A two-photon mitochondria-targeted fluorescent probe for the detection of pH fluctuation in tumor and living cells.

Abstract Developing small-molecular fluorescent sensors for the detection of pH fluctuation is highly demanded yet challenging. Herein, a novel pH sensor, stilbazolium-based compound L1 , was rational designed and developed. Notably, the two-photon activity responds strongly to protonation due to the increased extent of symmetrical charge transfer within molecule. Benefiting from the considerable two-photon activity and biocompatibility, it was observed that L1 could certainly sensor pH changes in living cells by using two-photon confocal microscopy and stimulated emission depletion nanoscopy methods. Highlights • L1 possess excellent water solubility and biocompatibility. • L1 responds strongly to pH fluctuation. • pH sensing mechanism was proposed by 1H NMR titration and mass spectra. • L1 can specific target to mitochondria and monitor pH changes in living cells. • L1 was successfully applied to tumor targeted imaging. [ABSTRACT FROM AUTHOR]