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CAS number 123632-39-3 YesY
PubChem 104978
ChemSpider 94730
Jmol-3D images Image 1
Molecular formula C36H30Cl2N2O13
Molar mass 769.54 g mol−1
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Fluo-3 is a fluorescence indicator of intracellular calcium (Ca2+). It is used to measure Ca2+ inside living cells in flow cytometry and confocal laser scanning microscopy using visible light excitation (compatible with argon laser sources operating at 488 nm). Fluo-3 is an essentially nonfluorescent compound, but upon binding of Ca2+ its fluorescence increases sharply with an emission maximum at 525 nm suitable for conventionally used detectors designed for fluorescein isothiocyanate (FITC) measurements. Whereas the salts of fluo-3 are unable to penetrate cells, loading can be achieved using its acetoxymethyl (AM) ester derivative. Once inside the cell, unspecific esterases cleave the ester effectively trapping fluo-3.[1]

As calcium is a key second messenger within cells, the specific properties of fluo-3 enable researchers to investigate the time-resolved dynamics of intracellular signal transduction in a diverse range of cells.[2][3]


  1. ^ Haugland, RP. Handbook of Fluorescent Probes and Research Products. Molecular Probes, 2010
  2. ^ Gamsjäger, T. Flow Cytometry of Intracellular Calcium in Platelets. Grin, 2012
  3. ^ Lambert, DG. Calcium Signaling Protocols. Humana Press, 2006