6.3.2 5-carboxyluorescein diacetate, acetoxymethyl ester (CFDA-AM) assay
The cytotoxicity is assessed using the fluorogenic dye 5-carboxyluorescein diacetate, acetoxymethyl ester (CFDA-AM). It measures the integrity of the plasma membrane. In order to convert a material that is membrane permeable, nonpolar, and nonfluorescent to a polar, fluorescent dye, carboxyfluorescein, the dye CFDA-AM can be used as a safe esterase substrate (CF). The cells’ conversion of CFDA-AM to CF implies plasma membrane integrity because only an intact membrane can preserve the cytoplasmic environment required for esterase activity(Özlem Sultan, 2012).This assay has the advantage of being relatively harmless to cells, requiring minimal incubation time, and being detectable at different wavelengths without interference. The main constraint of this assay is fluorescent interference from test chemicals, which affects the endpoint readings.