NIR Remote-Controlled "Lock-Unlock" Nanosystem for Imaging Potassium Ions in Living Cells.

Despite great achievements in sensitive and selective detection of important biomolecules in living cells, it is still challenging to develop smart and controllable sensing nanodevices for cellular studies that can be activated at desired time in target sites. To address this issue, we have constructed a remote-controlled "lock-unlock" nanosystem for visual analysis of endogenous potassium ions (K+), which employed a dual-stranded aptamer precursor (DSAP) as recognition molecules, SiO2 based gold nanoshells (AuNS) as nanocarriers, and near-infrared ray (NIR) as the remotely applied stimulus. With the well-designed and activatable DSAP-AuNS, the deficiencies of traditional aptamer-based sensors have been successfully overcome, and the undesired response during transport has been avoided, especially in complex physiological microenvironments. While triggered by NIR, the increased local temperature of AuNS induced the dehybridiztion of DSAP, realized the "lock-unlock" switch of the DSAP-AuNS nanosystem, activated the binding capability of aptamer, and then monitored intracellular K+ via the change of fluorescence signal. This DSAP-AuNS nanosystem not only allows us to visualize endogenous ions in living cells at a desired time but also paves the way for fabricating temporal controllable nanodevices for cellular studies.