Cell-Surface-Anchored Ratiometric DNA Nanoswitch for Extracellular ATP Imaging.

The precise detection of extracellular ATP, although a challenging task, is of great significance for understanding the related cell processes. Herein, we developed a ratiometric DNA nanoswitch by employing a DNA tweezer and split aptamer. The nanoswitch is composed of three specially designed ssDNA strands, namely, the central strands O1, O2, and O3. This nanoswitch can be anchored on the cell membrane by cholesterol labeled at the 3' end of O3. Initially, the DNA tweezer adopts an open state, separating the dual fluorophores and giving rise to a low FRET (fluorescence resonance energy transfer) ratio. The presence of ATP induces the binding of the two split aptamers to alter the structure of the nanoswitch from the open state to the closed state, bringing the donor and the acceptor closer together and generating high FRET efficiency. The results demonstrated that the ratiometric DNA nanoswitch can be applied for quantitative analysis and real-time monitoring of the changes in extracellular ATP. We believe that the cell surface-anchored DNA nanoswitch has promising prospects for use as a powerful tool for the understanding of different ATP-related physiological activities.