Electrochemical DNA biosensor for the detection of DNA hybridization with the amplification of Au nanoparticles and CdS nanoparticles.

In this article, colloidal gold nanoparticles (Au NPs) and carboxyl group-functionalized CdS Nanoparticles (CdS NPs) were immobilized on the Au electrode surface to fabricate a novel electrochemical DNA biosensor. Both Au NPs and CdS NPs, well known to be good biocompatible and conductive materials, could provide larger surface area and sufficient amount of binding points for DNA immobilization. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments were performed to follow the whole electrode fabrication process. DNA immobilization and hybridization were characterized with differential pulse voltammetry (DPV) by using [Co(phen)(2)(Cl)(H(2)O)]Cl.2H(2)O as an electrochemical hybridization indicator. With this approach, the target DNA could be quantified at a linear range from 2.0x10(-10) to 1.0x10(-8) M, with a detection limit of 2.0x10(-11) M by 3sigma. In addition, the biosensor exhibited a good repeatability and stability for the determination of DNA sequences.