A noteworthy interface-targeting fluorescent probe for long-term tracking mitochondria and visualizing mitophagy

Mitochondria are crucial for physiological activities, and alterations in mitochondrial function will lead to diverse human diseases. However, the tracking and long-term visualizing mitochondria are still deficient, which limits the research related to mitochondria. Inspired by the exceptional interfacial architecture of mitochondria, we proposed the interface-targeting model for designing fluorescent probes that could track and long-term visualize mitochondria with high selectivity in living cells, tissues, and zebrafish. And (E)-4-(2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)vinyl)-1-dodecylpyridin-1-ium iodide (CVP) with a cationic pyridinium unit and a C₁₂-chain for targeting mitochondria was synthesized in this work. Thanks to the C₁₂-chain, CVP has excellent permeability in tissues and zebrafish. In comparison to traditional mitochondrial probes, CVP stained mitochondria in short time and long-term track mitochondria without being affected by mitochondrial membrane potential because of the distal long alkyl chain, which enhanced the binding affinity of CVP to mitochondria. The phospholipid-biomimetic structure of CVP endowed it with high selectivity to mitochondria, which decreased the background noise. So CVP could stain mitochondria in tissues and zebrafish with high fidelity through no washing procedures. Particularly, four kinds of mitochondria were visualized by CVP in tissues. In addition, CVP can be applied to track the mitophagy behavior in situ and real-time. All of them demonstrated that the interface-targeting model is an effective strategy for designing mitochondrial probes with high selectivity.