Orderly Assembled, Self-Powered FRET Flares for MicroRNA Imaging in Live Cells.

Signal amplification provides unparalleled opportunities for visualizing low-abundance targets in living cells. However, self-powered signal amplification has not been achieved because of the lack of "fuel" in living cells. Thus, the aim of this work was to develop an integrated amplification platform for the detection of intracellular miRNA by itself. This system, termed self-powered FRET flares (SPF), was first established by self-assembly to form a DNA nanostructure, and then the FRET flares and fuel DNA as the driving force were precisely and orderly loaded on it, which was able to power target recycle and realize signal amplification without any auxiliary additives under the trigger of intracellular miRNA-21. In addition, it employed AS1411 aptamer to target specific cancer cells and facilitated cell internalization of assembly DNA nanostructures. As a proof of concept, we demonstrated that SPF enabled rapid response to miRNA-21 and improvement of the detection sensitivity compared to previously proposed FRET flares without amplification. This strategy is promising for advancing integrated and self-powered nanomachines to execute diverse tasks, facilitating their biological and medical application.