Visualizing hypochlorous acid as a key oxidative stress biomarker in drug-induced liver injury with a red-emitting probe.

Drug-induced liver injury (DILI) is a common form of hepatotoxicity resulting from adverse drug reactions. Extensive studies indicate that reactive oxygen species (ROS) levels undergo significant alterations during the progression of DILI. Among various ROS, hypochlorous acid (HClO)-produced in substantial amounts during oxidative stress in liver injury-has emerged as a potential biomarker for DILI. In this work, we developed a fluorescent probe based on a benzopyran-derived fluorophore with diaminomaleonitrile as the HClO-specific recognition unit. Upon reaction with HClO, the probe emits intense red fluorescence. It demonstrates favorable sensing properties, including a fast response time (1 min), a low detection limit (26.7 nM), high selectivity toward HClO, good stability under physiological pH conditions, and low cytotoxicity. The probe enables quantitative detection of HClO within a linear range of 0-10 μM. Cellular experiments using HepG2 and HuH-7 cells confirmed its capability to monitor both exogenous and endogenous HClO. In an acetaminophen (APAP)-induced DILI model, the fluorescence intensity correlated positively with the degree of liver injury. Furthermore, imaging studies in zebrafish and mice validated that the probe can successfully track dynamic changes in HClO levels in vivo and reflect the progression of DILI. This probe thus represents an efficient tool for detecting and studying HClO-associated pathological processes, particularly DILI, with considerable potential for biomedical applications.