High-Photostability Perylene-Derived Probe Enables Accurate Dual-Modality Imaging of Mitochondrial Membrane Potential.

Mitochondrial membrane potential (MMP) is a key indicator of mitochondrial function and cellular health. Fluorescence intensity-based methods are widely used for MMP monitoring, where probe photostability is critical for accurate quantification. To improve imaging reliability, we developed a photostable mitochondrial-targeted probe, PDI-TPP, by linking perylene diimide (PDI) with triphenylphosphonium (TPP). To the best of our knowledge, this is the first report of PDI being rationally designed and synthesized as a FRET donor for MMP sensing. Acting as a FRET donor, PDI-TPP pairs with SiR-BA, which is synthesized by conjugating silicon-rhodamine with butyric acid, to achieve dual-modality imaging through both fluorescence intensity ratio and lifetime. Compared to our previous donor OR-C8, PDI-TPP shows significantly enhanced photostability, reducing photobleaching artifacts and enabling dynamic visualization of MMP changes. This work provides a more accurate tool for mitochondrial imaging and functional studies.