Fabrication of a carboxylesterases-activated near-infrared fluorescence probe for assisting hepatocellular carcinoma surgery in mice and clinical blood serum testing

Carboxylesterases (CES) is a family of hydrolases, which are mainly localized in the endoplasmic reticulum and cytosol in cells and can catalyze the hydrolysis of carboxylic esters to generate acids and alcohols. The changes of CES level are closely related to the liver disease, such as early onset liver injury induced diabetes and advanced liver cancer. Herein, a new activatable near-infrared (NIR) fluorescent probe PCES (Probe of Carboxylesterases) for imaging CES was rationally designed. The probe can not only specifically sense CES in buffer solution with a 49-fold fluorescence enhancement at 780 nm and a 2.5 mU/mL detection limit, but also can sensitively visualize CES changes with low cytotoxicity and good biocompatibility in living cells. Applying this agent, the fluctuation of CES levels was monitored under high glucose stimulation. The mechanism of ferroptosis in diabetes mellitus has also been preliminarily explored. Besides, PCES was utilized for imaging CES of hepatocellular carcinoma and effectively assisting the tumor surgical operation in vivo. In addition, the practical serum samples were detected from clinical patients suffered diabetes and liver cancer with the help of probe PCES, demonstrating the differentiated CES levels. With the favorable characteristics of fluorescence sensing and practicability of imaging CES in living cells, mice, and clinical serum samples, PCES can help the better understanding for the relation- ships of liver diseases with CES and has the potential as a useful agent for the diagnosis and treatment of clinical liver diseases.