Real-time visualization of lysosomal pH fluctuations in living cells with a ratiometric fluorescent probe

Abnormal variations of lysosomal pH values are closely associated with various diseases, thus it is of great necessity to develop some reliable lysosome-targeted fluorescent probes for real-time monitoring pH changes. Herein, a pyridine-decorated ratiometric fluorescent probe Lyso-CMCP based on camphor-coupled coumarin fluorophore was developed for monitoring pH fluctuations in lysosome of living cells. Lyso-CMCP could sensitively and selectively respond to acidic pH in the range of 7.54-3.19 with a significantly red-shifted fluorescence emission from 455 nm to 516 nm. Besides, this probe also possessed some favorable features, such as good photostability, fine reversibility, excellent anti-interference ability, and low cytotoxicity. The pK(a) value of 5.14 endowed Lyso-CMCP with the potential to accumulate in lysosomes. With this probe in hand, the lysosomal pH fluctuations were successfully monitored and quantified by ratiometric fluorescence imaging.

Automated summary

A lysosome-targeted fluorescent probe Lyso-CMCP was developed for real-time monitoring pH changes in living cells. This probe showed sensitive and selective response to acidic pH and had favorable features including good photostability, reversibility, anti-interference ability, and low cytotoxicity. The lysosomal pH fluctuations were successfully monitored and quantified by ratiometric fluorescence imaging using this probe.