Phenanthroline-linked berberine dimer and fluorophore-tagged DNA conjugate for the selective detection of microRNA-185: Experimental and molecular docking studies.

A phenanthroline (phen) tethered berberine dimer 1 is synthesized and further conjugated with carboxyfluorescein (FAM)-labeled single-stranded probe DNA (P-DNA) to give P-DNA@1. The mutual interaction of these two components triggers the fluorescence quenching of FAM, and the non-emissive P-DNA@1, in turn, functions as a sensor to detect cancer-associated microRNA-185 (miRNA-185), characterized by the FAM fluorescence recovery. The results show that P-DNA@1 is capable of detecting miRNA-185 in 2 min with the detection limit of 0.2 nM. The detection mechanism was supported by fluorescence anisotropy, binding constant and molecular docking study. Competing experiments further indicate that P-DNA@1 exhibits a high selectivity for miRNA-185 thus has a good potential in the diagnosis of related cancer at the early stage.