Live-Cell MicroRNA Imaging through MnO2 Nanosheet-Mediated DD-A Hybridization Chain Reaction.

Innovative techniques to visualize native microRNAs (miRNAs) in live cells can dramatically impact current research on the roles of miRNA in biology and medicine. Here, we report a novel approach for live-cell miRNA imaging using a biodegradable MnO2 nanosheet-mediated DD-A FRET hybridization chain reaction (HCR). The MnO2 nanosheets can adsorb DNA hairpin probes and deliver them into live cells. After entering cells, the MnO2 nanosheets are degraded by cellular GSH. Then, the target miR-21 triggers cascaded assembly of the liberated hairpin probes into long dsDNA polymers, which brings each two FAMs (donor) and one TAMRA (acceptor) into close proximity to generate significantly enhanced DD-A FRET signals, which was discovered and proven by our previous report. We think the developed approach can serve as an excellent intracellular miRNAs detection tool, which promises the potential for biological and disease studies.