A novel carboxylesterase 2-targeted fluorescent probe with cholic acid as a recognition group for early diagnosis of drug- and environment-related liver diseases

Due to the detrimental effects of various harmful substances-such as carcinogens, drug toxicity, and environmental pollutants-on the liver, which can trigger or exacerbate conditions like hepatocellular carcinoma (HCC), drug-induced liver injury (DILI), and non-alcoholic fatty liver disease (NAFLD), accurate detection and monitoring of these diseases are crucial for effective treatment. Carboxylesterase 2 (CES2) is primarily found in the liver and, as a potential biomarker, its accurate detection can enhance the early diagnosis and treatment efficacy of liver diseases. Traditional fluorescence probes for CES2 detection suffer from non-specific recognition groups, leading to poor targeting specificity. To address this limitation, we propose a novel CES2-responsive fluorescent probe utilizing cholic acid (CA) as a recognition group. The probe, LAN-CA, was synthesized by esterifying CA with a near-infrared fluorophore, LAN-OH. This novel fluorescent probe leverages the unique affinity of CA for hepatocytes, ensuring that LAN-CA remains and accumulates specifically within the hepatoenteric circulation. In vitro experiments showed that the probe exhibits superior optical performance compared to traditional benzoate-based probe (LAN-PH), with a detection limit of 0.015 μg/mL. Examination of 56 common biological interferents demonstrated that using CA as a recognition group offers high selectivity. Cell experiments confirmed that LAN-CA is an effective tool for monitoring endogenous CES2 in live cells. Comprehensive evaluations of fluorescence imaging in various mouse models of liver diseases, such as HCC, DILI, and NAFLD, demonstrated that LAN-CA provides exceptional imaging accuracy and therapeutic monitoring capabilities. In conclusion, this probe not only can be a promising tool for accurate liver disease diagnosis, but also can provide valuable insights into treatment efficacy.