AAT Bioquest

FastClick™ XFD750 Azide

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The reaction (Green Bar) of FastClick Cy5 Azide with coumarin alkyne occurs under extremely mild conditions (e.g., [Azide] = 0.02 mM, [Alkyne] = 0.02 mM, [CuSO4] = 0.02 mM, [Sodium Ascorbate] = 5 mM, in 100 mM HEPES) under which the common Cy5 azide does not effectively react with the coumarin alkyne substrate.
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Physical properties
Molecular weight1211.33
Spectral properties
Correction Factor (260 nm)0.00
Correction Factor (280 nm)0.04
Extinction coefficient (cm -1 M -1)240000
Excitation (nm)752
Emission (nm)776
Quantum yield0.121
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
Alternative formats
FastClick™ XFD750 Alkyne


See also: Click Chemistry
Molecular weight
Correction Factor (260 nm)
Correction Factor (280 nm)
Extinction coefficient (cm -1 M -1)
Excitation (nm)
Emission (nm)
Quantum yield
FastClick™ XFD750 Azide contains both the CAG moiety of FastClick (for assisting click efficiency) and Alexa Fluor® 750 fluorophore (as the fluorescence tag) for developing Alexa Fluor® 750-based fluorescent probes. It readily reacts with an alkyne-containing biomolecule under extremely mild conditions. Alexa Fluor® 750 is a commonly used near infrared (NIR) fluorophore for labeling proteins, nucleic acids, or other biomolecules. It has moderate photostability and excitation that matches the common 750 nm laser line. Its conjugates are widely used for in vivo imaging and flow cytometry applications in combination with the widely available Cy7 filter set. It is a water-soluble Cy75 derivative that has pH-insensitive fluorescence from pH 4 to pH 10. Alexa Fluor® 750 dye is particularly useful in stochastic optical reconstruction microscopy (STORM), where it is an exceptional reporter for both dSTORM and nSTORM. It is also used in super-resolution microscopy (SRM) applications. Alexa Fluor® is a trademark of ThermoFisher Scientific. FastClick™ reagents have been developed by the scientists of AAT Bioquest for enhancing the yield and reaction speed of copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. They contain a copper-chelating ligand that significantly stabilizes the Cu(I) oxidation state and thus accelerates the click reaction. They do not require the use of an external copper-chelator (such as the common THPTA or BTTAA). The high concentration of copper chelators is known to have a detrimental effect on DNA/RNA, thus causing biocompatibility issues. The introduction of a copper-chelating moiety at the reporter molecule allows for a dramatic raise of the effective Cu(I) concentration at the reaction site and thus accelerates the reaction. Under extremely mild conditions the FastClick™ azides and alkynes react much faster in high yield compared to the corresponding conventional CuAAC reactions.


Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of FastClick™ XFD750 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 mM82.554 µL412.769 µL825.539 µL4.128 mL8.255 mL
5 mM16.511 µL82.554 µL165.108 µL825.539 µL1.651 mL
10 mM8.255 µL41.277 µL82.554 µL412.769 µL825.539 µL

Molarity calculator

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Spectral properties

Correction Factor (260 nm)0.00
Correction Factor (280 nm)0.04
Extinction coefficient (cm -1 M -1)240000
Excitation (nm)752
Emission (nm)776
Quantum yield0.121

Product Family

NameExcitation (nm)Emission (nm)Extinction coefficient (cm -1 M -1)Quantum yieldCorrection Factor (260 nm)Correction Factor (280 nm)
FastClick™ Cy3 Azide55556915000010.1510.070.073
FastClick™ Cy5 Azide65167025000010.271, 0.420.020.03
FastClick™ Cy7 Azide7567792500000.30.050.036
FastClick™ XFD350 Azide34344119000-0.250.19
FastClick™ XFD488 Azide499520710000.9210.300.11
FastClick™ XFD555 Azide5535681500000.110.080.08
FastClick™ XFD647 Azide6506712390000.3310.000.03



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