A bioanode based on MWCNT/protein-assisted co-immobilization of glucose oxidase and 2,5-dihydroxybenzaldehyde for glucose fuel cells

This paper describes an easy-to-prepare, robust bioanode constructed on a polyester-supported screen-printed carbon paste electrode (SPCE) for glucose biofuel cells. To prepare the bioanode, carboxylated multi-walled carbon nanotubes (MWCNTs) were drop-coated on the SPCE first, and then a crosslinked matrix composed of glucose oxidase (GOx), 2,5-dihydroxybenzaldehyde (DHB), bovine serum albumin (BSA) and glutaraldehyde was coated atop the MWCNTs. It was found that the MWCNTs assisted the immobilization of the crosslinked matrix, enhanced the electron-shuttling process, and showed electrocatalytic effect to gluconic acid, which allowed squeeze more electrons out of a glucose molecule. Inside the matrix, DHB mediators could couple to GOx and BSA via the Schiff base reaction, and GOx and BSA could crosslink to each other with glutaraldehyde. From cyclic voltammetry, it was estimated that 3.63 nmol cm−2 of DHB was anchored on the bioanode, and no mediator leaching was observed. The bioanode also attained reproducible flow-injection analysis (FIA) signals for glucose sensing (RSD = 4.99%) and retained 84% of the initial response after keeping in a buffer at 4 °C for a week. In addition, the bioanode obeyed the Michaelis–Menten kinetics. Finally, we demonstrated that a glucose biofuel cell assembled with an optimal bioanode and a laccase/ABTS cathode generated an electric power of 45 μW cm−2 from 1 M glucose at 37 °C.