A dicyanomethylene-4H-benzopyran based fluorescent probe for monitoring cysteine fluctuation during liver injury.

As an essential biothiol, cysteine (Cys) is critical for regulating intracellular redox homeostasis. Dysregulated Cys levels correlated with various pathological conditions, establishing its value as a pathological biomarker. Drug-induced hepatocellular injury was frequently associated with aberrant fluctuations in intracellular Cys concentrations, highlighting the importance of developing highly specific Cys-responsive fluorescent probes for the early diagnosis and therapeutic monitoring of liver injury. In this study, a novel near-infrared (NIR) fluorescent probe BHC-A, was synthesized based on a dicyanomethylene-4H-benzopyran scaffold for the selective detection of Cys in both in vitro and in vivo models. BHC-A exhibited a large stokes shift (> 200 nm), high specificity and superior sensitivity to Cys, with a detection limit of 0.37 μM. The probe was successfully utilized for fluorescence imaging of Cys in live cells and enabled real-time monitoring of Cys fluctuations during acetaminophen-induced HepG2 hepatocyte injury. Furthermore, BHC-A facilitated in vivo visualization of Cys through NIR fluorescence imaging in animal models. Therefore, BHC-A provides represents a potential analytical tool for the early diagnosis of liver injury and high-throughput drug screening applications.