Experimental and theoretical studies of electrochemical oxidation of nicotinamide adenine dinucleotide at the modified SWCNT and graphene oxide.

In recent years, nicotinamide adenine dinucleotide (NADH) and its oxidized form (NAD+) have withdrawn a substantial attention since they possess a significant place in both biosensor and biofuel cell studies. However, the transformation of NADH to NAD+ brings about the surface passivation and fouling at the most of corresponding conductive materials; consequently, significant decrease takes place in the current. In order to overcome these drawbacks, we have performed the surface functionalization of single-walled carbon nanotube (SWCNT) and graphene oxide (GO) immobilized onto glassy carbon surface with dihydroxybenzene (di-HB) using solid-phase synthesis methodology. The di-HB-modified SWCNT and GO were found to exhibit great catalytic activity as they reduce required overpotential of electrochemical oxidation of NADH and lead to enhancement in the peak current, compared with unmodified carbon electrodes. Molecular docking simulation technique was also carried out to enlighten attained experimental findings in detail, and we have found that increase in the binding affinity of NAD+ to functionalized carbon surfaces with di-HB is related to formation of hydrogen bonding interactions Furthermore, our experimental and theoretical outputs were also found to be quite consistent in terms of reactivity of modified surfaces to NADH oxidation.