A ratiometric pH probe for intracellular pH imaging

In this paper, a ratiometric fluorescence pH probe ECBT is facilely developed by ethylene bridging of N-ethyl-3-carbazolecarboxaldehyde and benzothiazole, which is a useful fluorescent probe for strongly acidic pH sensing. The pH titration experiments show that it exhibits high selectivity and sensitivity, good photostability and excellent reversibility for pH sensing and can be used in quantitative fluorescence imaging. In addition, laser scanning confocal microscopy of Escherichia coli cells demonstrated that this probe might be used to monitor the minor pH fluctuations in biological systems under strongly acidic condition.