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A selective electrochemical sensor based on poly(3,4-ethylenedioxythiophene) (PEDOT) - Prussian blue nanoparticles (PBNPs) for hydrogen peroxide (H 2 O 2 ) determination was prepared by innovative sinusoidal voltage (SV) method. The successful incorporation of citrate-stabilized PBNPs into PEDOT matrix was confirmed by energy dispersive X-ray analysis (EDX), Raman spectroscopy, UV-Vis spectroelectrochemistry and cyclic voltammetry measurements. The SV preparation method provides a PEDOT-PBNPs coating with rough surface morphology and good electrocatalytic activity toward H 2 O 2 reduction. The amperometric response of PEDOT-PBNPs-based sensor at -50 mV vs. Ag/AgCl is linear within the range of concentrations from 5 μM to 1 mM H 2 O 2 with a detection limit of 1.4 μM H 2 O 2 . The proposed Pt/PEDOT-PBNPs sensor displays good repeatability, reproducibility, operational stability as well as good selectivity toward H 2 O 2 determination in the presence of interfering species like dopamine (DA), uric acid (UA), KNO 2 glucose (Glu), KNO 3 and ascorbic acid (AA), and was successfully applied to H 2 O 2 determination in human blood samples without biofouling., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The electrodeposition of poly(3,4-ethylenedioxythiophene)-tyrosinase (PEDOT-Ty) biocomposite material onto gold electrode has been achieved by means of a sinusoidal voltages (SV) method. The SV method consists in the superimposition of a sinusoidal voltage (sin wave) with fixed frequency and amplitude onto a d.c. potential. The influence of electrochemical parameters like frequency and amplitude of SV signal, d.c. potential value, deposition time, on the electrodeposition process has been investigated. The biocomposite material has been prepared as a thin layer onto quartz crystals coated with gold. The frequency change of the quartz crystal during the electrodeposition of the biocomposite material was recorded simultaneously with the measured current response. The morphology of the deposited PEDOT-Ty coatings was investigated by scanning electron microscopy. The electrochemical behavior of the biocomposite material in aqueous solution was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The use of d.c. potential value of 0.6 V revealed the contribution of the SV component to the electrodeposition process. The PEDOT-Ty modified electrode was used as an electrochemical biosensor in the voltammetric determination of dopamine in the presence of hydroquinone. The analytical performances of the prepared biosensors were also investigated. [ABSTRACT FROM AUTHOR]

Abstract: The amperometric detection of dopamine (DA) and catechol (CT) was achieved at tyrosinase (Ty)-poly(3,4-ethylenedioxythiophene) (PEDOT) bio-composite film-modified gold (Au) disc microelectrode arrays. The PEDOT-Ty bio-composite coatings were prepared by electrochemical polymerization of the corresponding monomer 3,4-ethylenedioxythiophene (EDOT) in the presence of various amounts of Ty on Au microelectrode arrays using sinusoidal voltages. The use of sinusoidal voltages in preparing bio-composite coatings is reported here for the first time. The bio-composite coatings deposited on different arrays by sinusoidal voltages and potentiostatic methods were compared. The bio-composite coatings were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), infrared reflection absorption spectroscopy (IRRAS), and atomic force microscopy (AFM). This new preparation procedure provided a simple and reliable enzyme immobilization preserving the enzymatic activity. The amperometric detection of DA and CT was achieved at a working potential of -0.2V in physiological buffered solutions. Multianalyte detection was achieved connecting different microelectrode arrays to a bipotentiostat. The analytical performance of the biosensor in terms of limit of detection, linear response range, sensitivity, and working stability, were investigated. The microelectrodes array based biosensor obtained by using sinusoidal voltages displayed a linear response for dopamine concentrations ranging from 10 to 150μM, with a limit of detection (3 Sb/m, where Sb is the standard deviation of the blank and m is the slope of the calibration plot) of 0.99μM. A linear response for catechol concentrations ranging from 10 to 60μM and a detection limit of 5.58μM were also obtained for this micro-biosensor. [Copyright &y& Elsevier]

Bio-composite coatings consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and tyrosinase (Ty) were successfully electrodeposited on conventional size gold (Au) disk electrodes and microelectrode arrays using sinusoidal voltages. Electrochemical polymerization of the corresponding monomer was carried out in the presence of various Ty amounts in aqueous buffered solutions. The bio-composite coatings prepared using sinusoidal voltages and potentiostatic electrodeposition methods were compared in terms of morphology, electrochemical properties, and biocatalytic activity towards various analytes. The amperometric biosensors were tested in dopamine (DA) and catechol (CT) electroanalysis in aqueous buffered solutions. The analytical performance of the developed biosensors was investigated in terms of linear response range, detection limit, sensitivity, and repeatability. A semi-quantitative multi-analyte procedure for simultaneous determination of DA and CT was developed. The amperometric biosensor prepared using sinusoidal voltages showed much better analytical performance. The Au disk biosensor obtained by 50 mV alternating voltage amplitude displayed a linear response for DA concentrations ranging from 10 to 300 µM, with a detection limit of 4.18 µM. [ABSTRACT FROM AUTHOR]

Abstract: To the best of the authors’ knowledge, this is the first report on the electrochemical polymerization of 3,4-ethylenedioxythiophene on gold (Au) disk microelectrode arrays using sinusoidal voltages. The use of electrochemical impedance spectroscopy (EIS) for the in situ deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) coating onto Au microelectrode arrays allowed the estimation of electrochemical parameters, such as charge transfer resistance and exchange current. The PEDOT coatings deposited on different arrays by sinusoidal voltages and potentiostatic methods were compared. The electrochemical characterization of both naked and PEDOT-modified microelectrode arrays by EIS and cyclic voltammetry (CV) revealed different diffusion regimes occurring at the microelectrodes surfaces. The electron transfer kinetics between the PEDOT coatings and redox probe in solution were also investigated. Results demonstrated the suitability of the new preparation procedure for electrogenerating PEDOT coatings. This novel procedure led to insights to the electrochemical properties and diffusion regimes occurring at both naked and modified microelectrode arrays. [Copyright &y& Elsevier]

The application of a novel Poly(3,4-ethylenedioxythiophene)-Tyrosinase/Sonogel-Carbon electrode (PEDOT-Tyr/SNGC) biosensor to beers and wines analysis is proposed. This biosensor implies a new Sinusoidal Current (SC) electrodeposition method to immobilize the enzyme generating a nanostructure surface. The biosensors were characterized electrochemically, employing cyclic voltammetry and electrochemical impedance spectroscopy. Sensitivity, limit of detection, and correlation coefficients of the linear fitting were 2.40 × 10−4 µA·µM−1, 4.33 µM, and R2 = 0.9987, respectively. Caffeic acid is used as the reference polyphenol. A sampling of nine beers (four lager, three stout, and two non-alcoholic beers), and four wines (three red and one white wine) purchased in a local store was performed. The Polyphenol indeces for beers and wines have been assessed using the proposed biosensor, and the obtained values are in agreement with the literature data. Antioxidant properties of the samples using the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical spectrophotometric method were also evaluated. The correlation between the polyphenol index and the antioxidant capacity was obtained for beers and wines. [ABSTRACT FROM AUTHOR]

In this work, biosensors based on Sonogel-Carbon electrodes modified with poly(3,4-ethylenedioxythiophene) – tyrosinase biocomposite materials have been developed using sinusoidal voltages and currents methods The sinusoidal voltages method uses a sinusoidal voltage signal of a 50 mHz fixed frequency and high amplitude superimposed on a direct current potential to modify the Sonogel-Carbon electrodes surface with the poly(3,4-ethylenedioxythiophene) – tyrosinase layer. A new preparation method involving the application of a sinusoidal current signal with fixed frequency and amplitude over a direct current has been developed as well. The experimental parameters of these methods have been optimized and selected in such a way to highlight the contribution of the sinusoidal component in the biosensors preparation. The advantages of the new preparation methods in terms of electrocatalytic and analytical efficiencies are presented. The analytical performances of the proposed biosensors towards benchmark analytes like dopamine, hydroquinone, and catechol have been investigated. The lowest limit of detection value of 7.10 μM and a high sensitivity value of 0.0037 μA/μM for dopamine determination were obtained with a biosensor prepared via the new sinusoidal currents method. The biosensors were successfully applied in the quantification of dopamine in pharmaceutical products. [ABSTRACT FROM AUTHOR]