A coumarin-based probe with far-red emission for the ratiometric detection of peroxynitrite in the mitochondria of living cells and mice.

Peroxynitrite (ONOO-) is a transient and reactive oxidant with significant roles in numerous biological processes. Research has established a correlation between excessive mitochondrial ONOO- production and various diseases. As such we developed a mitochondria-targeting, fluorescence-based ratiometric probe using a boronate group for ONOO- recognition and coumarin as the fluorophore. The probe exhibited a 615 nm far-red emission, and a new fluorescence emission at 475 nm developed upon adding ONOO-.The probe possessed high sensitivity and selectivity for ONOO- detection with distinct ratiometric fluorescent output and a low detection limit of 11 nM. Significantly, Probe 1 could monitor ONOO- level fluctuations in biological systems due to its superior spectral properties and low toxicity. Notably, probe 1 has been effectively used for imaging in live HepG2 cells, zebrafish, Arabidopsis thaliana, and liver injury mouse tissues.