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Fura-FF, pentapotassium salt [Fura-2FF, pentapotassium salt] *CAS 192140-58-2*

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Physical properties
Dissociation constant (Kd, nM)5500
Molecular weight853.94
Spectral properties
Excitation (nm)336
Emission (nm)505
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
StorageFreeze (< -15 °C); Minimize light exposure


Molecular weight
Dissociation constant (Kd, nM)
Excitation (nm)
Emission (nm)
Among the ratiometric calcium indicators, Fura-2 and Indo-1 are most commonly used. Fura-2 is excitation-ratioable while Indo-1 is emission-ratioable. Fura-2 is preferred for ratio-imaging microscopy, in which it is more practical to change excitation wavelengths than emission wavelengths. Upon binding Ca2+, Fura-2 exhibits an absorption shift that can be observed by scanning the excitation spectrum between 300 and 400 nm, while monitoring the emission at ~510 nm. The cell-impermeant Fura-2FF is an analog of Fura-2 with much lower calcium binding affinity, Kd ~10 µM.


Common stock solution preparation

Table 1. Volume of Water needed to reconstitute specific mass of Fura-FF, pentapotassium salt [Fura-2FF, pentapotassium salt] *CAS 192140-58-2* to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

0.1 mg0.5 mg1 mg5 mg10 mg
1 mM117.104 µL585.521 µL1.171 mL5.855 mL11.71 mL
5 mM23.421 µL117.104 µL234.208 µL1.171 mL2.342 mL
10 mM11.71 µL58.552 µL117.104 µL585.521 µL1.171 mL

Molarity calculator

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Spectral properties

Excitation (nm)336
Emission (nm)505



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An essential role of NAD (P) H oxidase 2 in UVA-induced calcium oscillations in mast cells
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View all 119 references: Citation Explorer
Load of calcium probe Fura -2/AM in Escherichia coli cells
Authors: Shao M, Wang HM, Liu ZH, Shen P, Cai RX.
Journal: Wei Sheng Wu Xue Bao (2005): 805
An Excel-based model of Ca2+ diffusion and fura 2 measurements in a spherical cell
Authors: McHugh JM, Kenyon JL.
Journal: Am J Physiol Cell Physiol (2004): C342
Problems caused by high concentration of ATP on activation of the P2X7 receptor in bone marrow cells loaded with the Ca2+ fluorophore fura-2
Authors: Paredes-Gamero EJ, Franca JP, Moraes AA, Aguilar MO, Oshiro ME, Ferreira AT.
Journal: J Fluoresc (2004): 711
Photonic crystal fibre enables short-wavelength two-photon laser scanning fluorescence microscopy with fura-2
Authors: McConnell G, Riis E.
Journal: Phys Med Biol (2004): 4757
Abnormal spectra alteration observed in Triton calibration method for measuring [Ca2+]i with fluorescence indicator, fura-2
Authors: Xu T, Yang W, Huo XL, Song T.
Journal: J Biochem Biophys Methods (2004): 219
Two-photon microscopy of fura-2-loaded cardiac myocytes with an all-solid-state tunable and visible femtosecond laser source
Authors: McConnell G, Smith GL, Girkin JM, Gurney AM, Ferguson AI.
Journal: Opt Lett (2003): 1742
AMPA-induced Ca(2+) influx in cultured rat cortical nonpyramidal neurones: pharmacological characterization using fura-2 microfluorimetry
Authors: Fischer W, Franke H, Scheibler P, Allgaier C, Illes P.
Journal: Eur J Pharmacol (2002): 53
Tyrosine kinase inhibitors and Ca2+ signaling: direct interactions with fura-2
Authors: Berts A, Minneman KP.
Journal: Eur J Pharmacol (2000): 35
Excitation wavelengths for fura 2 provide a linear relationship between [Ca(2+)] and fluorescence ratio
Authors: Palmer BM, Moore RL.
Journal: Am J Physiol Cell Physiol (2000): C1278
Selective measurement of endothelial or smooth muscle [Ca(2+)](i) in pressurized/perfused cerebral arteries with fura-2
Authors: Marrelli SP., undefined
Journal: J Neurosci Methods (2000): 145