Merck, 17783-5MG, Calcein-AM

Liposomes contain a self-quenching fluorescent dye called calcein. It is a fluorescent dye with excitation and emission wavelengths of 495/515 nm, respectively. It self-quenches at concentrations above 70mM and is commonly used as an indicator of lipid vesicle leakage. The leakage rate is calculated on the basis of the fluorescence increment as the entrapped calcein is leaked out of the liposomal compartment. It is used as a complexometric indicator for titration of calcium ions with EDTA, and for fluorometric determination of calcium.