A NADH biosensor based on diphenylalanine peptide/carbon nanotube nanocomposite

The fabrication and notably improved performance of composite electrodes based on the nanocomposite of diphenylalanine peptide-covered multiwalled carbon nanotube (PP–MWCNT) is described. The synthesis of the nanocomposite of PP–MWCNT is a self-assembly process of diphenylalanine peptide (PP) along carbon nanotube (MWCNT) via aromatic stacking interaction combined with hydrogen bond of diphenylalanine peptide. PP–MWCNT modified electrode was fabricated by a simple casting method, and studied with cyclic voltammetry (CV) and chronoamperometry. PP–MWCNT modified electrode showed a high, direct and unmediated response to β-reduced coenzyme nicotinamide adenine dinucleotide (NADH) at a potential of 0.600 V (vs. SCE), which had reduced the overvoltage of NADH oxidation by 0.200 V in comparison with the bare electrode. Furthermore, the current response of NADH at PP–MWCNT modified electrode is about five times higher than that of the bare electrode. Thus, PP–MWCNT provides a new candidate for fabrication of biosensor based on β-coenzyme nicotinamide adenine dinucleotide (NAD+)-dependent dehydrogenases. Herein, an ethanol biosensor was prepared by crosslinking ethanol dehydrogenase (ADH), bovine serum albumin (BSA) and PP–MWCNT onto the electrode. The ethanol biosensor exhibited a good linearity ranged from 30 μM to 700 μM with a high sensitivity of 30.00 nA/μM cm−2 and with a low detection limit of 12 μM.

Research highlights
► An electrochemical active nanocomposite of diphenylalane dipeptide/multiwalled carbon nanotubes has been prepared on the basis of noncovalent assembly.
► The as-prepared nanocomposite can offer a remarkable decrease of the overvoltage of NADH oxidation, which makes it available in a high-sensitive ethanol biosensor.