Highly sensitive amperometric biosensor for determination of NADH and ethanol based on Au-Ag nanoparticles/poly(L-Cysteine)/reduced graphene oxide nanocomposite.

This work presents the fabrication of a novel nicotinamide adenine dinucleotide (NADH) sensor using gold-silver bimetallic nanoparticles (Au-AgNPs), poly(L-Cysteine) (P(L-Cys)) and electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE/Au-AgNPs/P(L-Cys)-ERGO). The composite electrode exhibited an excellent electrocatalytic response towards NADH at a low oxidation potential (+ 0.35V) and minimization of surface contamination due to the synergistic effects of the Au-AgNPs, polymer and ERGO. Under optimum conditions, modified sensors allowed the detection of NADH with a wide linear range from 0.083µM to 1.05mM with a low detection limit of 9.0nM (S/N = 3). Moreover, this modified electrode was also used as a sensitive ethanol biosensor, which was prepared with alcohol dehydrogenase (ADH) via glutaraldehyde, bovin serum albumin and nafion (Naf). There was a linear response for ethanol in the concentration range from 0.017 to 1.845mM with a low detection limit of 5.0µM (S/N = 3). The GCE/Au-AgNPs/P(L-Cys)-ERGO/ADH/Naf electrode can be successfully used for the determination of ethanol in different commercial beverages.