A novel copper(Ⅱ) complex-based fluorescence probe for nitric oxide detecting and imaging

A novel copper(II) complex CuQNE with a naphthalimide-containing ligand was synthesized as a fluorescent sensor of nitric oxide (NO). It featured eightfold fluorescent enhancement toward NO from a dark-background with the detection limit of NO about 1 nM in aqueous solution. The fluorescence response of the CuQNE was specific for NO, the presence of other reactive oxygen species (ROS) and reactive nitrogen species (RNS) did not interfere with the detection of NO in aqueous solution. LC–MS and IR spectra of the reaction mixture both demonstrated that the fluorescence enhancement was possibly attributed to an NO-induced nitrosation of the amino group. Confocal fluorescence images of MCF-7 cells suggested that CuQNE could be applied for monitoring intracellular NO.