Aggregation-induced emission luminogen-assisted stimulated emission depletion nanoscopy for super-resolution mitochondrial visualization in live cells

Aggregation-induced emission luminogens (AIEgens) are fluorescent agents that are ideal for bioimaging and have been widely used for organelle targeting, cellular mapping, and tracing. Owing to their promising characteristics, AIEgen-based nanoparticles have recently been used for the stimulated emission depletion (STED) super-resolution imaging of fixed cells. In the present study, and for the first time, we used an AIEgen for dynamic STED nanoscopic imaging of a specific organelle in live cancer cells. TPA-T-CyP is a synthetic red&NIR-emitting luminogen with AIE features that can spontaneously and specifically aggregate on mitochondria without the need for encapsulation or surface modification. The STED efficiency of aggregated TPA-T-CyP can reach more than 80%, and super-resolution imaging of TPA-T-CyP-stained mitochondria in live HeLa cells is possible, with a lateral spatial resolution of 74 nm. We found that TPA-T-CyP enabled the dynamic visualization of mitochondria, and the motion, fusion, and fission of mitochondria were clearly observable on a super-resolution scale. AIEgen-based super-resolution organelle visualization has great potential for many basic biomedical studies.