a glassy carbon electrode (GCE) for simultaneous voltammetric determination of six over-the-counter (OTC) drug molecules: ascorbic acid (AA), levodopa (LD), acetaminophen (AC), diclofenac (DI), acetylsalicylic acid (AS) and caffeine (CA). The nanocomposite (tPANI-Au@Pt-MWCNT) was characterized with transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Using the sensor (GCE-tPANI-Au@Pt-MWCNT) in connection with differential pulse voltammetry (DPV), the calibration plots were determined to be linear up to 570.0, 60.0, 60.0, 115.0, 375.0 and 520.0 µM with limit of detection (LOD) of 1.5, 0.25, 0.15, 0.2, 2.0, and 5.0 µM for AA, LD, AC, DI, AS and CA, respectively. The nanocomposite-modified sensor was successfully used for the determination of these redox-active compounds in commercially available OTC products such as energy drinks, cream and tablets with good recovery yields ranging from 95.48 ± 0.53 to 104.1 ± 1.63%. We envisage that the electrochemical sensor provides a promising platform for future applications towards the detection of redox-active drug molecules in pharmaceutical quality control studies and forensic investigations.
      Citation: Chemosensors
      PubDate: 2021-01-28
      DOI: 10.3390/chemosensors9020024
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 25: Carbon Dots Fluorescence-Based
           Colorimetric Sensor for Sensitive Detection of Aluminum Ions with a
           Smartphone

    • Authors: Wei Wei, Juan Huang, Wenli Gao, Xiangyang Lu, Xingbo Shi
      First page: 25
      Abstract: In this work, blue emission carbon dots (CDs) are synthesized in the one-pot solvothermal method using naringin as precursor. The CDs are used to develop a ratiometric fluorescence sensor for the sensitive analysis of Al3+ with a detection limit of 113.8 nM. A fluorescence emission peak at 500 nm gradually appears, whereas the original fluorescence peak at 420 nm gradually decreases upon the increase in the Al3+ concentration. More importantly, the obvious color change of the CDs probe from blue to green under a 360 nm UV lamp can be identified by a smartphone and combined with the RGB (red/green/blue) analysis. This results in a visual and sensitive analysis of Al3+ with a detection limit of 5.55 μM. Moreover, the high recovery is in the 92.46–104.10% range, which demonstrates the high accuracy of this method for actual samples’ analysis. The use of a smartphone and the RGB analysis greatly simplifies the operation process, saves equipment cost, shortens the detection time, and provides a novel method for the instant, on-site, visual detection of Al3+ in actual samples.
      Citation: Chemosensors
      PubDate: 2021-01-29
      DOI: 10.3390/chemosensors9020025
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 26: Development of an ImmunoFET for Analysis
           of Tumour Necrosis Factor-α in Artificial Saliva: Application for Heart
           Failure Monitoring

    • Authors: Daiva Vozgirdaite, Hamdi Ben Halima, Francesca G. Bellagambi, Albert Alcacer, Francisio Palacio, Nicole Jaffrezic-Renault, Nadia Zine, Joan Bausells, Abdelhamid Elaissari, Abdelhamid Errachid
      First page: 26
      Abstract: Assessing tumour necrosis factor-α (TNF-α) levels in the human body has become an essential tool to recognize heart failure (HF). In this work, label-free, rapid, easy to use ImmunoFET based on an ion-sensitive field effect transistor (ISFET) was developed for the detection of TNF-α protein. Monoclonal anti-TNF-α antibodies (anti-TNF-α mAb) were immobilized on an ISFET gate made of silicon nitride (Si3N4) after salinization with 11-(triethoxysilyl) undecanal (TESUD). The obtained ISFET functionalized with the mAbs (ImmunoFET) was used to detect TNF-α protein in both phosphate buffer saline (PBS) and artificial saliva (AS). The change in the threshold voltage of the gate (∆VT) showed approximately linear dependency on the concentration of the antigens in the range 5–20 pg/mL for both matrixes. The cross-selectivity study showed that the developed ImmunoFET demonstrated to be selective towards TNF-α, when compared to other HF biomarkers such as N-terminal pro-brain natriuretic peptide (NT-proBNP), interleukin-10 (IL-10), and cortisol, even if further experiments have to be carried out for decreasing possible unspecific absorption phenomena. To the best of our knowledge, this is the first ImmunoFET that has been developed based on Si3N4 for TNF-α detection in AS by electrical measurement.
      Citation: Chemosensors
      PubDate: 2021-01-29
      DOI: 10.3390/chemosensors9020026
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 27: Optimization of ZnO Nanorods Concentration
           in a Micro-Structured Polymeric Composite for Nanogenerators

    • Authors: Andreia dos Santos, Filipe Sabino, Ana Rovisco, Pedro Barquinha, Hugo Águas, Elvira Fortunato, Rodrigo Martins, Rui Igreja
      First page: 27
      Abstract: The growing use of wearable devices has been stimulating research efforts in the development of energy harvesters as more portable and practical energy sources alternatives. The field of piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), especially employing zinc oxide (ZnO) nanowires (NWs), has greatly flourished in recent years. Despite its modest piezoelectric coefficient, ZnO is very attractive due to its sustainable raw materials and the facility to obtain distinct morphologies, which increases its multifunctionality. The integration of ZnO nanostructures into polymeric matrices to overcome their fragility has already been proven to be fruitful, nevertheless, their concentration in the composite should be optimized to maximize the harvesters’ output, an aspect that has not been properly addressed. This work studies a composite with variable concentrations of ZnO nanorods (NRs), grown by microwave radiation assisted hydrothermal synthesis, and polydimethylsiloxane (PDMS). With a 25 wt % ZnO NRs concentration in a composite that was further micro-structured through laser engraving for output enhancement, a nanogenerator (NG) was fabricated with an output of 6 V at a pushing force of 2.3 N. The energy generated by the NG could be stored and later employed to power small electronic devices, ultimately illustrating its potential as an energy harvesting device.
      Citation: Chemosensors
      PubDate: 2021-01-31
      DOI: 10.3390/chemosensors9020027
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 28: Quantification of Pharmaceutical
           Bitterness Using a Membrane Electrode Based on a Hydrophobic Tetrakis
           [3,5-Bis (trifluoromethyl) phenyl] Borate

    • Authors: Xiao Wu, Takeshi Shiino, Yusuke Tahara, Hidekazu Ikezaki, Kiyoshi Toko
      First page: 28
      Abstract: Technologies for quantifying bitterness are essential for classifying medicines. As previously reported, taste sensors with lipid polymer membranes can respond to bitter hydrochloride substances in pharmaceuticals. However, the acid hydrolysis reaction between the lipid phosphoric acid di-n-decyl ester (PADE) and the plasticizer tributyl o-acetylcitrate (TDAB) led to a deterioration in sensor responses during storage. Given the cost of transportation and preservation for commercialization, membrane components that maintain physical and chemical stability during long-term storage are needed. Here we present a membrane electrode based on hydrophobic tetrakis [3,5-bis (trifluoromethyl) phenyl] borate (TFPB) and a plasticizer 2-nitrophenyl octyl ether (NPOE) for the quantification of pharmaceutical bitterness; they maintain a stable response before and after accelerated deterioration, as well as high selectivity and sensitivity. It is a first attempt to use a completely dissociative substance to replace non-completely dissociative lipids. Our work offsets the long-term stability issue of a bitterness sensor with a negatively charged hydrophobic membrane. Meanwhile, we provide the opportunity to select surface charge modifiers for a membrane surface using ester plasticizers containing oppositely charged impurities.
      Citation: Chemosensors
      PubDate: 2021-01-31
      DOI: 10.3390/chemosensors9020028
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 29: Quantitative Fiber-Enhanced Raman Sensing
           of Inorganic Nitrogen Species in Water

    • Authors: Hugo Kerdoncuff, Lisa C. Deleebeeck, Mikael Lassen
      First page: 29
      Abstract: Fast and efficient water quality monitoring is essential in the pursuit of reducing the impact of human activities on the environment. We address this issue by presenting a sensing system and method based on Raman spectroscopy in liquid-filled capillaries, that enables quantitative measurement of polyatomic anions in solution. We demonstrate quantitative measurement of nitrate concentrations in water via multivariate analysis with partial least squares regression. We achieve a limit of detection of 0.13 millimolar for a measurement time of 30 s. Our Raman method is compared with gravimetrically measured concentration with good agreement and reproducibility. The Raman monitoring method can be performed in a continuous manner, thus suitable for fast continuous monitoring of water and wastewater quality.
      Citation: Chemosensors
      PubDate: 2021-01-31
      DOI: 10.3390/chemosensors9020029
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 30: Recent Advances in Perylene Diimide-Based
           Active Materials in Electrical Mode Gas Sensing

    • Authors: Salman Ali, Akhil Gupta, Mahnaz Shafiei, Steven J. Langford
      First page: 30
      Abstract: This review provides an update on advances in the area of electrical mode sensors using organic small molecule n-type semiconductors based on perylene. Among small organic molecules, perylene diimides (PDIs) are an important class of materials due to their outstanding thermal, chemical, electronic, and optical properties, all of which make them promising candidates for a wide range of organic electronic devices including sensors, organic solar cells, organic field-effect transistors, and organic light-emitting diodes. This is mainly due to their electron-withdrawing nature and significant charge transfer properties. Perylene-based sensors of this type show high sensing performance towards various analytes, particularly reducing gases like ammonia and hydrazine, but there are several issues that need to be addressed including the selectivity towards a specific gas, the effect of relative humidity, and operating temperature. In this review, we focus on the strategies and design principles applied to the gas-sensing performance of PDI-based devices, including resistive sensors, amperometric sensors, and operating at room temperature. The device properties and sensing mechanisms for different analytes, focusing on hydrazine and ammonia, are studied in detail, and some future research perspectives are discussed for this promising field. We hope the discussed results and examples inspire new forms of molecular engineering and begin to open opportunities for other rylene diimide classes to be applied as active materials.
      Citation: Chemosensors
      PubDate: 2021-02-01
      DOI: 10.3390/chemosensors9020030
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 31: Identification of Mint Scents Using a QCM
           Based E-Nose

    • Authors: Salih Okur, Mohammed Sarheed, Robert Huber, Zejun Zhang, Lars Heinke, Adnan Kanbar, Christof Wöll, Peter Nick, Uli Lemmer
      First page: 31
      Abstract: Mints emit diverse scents that exert specific biological functions and are relevance for applications. The current work strives to develop electronic noses that can electronically discriminate the scents emitted by different species of Mint as alternative to conventional profiling by gas chromatography. Here, 12 different sensing materials including 4 different metal oxide nanoparticle dispersions (AZO, ZnO, SnO2, ITO), one Metal Organic Frame as Cu(BPDC), and 7 different polymer films, including PVA, PEDOT:PSS, PFO, SB, SW, SG, and PB were used for functionalizing of Quartz Crystal Microbalance (QCM) sensors. The purpose was to discriminate six economically relevant Mint species (Mentha x piperita, Mentha spicata, Mentha spicata ssp. crispa, Mentha longifolia, Agastache rugosa, and Nepeta cataria). The adsorption and desorption datasets obtained from each modified QCM sensor were processed by three different classification models, including Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and k-Nearest Neighbor Analysis (k-NN). This allowed discriminating the different Mints with classification accuracies of 97.2% (PCA), 100% (LDA), and 99.9% (k-NN), respectively. Prediction accuracies with a repeating test measurement reached up to 90.6% for LDA, and 85.6% for k-NN. These data demonstrate that this electronic nose can discriminate different Mint scents in a reliable and efficient manner.
      Citation: Chemosensors
      PubDate: 2021-02-04
      DOI: 10.3390/chemosensors9020031
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 32: Silica Layer Used in Sensor Fabrication
           from a Low-Temperature Silane-Free Procedure

    • Authors: Pei-Cheng Jiang, Yu-Ting Chow, Chi-Wei Chien, Cheng-Hsun-Tony Chang, Chii-Ruey Lin
      First page: 32
      Abstract: Silica (SiO2, silicon dioxide—a dielectric layer commonly used in electronic devices) is widely used in many types of sensors, such as gas, molecular, and biogenic polyamines. To form silica films, core shell or an encapsulated layer, silane has been used as a precursor in recent decades. However, there are many hazards caused by using silane, such as its being extremely flammable, the explosive air, and skin and eye pain. To avoid these hazards, it is necessary to spend many resources on industrial safety design. Thus, the silica synthesized without silane gas which can be determined as a silane-free procedure presents a clean and safe solution to manufactures. In this report, we used the radio frequency (rf = 13.56 MHz) plasma-enhanced chemical vapor deposition technique (PECVD) to form a silica layer at room temperature. The silica layer is formed in hydrogen-based plasma at room temperature and silane gas is not used in this process. The substrate temperature dominates the silica formation, but the distance between the substrate and electrode (DSTE) and the methane additive can enhance the formation of a silica layer on the Si wafer. This silane-free procedure, at room temperature, is not only safer and friendlier to the environment but is also useful in the fabrication of many types of sensors.
      Citation: Chemosensors
      PubDate: 2021-02-04
      DOI: 10.3390/chemosensors9020032
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 33: Recent Advances in Optical,
           Electrochemical and Field Effect pH Sensors

    • Authors: Federico Vivaldi, Pietro Salvo, Noemi Poma, Andrea Bonini, Denise Biagini, Lorenzo Del Noce, Bernardo Melai, Fabio Lisi, Fabio Di Francesco
      First page: 33
      Abstract: Although its first definition dates back to more than a century ago, pH and its measurement are still studied for improving the performance of current sensors in everyday analysis. The gold standard is the glass electrode, but its intrinsic fragility and need of frequent calibration are pushing the research field towards alternative sensitive devices and materials. In this review, we describe the most recent optical, electrochemical, and transistor-based sensors to provide an overview on the status of the scientific efforts towards pH sensing.
      Citation: Chemosensors
      PubDate: 2021-02-05
      DOI: 10.3390/chemosensors9020033
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 34: Nanocrystalline Oxides NixCo3−xO4:
           Sub-ppm H2S Sensing and Humidity Effect

    • Authors: Kseniya Prikhodko, Abulkosim Nasriddinov, Svetlana Vladimirova, Marina Rumyantseva, Alexander Gaskov
      First page: 34
      Abstract: In this work, p-type oxide semiconductors, Co3O4 and complex oxides NixCo3−xO4 (x = 0.04, 0.07, 0.1), were studied as materials for sub-ppm H2S sensing in the temperature range of 90–300 °C in dry and humid air. Nanocrystalline Co3O4 and NixCo3−xO4 (x = 0.04, 0.07, 0.1) were prepared by coprecipitation of cobalt and nickel oxalates from nitrate solutions and further annealing at 300 °C. The surface reactivity of the obtained materials toward H2S both in dry and humid atmosphere (relative humidity at 25 °C R.H. = 60%) was investigated using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Sensor measurements showed a decrease in sensor signal toward 1 ppm H2S with an increase in Ni content because of a decrease in chemisorbed surface oxygen species. On the other hand, sensor signal increases for all samples with increasing the relative humidity that depends on reactivity of the surface hydroxyl groups, which stimulate the decomposition of surface sulfites and provide better surface regeneration at higher temperature. This assumption was additionally confirmed by the faster saturation of the conductivity curve and a decrease in the sensor response time in humid air.
      Citation: Chemosensors
      PubDate: 2021-02-07
      DOI: 10.3390/chemosensors9020034
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 35: Graphite Studded with Facile-Synthesized
           Cu2O Nanoparticle-Based Cubes as a Novel Electrochemical Sensor for Highly
           Sensitive Voltametric Determination of Mebeverine Hydrochloride

    • Authors: Ahmed H. Naggar, Ahmed Kotb, Ahmed A. Gahlan, Mahmoud H. Mahross, Abd El-Aziz Y. El-Sayed, Adel A. Abdelwahab
      First page: 35
      Abstract: Herein, a feasible chemical reduction method followed by intensive mixing was applied for the preparation of an attractive material based on graphite studded with cuprous oxide nanoparticle-based cubes (Cu2ONPs–C@G). Transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV) were utilized for characterization. Cuprous oxide nanoparticles (Cu2ONPs), with a diameter range mainly distributed from 4 to 20 nm, aggregate to form microcubes (Cu2ONPs–C) with an average diameter of about 367 nm. Paste electrode was prepared using Cu2ONPs–C@G (Cu2ONPs–C@G/PE) for voltametric quantification of the musculotropic antispasmodic drug: mebeverine hydrochloride (MEB). The electrochemical behavior of MEB was studied using CV, and the optimum analytical parameters were investigated using square wave adsorptive anodic stripping voltammetry (SWAdASV). Moreover, density functional theory (DFT) was used to emphasize the ability of MEB to form a complex with Cu2+, confirming the suggested electrochemical behavior of MEB at Cu2ONPs–C@G/PE. With good stability and high reproducibility, SWAdASV of Cu2ONPs–C@G/PE shows successful quantification of MEB over the concentration range of 5.00 × 10−11–1.10 × 10−9 M with lower limit of detection (LOD) and lower limit of quantification (LOQ) values of 2.41 × 10−11 M and 8.05 × 10−11 M, respectively. Finally, accurate quantification of MEB in dosage forms (tablets) and biological fluids (spiked human urine and plasma samples) was achieved using Cu2ONPs-C@G/PE.
      Citation: Chemosensors
      PubDate: 2021-02-09
      DOI: 10.3390/chemosensors9020035
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 36: AgNWs@TiO2 and AgNPs@TiO2 Double-Layer
           Photoanode Film Improving Light Capture and Application under Low
           Illumination

    • Authors: Jung-Chuan Chou, Yu-Che Lin, Chih-Hsien Lai, Po-Yu Kuo, Yu-Hsun Nien, Ruei-Hong Syu, Zhen-Rong Yong, Yi-Ting Wu
      First page: 36
      Abstract: In this article, silver nanowires (AgNWs) were prepared and introduced into the double-layer photoanode of dye-sensitized solar cells (DSSCs). Silver nanowires with a diameter of about 50–60 nm and a length of 1–2 mm were prepared by the polyol method. The power conversion efficiency of the double-layer photoanode DSSC made of AgNWs@TiO2 and AgNPs@TiO2 composite materials is 6.38%. Compared with the unmodified DSSC, the composite double-layer photoanode combined with AgNWs and AgNPs increased the efficiency of DSSC by 58.7%. This increased efficiency was mainly due to the localized surface plasmon resonance effect caused by AgNPs and AgNWs. The increased light collection was caused by the plasma effect of AgNPs, and it increased the short-circuit photocurrent density (JSC). The conductive properties of AgNWs improved interface charge transfer and delay charge recombination. The effect of a low light environment on DSSC efficiency was also investigated, and the best photovoltaic conversion efficiency under an irradiance of 10 mW/cm2 was found to be 8.78%.
      Citation: Chemosensors
      PubDate: 2021-02-11
      DOI: 10.3390/chemosensors9020036
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 37: Gold Nanoframe Array Electrode for
           Straightforward Detection of Hydrogen Peroxide

    • Authors: Agnes Purwidyantri, Ya-Chung Tian, Gardin Muhammad Andika Saputra, Briliant Adhi Prabowo, Hui-Ling Liu, Chia-Ming Yang, Chao-Sung Lai
      First page: 37
      Abstract: The nanostructuring of a sensing membrane is performed through colloidal nanosphere lithography (NSL) techniques with a tiny polystyrene nanobead template 100 nm in size. The solvent ratio adjustment has been proven to be effective in assisting the monolayer deposition of small templating particles with minimal defects. Two distinct structures, namely, a billowy gold nanostructure (BGN) where the nanobead template is left unetched and a gold nanoframe array (GNA) with a regular ring-like structure after template removal, are used for the extended-gate field-effect transistor (EGFET) electrodes. The GNA structure generates an electroactive surface area significantly (~20%) larger than its geometrical area as well as a greater surface roughness than the BGN. When integrated with the portable constant voltage–constant current (CVCC) FET circuitry for pH screening to determine the optimized measurement conditions for H2O2 sensing, the GNA sensing membrane also shows more improved Nernstian sensitivity at ~50 mV/pH than the BGN electrode. The more optimized sensitivity is then proven using the GNA in the detection of H2O2, the most common representative reactive oxygen species (ROS) involved in the environment, food, and neurodegenerative diseases, such as Parkinson´s and Alzheimer´s diseases. The GNA electrode has a sensitivity of 70.42 mV/log µM [H2O2] and a limit of detection (LoD) of 1.183 µM H2O2. The integrated ion sensing system employing unique, highly ordered gold array gate electrodes and a portable CVCC circuit system has shown a stable real-time output voltage signal, representing an alternative to bulky conventional FET devices for potential on-site H2O2 detection.
      Citation: Chemosensors
      PubDate: 2021-02-16
      DOI: 10.3390/chemosensors9020037
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 38: Pb(II) Determination in a Single Drop
           Using a Modified Screen-Printed Electrode

    • Authors: Nika Žurga, David Majer, Matjaž Finšgar
      First page: 38
      Abstract: This work presents the development and validation of an electroanalytical method for Pb(II) determination in a single drop. The electrochemical sensors used were an unmodified screen-printed electrode (SPE) and a Bi-film SPE (BiFSPE). Anodic square wave stripping voltammetry (SWASV) was performed at an accumulation potential of −1.5 V vs. Ag/AgCl and an accumulation time of 60 s. Electroanalysis with an unmodified SPE did not yield satisfactory results, whereas the BiFSPE was a much better analysis method. The linear concentration using the BiFSPE was in the range of 138.8–162.5 µg/L. The accuracy and precision were evaluated for different spiked concentrations, but the method using the unmodified SPE was neither accurate nor precise. Using the BiFSPE, the method was found to be both accurate and precise for Pb(II) determination at a concentration of 140.0 μg/L, with recovery and relative standard deviation (RSD) of 106.6% and 12.1%, respectively. In addition, using the BiFSPE, LOD and LOQ values of 1.2 μg/L and 3.3 μg/L were obtained, respectively. The possible interference effect on Pb(II) stripping signal was checked in the presence of Cd(II), Zn(II), Cu(II), Sn(IV), Sb(III), Hg(II), Fe(III), As(V), K(I), I−, Ca(II), and NO3−. Electrochemical impedance spectroscopy measurements were also performed for the unmodified SPE and BiFSPE. The application of single drop Pb(II) analysis was tested by real water sample analysis.
      Citation: Chemosensors
      PubDate: 2021-02-18
      DOI: 10.3390/chemosensors9020038
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 39: Colorimetric Chemosensor Array for
           Determination of Halides

    • Authors: Michal Šídlo, Přemysl Lubal, Pavel Anzenbacher
      First page: 39
      Abstract: The halide anions are essential for supporting life. Therefore, halide anion analyses are of paramount importance. For this reason, we have performed both qualitative and quantitative ana- lyses of halides (chloride, bromide, iodide) using the Tl(III) complex of azodye, 4-(2-pyridylazo)re- sorcinol (PAR), a potential new chemical reagent/sensor that utilizes the substitution reaction whereas the Tl(III)PAR complex reacts with a halide to yield a more stable thallium(III)-halide while releasing the PAR ligand in a process accompanied by color change of the solution. The experimental conditions (e.g., pH, ratio metal ion-to-ligand ratio, etc.) for the substitution reaction between the metal complex and a halide were optimized to achieve increased sensitivity and a lower limit of detection (chloride 7 mM, bromide 0.15 mM, iodide 0.05 mM). It is demonstrated that this single chemosensor can, due to release of colored PAR ligand and the associated analyte-specific changes in the UV/VIS spectra, be employed for a multicomponent analysis of mixtures of anions (chloride + bromide, chloride + iodide, bromide + iodide). The spectrophotometric data evaluated by artificial neural networks (ANNs) enable distinguishing among the halides and to determine halide species concentrations in a mixture. The Tl(III)-PAR complex was also used to construct sensor arrays utilizing a standard 96-well plate format where the output was recorded at several wavelengths (up to 7) using a conventional plate reader. It is shown that the data obtained using a digital scanner employing only three different input channels may also be successfully used for a subsequent ANN analysis. The results of all approaches utilized for data evaluation were similar. To increase the practical utility of the chemosensor, we have developed a test paper strip indicator useful for routine naked-eye visual determination of halides. This test can also be used for halide anion determination in solutions using densitometer. The methodology described in this paper can be used for a simple, inexpensive, and fast routine analysis both in a laboratory as well as in a field setting.
      Citation: Chemosensors
      PubDate: 2021-02-18
      DOI: 10.3390/chemosensors9020039
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 40: A Paper-Based Ultrasensitive Optical
           Sensor for the Selective Detection of H2S Vapors

    • Authors: Alejandro P. Vargas, Francisco Gámez, Javier Roales, Tânia Lopes-Costa, José M. Pedrosa
      First page: 40
      Abstract: A selective and inexpensive chemical paper-based sensor for the detection of gaseous H2S is presented. The triggering of the sensing mechanism is based on an arene-derivative dye which undergoes specific reactions in the presence of H2S, allowing for colorimetric analysis. The dye is embedded into a porous cellulose matrix. We passively exposed the paper strips to H2S generated in situ, while the absorbance was monitored via an optic fiber connected to a spectrophotometer. The kinetics of the emerging absorbance at 534 nm constitute the sensor response and maintain a very stable calibration signal in both concentration and time dimensions for quantitative applications. The time and concentration dependence of the calibration function allows the extraction of unusual analytical information that expands the potential comparability with other sensors in the literature, as the limit of detection admissible within a given exposure time. The use of this specific reaction ensures a very high selectivity against saturated vapors of primary interferents and typical volatile compounds, including alkanethiols. The specific performance of the proposed sensor was explicitly compared with other colorimetric alternatives, including standard lead acetate strips. Additionally, the use of a smartphone camera to follow the color change in the sensing reaction was also tested. With this straightforward method, also affordable for miniature photodiode devices, a limit of detection below the ppm scale was reached in both colorimetric approaches.
      Citation: Chemosensors
      PubDate: 2021-02-19
      DOI: 10.3390/chemosensors9020040
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 41: Metal–Oxide Nanowire Molecular
           Sensors and Their Promises

    • Authors: Hao Zeng, Guozhu Zhang, Kazuki Nagashima, Tsunaki Takahashi, Takuro Hosomi, Takeshi Yanagida
      First page: 41
      Abstract: During the past two decades, one–dimensional (1D) metal–oxide nanowire (NW)-based molecular sensors have been witnessed as promising candidates to electrically detect volatile organic compounds (VOCs) due to their high surface to volume ratio, single crystallinity, and well-defined crystal orientations. Furthermore, these unique physical/chemical features allow the integrated sensor electronics to work with a long-term stability, ultra-low power consumption, and miniature device size, which promote the fast development of “trillion sensor electronics” for Internet of things (IoT) applications. This review gives a comprehensive overview of the recent studies and achievements in 1D metal–oxide nanowire synthesis, sensor device fabrication, sensing material functionalization, and sensing mechanisms. In addition, some critical issues that impede the practical application of the 1D metal–oxide nanowire-based sensor electronics, including selectivity, long-term stability, and low power consumption, will be highlighted. Finally, we give a prospective account of the remaining issues toward the laboratory-to-market transformation of the 1D nanostructure-based sensor electronics.
      Citation: Chemosensors
      PubDate: 2021-02-22
      DOI: 10.3390/chemosensors9020041
      Issue No: Vol. 9, No. 2 (2021)
       
  • Chemosensors, Vol. 9, Pages 9: Interpretation of Quartz Crystal
           Microbalance Behavior with Viscous Film Using a Mason Equivalent Circuit

    • Authors: Sawit Na Songkhla, Takamichi Nakamoto
      First page: 9
      Abstract: In odor sensing based on Quartz Crystal Microbalances (QCMs), the sensing film is crucial for both sensor sensitivity and selectivity. The typical response of the QCM due to sorption is a negative frequency shift. However, in some cases, the sorption causes a positive frequency shift, and then, Sauerbrey’s equation and Kanazawa’s equation cannot be applied to this situation. We model the QCM response with a Mason equivalent circuit. The model approximates a single layer of a uniform viscous coating on the QCM. The simulation of the equation circuit shows the possibility of the positive frequency change when the sorption occurs, which is the situation we find in some of the odor sensing applications. We measured the QCM frequency and resistance using the Vector Network Analyzer (VNWA). The QCMs were coated with glycerol, PEG2000, and PEG20M. To simulate odor exposure, a microdispenser was used to deposit the water. A positive frequency shift was observed in the case of PEG2000, and a negative frequency change was obtained for PEG20M. These results can be explained by the Mason equivalent circuit, with the assumption that when the film is exposed to water, its thickness increases and its viscosity decreases.
      Citation: Chemosensors
      PubDate: 2021-01-02
      DOI: 10.3390/chemosensors9010009
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 10: Nanoplasmonic Biosensing Approach for
           Endotoxin Detection in Pharmaceutical Field

    • Authors: Adriano Colombelli, Elisabetta Primiceri, Silvia Rizzato, Anna Grazia Monteduro, Giuseppe Maruccio, Roberto Rella, Maria Grazia Manera
      First page: 10
      Abstract: The outer membrane of Gram-negative bacteria contains bacterial endotoxins known as Lipopolysaccharides (LPS). Owing to the strong immune responses induced in humans and animals, these large molecules have a strong toxic effect that can cause severe fever, hypotension, shock, and death. Endotoxins are often present in the environment and medical implants and represent undesirable contaminations of pharmaceutical preparations and medical devices. To overcome the limitations of the standard technique, novel methods for early and sensitive detection of LPS will be of crucial importance. In this work, an interesting approach for the sensitive detection of LPS has been realized by exploiting optical features of nanoplasmonic transducers supporting Localized Surface Plasmon Resonances (LSPRs). Ordered arrays of gold nano-prisms and nano-disks have been realized by nanospheres lithography. The realized transducers have been integrated into a simple and miniaturized lab-on-a-chip (LOC) platform and functionalized with specific antibodies as sensing elements for the detection of LPS. Interactions of specific antibodies anchored on protein A-modified sensor chips with the investigated analyte resulted in a spectral shift in the plasmonic resonance peak of the transducers. A good linear relationship between peak shifts and the LPS concentration has been demonstrated for the fabricated nano-structures with a detection limit down to 5 ng/mL. Integration with a proper microfluidic platform demonstrates the possibility of yielding a prototypal compact device to be used as an analytical test for quality determination of pharmaceutical products.
      Citation: Chemosensors
      PubDate: 2021-01-04
      DOI: 10.3390/chemosensors9010010
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 11: Comparing Surface Plasmon-Optical and
           Electronic Immuno-Sensing of Affinity Interactions—A Case Study

    • Authors: Wolfgang Knoll, Jing Liu, Fang Yu, Lifang Niu, Ciril Reiner-Rozman, Ingo Köper
      First page: 11
      Abstract: In this case study, we provide a few examples for affinity-sensors based on optical detection concepts and compare them with electronic read-out schemes. We concentrate and briefly summarize two of the most advanced versions in each category: one is a surface-plasmon field-enhanced fluorescence spectroscopic approach, while in the electronic sensing domain we concentrate on graphene-based field-effect transistors as the read-out platform. Both transduction principles are surface-sensitive and-selective, however, with penetration lengths into the analyte solution (e.g., into a flow cell attached) that are very different and that depend on totally different physical principles: while for surface-plasmons the evanescent character of the plasmon mode, propagating along the noble metal-solution interface with a penetration length in the order of 100 nm (for Au/water and a laser wavelength of = 632.8 nm), the “penetration depth” in electronic transistor-based sensing is governed by the Debye length which, for a physiological salt environment, amounts to less than 1 nm. Taking these differences into account, one can optimize the sensor read-out by the appropriate interfacial architecture used to functionalize the transducers by immobilizing one of the affinity interaction partners. We will discuss this for both concepts by giving a few examples of the achievable limit of detection for both methods. The examples discussed include a classical system, i.e., the binding of human chorionic gonadotropin (hCG) to its surface-immobilized antibodies or Fab fragments, the detection of lipopolysaccharides in a tethered bimolecular lipid membrane, and, as an example for small analyte detection by antibodies, the monitoring of aflatoxin B1, a member of the food toxin family of mycotoxins.
      Citation: Chemosensors
      PubDate: 2021-01-05
      DOI: 10.3390/chemosensors9010011
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 12: How to Improve the Performance of
           Electrochemical Sensors via Minimization of Electrode Passivation

    • Authors: Jiri Barek
      First page: 12
      Abstract: It follows from critical evaluation of possibilities and limitations of modern voltammetric/amperometric methods that one of the biggest obstacles in their practical applications in real sample analysis is connected with electrode passivation/fouling by electrode reaction products and/or matrix components. This review summarizes possibilities how to minimise these problems in the field of detection of small organic molecules and critically compares their potential and acceptability in practical laboratories. Attention is focused on simple and fast electrode surface renewal, the use of disposable electrodes just for one and/or few measurements, surface modification minimising electrode fouling, measuring in flowing systems, application of rotating disc electrode, the use of novel separation methods preventing access of passivating particles to electrode surface and the novel electrode materials more resistant toward passivation. An attempt is made to predict further development in this field and to stress the need for more systematic and less random research resulting in new measuring protocols less amenable to complications connected with electrode passivation.
      Citation: Chemosensors
      PubDate: 2021-01-06
      DOI: 10.3390/chemosensors9010012
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 13: Capacitance Electrochemical pH Sensor
           Based on Different Hafnium Dioxide (HfO2) Thicknesses

    • Authors: Zina Fredj, Abdoullatif Baraket, Mounir Ben Ali, Nadia Zine, Miguel Zabala, Joan Bausells, Abdelhamid Elaissari, Nsikak U. Benson, Nicole Jaffrezic-Renault, Abdelhamid Errachid
      First page: 13
      Abstract: Over the past years, to achieve better sensing performance, hafnium dioxide (HfO2) has been studied as an ion-sensitive layer. In this work, thin layers of hafnium dioxide (HfO2) were used as pH-sensitive membranes and were deposited by atomic layer deposition (ALD) process onto an electrolytic-insulating-semiconductor structure Al/Si/SiO2/HfO2 for the realization of a pH sensor. The thicknesses of the layer of the HfO2 studied in this work was 15, 19.5 and 39.9 nm. HfO2 thickness was controlled by ALD during the fabrication process. The sensitivity toward H+ was clearly higher when compared to other interfering ions such as potassium K+, lithium Li+, and sodium Na+ ions. Mott−Schottky and electrochemical impedance spectroscopy (EIS) analyses were used to characterise and to investigate the pH sensitivity. This was recorded by Mott–Schottky at 54.5, 51.1 and 49.2 mV/pH and by EIS at 5.86 p[H−1], 10.63 p[H−1], 12.72 p[H−1] for 15, 19.5 and 30 nm thickness of HfO2 ions sensitive layer, respectively. The developed pH sensor was highly sensitive and selective for H+ ions for the three thicknesses, 15, 19.5 and 39.9 nm, of HfO2-sensitive layer when compared to the other previously mentioned interferences. However, the pH sensor performances were better with 15 nm HfO2 thickness for the Mott–Schottky technique, whilst for EIS analyses, the pH sensors were more sensitive at 39.9 nm HfO2 thickness.
      Citation: Chemosensors
      PubDate: 2021-01-10
      DOI: 10.3390/chemosensors9010013
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 14: Nanomaterials Based Electrochemical
           Sensors for Serotonin Detection: A Review

    • Authors: Dorin Dăscălescu, Constantin Apetrei
      First page: 14
      Abstract: The present review deals with the recent progress made in the field of the electrochemical detection of serotonin by means of electrochemical sensors based on various nanomaterials incorporated in the sensitive element. Due to the unique chemical and physical properties of these nanomaterials, it was possible to develop sensitive electrochemical sensors with excellent analytical performances, useful in the practice. The main electrochemical sensors used in serotonin detection are based on carbon electrodes modified with carbon nanotubes and various materials, such as benzofuran, polyalizarin red-S, poly(L-arginine), Nafion/Ni(OH)2, or graphene oxide, incorporating silver-silver selenite nanoparticles, as well as screen-printed electrodes modified with zinc oxide or aluminium oxide. Also, the review describes the nanocomposite sensors based on conductive polymers, tin oxide-tin sulphide, silver/polypyrole/copper oxide or a hybrid structure of cerium oxide-gold oxide nanofibers together with ruthenium oxide nanowires. The presentation focused on describing the sensitive materials, characterizing the sensors, the detection techniques, electroanalytical properties, validation and use of sensors in lab practice.
      Citation: Chemosensors
      PubDate: 2021-01-14
      DOI: 10.3390/chemosensors9010014
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 15: Electrochemical Detection of a Local
           Anesthetic Dibucaine at Arrays of Liquid Liquid MicroInterfaces

    • Authors: Eissa Mohamed Almbrok, Nor Azah Yusof, Jaafar Abdullah, Ruzniza Mohd Zawawi
      First page: 15
      Abstract: Electrochemical characterization and detection of protonated dibucaine (DIC+) at microinterface array across water 1,6-dichlorohexane were performed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Some thermodynamic parameters of dibucaine, such as the standard transfer potential, the Gibbs energy of transfer and the partition coefficient, were estimated by CV. In addition to the analytical parameters, the impact of bovine serum albumin (BSA) on dibucaine detection (in artificial serum matrices) was also investigated. DPV was applied to detect a lower concentration of DIC+, resulting in a detection limit of 0.9 ± 0.06 µM. While the presence of BSA affected CV, demonstrated as reduced current responses, DPV was confirmed to be an efficient method for lowering concentrations of the dibucaine detection in the artificial serum matrix in the presence of BSA, with a limit of detection (LOD) of 1.9 ± 0.12 µM.
      Citation: Chemosensors
      PubDate: 2021-01-15
      DOI: 10.3390/chemosensors9010015
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 16: Bicyclic 1,3a,6a-Triazapentalene
           Chromophores: Synthesis, Spectroscopy and Their Use as Fluorescent Sensors
           and Probes

    • Authors: Yingchun Wang, Tomas Opsomer, Wim Dehaen
      First page: 16
      Abstract: The 1,3a,6a-triazapentalene (TAP) is an aromatic heterocyclic fluorescent dye with interesting features such as its small size, large Stokes shift, solvatochromism, and emission wavelengths that are spread across the visible spectrum. TAPs have been synthesized via different synthetic strategies involving click−cyclization−aromatization domino reactions, gold-catalyzed cyclization of propargyl triazoles or triazolization of acetophenones. As a result, TAPs with diverse substitution patterns were obtained, showing varying fluorescence properties. Based on these properties, several TAPs have been selected and studied as fluorescent imaging probes in living cells and as sensors. This mini review provides an overview of the research on the bicyclic TAPs and does not comment on the literature about benzo or otherwise fused systems. The synthetic methodologies for the preparation of TAPs, the substituent effects on the fluorescence properties, and the behavior of the TAP core as an element of biological imaging probes and sensors are discussed.
      Citation: Chemosensors
      PubDate: 2021-01-15
      DOI: 10.3390/chemosensors9010016
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 17: Preparation and Characterization of
           Au/NiPc/Anti-p53/BSA Electrode for Application as a p53 Antigen Sensor

    • Authors: Yen-Jou Chen, Yu-Ren Peng, Hung-Yu Lin, Tsung-Yu Hsueh, Chao-Sung Lai, Mu-Yi Hua
      First page: 17
      Abstract: While the tumor suppressor protein p53 regulates the cell cycle to prevent cell damage, it also triggers apoptosis and prevents cancer. These inhibitory functions may disappear once the p53 gene is mutated. Under these circumstances, the detection of p53 protein concentrations can have significant clinical applications. In this study, nickel phthalocyanine (NiPc) was coated on a gold electrode to produce a modified Au/NiPc electrode. p53 antibodies were bonded to the Au/NiPc electrode by the Ni+2 ion in NiPc, which can be self-assembled with the imidazole group of the p53 protein. The Au/NiPc/anti-p53 electrode was subsequently dripped with a buffer solution of bovine serum albumin (BSA) to form the Au/NiPc/anti-p53/BSA electrode, which was used for the detection of p53 antigen under 10 mM potassium ferricyanide/potassium ferrocyanide (K3Fe(CN)6/K4Fe(CN)6) solution by cyclic voltammetry and differential pulse voltammetry analyses. The linear detection range and the sensitivity for the p53 antigen were 0.1–500 pg/mL and 60.65 μA/Log (pg/mL)-cm2, respectively, with a detection time of 90–150 s. In addition, Au/NiPc/anti-p53 (100 ng/mL)/BSA electrodes were tested for specificity using glucose, bovine serum albumin, histidine, ascorbic acid, uric acid, prostate-specific antigen, human serum albumin, and human immunoglobulin G. All p-values were <0.0005, indicating an outstanding specificity.
      Citation: Chemosensors
      PubDate: 2021-01-19
      DOI: 10.3390/chemosensors9010017
      Issue No: Vol. 9, No. 1 (2021)
       
  • Chemosensors, Vol. 9, Pages 18: Acknowledgment to Reviewers of
           Chemosensors in 2020

    • Authors: Chemosensors Editorial Office Chemosensors Editorial Office
      First page: 18
      Abstract: Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Chemosensors maintains its standards for the high quality of its published papers [...]
      Citation: Chemosensors
      PubDate: 2021-01-19
      DOI: 10.3390/chemosensors9010018
      Issue No: Vol. 9, No. 1 (2021)
       
 
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