Ethidium bromide-adsorbed graphene templates as a platform for preferential sensing of DNA.

Sulfonated graphene (SG) and graphene oxide (GO) are used as an ethidium bromide (EtBr, E) binding platform, to preferentially sense DNA (D) among the other biomolecules such as RNA (R), bovine serum albumin (BSA, P) and glucose (G) using spectroscopic techniques. EtBr loses its intrinsic fluorescence property after binding with SG. DNA can "turn on" the quenched fluorescence of an SG-EtBr hybrid to a greater extent compared to the RNA, BSA, and glucose. UV-vis absorption spectra and circular dichroism (CD) spectra also support the higher ability of DNA to release adsorbed EtBr from the SG surface in comparison to the above-mentioned biomolecules. Compared to GO-EtBr, the SG-EtBr hybrid is superior to preferentially sense DNA, as the enhancement of fluorescence intensity is 16 times in the later but it is 4.5 times in the former from their respective complexes. An analysis of Raman spectral data indicates that the interaction of EtBr in its adsorbed state on an SG template is greater with DNA than with RNA.