2’-7’dichlorofluorescin diacetate (DCFH-DA) is a cell-permeant reagent fluorogenic dye that measures hydroxyl, peroxyl, and other ROS activity in the cell. After cell uptake, DCFH-DA is deacetylated by cellular esterases to a non-fluorescent compound, which is later oxidized by ROS into 2’-7’dichlorofluorescein (DCF) with maximum excitation and emission spectra of 495 nm and 529 nm, respectively.