An ultrasensitive ratiometric fluorescent probe based on the ICT-PET-FRET mechanism for the quantitative measurement of pH values in the endoplasmic reticulum (ER).

Herein, we present a dual-site ratiometric fluorescent probe based on the ICT-PET-FRET mechanism for the detection of pH in the ER. The probe showed a highly sensitive response to pH in the range of 5.0-7.2, and could be applied for the quantitative measurement of the pH values in the ER during ER stress and dexamethanose-induced stimulation.