Graphene quantum dots mediated electron transfer in DNA base pairs

Abstract

Graphene quantum dots (GQDs) were connected to [Ru(bpy)₃]²⁺ to sense DNA-mediated charge transfer. Interaction between abasic site double stranded DNA (Abasic-DNA) and [Ru(bpy)₃–GQD]²⁺ was investigated by absorption spectroscopy, gel electrophoresis, circular dichroism, and melting temperature measurements. The results indicate that [Ru(bpy)₃–GQD]²⁺ could be intercalated into double stranded DNA. Using [Ru(bpy)₃–GQD]²⁺ as a signal molecule, the charge transfer performance of DNA-intercalated [Ru(bpy)₃–GQD]²⁺ was determined using electrochemical and electrochemiluminescence measurements. Various DNA types were immobilized on Au electrodes via Au–S bonds. Electrochemiluminescence and electrochemical measurements indicate that [Ru(bpy)₃–GQD]²⁺ could enhance DNA-mediated charge transfer when intercalated into an abasic site of double stranded DNA. And comparing with [Ru(bpy)₃]²⁺, it can be concluded that GQDs intercalate into the DNA duplex by acting as a base analog, thus enhancing DNA charge transfer. These findings suggest that the DNA–GQD structure could aid the development of molecular devices and electric drivers, and broaden the application of DNA charge transfer.