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CalFluor 647 Azide (CCT-1372)

CalFluor 647 Azide is a fluorogenic azide probe that is activated by Cu-catalyzed or metal-free click reaction. This azide probe is not fluorescent until it is reacted with alkynes. CalFluor 647 Azide is a water-soluble probe, and its excitation band is a good match for the 633 nm or 647 nm laser lines.


A major shortcoming of the visualization of alkyne-tagged biomolecules with fluorescent azide probes through CuAAC is the need to remove unreacted fluorescent probes. This is particularly problematic when imaging the intracellular environment, tissues of living organisms, or visualizing biomolecules in vivo. Failure to remove all unreacted fluorescent probes is also one of the major contributors to background signal and non-specific binding.

To overcome this shortcoming, Carolyn Bertozzi’s group has designed fluorogenic azide probes that are activated by Cu-catalyzed or metal-free click chemistry. These azide probes are not fluorescent until they react with alkynes. Termed the CalFluors, these probes possess emission maxima that range from green to far-red wavelengths, and enable sensitive biomolecule detection under no-wash conditions. A number of reports show that CalFluor probes are an indispensable tool for sensitive visualization of metabolically labeled molecules (glycans, DNA, RNA, and proteins) in cells, developing zebrafish, and mouse brain tissue slices under no-wash conditions.


Unit Size1 mg, 5 mg
Abs/Em Maxima, triazole after click reaction657/674 nm
Spectrally similar dyes
Alexa Fluor® 647, CF® 647, DyLight® 649, Cy5
Molecular weight933.24
SolubilityWater, DMSO
Purity>95% (HPLC)
AppearanceDark red amorphous solid
Storage Conditions-20°C. Desiccate
Shipping ConditionsAmbient temperature


CalFluor Azide Probes are covered by U.S. Patent No.: 9,410,958.

This product may be used for research purposes only. It is not licensed for resale and may only be used by the buyer. This product may not be used and is not licensed for clinical assays, where the results of such assays are provided as a diagnostic service. If a diagnostic or therapeutic use is anticipated, then a license must be requested from the University of California. The availability of such diagnostic and therapeutic use license(s) cannot be guaranteed from the University of California.

Selected References

  1. Shieh P., et al. (2015). CalFluors: A Universal Motif for Fluorogenic Azide Probes across the Visible SpectrumJ. Am. Chem. Soc., 137: 7145−51. [PubMed]
  2. Pawlak, J. B., et al. (2016). The Optimization of Bioorthogonal Epitope Ligation within MHC‑I Complexes. ACS Chem. Biol., 11: 3172−8. [PubMed]
  3. Jun Kit Ow, M., et al. (2020). Super-Resolution Fluorescence Microscopy Reveals Nanoscale Catalytic Heterogeneity on Single Copper Nanowires. ACS Appl. Nano Mater.,3, 4, 3163–7. [ACSPublications]

Applicable patents and legal notices are available at legal notices.

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