Widely used as a fluorescent probe to detect reactive oxygen species (ROS) in biological systems. It is cell-permeable and becomes highly fluorescent upon oxidation by intracellular ROS, making it ideal for monitoring oxidative stress in live cells. Commonly applied in flow cytometry, fluorescence microscopy, and plate reader assays to assess cellular redox status. Frequently used in studies related to inflammation, apoptosis, neurodegenerative diseases, and toxicology to evaluate oxidative damage. Its sensitivity to a broad range of ROS allows for general assessment of oxidative activity, though it does not specify the exact type of ROS involved.