Electric field-mediated regulation of enzyme orientation for efficient electron transfer at the bioelectrode surface: A molecular dynamics study

Surface immobilization with favorable orientation of biocatalysts is critical for developing bioelectrochemical devices. To improve the performance of electrochemical electrodes, biocatalyst surface modification and engineering has been attempted via expensive and complex fabrication processes. For proper orientation and deposition of biomolecules on the surface, application of external electric field (EF) to small molecules has been suggested. Here, to the best of our knowledge, a unidirectional external EF was applied for the first time to oxygen-reducing enzymes with high catalytic activity and a Laccase-graphene interface was constructed using computational methods. The external EF rotated the active site of laccase, resulting improvement in the electron transfer rate compared to enzymes physically immobilized on graphene. The external EF fabrication process was also evaluated for graphene congeners (graphene oxide (GO) and reduced GO (rGO)). The morphology of the electrode surface was visualized, and computational methods were applied to verify binding conformation, orientations of dipole moment, secondary structure, and binding stability. Graphene was the most promising material compared to GO and rGO by 10 and 5 % for DET rate, respectively. Results suggest that using an external EF to favorably orientate the Laccase-graphene interface may be a simple, economical, and efficient approach for bioelectrode fabrication.