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.