A naphthalimide-based lysosome-targeting fluorescent probe for the selective detection and imaging of endogenous peroxynitrite in living cells.

ABSTRACT

The morpholine (ML) group can be used as a targeting unit for lysosomes. Here, a novel turn-off fluorescence probe for the highly selective imaging of peroxynitrite (ONOO-) produced by the endogenous stimulation of lysosomes in living cells is presented. The probe, denoted ML-NAP-DPPEA, comprises ML and 2-(diphenylphosphino)ethylamine (DPPE) groups attached to the fluorophore naphthalimide (NAP). ML-NAP-DPPEA shows excellent properties, including high selectivity for ONOO-, low cytotoxicity, and no interference, leading to low detection limits (17.6 nM). In the presence of ONOO-, the secondary amine group (NH) is oxidized to an electron-withdrawing group (HN → O), which quenches the fluorescence of ML-NAP-DPPEA. This intracellular lysosomal imaging technique was tested, and the results pointed to its potential use as a probe for studying the biological function and pathological effects of ONOO- in subcellular structure. Graphical abstract.