Gold electrode modified with a self-assembled glucose oxidase and 2,6-pyridinedicarboxylic acid as novel glucose bioanode for biofuel cells

In this study, we have constructed a gold electrode modified with (3-aminopropyl)trimethoxysilane/2,6-pyridinedicarboxylic acid/glucose oxidase (abbreviated as, Au/ATS/PDA/GOx) by sequential chemical adsorption. Au/ATS/PDA/GOx electrode was characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and Electrochemical Impedance Spectroscopy (EIS). The data from FT-IR illustrated deposition of ATS, PDA and GOx on the surface of gold electrode. The latter has been confirmed by EIS which showed that the electron transfer resistance of the electrode increases after adsorption of each supplementary layer. Linear sweep voltammetry (LSV) in phosphate buffer solution containing 5 mM glucose displayed that compared to Au/ATS/GOx, oxidation of glucose at Au/ATS/PDA/GOx electrode starts 461 mV earlier. This gain in potential is attributed to presence of PDA in the constructed Au/ATS/PDA/GOx electrode, which plays some sort of electron mediator for glucose oxidation. The Au/ATS/PDA/GOx electrode was stabilized by an outer layer of polystyrene sulfonate (PSS) and was connected to a Pt electrode as cathode and the non-compartmentalized cell was studied under air in phosphate buffer solution pH 7.4 containing 10 mM glucose. Under these conditions, the maximum power density reaches 0.25 μW mm−2 (25 μW cm−2) for the deposited GOx layer that has an estimated surface coverage of ∼70% of a monolayer.