Smart Dual-Emissive Probe toward the Visualization of Mitochondrial Membrane Potential during Ischemia-Reperfusion Injury

Mitochondrial membrane potential (ΔΨm) plays central roles in signal transduction, metabolism, and other critical biological processes, which was also a crucial indicator of cellular status. Dual-emissive fluorescent probes represent promising molecular tools for investigating ΔΨm. Nevertheless, most of them relied on aggregation/monomer mechanisms and are susceptible to interferences such as uneven staining. To address this limitation, herein, a subcellular-migratory and polarity-responsive fluorescent probe (N-Py) was constructed for the visualization of ΔΨm in a dual-emissive manner. N-Py specifically targeted mitochondria and exhibited yellow fluorescence in live cells. Upon depolarization of ΔΨm, N-Py translocated from mitochondria to intracellular RNA with the emission red-shifted to orange-red color, owing to the higher polarity of RNA than mitochondrial membranes. Reversible tracking of ΔΨm was achieved by N-Py. By virtue of this probe, in situ and real-time visualization of cellular oxidative damage was realized, along with monitoring of apoptosis triggered by ultraviolet irradiation, toxins, and anticancer drugs. Notably, N-Py featured a compact molecular architecture, and its cationic salt moiety possessed a molecular weight of merely 239, endowing the probe with extensive application prospects. Furthermore, N-Py was applied to successfully monitor ischemia-reperfusion injury, and the protective effect of cyclosporin A (an inhibitor of the mitochondrial permeability transition pore) against ischemia-reperfusion injury was unambiguously validated with this probe.