Enzyme-based sensing of glucose using a glassy carbon electrode modified with a one-pot synthesized nanocomposite consisting of chitosan, reduced graphene oxide and gold nanoparticles

Abstract

A nanocomposite was prepared that consists of chitosan, reduced graphene oxide and gold nanoparticles by in-situ and simultaneous reduction of graphene oxide and hexachloroaurate whereby chitosan acts as a reducing and stabilizing agent. The nanocomposite was then deposited on a glassy carbon electrode, and glucose oxidase (GOx) was immobilized on its surface to obtain a glucose biosensor. The immobilized GOx displays fast electron transfer with a transfer rate constant of 2.80 s−1. Operated at a working voltage of −0.45 V (vs. Ag/AgCl), the sensor gives a linear response to glucose in the 0.05 to 1.2 mM concentration range, with a sensitivity of 13.58 μA mM−1 cm−2, and a 0.52 μM detection limit. The apparent Michaelis-Menten constant is 2.39 mM. It also possesses good selectivity, reproducibility and stability.