Cell biology 

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 the membrane-permeant version of calcein: calcein AM, which hydrolyzes into calcein once inside cells.

• λEx/λEm = 494/517 nm (pH 8).
• ε = 75,000
• Yellow-orange solid soluble in DMSO, DMF or pH>6 water
• Store at -4°C and protect from light
• C₃₀H₂₆N₂O₁₃
• MW: 623