Single Electrochemical Impacts of Shewanella oneidensis MR-1 Bacteria for Living Cells Adsorption onto a Polarized Ultramicroelectrode Surface

Funding Information: This work is supported by Nantes Université and the Région Pays de la Loire (Rising stars program, e-NANOBIO). The authors acknowledge the France-Portugal PHC PESSOA 2022 program for support, project 47857YM. Funding Information: This work is supported by Nantes Université and the Région Pays de la Loire (Rising stars program, NANOBIO). The authors acknowledge the France‐Portugal PHC PESSOA 2022 program for support, project 47857YM. e‐ Publisher Copyright: © 2022 The Authors. ChemElectroChem published by Wiley-VCH GmbH.Single electrochemical impacts of Shewanella oneidensis MR-1 Gram-negative electroactive bacteria onto ultramicroelectrode surfaces are reported and in-depth analysed. Chronoamperometry measurements recorded onto 10 μm-diameter Pt and 7 μm-diameter carbon fibre disk ultramicroelectrodes in a 20 mM potassium ferrocyanide aqueous solution in the presence of living bacteria show an electrostatic attraction of Shewanella cells onto the ultramicroelectrode surface polarized at +0.8 V vs Ag/AgCl. Single current step events analysis and atomic force microscopy experiments confirm the adsorption of living bacteria following the collision onto the ultramicroelectrode surface. The bacteria washing step before the chronoamperometry measurements leads to lower current step events related to the smaller size of the living cells. The electrostatic attraction of the negatively charged bacteria onto the positively charged ultramicroelectrode surface polarized at the oxidation potential of ferrocyanide is clearly demonstrated.publishersversionpublishe

MODIFIED SCREEN-PRINTED CARBON ELECTRODES WITH TYROSINASE FOR DETERMINATION OF PHENOLIC COMPOUNDS IN SMOKED FOOD

A screen-printed carbon electrode modified with tyrosinase (SPCE-Tyr/Paa/Glut) has been developed for the determination of phenol concentration in real samples. The resulting SPCE-Tyr/Paa/Glut was prepared in a one-step procedure, and was then optimized as an amperometric biosensor operating at 0 mV versus Ag/AgCl for phenol determination in flow injection mode. Phenol detection was realized by electrochemical reduction of quinone produced by tyrosinase activity. The possibility of using the developed biosensor to determine phenol concentrations in various smoked products (bacon, ham, chicken and salmon) was also evaluated. Gas chromatography (GC) method was used for result validation obtained in flow injection mode using amperometric biosensor. The result showed good correlation with those obtained by flowinjection analysis (FIA)

One-step screen-printed electrode modified in its bulk with HRP based on direct electron transfer for hydrogen peroxide detection in flow injection mode

0956-566

Examination of the electrochemical reactivity of screen printed carbon electrode treated by radio-frequency argon plasma

The surface of screen printed carbon electrode (SPCE) with partially blocked surface was treated by argon plasma in order to improve their electrochemical performances. The argon plasma was generated by a radio-frequency electrical discharge at low pressure. Study of the electrode surface by scanning electronic microscopy (SEM) has revealed a significant change of the morphology of the SPCE surface after plasma pre-treatment. The electrochemical reactivity of the SPCEs was characterized using cyclic voltammetry. A drastic enhancement of the SPCEs electrochemical reactivity was highlighted after plasma pre-treatment. The effect of biasing the SPCE surface during the plasma treatment has been investigated and showed that depending on the nature of plasma treatment, the same electrode could show a radial or planar diffusion. Keywords: Screen printed carbon electrode (SPCE), Argon plasma treatment, Cyclic voltammetry, Microelectrodes arrays, Electrochemical reactivit

The synergetIc effect of redox mediators and peroxidase in a bienzymatic biosensor for glucose assays in FIA

A bienzymatic biosensor incorporating a mediator has been developed in order to achieve a fast and selective detection of glucose in a flow injection system. The working electrode is based on a carbon paste matrix bulk modified with glucose oxidase (GOD) and horseradish peroxidase (HRP) as well as with ferrocene acting as an electron transfer mediator between the electrode and HRP. The proximity of these three components enhances the electron transfer within the electrode. Simple polishing on a paper sheet easily renews the electrode surface. Moreover, the applied working potential (–0.050 V $vs.$ Ag/AgCl) is low, hereby decreasing the interference from electroactive compounds and thus increasing the selectivity of the biosensor. The characteristics of the developed bienzymatic electrode are presented in terms of sensitivity, linear detection range, accuracy and operational stability

Screen-printed carbon electrode modified on its surface with amorphous carbon nitride thin film: Electrochemical and morphological study

0013-468

Argon plasma treatment to enhance the electrochemical reactivity of screen-printed carbon surfaces

International audienceRadiofrequency argon plasma was used for screen-printed carbon electrodes (SPCE) surface treatment. The cyclic voltammetry of ferri/ferrocyanide as redox couple showed a remarkable improvement of the electrochemical reactivity of the SPCE after the plasma treatment. The effect of the plasma growth conditions on the efficiency of the treatment procedure was evaluated in term of electrochemical reactivity of the SPCE surface. The electrochemical study showed that the electrochemical reactivity of the treated electrodes was strongly dependant on radiofrequency power, treatment time and argon gas pressure. Xray photoelectron spectroscopy (XPS) analysis showed a considerable evolution on the surface chemistry of the treated electrodes. Our results clearly showed that the argon plasma treatment induces a significant increase in the C-SP2/C-SP3 ratio. The scanning electron micrograph (SEM) also showed a drastic change on the surface morphology of the treated SPCEs

Biocompatible carbon-based screen-printed electrodes for the electrochemical detection of nitric oxide

1388-248