A new biocatalyst employing pyrenecarboxaldehyde as an anodic catalyst for enhancing the performance and stability of an enzymatic biofuel cell

A new enzyme catalyst consisting of pyrenecarboxaldehyde (PCA) and glucose oxidase (GOx) immobilized on polyethyleneimine (PEI) and a carbon nanotube supporter (CNT/PEI/[PCA/GOx]) is suggested, and the performance and stability of an enzymatic biofuel cell (EBC) using the new catalyst are evaluated. Using PCA, the amount of immobilized GOx increases (3.3 U mg(-1)) and the electron transfer rate constant of the CNT/PEI/[PCA/GOx] is promoted (11.51 s(-1)). Also, the catalyst induces excellent EBC performance (maximum power density (MPD) of 2.1 mW cm(-2)), long-lasting stability (maintenance of 93% of the initial MPD after 4 weeks) and superior catalytic activity (flavin adenine dinucleotide redox reaction rate of 0.62 mA cm(-2) and Michaelis-Menten constant of 0.99 mM). These characteristics are ascribed to effects of (i) electron collection due to hydrophobic interactions, (ii) electron transfer pathways due to pi-conjugated bonds and (iii) enzyme stabilization due to p-hydrogen bonds that are newly induced by the PCA/GOx composite. The existence of such positive interactions is properly verified using X-ray photoelectron spectroscopy and enzyme activity measurements.