Mitochondrial STED Imaging and Membrane Potential Monitoring with a Cationic Molecular Probe

Mitochondria are essential organelles that not only undergo dynamic morphological changes but also exhibit functional activities such as mitochondrial membrane potential (MMP). While super‐resolution techniques such as stimulated emission depletion (STED) nanoscopy can visualize the ultrastructure of mitochondria and the MMP probe can monitor mitochondria function, few dyes meet both demands. Here, a small molecule (MitoPDI‐90) based on perylene diimide with cationic groups is reported and used for mitochondrial STED imaging and MMP indication. Characterized by excellent photostability, biocompatibility, and high quantum yield, MitoPDI‐90 exhibits STED imaging compatibility, facilitating visualization of mitochondrial cristae and time‐lapse imaging of highly dynamic mitochondria in living cells. Besides, MitoPDI‐90 targets the mitochondria through electrical potential, also enabling live‐cell MMP monitoring. MitoPDI‐90 allows for super‐resolution visualization and time‐lapse imaging of mitochondria, and more importantly, indication of changes in MMP, providing insight into the functional activity of live‐cell mitochondria.