A convenient ratiomeric pH probe and its application for monitoring pH change in living cells

• Synthesized a simple probe which responds sensitively toward pH change both in vitro and in vivo.
• This probe emits bright red light in acid solution and green light in alkaline solution, and the color change can be converted in multiple cycles along with the dynamic change of pH.
• Compared with other pH probes reported, this probe has good water solubility, negligible cytotoxicity, and can permeate cell membrane and nucleus in which the pH value is closely related to many diseases.
• Probe 2 can also be used as a lysosome maker in living cells. These findings suggest that this probe has potential application in pH detecting for disease diagnosis.

Intracellular pH changes play vital functions in many biological processes. Convenient detection of pH change in living cells has attracted more and more attractions. In this paper, we synthesized a simple probe which response sensitively toward pH change both in vitro and in vivo. This probe emits red light in acidic solution and green light in basic solution. The color change can be converted in multiple cycles along with the dynamic change of pH. The probe has good water solubility, negligible cytotoxicity and excellent permeability of cell membrane and nucleus. Moreover, the probe present here can also be used as a lysosome maker in living cells. pH value in these organs is closely related to many diseases, so these findings suggest that the probe has potential application in pH detecting for disease diagnosis.