A ratiometric fluorescent probe based on a coumarin-hemicyanine scaffold for sensitive and selective detection of endogenous peroxynitrite

In the study described herein, the red emitting probe CHCN, which possesses a linked coumarin-hemicyanine scaffold, was developed for detection of peroxynitrite (ONOO^-) under physiological conditions. The studies show that CHCN displays a dual ratiometric and colorimetric response to ONOO^- that is caused by an oxidation process. A possible mechanism of this oxidation process was proposed and confirmed by ESI-MS spectra for the first time. CHCN shown highly selective and sensitive towards ONOO^- with a low limit of detection LOD (49.7nM). Moreover, CHCN has appreciable cell permeability and, as a result, it is applicable to ratiometric detection of exogenous and endogenous ONOO^- in living cells during phagocytic immune response. We anticipate that, owing to their ideal properties, probes of this type will find great use in explorations of the role played by ONOO^- in biology.