Direct observation of adsorption and desorption of ds-DNA on graphene oxide and graphene oxide-gold nanoparticle hybrid material: A kineto-mechanistic investigation

Abstract

Graphene oxide (GO) and its functional derivatives have found tremendous application in the development of biosensors for the detection of nucleic acid hybridization. In this work, we have systematically investigated the adsorption mechanism of oligonucleotides on both GO and graphene oxide-gold nanoparticle (GO-AuNP) hybrid surface and also recovered the adsorbed DNA by applying complementary strands by employing ensemble and single-molecule fluorescence methods. A remarkable observation about the adsorption and desorption mechanism of double-stranded DNA (ds-DNA) on graphene oxide (GO) and GO-AuNP surface has been monitored. The efficiency and rate of adsorption are found to be higher for the GO-AuNP hybrid material compared to that of only GO. The results from the single-molecule-FRET (sm-FRET) indicate that the adsorption of the ds-DNA on the GO-AuNP hybrid material takes place by completely unzipping the strands, i.e. the DNA adsorbs as single-stranded DNA. However, no such clear evidence was observed for the GO. The sm-FRET results reveal the DNA hybridization mechanism to happen “in situ”, i.e. hybridization between the probe and target DNA to form a ds-DNA and desorption thereafter from the GO surface takes place simultaneously. These results also demonstrate that the electrostatic interaction between DNA and GO is of little importance to the overall theory of interaction. This investigation improves the fundamental understanding of DNA hybridization dynamics on GO surface opening new windows in the field of biophysics, sensing, and therapeutic application.