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 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.