A BODIPY-derived fluorescent probe for cellular pH measurements.

Abstract In this study, BODIPY-appended calix[4]arene was chosen as a fluorescent probe for intracellular pH. The compound with cell permeability can monitor the minor pH change near neutrality inside the cell and is the first BODIPY-derived probe reported for cytosolic pH. Owing to a high level of cell retention and minor cytotoxicity of the probe, stable fluorescence is provided in the cells for 24 h, facilitating the precise observation of intracellular pH. A model of cell apoptosis was designed by exposure of the cells to a low concentration of hydrogen peroxide. An increase in the fluorescence of the cells confirmed that BODIPY-appended calix[4]arene sensed the fluctuation of the cellular pH during early cell apoptosis. The developed fluorescent pH probe will be useful for the study of cell apoptosis.