AIE Nanoparticles with High Stimulated Emission Depletion Efficiency and Photobleaching Resistance for Long‐Term Super‐Resolution Bioimaging

Abstract Stimulated emission depletion (STED) nanoscopy is a typical super‐resolution imaging technique that has become a powerful tool for visualizing intracellular structures on the nanometer scale. Aggregation‐induced emission (AIE) luminogens are ideal fluorescent agents for bioimaging. Herein, long‐term super‐resolution fluorescence imaging of cancer cells, based on STED nanoscopy assisted by AIE nanoparticles (NPs) is realized. 2,3‐Bis(4‐(phenyl(4‐(1,2,2‐triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TTF), a typical AIE luminogen, is doped into colloidal mesoporous silica to form fluorescent NPs. TTF@SiO 2 NPs bear three significant features, which are all essential for STED nanoscopy. First, their STED efficiency can reach more than 60%. Second, they are highly resistant to photobleaching, even under long‐term and high‐power STED light irradiation. Third, they have a large Stokes' shift of ≈150 nm, which is beneficial for restraining the fluorescence background induced by the STED light irradiation. STED nanoscopy imaging of TTF@SiO 2 ‐NPs‐stained HeLa cells is performed, exhibiting a high lateral spatial resolution of 30 nm. More importantly, long‐term (more than half an hour) super‐resolution cell imaging is achieved with low fluorescence loss. Considering that AIE luminogens are widely used for organelle targeting, cellular mapping, and tracing, AIE‐NPs‐based STED nanoscopy holds great potential for many basic biomedical studies that require super‐resolution and long‐term imaging.