Development of electrochemical DNA biosensor based on gold nanoparticle modified electrode by electroless deposition

In this article, a simple strategy of electroless deposition for gold nanoparticle (Au NP) modification on the conductive substrate is developed. The morphology of Au NP modified electrode could be controlled to some extent by choosing different solution concentrations, deposition times, etc. The Au NP modification increased the electrode surface area largely, and the surface area after Au NP modification on the polyelectrolyte multilayer (PEM) assembled electrode was about 3.3 times that of the planar gold electrode. The enhancement of DNA immobilization and hybridization on the Au NP modified electrode were characterized by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) with the use of Ru(NH(3))(6)(3+) as an electrochemical redox indicator. With this approach, the sensitivity of Au NP modified PEM electrode for target DNA could reach 1x10(-11)M. Compared with that of planar gold electrode, the detection limit was increased to be about 3 orders of magnitude.