DAF-FM DA (also known as diaminofluorescein-FM diacetate), an analogue of DAF-FM, is a novel, fluorescent and cell-permeable nitric oxide (NO) indicator. It can be transformed into DAF-FM when exposed to oxygen and NO via a deacetylation reaction catalyzed by intracellular esterases, thus can be detected by instruments(e.g. fluorescent microplate readers and
fluorometers, flow cytometers, microscopes) that can detect fluorescein.