An electrochemical biosensor based on Au nanoparticles decorated reduced graphene oxide for sensitively detecting of Hg2+

The present work describes an electrochemical Hg2+ ion biosensor which used Au nanoparticles decorated reduced graphene oxide (Au NPs-RGO) for generating electrochemical signal as indicator involving. Hg2+ ions specifically captured two thymine bases (T) of DNA probe to form T-Hg2+-T stable base pairs, therefore, Hg2+ ion solution induced the structure of Au NPs-RGO modified thiol-functionalized DNA probe from single-strand to hairpin. The DNA 1 modified on Au electrode is complementary with Au NPs-RGO modified single-stranded DNA probe. Therefore, the amount of Au NPs-RGO adsorbed on electrode is decreased when the concentrations of Hg2+ ions increase. The current response of the fabricated biosensor is monitored on ferricyanide system, which exhibits a wide linear range of 0-2000 nM and a high selectivity towards Hg2+ ion. Besides, there are no co-factors used in the process of fabricating biosensor. Moreover, the biosensor is applied for detecting Hg2+ ions in water sample with satisfactory results.