A ratiometric fluorescent probe with dual-targeting capability for heat shock imaging

HSO₃^- is an important reactive sulfur species that maintains the normal physiological activities of living organisms and participates in a variety of redox homeostatic processes. It has been found that changes in HSO₃^- levels is closely related to the heat stroke phenomenon of the organism. Heat stroke causes damage to normal cells, which in turn causes damage to the body and even death. It is crucial to accurately monitor and track the physiological behavior of HSO₃^- during heat stroke. Herein, a ratiometric multifunctional fluorescent probe DRM-SO₂ with dual-targeting ability to rapidly and precisely recognize HSO₃^- being constructed based on the FRET mechanism. DRM-SO₂ has extra Large Stokes shift (216 nm), very high sensitivity (DL = 12.2 nM), fast response time and good specificity. When DRM-SO₂ undergoes Michael addition with HSO₃^-, the fluorescence emission peak was blue-shifted from 616 nm to 472 nm, and a clear ratiometric signal appeared. The interaction between lysosomes and mitochondria in maintaining cellular homeostasis was investigated by the dual-targeting ability of the probe using HSO₃^- as a mediator. DRM-SO₂ achieved successful targeting and real-time monitoring of exogenous and endogenous HSO₃^- in the cells. More importantly, imaging experiments in heat stroke mice revealed high HSO₃^- expression in intestinal tissues. This provides new ideas and research tools for early prevention of heat stroke-induced diseases such as intestinal injuries. In addition, the semi-quantitative monitoring experiments for paper-based visualization of HSO₃^- make the probe promising for the design of portable detectors.