Electrochemical DNA biosensor fabrication with hollow gold nanospheres modified electrode and its enhancement in DNA immobilization and hybridization

In this article, hollow gold nanospheres (HGN) were prepared by using Co nanoparticles as sacrificial templates and varying the stoichiometric ratio of HAuCl4 over the reductants. The HGN was then modified on the electrode surface via a 1,6-hexanedithiol linking agent to fabricate a novel electrochemical DNA biosensor. The whole DNA biosensor fabrication process was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods with the use of ferricyanide as an electrochemical redox indicator. The probe DNA immobilization and hybridization on the modified electrode was further studied with CV and differential pulse voltammetry (DPV) methods by using Co(phen)33+ as an electrochemical hybridization indicator. Results revealed that the HGN modified electrode, especially for the HGN with the outer surface surrounded by densely spike-like nanocrystallites, could largely enhance the DNA hybridization ability. The fabricated DNA biosensor was proved to have a low detection limit (1 pM) and a wide dynamic range (from 1 pM to 10 nM) with a high stability and reusability.