Recent advances on organic fluorescent probes for stimulated emission depletion (STED) microscopy.

Stimulated emission depletion (STED) microscopy has become a useful tool to visualize and dynamic monitor at an ultra-high resolution in both biological research and material science. For STED technology, fluorescent probes are irreplaceable in imaging process. Among them, organic fluorescent probes exhibit characteristics of superior photo-stability, high brightness, large Stokes' shifts and excellent biocompability, thus resulting in wide applications in STED microscopy. Based on this consideration, in this review, the recent advances on organic fluorescent probes, including typical organic fluorescent probes, aggregation-induced emission luminogens (AIEgens), polymer dots and other nanoparticles, are introduced. The applications of organic fluorescent probes in biological imaging, such as live-cell, tissue and in-vivo imaging, and also material monitoring on the nanometer scale by using STED microscopy are then included. Based on these results, the rules to design new materials for STED microscopy are provided to enhance their imaging performance and then further enrich their real-world applications in future research.