A Novel and Enhanced Membrane-Free Performance of Glucose/O2 Biofuel Cell, Integrated With Biocompatible Laccase Nanoflower Biocathode and Glucose Dehydrogenase Bioanode

In this research, a novel glucose/O
₂
biofuel cell was developed with glucose dehydrogenase bioande and laccase biocathode. For the preparation of a bioanode, glassy carbon electrode was modified in a layer by layer structure of graphene oxide nano-sheets, glucose dehydrogenase, and nicotine amide adenine dinucleotide by electrostatic affinities and the capping layer consist of glutaraldehyde, bovine serum albumin and glucose dehydrogenase. The proposed system depicted a high bioelectrocatalytic activity toward glucose oxidation and the oxidation commenced at -0.30 V (vs. Ag/ AgCl). For implementation in a biofuel cell, a biocompatible enzyme-based cathode was developed. Therefore, laccase nanoflowers were immobilized onto gold nanoparticles, which were electrodeposited on a gold electrode and polydopamine biofilm was employed to keep the immobilized laccase nanoflowers in place. The biocathode illustrated a high electrocatalytic activity toward oxygen reduction reaction with a direct electron transfer at a positive potential of +0.61 V (vs. Ag/AgCl). The prepared bioelectrodes were integrated into a glucose/O
₂
biofuel cell system, without a membrane and the performance and the stability of the biofuel cell were evaluated in vitro. The obtained operating circuit voltage and maximum current densities were 0.86 V and 1.11 mA · cm
^-2
and maximum power density of 0.40 mW · cm
^-2
was achieved at 0.67 V (vs. Ag/AgCl). The output power of the biofuel cell is almost persistent after 24 days of sustained operation. The achieved results suggest that the proposed modifications provide a high performance and very stable biofuel cell for application in implantable medical devices.