Enhanced Bioelectrocatalysis Using Au-Nanoparticle/Polyaniline Hybrid Systems in Thin Films and Microstructured Rods Assembled on Electrodes

Composite materials consisting of polyaniline/poly(4-styrene-sulfonate) (PAn/PSS) or polyaniline/Au nanoparticles capped with 2-mercaptoethane sulfonic acid (PAn/Au-NPs) are prepared in the form of thin films (thickness ca. 90 nm) on Au electrodes or in the form of microrods linked to a Au surface. The composite materials in the microrod structures are electrochemically prepared in porous alumina membranes coated with a Au film, followed by the dissolution of the membrane. Chronoamperometric experiments reveal that the charge transport in the PAn/Au-NPs system is ca. 25-fold enhanced as compared to the analogous PAn/PSS system. The different polyaniline composite assemblies were used as catalysts for the electrochemical oxidation of ascorbic acid and as electron-transfer mediators for the bioelectrocatalytic activation of glucose oxidase (GOx) toward the oxidation of glucose. The PAn/Au-NPs system in the microrod structure reveals superior function as the catalyst for the electrochemical oxidation of ascorbic acid and in the bioelectrocatalytic activation of GOx because of the high surface area of the assembly and the enhanced charge-transport properties of the composite material.