A Highly Selective, Cell-Permeable Fluorescent Nanoprobe for Ratiometric Detection and Imaging of Peroxynitrite in Living Cells

Peroxynitrite (ONOO-) is a highly reactive species implicated in the pathology of numerous diseases and there is currently great interest in developing fluorescent probes that can selectively detect ONOO- in living cells. Herein, a polymeric micelle-based and cell-penetrating peptide-coated fluorescent nanoprobe that incorporates ONOO- indicator dye and reference dye for the ratiometric detection and imaging of ONOO- has been developed. The nanoprobe effectively avoids the influences from enzymatic reaction and high-concentration (OH)-O-center dot and ClO-. The improved ONOO- selectivity of the nanoprobe is achieved by a delicate complementarity of properties between the nanomatrix and the embedded molecular probe ( BzSe-Cy). This nanoprobe also has other attractive properties, such as good water solubility, photostability, biocompatibility, and near-infrared excitation and emission. Fluorescence imaging experiments by confocal microscopy show that this nanoprobe is capable of visualizing ONOO- produced in living cells and it exhibits very low toxicity and good membrane permeability. We anticipate that this technique will be a potential tool for the precise pathological understanding and diagnosis of ONOO--related human diseases.