Colorimetric and electrochemical study on the interaction between gold nanoparticles and unmodified DNA

Gold nanoparticles have been widely adopted to fabricate DNA sensors and aptasensors. Nevertheless, detailed information deep into the mechanism of the interaction between gold nanoparticles and DNA is still under investigation. In this work, we have employed colorimetric and electrochemical methods to study the interaction between unmodified DNA and colloidal as well as surfaceconfined gold nanoparticles. It is observed that in both cases, only single-stranded DNA may interact with the nanoparticles; however, the interaction processes are quite different. Single-stranded DNA binds to colloidal gold nanoparticles rapidly and weakly, while the binding is much longer and stronger in the case of surface-confined gold nanoparticles. We have discussed the differences and further proposed possible mechanisms. The results we present in this paper might be helpful for the deep understanding of the interaction between nanomaterials and DNA, and benefit the design of AuNPs-based DNA sensors and aptasensors.