polyethyleneimine wrapped carbon nanotubes in situ formed gold nanoparticles decorated with DNA and NAD+ as a novel bioeletrochemical sensing platform

The polyethyleneimine (PEI) wrapped multi walled carbon nanotubes functionalized with a carboxylic acid group (CNTs-COOH) gold nanoparticles (AuNPs)/DNA modified gold (Au) electrode has been utilized as a platform to immobilize electrogenerated NAD+ oxidation products (2,8-dihydroxyadeninedinucleotide (DHA)). During potential cycling, the adenine moiety of NAD+ molecule is reduced and gives rise to generation of a redox active system that shows great electrocatalytic activity toward hydrogen peroxide (H2O2) reduction. Electrocatalytic reduction of H2O2 on the surface of modified electrode was investigated with cyclic voltammetry, electrochemical impedance spectroscopy (EIS), hydrodynamic voltammetry and chronoamperometry methods. The cyclic voltammetric results indicated the ability of AuNPs/PEI/CNT-COOH/DNA/DHA modified Au electrode to catalyze the reduction of H2O2. AuNPs/PEI/CNTs-COOH nanocomposite combined the advantages of PEI-well dispersed CNTs-COOH and in situ formed AuNPs, thus endowed with high stability and some special properties to the enzyme-free sensor.