A Three-Channel Fluorescent Probe That Distinguishes Peroxynitrite from Hypochlorite

A novel fluorescent probe for peroxynitrite, PN600, was rationally designed on the basis of a unique fluorophore assembly approach. PN600 is a green-emitting coumarin derivative. Upon oxidation by peroxynitrite, PN600 is transformed into a highly fluorescent red-emitting resorufin derivative via an orange-emitting intermediate. This three-channel signaling capability enables PN600 to differentiate peroxynitrite from other reactive oxygen and nitrogen species, including hypochlorite and hydroxyl radical. Moreover, PN600 is membrane-permeable and compatible with common TRITC filter sets and displays low cytotoxicity. Therefore, PN600 is a promising candidate for in vitro peroxynitrite imaging.