Facile development of highly sensitive femtomolar electrochemical DNA biosensor using gold nanoneedle-modified electrode

In this paper, a simple one-step electrochemical method was employed for the deposition of gold nanostructures. Different morphologies (Au-nanorods and Au-nanoneedles) were obtained using different concentrations of gold chloride (HAuCl4 center dot 3H(2)O) solution. The gold nanostructure-modified surface was used for the fabrication of DNA biosensor, which was characterized by cyclic voltammetry and differential pulse voltammetry. The DNA immobilization and hybridization on Au-nanorods and Au-nanoneedles showed a detection limit of 10 fM and 0.2 fM, respectively, with wide dynamic range of 0.2 fM to 10 nM. The Au-nanoneedle electrode showed improved detection limit, which is fifty times lower than that of the Au-nanorods. The electrochemical DNA biosensor showed a good selectivity and sensitivity towards the detection of target DNA. The enhancement in response of DNA biosensor would be an exciting addition in clinical diagnosis due to an improved detection limit.