Illuminating Mitochondrial Dynamics: Ultrahigh Labeling Stability Probe for Long-Term SIM Super-Resolution Imaging of Mitochondria

Delineating intricate mitochondrial dynamic changes over extended time scales through combined fluorescent probes and super-resolution microscopy is pivotal for deciphering the pathogenesis of mitochondrial-related diseases. However, a major challenge lies in the scarcity of probes that simultaneously exhibit robust labeling stability, exceptional photostability, and minimal cytotoxicity. Herein, rational design and screening yielded a novel covalent mitochondrial probe, HZ Mito Red. Due to its exceptional covalent labeling efficiency, HZ Mito Red exhibits superior mitochondrial labeling stability, with a 10-fold improvement compared to Mito Tracker Red (MTR). Furthermore, it exhibits remarkable photostability, retaining over 80% fluorescence after 300 SIM images, and negligible phototoxicity, preserving mitochondrial integrity even after 400 SIM images of continuous imaging. These advantageous properties facilitated the pioneering of high signal-to-noise, long-term dynamic SIM super-resolution imaging of mitochondria during ferroptosis, apoptosis, and autophagy, achieving unprecedented detailed delineation of mitochondrial morphology. Additionally, engineered for multichannel mitochondrial imaging, HZ Mito Deep Red mirrors the exceptional labeling stability of HZ Mito Red, achieving near-phototoxicity-free dynamic tracking with 60% fluorescence retention after 300 SIM images. Significantly, both HZ Mito Red and HZ Mito Deep Red are compatible with cell immunofluorescence staining. This study provides a robust and versatile tool for the in-depth analysis of mitochondrial dynamics in disease states.