Mass transport effect on graphene based enzyme electrochemical biosensor for oxalic acid detection

Graphene has been widely used to construct enzyme biosensors, with most research focused on improving electron transfer. While most of electrochemical process on graphene-modified electrode has been demonstrated to be a diffusion-controlled, the restacking of graphene has resulted in nonefficient mass transport. Herein, oxalate oxidase (OxOx) immobilized on chemically reduced graphene oxide (CRGO) can suppress the aggregation of CRGO and exhibit significantly improved mass transport and can be used as biosensor with excellent sensitivity to oxalic acid. More importantly, the amount of CRGO has a significant effect on electron transfer and the mass transport. By adjusting amount of CRGO, we demonstrate that the electron-transfer rate and mass-diffusion efficiency have a synergistic effect on the electrochemical performance of biosensors. Improving the mass diffusion rate can greatly enhance the electrochemical properties of a graphene based biosensor; therefore, the efficient mass transport on graphene based electrodes should receive more attention. A detailed understanding of this could be further applied to other graphene-based enzyme biosensors.