Hot-Band Absorption of a Cationic RNA Probe Enables Visualization of ΔΨ m via the Controllable Anti-Stokes Shift Emission.

Mitochondrial membrane potential (ΔΨ m ) is an important biophysical parameter playing central roles in cell apoptosis, mitochondrial dysfunction, and other biological and pathological processes. Herein, we have rationally designed and fabricated a unique fluorescent probe for convenient ΔΨ m visualization based on hot-band absorption and controllable anti-Stokes shift emission. The robust probe was excitable via hot-band absorption and emitted anti-Stokes upconversion emission and Stokes downconversion fluorescence simultaneously. The anti-Stokes emission could be efficiently inhibited upon the binding to RNA. The cationic probe targeted mitochondria in living cells with high ΔΨ m and displayed both anti-Stokes green emission and ordinary red fluorescence. After the decrease of ΔΨ m , the probe immigrated out of mitochondria to RNA and nucleolus, which showed only red emission owing to the inhibition of anti-Stokes fluorescence. In this manner, the ΔΨ m could be visualized in dual-color mode. The probe enabled clearly monitoring the reversible changes in ΔΨ m and was successfully employed to visualize oxidative damage of living cells. The decrease of ΔΨ m in living tissues was also successfully observed with the newly designed probe.