A tri-response colorimetric-fluorescent probe for pH and lysosomal imaging

Intracellular pH has been associated with multiple biological processes. However, fluorescent probes for pH are limited. Herein, a new pH fluorescent probe was developed based on reversible structural changes. This probe provided three reversible pH response modes within 2.00-12.00. Under the acidic conditions, there is no -fluorescence, under the neutral conditions, the emission is at 650 nm, under the alkaline conditions, the emis-sions at 650 nm decreases and at 460 nm appears and increases simultaneously. The probe solution presented distinct colors response to the pH values from 2.00 to 12.00. The fluorescent response from pH 2.00-12.00 makes the probe suitable for the monitoring pH in living cells. Moreover, the imaging results confirm that probe S can be applied in fluorescence imaging in living cells.