Fluo-4 AM, green fluorescent calcium indicator

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1892-50ug 50 ug –   in stock
1892-500ug 500 ug $279 in stock
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Fluo-4 AM is a cell-permeable Ca2+-indicator that is metabolized by intracellular esterase, leading to a bright green fluorescent signal upon Ca2+-binding (excitation/emission λ at 494/506 nm). Fluo-4 AM is used for visualization and measurement of intracellular Ca2+. It is well suited for fluorometric and imaging applications such as microscopy, flow cytometry, spectrofluorometry, and fluorometric high-throughput microplate screening assays [1].

Fluo-4 AM is similar in structure and spectral properties to the widely used Ca2+-indicator, Fluo-3, but it has certain advantages over Fluo-3, such as brighter fluorescence emission, high rate of cell permeation, and a Kd for Ca2+ in buffer of 345 nM. Because of its higher fluorescence emission intensity, Fluo-4 AM can be used at lower intracellular concentrations, making its use less toxic for live cells.

As Fluo-4 AM does not covalently bind to cellular components, it may be actively effluxed from the cell by organic anion transporters. In vivo cell imaging with Fluo-4 AM is usually performed within one or two hours after loading, but the dye can be re-loaded to cells if it is needed. Fluo-4 AM can also be fixed in situ by EDC/EDAC for downstream immunofluorescence studies.

Fluo-4 AM has low solubility in the water. It is recommended to prepare 1 mM stock solution in labeling grade DMSO prior to cell loading. Use the final concentration of 1-5 μM and incubation at 37 °C for 15-60 min as a start point of your protocol.


[1] Gee K.R. et al. Chemical and physiological characterization of fluo-4 Ca(2+)-indicator dyes. Cell Calcium. 2000. 27(2). 97-106.

Absorption and emission spectra of Fluo-4 AM (calcium-bound form)

Absorption and emission spectra of Fluo-4 AM (calcium-bound form)

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General properties

Appearance: orange-red powder
Molecular weight: 1096.95
CAS number: 273221-67-3
Molecular formula: C51H50F2N2O23
IUPAC name: N-[4-[6-[(Acetyloxy)methoxy]-2,7-difluoro-3-oxo-3H-xanthen-9-yl]-2-[2-[2-[bis[2-[(acetyloxy)methoxy]-2-oxoethyl]amino]-5-methylphenoxy]ethoxy]phenyl]-N-[2-[(acetyloxy)methoxy]-2-oxoethyl]glycine (acetyloxy)methyl ester
Solubility: good in DMSO
Quality control: NMR 1H and HPLC-MS (95+%)
Storage conditions: 24 months after receival at -20°C in the dark. Transportation: at room temperature for up to 3 weeks. Desiccate.
MSDS: Download
Product specifications

Spectral properties

Excitation/absorption maximum, nm: 494
Emission maximum, nm: 518
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