Fluorescent detection of hypochlorous acid based on nicking enzyme-induced signal amplification

Hypochlorous acid (HClO) is an important reactive oxygen species (ROS) predominantly produced by myeloperoxidase in biological systems. It plays a crucial role in intrinsic immune defense mechanisms in the body. Abnormal HClO levels have been demonstrated to disrupt physiological balance and thus contribute to the development of multiple pathologies, including atherosclerosis, neuroinflammation, keloid fibrosis, and tumors. This study proposed a highly sensitive and specific method for quantification of HClO. The quantification of HClO was based on nickase-assisted signal amplification and fluorescence enhancement (caused by thioflavin T binding to the G-quadruplex). Under optimal conditions, the method had a linear detection range of 0.01-3 µM and a limit of detection of 10 nM. The assay was also effective in various actual samples (tap water, cell lysates, and serum). It may have broad application potential in HClO detection-related fields.