All-Visible-Light Activated Diarylethene Photoresponsive Probe for Lysosomal STORM Imaging

Stochastic optical reconstruction microscopy (STORM) breaks through the diffraction limit of conventional optical imaging, allowing biological processes to be visualized with nanoscale precision. The diarylethene have attracted particular attention because of their remarkable reversibility, excellent thermal stability and fatigue resistance. Photoswitchable diarylethene with easy modification and tunable fluorescence eliminate the need of any additives in single-molecule localization techniques, and have gained new development opportunities in STORM imaging. However, most diarylethene probes currently used for STORM imaging usually require a beam of phototoxic ultraviolet (UV) laser to control the transition between the fluorescent and dark states, and also lack the capability of organelle recognition. Here, we propose a novel STORM fluorescence probe design strategy. By combing the intramolecular proton transfer (IPT) fluorophore on one side and the lysosomal targeting group on the other side with the diarylethene, we have successfully synthesized the molecule HMN which can not only regulate the fluorescence blinking between the bright and dark states by harmless all-visible light, but also have excellent lysosome targeting ability. These properties are benefit for the intracellular STORM imaging of lysosomes. HMN exhibits excellent fatigue resistance, sensitive fluorescence switching, accurate lysosome recognition capability, and its fluorescence can be activated by 488 nm laser and deactivated by using 561 nm laser without requiring any additives to the imaging media. With the photoresponsive probes HMN, we achieved STORM imaging with all-visible light, which contributes to determine the subcellular distribution of lysosomes and enable super-resolution of a single lysosome up to 99 nm.