Pyrroloquinoline Quinone-Dependent Enzymatic Bioanode: Incorporation of the Substituted Polyaniline Conducting Polymer as a Mediator

One of the main technological issues with enzymatic biofuel cells and biosensors is improving the electron transfer between the enzyme and the current collector to improve current densities. In this study, we show the use of a conducting polymer to mediate pyrroloquinoline quinone-dependent enzymatic bioelectrocatalysis. A self-doped polyaniline (PANi) film is electropolymerized on a Toray carbon paper electrode surface to covalently bond enzymes to this three-dimensional interface. Sulfonic acid groups are introduced into the PANi backbone structure to increase the polymer conductivity at neutral pH via a self-doping process, and the carboxyl groups can be activated to covalently bond to enzymes. The electropolymerization of 2-methoxyaniline-5-sulfonic acid and 3-aminobenzoic acid is optimized with respect to the rate of the bioelectrocatalytic conversion of enzyme substrates. Comparing this PANi conducting copolymer enzyme immobilization technique with the hydrophobically modified Nafion encapsulation-b...