5-CFDA-AM is a cell-permeable esterase substrate employed as an active probe to assess enzyme activity and cell membrane integrity. Electroneutral and capable of entering cells at concentrations lower than CFDA, it undergoes intracellular hydrolysis by esterases, generating carboxyfluorescein, which possesses an extra negative charge, allowing for improved cellular retention [1].

5(6)-CFDA (5-(6)-Carboxyfluorescein diacetate) is a cell-permeant esterase substrate that can serve as a viability probe that measures both enzymatic activities, which is required to activate its fluorescence, and cell-membrane integrity, which is required for intracellular retention of their fluorescent product.