A phenothiazine coumarin based ratiometric fluorescent probe for real-time detection of lysosomal hypochlorite in living cell and zebra fish.

Hypochlorite (ClO), a type of reactive oxygen species (ROS), plays an essential role in complex biological systems. Real-time detection of the content and distribution of ClO in cells or subcellular organelle is critically essential. In this paper, a lysosomal-targeted fluorescent probe, Cou-Lyso, was constructed for real-time detection of ClO in a ratiometric manner, achieving high sensitivity with a low detection limit (0.58 μM). Upon reaction with ClO, this probe was subjected to a significant fluorescence change from red emission (λem = 610 nm) to green emission (λem = 535 nm) with the ratio of I/I displaying a 76-fold enhancement from 0.04 to 3.03. The confocal imaging experiments for Cou-Lyso showed that this probe could detect ClO in living cell and zebra fish. This probe has been successfully applied to stain lysosome and image lysosomal ClO based on co-localization imaging experiments.