Direct electrochemistry of glucose oxidase at reduced graphene oxide/zinc oxide composite modified electrode for glucose sensor

We prepared the reduced graphene oxide (RGO)/zinc oxide (ZnO) composite on glassy carbon electrode (GCE) by simple and green electrochemical approach. Glucose oxidase (GOx) was immobilized at RGO/ZnO composite modified GCE. The immobilized GOx showed a pair of stable and well-defined reversible redox peaks at the RGO/ZnO composite, with a formal potential (E ^0') of -0.40 V and a peak to peak separation (ΔE _p) of 70 mV. GOx is strongly adsorbed on the RGO/ZnO composite matrix by the electrostatic interaction between negatively charged GOx and positively charged RGO/ZnO composite. Further, the fabricated glucose biosensor showed good performance over an acceptable linear range from 0.02 to 6.24 mM with a detection limit of 0.02 mM. This composite material could be a promising material for various enzyme based biosensors.