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.