Sulfonium perchlorate based near-infrared fluorescent probe targeting lysosome for pH imaging in living cells and tumor-bearing mice.

Abstract

Due to the accumulation of lactate and other acidic metabolites from insufficient blood supply and hypoxia, the acidic microenvironment of tumors not only accelerates tumor growth and spread but may also affect immune cell function, thereby aiding tumor development. Therefore, real-time monitoring of pH fluctuations in intracellular and living systems provides crucial insights into physiological and pathological processes. This research introduced a novel NIR fluorescent probe, termed SOH, for pH imaging in living cells and tumor-bearing mice. This sulfonium perchlorate probe exhibited excellent optical properties, including large Stokes shift, significant lysosome-targeting capability, and superior photostability. SOH was effectively used for real-time pH imaging in HepG2 cells and for visualizing the weakly acidic microenvironment within tumor tissue in mice. It shows promising potential as an early tumor diagnostic tool in vivo.