A sensitive fluorescent probe for monitoring hypochlorous acid levels in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease. Hypochlorous acid (HClO) is a signature reactive oxygen species (ROS) closely associated with the progression of RA. Here, we report a novel fluorescent probe, ZCP1, which exhibits high sensitivity to HClO. In the presence of HClO, ZCP1 demonstrates a rapid detection time of 20 s and a low detection limit of 19.1 nM, allowing for fast and sensitive reactions with HClO, with a 150-fold fluorescence enhancement. ZCP1 can be employed for fluorescent detection of both exogenous and endogenous HClO levels in live cells. Furthermore, ZCP1 has been utilized to detect endogenous HClO in a mouse model of RA. This work provides a reliable tool for monitoring endogenous HClO both in vivo and in vitro, offering significant potential for future biological and pathological studies related to HClO.