Fluorescence-based detection of hypochlorous acid using catalytic hairpin assembly and G-quadruplex.

Hypochlorous acid (HClO), a key reactive oxygen species (ROS), plays a crucial role in maintaining innate immunity and physiological homeostasis. Abnormal HClO levels can disrupt biological equilibrium, thereby contributing to the onset and progression of diseases such as ulcerative colitis and atherosclerosis. Herein, we developed a highly sensitive and specific quantitative analytical method for the accurate detection of HClO. This approach enhances the fluorescence of the system through G-quadruplex-ThT binding and further amplifies the signals by inducing catalytic hairpin assembly. Under optimized conditions, the method achieved a dynamic range of 0.01 to 1 μM with a detection limit of 9.423 nM. Moreover, it was successfully applied to quantify HClO in tap water, human serum, and cell lysates. These results underscore its strong potential for applications in HClO-related fields such as disease diagnosis.