Calcein is a highly negatively charged, water-soluble fluorescein derivative. Its fluorescence is nearly independent of pH in the range between 6.5 and 12. The dye can be introduced into cells by microinjection and is useful for cell tracing and for the study of cell membrane integrity and fusion. Biotium also offers calcein AM, the membrane-permeant version of calcein that hydrolyzes into calcein once inside cells.
&lamba;Ex/&lamba;Em = 494/517 nm (pH 8).
ε = 75,000
Yellow-orange solid soluble in DMSO, DMF or pH>6 water
