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.