Cyanine dyes are molecules containing polymethine bridges between two nitrogen atoms with a delocalized charge which have been used for many years as dyes in life science. Since the Cy3, Cy5 and Cy7 were made commercially available as succinimidyl esters in the early 1990s, cyanine dyes began to be used widely as labels for nucleic acids. Because of the good properties of low non-specific binding to biomolecules and bright fluorescence owing to their huge extinction coefficients and good quantum yields, the Cy dyes have been widespread used in DNA and RNA labelling. Cyanine dyes can be divided into two groups based on water solubility: non-sulfonated cyanines and sulfonated cyanines.
Available non-sulfonated dyes include Cy3, Cy3.5, Cy5, Cy5.5, Cy7, and Cy7.5. Cy stands for 'cyanine', and the first digit identifies the number of carbon atoms between the indolenine groups. The suffix .5 is added for benzo-fused cyanines. Most derivatives of non-sulfonated cyanines have low aqueous solubility except for hydrochlorides of hydrazides and amines. They are organic co-solvent soluble (5-20% of DMF or DMSO). When these molecules are used for biomolecule labeling, they should be dissolved in organic solvent first, and added to a solution of biomolecule (protein, peptide, amino-labeled DNA) in appropriate aqueous buffer. Fluorescent properties of non-sulfonated cyanines have little dependence on solvent and surrounding.
Available sulfonated cyanines include sulfo-Cy3, sulfo-Cy5, and sulfo-Cy7, which have additional sulfo-groups that facilitate dissolution of dye molecules in aqueous phase. Charged sulfonate groups decrease aggregation of dye molecules and heavily labeled conjugates. Sulfonated cyanines are highly water soluble, and they do not use organic co-solvent for the labeling in aqueous environment.
- Cat.No. Product Name Information
Cy3 NHS ester (non-sulfonated)
Cyanine, a kind of synthetic dye belonging to the polymethine group, is still used in industry to increase the sensitivity range of photographic emulsions (such as increasing the wavelength range and making the film panchromatic), and in biotechnology more recently.
- A8101 Cy3.5 NHS ester (non-sulfonated) Cy3.5 NHS ester is a reactive dye for the labeling of amino-groups in peptides, proteins, and oligonucleotides.
- A8102 Cy5 NHS ester (non-sulfonated) During last years, Cy5 flurophore has become an incredibly popular label in life science research and diagnostics.
- A8103 Cy5.5 NHS ester (non-sulfonated) Cy5.5-NHS ester, also called Cy5.5 mono N-hydroxysuccinamide ester or Cy5.5 monofunctional N-hydroxysuccinimide (NHS) ester, is a near-infrared fluorescence and cyanine dye able to dissolve in anhydrous dimethylformamide (DMF) or dimethylsulfoxide (DMSO), bears an excitation maximum of 675 nm and an emission maximum of 693 nm .
Cy7 NHS ester (non-sulfonated)
Cy7 NHS ester, also called Cy7 monofunctional N-hydroxysuccinimide ester or Cy7-NHS , is a near-infrared fluorescent  and soluble sulfonated cyanine dye  with a molecular weight of 828 Da, able to be dissolved in DMSO  and ready for conjugation to proteins .
- A8105 Cy7.5 NHS ester (non-sulfonated) Cy7.5 is a NIR dye with very long-wave emission.
- A8107 Cy3 NHS ester Water soluble, amino-reactive Cy3 dye.
Cy5 NHS ester
Water soluble Cy5 succinimidyl ester (SE), for the labeling of various amine-containing molecules in aqueous phase, without use of organic co-solvent.
- A8109 Cy7 NHS ester Water soluble near infrared dye Cy7, amine-reactive succinimide ester.
- A8111 Cy3 azide (non-sulfonated) Cy3 dye azide for Click Chemistry.