Name: Fura-2 AM
Brand: AAT Bioquest
SKU: 21020
Availability: InStock

Fura-2, AM

CAS 108964-32-5

Fura-2 AM is a UV-excitable ratiometric calcium indicator that shifts excitation wavelength upon calcium binding, enabling quantitative measurement of intracellular calcium concentrations independent of dye loading and cell thickness.

Ratiometric Calcium Measurement: Excitation shift from 380 nm (free) to 340 nm (Ca²⁺-bound)
Quantitative [Ca²⁺] Determination: K_d = 145 nM, independent of dye concentration or cell thickness
UV-Excitable Design: Emission at 510 nm allows multicolor experiments with visible dyes
Calibration-Friendly: Rmax/Rmin determination enables absolute calcium quantification

Fluorescence excitation spectra of Fura-2 in solutions conctaining 0 to 39uM free Ca2+.

Protocol

COA

Catalog	Size	Price	Quantity
21020	1 mg	Price
21022	50 mg	Price

Overview

Fura-2 AM is a cell-permeable, ratiometric calcium ion indicator that emits green fluorescence upon UV excitation.

Fura-2 AM is the membrane permeable form of Fura-2. It belongs to a class of ratiometric calcium indicators, which also contain fluorescent dyes such as Indo-1. These probes quantitate calcium by observing changes at two wavelengths of a fluorophore upon calcium chelation and computing the ratio of these two points. This is in contrast to intensiometric probes, like Fluo-4, where a single spectral value is utilized.

Principles and mechanisms

Upon calcium binding, Fura-2 will exhibit an absorption shift in the 300 to 400 nm range, where the calcium free dye has an excitation maximum of 380 nm while the calcium bound dye has an excitation maximum of 340 nm. This change in absorbance can be measured by scanning the excitation spectrum, while monitoring the emission at 510 nm. The calculated 340/380 nm ratio is proportional to intracellular calcium ion concentrations.

Fura-2 vs Fluo-4

Ratiometric dyes like Fura-2 have several advantages over single-wavelength calcium probes, such as Fluo-4, namely, mitigating the effects of dye loading, leaking and photobleaching.

Fura-2 vs Indo-1

Fura-2 is an excitation ratiometric dye, wherein the absorbance spectra shifts (340/380 nm). Indo-1 is an emission ratiometric dye, wherein the emission spectra shifts (400/480 nm).

Calculators

Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of Fura-2, AM *CAS 108964-32-5* to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

	0.1 mg	0.5 mg	1 mg	5 mg	10 mg
1 mM	99.814 µL	499.072 µL	998.143 µL	4.991 mL	9.981 mL
5 mM	19.963 µL	99.814 µL	199.629 µL	998.143 µL	1.996 mL
10 mM	9.981 µL	49.907 µL	99.814 µL	499.072 µL	998.143 µL

Molarity calculator

Enter any two values (mass, volume, concentration) to calculate the third.

Mass (Calculate)		Molecular weight		Volume (Calculate)		Concentration (Calculate)		Moles
mg	÷	1001.86 g/mol	=	mL	x	mM	=	mmol

Citations

View all 28 citations: Citation Explorer

Pharmacological modulation of TRPV2 enhances migration and induces Immunoglobulin E (IgE)-independent degranulation of mast cells

Authors:

Leipe, Andrea and Raudszus, Rick and Urban, Nicole and Schaefer, Michael and Hill, Kerstin

Journal:

Cell Calcium (2026): 103166

Electrical coupling between transplanted cardiomyocytes and host myocardium to prevent arrhythmia

Authors:

Guragain, Bijay and Ye, Lei and Rogers, Jack M and Zhang, Jianyi

Journal:

Disease Models \& Mechanisms (2026): dmm052768

FOXM1 inhibitor, RCM-1, enhances venetoclax mediated apoptosis through downregulation of ATP2B4 in rhabdomyosarcoma

Authors:

Merjaneh, Nawal and Lan, Ying-Wei and Deng, Zicheng and Donovan, Johnny and Wang, Guolun and Do, Jonathan and Juan, Tiffany and Xia, Xiaomei and Kalinichenko, Vladimir V and Kalin, Tanya V

Journal:

International Journal of Oncology (2026): 1--16

A natural small molecule alleviates liver fibrosis by targeting apolipoprotein L2

Authors:

Gan, Lu and Jiang, Qiwei and Huang, Dong and Wu, Xueji and Zhu, Xinying and Wang, Lei and Xie, Wei and Huang, Jialuo and Fan, Runzhu and Jing, Yihang and others,

Journal:

Nature Chemical Biology (2024): 1--11

Regulation of Calcium entry by cyclic GMP signaling in Toxoplasma gondii

Authors:

Triana, Miryam A Hortua and M{\'a}rquez-Nogueras, Karla M and Fazli, Mojtaba Sedigh and Quinn, Shannon and Moreno, Silvia NJ

Journal:

Journal of Biological Chemistry (2024): 105771

References

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

Physical properties

Dissociation constant (K_d, nM)	145
Molecular weight	1001.86
Solvent	DMSO

Spectral properties

Excitation (nm)	336
Emission (nm)	505

Usage and storage

Intended use	Research Use Only (RUO)
Storage	Freeze (< -15 °C); Minimize light exposure
CAS	108964-32-5

Instrument settings

Fluorescence microscope
Excitation	Fura 2 filter set
Emission	Fura 2 filter set
Recommended plate	Black wall/clear bottom

Fluorescence microplate reader
Excitation	340, 380
Emission	510
Cutoff	475
Recommended plate	Black wall/clear bottom
Instrument specification(s)	Bottom read mode/Programmable liquid handling

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Page updated on July 19, 2026