Graphene quantum dots mediated electron transfer in DNA base pairs

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.