The Bioimaging Story of AIEgens.

Observations of the micro world, especially the structures of organelles, have been attractive topics since the 17th century. As a powerful detection tool, the fluorescence technique has played a significant role in bioimaging to provide more details and enhance the signal-to-noise ratio compared to that of traditional optical microscopes. The boom of aggregate-induced emission luminogens (AIEgens) in the last two decades has revolutionized the design strategy of luminescent materials for biological applications. This Review summarizes the advantages and recent progress of AIEgens in imaging and tracking. Different imaging strategies of AIEgens including turn-on imaging, stimuli-response sensing, and long-term tracking are presented. NIR AIEgens used for in-depth bioimaging via different methods are also discussed. Finally, we propose several potential development directions for AIEgens in bioimaging.