A dual-response mitochondria-targeted NIR fluorescent probe with large Stokes shift for monitoring viscosity and HOCl in living cells and zebrafish

Mitochondria are important subcellular organelles involved in many cellular activities. Therefore, it is very important to monitor the concentration of various substances in mitochondria. In this work, we constructed a dual-response mitochondria-targeted fluorescent probe HBTN for the detection of viscosity and HOCl in vitro and in vivo. HBTN not only has a long emission wavelength with an emission peak of 680 nm, but also has a large Stokes shift of 278 nm. The fluorescence intensity of probe HBTN at 680 nm has a good linear relationship with solution viscosity, which can be used for quantitative detection of viscosity. In addition, the probe HBTN enables ratiometric detection of HOCl with a low detection limit (DL = 24.5 nM) and rapid response (<20 min). More importantly, the probe HBTN has been successfully applied to the detection of viscosity and exogenous/endogenous HOCl in the mitochondria of MCF-7 cells. Furthermore, the probe HBTN has been implemented in imaging viscosity and HOCl in zebrafish. HBTN is expected to be a practical tool for monitoring viscosity and HOCl in vivo.