Applications of carbon nanotubes to electrochemical DNA sensors: a new strategy to make direct and selective hybridization detection from SWNTs

Qi Dong Zhang, Benoît Piro, Vincent Noël, Steeve Reisberg and Minh-Chau Pham

Abstract

In this paper, we first review different strategies reported in the literature to elaborate electrochemical DNA sensors based on carbon nanotubes. Then we report a new strategy to graft both redox and DNA probes onto carbon nanotubes to make a label-free DNA sensor. Oxidized single-walled carbon nanotubes are first immobilized on a self-assembled monolayer of cysteamine. Then a redox probe, a quinone derivative 3-[(2-aminoethyl) sulfanyl-5-hydroxy-1,4-naphthoquinone], is grafted onto the free carboxylic groups of the nanotubes. After that, for DNA probe grafting, new carboxylic sites are generated via an aryl diazonium route. After hybridization with a complementary sequence, the conformational changes of DNA could influence the redox kinetics of quinone, leading to a current increase in the redox signal, detected by square wave voltammetry. The system is selective, as it can distinguish a single mismatched sequence from the complementary one