Old trees bloom new flowers, lysosome targeted near-infrared fluorescent probe for ratiometric sensing of hypobromous acid in vitro and in vivo based on Nile red skeleton

Hypobromous acid (HOBr), one of the significant reactive oxygen species (ROS) that acts as an important role in human immune system, however the increasing level of HOBr in human body can cause the disorder of eosinophils (EPO), leading to oxidative stress in organelles, and further causing a series of diseases. In this study, a ratiometric fluorescent probe DMBP based on Nile red skeleton was developed to detect HOBr specifically by the electrophilic substitution with HOBr. DMBP emits near-infrared (NIR) fluorescence at 653 nm, after reacting with HOBr, the emission wavelength of DMBP shifted blue and a new peak appeared at 520 nm, realizing a ratiometric examination of HOBr with a limit of detection of 89.00 nM. Based on its sensitive and specific response to HOBr, DMBP was applied in the visual imaging of HOBr in HepG2 cells and zebrafish. Foremost, probe DMBP has excellent lysosome targeting ability and NIR emission reduced the background interference of biological tissues, providing a potential analytical tool to further investigate the role of HOBr in lysosome.