AAT Bioquest

FastClick™ 6-ROX 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 weight746.87
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™ 6-ROX Alkyne


See also: Click Chemistry
Molecular weight
FastClick™ 6-ROX Azide contains both the CAG moiety of FastClick (for assisting click efficiency) and 6-ROX fluorophore (as the fluorescence tag) for developing 6-ROX-based fluorescent probes. 6-ROX azide is one of the most widely used red fluorophores, in particular, for labeling alkyne-modified oligonucleotides and other small biomolecules. It has almost the identical fluorescence spectra to Alexa Fluor 594, a rhodamine analog. 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. Click chemistry was developed by K. Barry Sharpless as a robust and specific method of ligating two molecules together. Two important characteristics make click chemistry attractive for assembling biomolecules. First, click reactions are bio-orthogonal, thus the click chemistry-functionalized biomolecules would not react with the natural biomolecules that lack a clickable functional group. Second, the reactions proceed with ease under mild conditions, such as at room temperature and in aqueous media.


Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of FastClick™ 6-ROX 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 mM133.892 µL669.461 µL1.339 mL6.695 mL13.389 mL
5 mM26.778 µL133.892 µL267.784 µL1.339 mL2.678 mL
10 mM13.389 µL66.946 µL133.892 µL669.461 µL1.339 mL

Molarity calculator

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View all 50 references: Citation Explorer
Functionalized [2.2]Paracyclophanedienes as Monomers for Poly(p-phenylenevinylene)s.
Authors: Mann, Arielle and Wang, Chengyuan and Dumlao, Bianca L and Weck, Marcus
Journal: ACS macro letters (2024): 112-117
Orthogonal End Labelling of Oligonucleotides through Dual Incorporation of Click-Reactive NTP Analogues.
Authors: Schönegger, Eva S and Crisp, Antony and Radukic, Marco and Burmester, Jonas and Frischmuth, Thomas and Carell, Thomas
Journal: Chembiochem : a European journal of chemical biology (2024): e202300701
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Journal: Bioorganic chemistry (2023): 106913
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Authors: Chaudhuri, Ritapa and Prasanth, Thumpati and Dash, Jyotirmayee
Journal: Angewandte Chemie (International ed. in English) (2023): e202215245
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Journal: Nucleic acids research (2023): e89
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Authors: Cheng, Jiannan and Yu, Qing and Tu, Kai and Wang, Jinying and Zhang, Lifen and Cheng, Zhenping
Journal: Macromolecular rapid communications (2023): e2200570
Artificial clickase-triggered fluorescence "turn on" based on a click bio-conjugation strategy for the immunoassay of food allergenic protein.
Authors: Zhang, Xianlong and Fan, Lihua and Su, Zhuoqun and Xu, Qinfeng and Xi, Lingyi and Li, Lin and Wu, Yongning and Li, Guoliang
Journal: Food chemistry (2023): 133882
Synthesis of surface protein-imprinted nanoparticles based on metal coordination and anchored carbon dots for enhanced fluorescence detection.
Authors: Liu, Zhiqiang and Zhang, Shiting and Jin, Siyu and Feng, Xingjia and Bai, Yufei and Han, Xiao and Fu, Guoqi
Journal: Talanta (2022): 123070
Facial Synthesis and Bioevaluation of Well-Defined OEGylated Betulinic Acid-Cyclodextrin Conjugates for Inhibition of Influenza Infection.
Authors: Chen, Yingying and Wang, Xinchen and Ma, Xinyuan and Liang, Shuobin and Gao, Qianqian and Tretyakova, Elena V and Zhang, Yongmin and Zhou, Demin and Xiao, Sulong
Journal: Molecules (Basel, Switzerland) (2022)
Conjugation of Oligo-His Peptides to Magnetic γ-Fe2O3@SiO2 Core-Shell Nanoparticles Promotes Their Access to the Cytosol.
Authors: Le Jeune, Mathilde and Secret, Emilie and Trichet, Michaël and Michel, Aude and Ravault, Delphine and Illien, Françoise and Siaugue, Jean-Michel and Sagan, Sandrine and Burlina, Fabienne and Ménager, Christine
Journal: ACS applied materials & interfaces (2022): 15021-15034