Catalytic reduction of benzoquinone at polyaniline and polyaniline/enzyme films

Abstract

The enzyme-mediator-conducting polymer model provides a convenient charge transporting immobilization matrix for redox enzymes in potential biosensor constructions. This study considers the charge transport mechanism in the benzoquinone (Q)-polyaniline (Pani) system. An enhanced current can be obtained on Pani, compared with Pt, using Q as enzyme mediator. Two-electron redox pathways are available for the Q/H2Q (hydroquinone) system, but the kinetics limit this conversion. On Pt, one-electron equivalent is estimated. On Pani-modified electrodes, reduction of Q on Pani is a nearly reversible two-electron process at stationary electrodes at low pH. At rotating electrodes, the initial reaction occurs at the surface of the polymer at pH 1.1, but the second electron transfer is prevented by loss of the intermediate from the surface before it can migrate into the film. At stationary electrodes, the H2Q product is stabilized, possibly by the formation of a charge-compensating complex between the H2Q anion/radical and the polymer. At higher pH, charge transfer through the polymer is slow and no reduction of Q occurs on the outside of the film, instead occurring in a layer at the electrode limited by the exchange kinetics there. Promotion of the two-electron pathways on Pani is proposed as the source of current enhancement when Q is employed as an enzyme mediator.

Electrochemistry of Conductive Polymers. XXVI. Effects of Electrolytes and Growth Methods on Polyaniline Morphology

“…[1][2][3][4][5][6][7][8][9][10] Most applications of the conjugated polymers are based on their electrochemical and optical properties. Also, these properties are closely related to the electrochemical reactions of the polymers.…”

Design and Fabrication of 3D Skyscraper Nanostructures and Their Application as Electrodes in Biosensors

“…The reduced-GOx will then be converted back to its original form by reacting with p-benzoquinone (BQ), a mediator having better solubility than most other popular mediators (Cooper et al, 1993). In a cascade of electrode reactions, the mediator gets reduced and then converted back to its original state at the electrode surface by giving away electrons.…”

Enzymatic Biofuel Cells—Fabrication of Enzyme Electrodes

“…An enzyme-mediator-conducting polymer model using benzoquinone (Q)-polyaniline (Pani) system was established by Cooper and Hall. An enhanced current can be obtained on Pani [71]. Ratiman et al [72] integrated polyaniline/poly(acrylic acid) films and redox enzymes for the study of the bioelectrocatalyzed oxidation of glucose or lactate.…”