Calcein is a fluorescein-based metallofluorescent indicator.

Calcein should be kept in dark at -20 ℃.

For best staining results, fresh 20mM stock of calcein should be made immediately prior to each experiment and storing on ice in the dark.

λ_ex 470 nm; λ_em 509 nm PH 7.4

Calcein is a fluorescein-based metallofluorescent indicator. It has been used in complexometric determination of Ca²⁺ in solution due to its reversible fluorescence in the bound/unbound form. When excited with blue light (of ∼488 nm) the calcein-Ca²⁺ complex emits a green fluorescence (∼520 nm) with a pH optimum between pH 8–9 . For cell staining, its acetoxymethyl (AM) ester form, Calcein AM, is usually used for the good cell permeability.

[1] Calcein Staining as a Tool to Investigate Coccolithophore Calcification