Carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) is an amine-reactive, cell-permeable dye generally used in animal cell proliferation research.

CFDA-SE is a modified CFSE with two hydroxyl groups on its fluorescein moiety replaced with acetates.

This change renders the molecule more hydrophobic and cell-permeable at the expense of its fluorescence property.

After entering cells by diffusion, CFDA-SE is cleaved by intracellular esterase enzymes to form CFSE.

As its reactive succinimidyl ester group is unmodified, CFDA-SE also covalently binds to lysine residues and other amine sources like CFSE.