Naphthylamine-based ratiometric fluorescence probe with a large Stokes shift for monitoring mitochondrial peroxynitrite

The design of ratiometric fluorescence probes with large Stokes shift is greatly significant in addressing the major challenges of detecting and imaging target substances in complex organisms. Such probes with a self-calibration function can minimize the interference of probe concentration and excitation light. In this study, a novel fluorophore of NA-Py with large Stokes shift of 158 nm, was easily obtained in one step. As a proof of concept, based on NA-Py, a fluorescence probe NA-BOH with strong intramolecular charge transfer (ICT) structural characteristics is designed for detecting peroxynitrite (ONOO-). NA-BOH exhibits red emission (627 nm) and a larger Stokes shift of 178 nm. Furthermore, it demonstrats rapid response (within 20 min) and high selectivity towards ONOO-, with ratiometric quantitative response (0-20 mu M), and high sensitivity (182 nM). Alongside excellent biocompatibility and remarkable mitochondrial targeting ability, NA-BOH is successfully utilized for the proportional imaging of ONOO- in living cells and zebrafish.