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Cal-520® azide

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Physical properties
Molecular weight934.82
Spectral properties
Excitation (nm)492
Emission (nm)515
Quantum yield0.751
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
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Molecular weight
Excitation (nm)
Emission (nm)
Quantum yield
Cal-520® azide is an excellent building block that can be readily used to prepare a calcium-sensitive bioconjugate for monitoring calcium change spatially for a specific target. It can be readily conjugated to alkyne-containing biomolecules via the well-known click chemistry. Calcium measurement is critical for numerous biological and neurological investigations. Fluorescent probes showing spectral responses upon binding calcium have enabled researchers to investigate changes in intracellular free calcium concentrations using fluorescence microscopy, flow cytometry, fluorescence spectroscopy, and fluorescence microplate readers. Cal-520® has been proven to be one of the best-known green fluorescent calcium indicators.


Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of Cal-520® azide 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 mM106.972 µL534.862 µL1.07 mL5.349 mL10.697 mL
5 mM21.394 µL106.972 µL213.945 µL1.07 mL2.139 mL
10 mM10.697 µL53.486 µL106.972 µL534.862 µL1.07 mL

Molarity calculator

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Spectral properties

Excitation (nm)492
Emission (nm)515
Quantum yield0.751

Product Family

NameExcitation (nm)Emission (nm)Quantum yield
Cal-520®, AM4925150.751



View all 50 references: Citation Explorer
Identifying subcutaneous tissue microcalcification by Fluo-3 AM imaging in cutaneous calciphylaxis.
Authors: Zhu, Xiaodong and Liu, Yuqiu and Yang, Xin and Liu, Bicheng and Zhang, Xiaoliang
Journal: Experimental dermatology (2022): 1632-1634
[The application of Fluo-3 AM in measurement of level of cytoplasmic calcium in thrombocytes by flow cytofluorometry].
Authors: Petrischev, N N and Vasina, L V and Selyutin, A V and Chepanov, S V and Selkov, S A
Journal: Klinicheskaia laboratornaia diagnostika (2017): 97-9
Basic methods for monitoring intracellular Ca2+ in cardiac myocytes using Fluo-3.
Authors: Bito, Virginie and Sipido, Karin R and Macquaide, Niall
Journal: Cold Spring Harbor protocols (2015): 392-7
[Application of the Ca2+ indicator fluo-3 and fluo-4 in the process of H2O2 induced apoptosis of A549 cell].
Authors: Zhang, Siyang and Li, Chunyan and Gao, Jian and Qiu, Xueshan and Cui, Zeshi
Journal: Zhongguo fei ai za zhi = Chinese journal of lung cancer (2014): 197-202
Temperature-induced labelling of Fluo-3 AM selectively yields brighter nucleus in adherent cells.
Authors: Meng, Guixian and Pan, Leiting and Li, Cunbo and Hu, Fen and Shi, Xuechen and Lee, Imshik and Drevenšek-Olenik, Irena and Zhang, Xinzheng and Xu, Jingjun
Journal: Biochemical and biophysical research communications (2014): 888-93
Triclocarban-induced change in intracellular Ca²⁺ level in rat thymocytes: cytometric analysis with Fluo-3 under Zn²⁺-free conditions.
Authors: Miura, Yukari and Chen, Xiaohui and Yamada, Saki and Sugihara, Aya and Enkhjargal, Molomjamts and Sun, Yuanzhi and Kuroda, Keiko and Satoh, Masaya and Oyama, Yasuo
Journal: Environmental toxicology and pharmacology (2014): 563-70
Predicting and avoiding subcellular compartmentalization artifacts arising from acetoxymethyl ester calcium imaging probes. The case of fluo-3 AM and a general account of the phenomenon including a problem avoidance chart.
Authors: Thompson, K and Dockery, P and Horobin, R W
Journal: Biotechnic & histochemistry : official publication of the Biological Stain Commission (2012): 468-83
Some characteristics of membrane Cd²+ transport in rat thymocytes: an analysis using Fluo-3.
Authors: Kawanai, Takuya and Fujinaga, Masahiro and Koizumi, Kazuki and Kurotani, Isao and Hashimoto, Erika and Satoh, Masaya and Imai, Shoji and Miyoshi, Norikazu and Oyama, Yasuo
Journal: Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine (2011): 903-14
A flow cytometric comparison of Indo-1 to fluo-3 and Fura Red excited with low power lasers for detecting Ca(2+) flux.
Authors: Bailey, Sheree and Macardle, Peter J
Journal: Journal of immunological methods (2006): 220-5
Functional fluo-3/AM assay on P-glycoprotein transport activity in L1210/VCR cells by confocal microscopy.
Authors: Orlický, J and Sulová, Z and Dovinová, I and Fiala, R and Zahradníková, A and Breier, A
Journal: General physiology and biophysics (2004): 357-66