Catalytic oxidation and determination of β-NADH using self-assembly hybrid of gold nanoparticles and graphene

A self-assembly hybrid of gold nanoparticles on graphene modified electrodes for low-potential NADH detection has been achieved. We used the natural polymer chitosan (Chit) to assist the stabilization of graphene in aqueous solution, and immobilize the electronegative Au nanoparticles (NPs) through electrostatic attraction. The synergy of Au NPs with graphene for catalytic oxidation of NADH made the overpotential ca. 220 mV less positive than that on the bare electrode, and remarkably increased the oxidation current. The amperometric sensors based on such modified electrodes for detection of NADH exhibited a good linearity from 1.5 to 320 mu M, and showed high sensitivity with a low detection limit of 1.2 mu M (S/N = 3). It could also exclude common interfering electroactive compounds like ascorbic acid and possessed good reproducibility and operational stability. Such eminent performance of the Au-RGO/Chit film together with the ability of graphene to significantly enhance the electron transfer between enzymes and the electrode suggested its promise for constructing novel graphene based dehydrogenase biosensors.