A pH-correctable, viscosity-susceptible fluorescent reporter for organellar sulfur dioxide

Multi-recognition fluorescent probes are recently generating curiosity in cellular imaging of complex microenvironments within organisms. However, it is extremely challenging to effectively detect mitochondria sulfur dioxide in the tanglesome cellular microenvironment because endogenous SO 2 indicators are incentive to viscosity and pH changes. The fluctuation of SO 2 is associated with inflammatory responses and disruption of acid-base homeostasis in the cellular microenvironment. Herein, we have described a unique multi-identification sensor MVP-SO 2 for detecting the pH, viscosity, and SO 2 . MVP-SO 2 combined two fluorescence signal emission channels of blue and red to explore the variation of pH and viscosity sensitively through the change of fluorescence intensity. At the same time, MVP-SO 2 can also monitor the fluctuation of SO 2 levels by Michael addition reaction. Furthermore, the probe has the characteristics of glorious long-term fluorescence stability and low cytotoxicity. Additionally, using this new novel sensor, not only the detection of pH and viscosity changes with drug stimulation has been successfully achieved, but also the fluctuation of exogenous and endogenous SO 2 levels over time under physiological conditions were monitored. This approach could further integrate with various disease models and provide a strategy for multi-signal detection. • A novel probe MVP-SO 2 exhibited excellent stability and anti-interference capability. • MVP-SO 2 has desirable response to viscosity and pH, and is exceptionally sensitive to SO 2 . • The new probe can detect the changes of mitochondrial microenvironment and SO 2 in the living cells. • The new probe can be employed to visualize the intracellular exogenous/endogenous SO 2 dynamic changes.