Graphene oxide-enhanced and proflavine-probed fluorescence polarization biosensor for ligand-RNA interaction assay

Proflavine could recognise HIV RRE (Rev response element) RNA, thus inhibiting its interaction with Rev peptide. Owing to the non-significant difference in fluorescence polarization (FP) signal between the proflavine and proflavine-RRE complex, it is not practicable for the identification of antagonists of HIV Rev peptide using proflavine as a FP probe. In the present study, graphene oxide (GO) was introduced to amplify the FP signal to enhance the sensitivity for the identification of Rev antagonists, thereby enabling the development of a primary GO-enhanced FP biosensor for the discovery of Rev antagonists. The effect of the amount of GO on the FP changes was investigated via displacement assay using a known Rev antagonist, neomycin B. The mechanism underlying the changes in FP caused by the addition of neomycin B was explored in the presence of GO. Finally, the performance of this biosensor was further evaluated using other 4 test drugs. The introduction of GO to this interaction system increased the practicability for the discovery of Rev antagonists using proflavine as a probe, and this label-free method does not suffer from limitations caused by fluorescent covalent labeling, thus providing a novel strategy for the characterization of ligand-RNA binding interactions.