CalFluor Azide Probes

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. The difficulty removing all unreacted fluorescent probes is also one of the major contributors to background signal and non-specific binding.

To overcome this shortcoming, the Carolyn Bertozzi 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 showed 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.

Ordering information

Description Ex/Em Emission Color Pkg. Size Product # Price
CalFluor 488 Azide 500/521 Green 1 mg 1369 – 1 $239.00
5 mg 1369 – 5 $895.00
CalFluor 555 Azide 561/583 Red 1 mg 1370 – 1 $239.00
5 mg 1370 – 5 $895.00
CalFluor 580 Azide 591/609 Red 1 mg 1371 – 1 $239.00
5 mg 1371 – 5 $895.00
CalFluor 647 Azide 657/674 Near IR 1 mg 1372 – 1 $239.00
5 mg 1372 – 5 $895.00

Selected References:

  1. Graham, A. J., et al. (2022). Extracellular Electron Transfer Enables Cellular Control of Cu(I)-Catalyzed Alkyne-Azide Cycloaddition. ACS Cent Sci., 8 (2), 246-257. [PubMed]
  2. Shieh P., et al. (2015). CalFluors: A Universal Motif for Fluorogenic Azide Probes across the Visible SpectrumJ. Am. Chem. Soc., 137: 7145−51. [PubMed]
  3. Pawlak, J. B., et al. (2016). The Optimization of Bioorthogonal Epitope Ligation within MHC‑I Complexes. ACS Chem. Biol., 11: 3172−8. [PubMed]

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.