Direct electrochemistry and bioelectrocatalysis of glucose oxidase in CS/CNC film and its application in glucose biosensing and biofuel cells

Abstract

Due to their unique physicochemical properties, carbon nanochips (CNCs) have been used for studies of the direct electrochemical and electrocatalytic properties of oxidoreductase. In this report, a glassy carbon electrode (GCE) was modified with CNCs, and glucose oxidase (GOx) was immobilized on the modified electrode surface. Chitosan (CS) was employed to fix the GOx/CNCs tightly to the surface of the GCE. Characterization of the modified electrode by SEM, TEM, and FT-IR showed that GOx remained in its native structure when immobilized in CNC film. The results of electrochemical impedance spectroscopy, cyclic voltammetry, and linear sweep voltammetry studies showed that direct electrochemical and bioelectrocatalytic activities of GOx were achieved and that the presence of CNCs enhanced the electrochemical response of GOx. Glucose had a linear current response from 0 to 1.9 mM, with a detection limit of 0.16 mM and an apparent Michaelis–Menten constant of 0.15 mM. The polarization curve of the biofuel cell revealed that the bioanode afforded an open circuit voltage of 0.59 V, maximum power density of 55 μW cm⁻², and maximum current density of 434 μA cm⁻². These results establish that the direct immobilization of protein onto the CNC surface can be used to achieve direct electron transfer of other redox enzymes. Furthermore, the findings provide a new perspective toward understanding the kinetics and thermodynamics of biological redox processes.