A lysosome-targetable fluorescent probe based on HClO-mediated cyclization reaction for imaging of hypochlorous acid

Misplaced or excessive hypochlorous acid in lysosomes has a close association with lots of diseases, so monitoring hypochlorous acid in lysosomes is particularly necessary. In the present work, a novel lysosome-targetable fluorescent probe (Lyso-R-HClO) for hypochlorous acid based on a HClO-mediated cyclization reaction was developed. In the fluorescent probe, the morpholine unit and the site of a HClO-mediated cyclization reaction were, respectively, used as the lysosome-targetable group and the response group. The probe has high selectivity and high sensitivity to hypochlorous acid, with a linear range from 5.0 × 10^-8 to 3.0 × 10^-6 M and a detection limit of 15 nM; it was successfully used to image endogenous and exogenous lysosomal HClO. Finally, Lyso-R-HClO was further applied to image lysosomal HClO produced in bacteria-infected macrophage with satisfactory results, which indicate that it is an useful tool for studies of lysosomal HClO and the role of lysosome.