Aggregation-Induced Emission (AIE) in Super-resolution Imaging: Cationic AIE Luminogens (AIEgens) for Tunable Organelle-Specific Imaging and Dynamic Tracking in Nanometer Scale

Organelle-specific imaging and dynamic tracking in ultrahigh resolution is essential for understanding their functions in biological research, but this remains a challenge. Therefore, a facile strategy by utilizing anion-π⁺ interactions is proposed here to construct an aggregation-induced emission luminogen (AIEgen) of DTPAP-P, not only restricting the intramolecular motions but also blocking their strong π-π interactions. DTPAP-P exhibits a high photoluminescence quantum yield (PLQY) of 35.04% in solids, favorable photostability and biocompatibility, indicating its potential application in super-resolution imaging (SRI) via stimulated emission depletion (STED) nanoscopy. It is also observed that this cationic DTPAP-P can specifically target to mitochondria or nucleus dependent on the cell status, resulting in tunable organelle-specific imaging in nanometer scale. In live cells, mitochondria-specific imaging and their dynamic monitoring (fission and fusion) can be obtained in ultrahigh resolution with a full-width-at-half-maximum (fwhm) value of only 165 nm by STED nanoscopy. This is about one-sixth of the fwhm value in confocal microscopy (1028 nm). However, a migration process occurs for fixed cells from mitochondria to nucleus under light activation (405 nm), leading to nucleus-targeted super-resolution imaging (fwhm= 184 nm). These findings indicate that tunable organelle-specific imaging and dynamic tracking by a single AIEgen at a superior resolution can be achieved in our case here via STED nanoscopy, thus providing an efficient method to further understand organelle's functions and roles in biological research.