Fluo-4 is used to measure
calcium
Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...
(Ca
2+) concentrations inside living cells, and is often used for
high-throughput screening
High-throughput screening (HTS) is a method for scientific discovery especially used in drug discovery and relevant to the fields of biology, materials science and chemistry. Using robotics, data processing/control software, liquid handling device ...
of receptor ligands and calcium permeable ion channels.
The green-fluorescent calcium indicator, Fluo-4, is an improved version of the calcium indicator,
Fluo-3
Fluo-3 is a fluorescence indicator of intracellular calcium (Ca2+), developed by Roger Y. Tsien. It is used to measure Ca2+ inside living cells in flow cytometry, and confocal laser scanning microscopy using visible light excitation (compatible ...
. It is commonly used as the non-fluorescent
acetoxymethyl ester (Fluo-4 AM) which is cleaved inside the cell to give the free, fluorescent Fluo-4. It loads faster, is brighter at equivalent concentrations and is well-excited by the 488 nm line of the argon-ion laser which is often used in biological research laboratories.
Fluo-4 and its cell-permeable AM ester are available from a few commercial vendors.
References
Biochemistry methods
Cell imaging
Chelating agents
Fluorone dyes
Fluoroarenes
Acetic acids
Phenol ethers
Anilines
Glycol ethers
Xanthenes
{{Ether-stub