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Cy3 NHS ester Catalog No.GC17345

Labeling of amino-groups in biomolecules.

Size Price Stock Qty
Sulfo- 5mg
In stock
Sulfo- 25mg
In stock

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Sample solution is provided at 25 µL, 10mM.

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Chemical Properties

Cas No. SDF
Chemical Name (2E)-1-[6-(2,5-dioxopyrrolidin-1-yl)oxy-6-oxohexyl]-3,3-dimethyl-2-[(E)-3-(1,3,3-trimethyl-5-sulfonatoindol-1-ium-2-yl)prop-2-enylidene]indole-5-sulfonate
Canonical SMILES CC1(C2=C(C=CC(=C2)S(=O)(=O)[O-])[N+](=C1C=CC=C3C(C4=C(N3CCCCCC(=O)ON5C(=O)CCC5=O)C=CC(=C4)S(=O)(=O)[O-])(C)C)C)C
Formula C34H38N3NaO10S2 M.Wt 735.80
Solubility very high in water, good in polar organic solvents (DMF, DMSO) Storage 24 months after receival at -20°C in the dark. Transportation: at room temperature for up to 3 weeks. Avoid prolonged exposure to light. Desiccate.
General tips For obtaining a higher solubility , please warm the tube at 37 ℃ and shake it in the ultrasonic bath for a while.Stock solution can be stored below -20℃ for several months.
Shipping Condition Evaluation sample solution : ship with blue ice
All other available size: ship with RT , or blue ice upon request
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**When preparing stock solutions always use the batch-specific molecular weight of the product found on the vial label and MSDS / CoA (available online).


Spectral properties

Excitation max (nm) 584 Emission max (nm) 563
Extinction Coefficient (M-1cm-1) 162000 Quantum Yield 0.1
CF260 0.03 CF280 0.06


Sulfonated cyanines are available for the labeling of many targets including:

• Soluble proteins, which are tolerant to addition of organic co-solvent • Fluorescence polarization (FP)
• Antibodies (with 5-10% of DMSO/DMF) • Fluorescence resonance energy transfer (FRET)
• DNA and oligonucleotides • Time-resolved fluorescence energy transfer (TR-FRET)
• Peptides • Fluorescence intensity (FI)
• Many small molecules  
• Sensitive proteins which are denatured by DMF or DMSO  
• Protein conjugation when purification is done by dialysis  
• Nanoparticles in aqueous solutions  
• Insoluble or hydrophobic proteins  


Sulfo-Cy3 NHS ester is a sulfonated, hydrophilic and highly water soluble dye. For labeling proteins and peptides, no organic co-solvent is needed. Sulfo-Cy3 NHS ester is ideal for proteins with low solubility and proteins prone to denaturation. Non-sulfonated Cy3 NHS ester is also available. In life science, the sulfonate groups make the Cy dyes soluble in water and also reduce fluorescence-quenching which can arise from dye–dye interactions.

In vitro, sulfo-Cy3 NHS ester can react with green-emitting QDs ligand-exchanged and LA/His-PIMA-PEG-NH2 to provide QD-dye conjugates [1].

[1] Reid, D. A.; Keegan, S.; Leo-Macias, A.; Watanabe, G.; Strande, N.T.; Chang, H.H.; Oksuz, B.A.; Fenyo, D.; Lieber, M.R.; Ramsden, D.A.; Rothenberg, E. Organization and dynamics of the nonhomologous end-joining machinery during DNA double-strand break repair. Proceedings of the National Academy of Sciences of the U.S.A., 2015, 112(20).