Graphene-oxide quenching-based molecular beacon imaging of exosome-mediated transfer of neurogenic miR-193a on microfluidic platform.

Graphene-oxide (GO) quenching-based molecular beacon was developed for rapid and sensitive detection of RNAs in living cells and tissues. Here, we applied GO quenching-based molecular beacon sensor to visualize neurogenic miR-193a levels delivered via exosomes during cell-non-autonomous neurogenesis in neural progenitor cells on a microfluidic platform. Exosomal transport was visualized using CD63-RFP plasmid vector, and FAM-labeled peptide nucleic acid (PNA) probe for the miR-193 sequence was designed to detect endogenous miR-193 expression. Fluorescence signals of FAM-PNA193a-GO were recovered in dibutyryl-cAMP-induced F11 cells, resulting from increased expression of miR-193a after neuronal differentiation. We observed delivery of miR-193a-containing exosomes released from differentiated donor F11 cells to recipient undifferentiated F11 cells. Fluorescence recovery was evident in exosome-stimulated recipient individual F11 cells in the microfluidic system. We propose molecular beacon imaging using PNA-GO complex for visualization of individual cellular expression of mature microRNAs. This system reveals the precise spatial localization and temporal sequences of mature miRNAs by intercellular exosomal delivery of messages for processes such as cell-non-autonomous neurogenesis.