Dynamic Assembly of DNA Nanostructures in Cancer Cells Enables the Coupling of Autophagy Activating and Real-Time Tracking.

Developing dynamic nanostructures for in situ regulation of biological processes inside living cells is of great importance in biomedical research. Herein we report the cascaded assembly of Y-shaped branched DNA nanostructure (YDN) during intracellular autophagy. YDN contains one arm with semi-i-motif sequence and Cy3-BHQ2, and another arm with an apurinic/apyrimidinic (AP) site and Cy5-BHQ3. Upon uptake by cancer cells, intermolecular i-motif structures are formed in response to lysosomal H+ , causing the formation of YDN-dimer and the recovery of Cy3 fluorescence; when escapes occur from the lysosome to the cytoplasm, the YDN-dimer responds to the overexpressed APE1, leading to the assembly of YDN into the DNA network and the fluorescence recovery of Cy5. Simultaneously, the cascaded assembly activates autophagy, and thus the process of assembly of YDN and autophagy flux can be spatiotemporally coupled. This work illustrates the potential of DNA nanostructures for the in situ regulation of intracellular dynamic events with spatiotemporal control.