Unveiling the Interaction of Duplex DNA with Graphene Oxide in the Presence of Two Diverse Binders: A Detailed Photophysical Study

Coupling of biomolecules with nanomaterials has drawn immense attraction because of the improved synergistic properties, functions, and biocompatible nature. Thus, this process manifests its important role and fascinating potential in various nanobiotechnogical, biomedical, biosensing, and imaging applications. In this work, fundamental understanding of the interfacial properties and the interaction of double-stranded DNA (dsDNA) with graphene oxide (GO) has been systematically investigated by employing two different DNA-binding probes. Our results suggest that the unusual adsorption of duplex DNA onto the GO surface has been facilitated due to the partial deformation of the helical structure of DNA as evident from circular dichroism (CD) spectroscopy. Depending on the location of the probes inside the DNA helix, the photophysical properties of the dye-bound DNA in the presence of GO have been changed. Interestingly, the translational diffusion and rotational motion of the minor groove-binding probe, 4'-6-diamidino-2-phenylindole (DAPI) bound DNA, have been significantly altered with the addition of GO. In contrast, efficient electron transfer may occur from the DNA-intercalated ethidium bromide (EB) to GO with a time constant of ∼300 fs as evident from the ultrafast time-resolved measurement. Conclusively, a basic understanding of the interaction mechanism and dynamics of two different probes inside DNA and at the DNA-GO interface opens up new windows for the future development of various nano/bio applications.