Development of a near-infrared fluorescent probe with large Stokes shift for carboxylesterases detection and its application in living systems

Accurate detection of carboxylesterases (CEs) plays a crucial role in various disease physiological processes and ester-containing drug metabolism. However, the reported near-infrared (NIR) fluorescent probes with short Stokes shift (<70 nm) limited their application of tracking CEs activity in complex bio-systems. Herein, a new "turn-on" NIR fluorescent probe for CEs detection (termed as CE-1) was developed based on dicyanoisophorone with large Stokes shift over 100 nm for the first time. The probe CE-1 (lambda ex/em = 535/665 nm) featured low cytotoxicity and high sensitivity (detection limit of 2.76 x 10-3 U/mL). Moreover, the CE-1 was successfully used to detect the level changes of CEs under drug-induced modulation in cell imaging, and real-time monitor the activity of CEs in mice models for biological imaging. Notably, these results indicate that the probe CE-1 can be applied for imaging and monitoring endogenous CEs in living systems. We believe that the probe CE-1 will be applied as a potential indicator of CEs for the clinical diagnosis of CEs-related diseases and rational use of drugs.