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Reactive Dyes & Biotin

CF® dyes, other dyes & biotin

Biotium offers our bright & photostable CF® dyes, other dyes, and biotin with a full selection of reactive chemistries.
Jump to a section below to learn more:

Amine-reactive NHS esters & labeling kits
Thiol-reactive dyes & thiol modifying reagents
For labeling carbonyl groups or carbohydrates
Aldehyde-reactive dyes
Azides, alkynes, BCN, tetrazine, & TCO
Tyramide dyes & TSA Signal Amplification Kits
Dye free acids & polar tracers
Reactive biotins and other biotin compounds

Amine-reactive succinimidyl esters

Succinimidyl esters (SE, also known as NHS esters) react with primary amines such as lysine residues in proteins. Succinimidyl ester labeling is commonly used for conjugation of proteins and antibodies. The reaction requires basic pH for amine groups on the target protein to be deprotonated and react with SE, and is usually performed in pH 8.3 bicarbonate buffer.

Succinimidyl ester dyes have the disadvantage of hydrolyzing over time in the presence of water. Heavily sulfonated dyes, such as the Alexa Fluor® dyes, DyLight® dyes and IRDye® are particularly hygroscopic, worsening the hydrolysis problem. In contrast, all of Biotium’s amine-reactive CF® dyes have a relatively stable form of SE, which is more resistant to hydrolysis than the SE in many of the Alexa Fluor® dyes. Accordingly, CF® dye SE products generally give consistently higher labeling efficiency, thus providing users a better value.

We offer more than 25 CF® Dyes in SE form. We also supply anhydrous DMSO, which can be used to prepare SE stock solutions that are stable at -20°C for up to one month. Our CF Dye and Biotin SE Protein Labeling Kits include everything you need for labeling and purification of 3 x 1 mg protein reactions. For fast and simple antibody labeling, also see our Mix-n-Stain™ Labeling Kits.

Our VivoBrite™ Rapid Antibody Labeling Kits for Small Animal Imaging include everything you need to prepare near-IR conjugates of our superior near-infrared CF® dyes for small animal imaging.

Cyanine NS succinimidyl esters are non-sulfonated cyanine dyes that can be used to label proteins, oligonucleotides and nucleic acids. Available in 3 colors, Cyanine 488NS, Cyanine 555NS, and Cyanine 647NS are non-sulfonated versions of Cy®2, Cy®3, and Cy®5, respectively. The dyes are designed to have matching charge and molecular weight for 2D DIGE platform. We also offer a wide selection of classic amine-reactive dye and biotinylation reagents.

CF® Dye Succinimidyl Esters, Protein Labeling Kits, & Related Products

CF® Dye Succinimidyl Esters• Amine-reactive chemistry widely used for protein and antibody labeling
• More than 25 bright & photostable CF® dye colors
• More stable SE for excellent labeling efficiency
CF® Dye & Biotin SE Protein Labeling Kits• Everything you need for labeling and purification of 3 x 1 mg protein reactions
• Wide selection of CF® dye colors plus biotin
VivoBrite™ Rapid Antibody Labeling Kits for Small Animal In Vivo Imaging• Everything you need for labeling and purification of 3 x 1 mg protein reactions for in vivo imaging
• Featuring our superior near-IR CF® dyes
Mix-n-Stain™ Labeling Kits• Simply and rapidly label small amounts of antibody with no purification required
• Label antibodies with CF® dyes, fluorescent proteins, tags, or enzymes
• Small ligand labeling kits available
Cyanine Dye SE• Structurally identical to Cy® dyes from GE Healthcare
• Cyanine 555 (Cy®3), Cyanine 647 (Cy®5), Cyanine 680 (Cy®5.5), & Cyanine 750 (Cy®7)
Cyanine NS SE• Non-sulfonated dyes with matching charge & MW for 2D DIGE
• Cyanine 488NS, Cyanine 555NS, and Cyanine 647NS
Classic Amine-Reactive Dyes & Biotin• Wide selection of classic amine-reactive dyes and biotinylation reagents
Anhydrous DMSO• Essential for preparation of SE stock solutions
Ultrafiltration Vials• For easy spin-column removal of free dye after labeling proteins
• 3K MWCO or 10K MWCO

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Thiol-reactive maleimide and MTS dyes

CF® Dye maleimides are thiol-reactive dyes. Maleimide reacts with thiol groups to form thioether-coupled products. The reaction can take place at pH 7 in the presence of amines. At neutral pH, the maleimide group does not react with histidine or arginine. Maleimide labeling can be a useful alternative to succinimidyl ester labeling in cases where modification of lysines alters antibody binding affinity or other biological activity of the target protein. We offer maleimide forms of more than 20 CF® dyes.

Methanethiosulfonate (MTS) is a fast-reacting and highly selective thiol-reactive functional group. We offer MTS with a selection of popular CF® dyes, biotin, classic dyes, and as thiol-modifying and cross-linking reagents.

We also offer many classic thiol-reactive dyes and biotin, as well as reducing agents commonly used in thiol conjugation protocols.

Thiol-Reactive CF® Dyes & Related Reagents

CF® Dye Maleimides• Commonly used thiol-reactive chemistry
• More than 20 bright & photostable CF® dye colors
CF® Dye MTS• Fast-reacting dyes with excellent thiol selectivity
• Available with a selection of popular CF® dyes
Other Thiol-Reactive Dyes & Compounds• Wide selection of classic dyes & biotin
MTS Thiol-Modification Reagents• Thiol-reactive methanethiosulfonate compounds and cross-linkers
• Useful for analysis of disulfide bonds in proteins
Reducing Agents• DTT & TCEP reducing agents frequently used for generating free thiols for labeling

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Dyes for labeling carbonyl groups and carbohydrates

Aminooxy reagents (also known as hydroxylamine or aminooxyacetamide) react with aldehydes or ketones to form a stable hydrazone compound under mild conditions without the use of a reducing agent. Aminooxy can be used to label abasic sites in damaged DNA or carbonyl groups resulting from protein oxidation. They also can be used to label carbohydrates or glycoproteins after oxidation of the carbohydrates to form carbonyl groups. The reaction is fast and can be further accelerated by adding aniline as a catalyst. Aminooxy reagents are superior labeling reagents to hydrazides, because they form more stable linkages.

Hydrazides also react with aldehydes or ketones, but form unstable hydrazone linkages. Hydrazides are non-toxic and highly water soluble, making them useful as fluid phase markers and fixable microinjectable cytoplasmic tracers.

We offer a wide selection of CF dye colors with aminooxy or hydrazide functional groups. We also offer CF®DI reactive dyes, which have matched molecular weight and charge for 2D DIGE platform. We also offer a wide selection of classic dyes and biotin in aminooxy and hydrazide forms.

Aminooxy & Hydrazide Reagents for Labeling Carbonyls and Carbohydrates

CF® Dye Aminooxy• Reacts with aldehydes & ketones to form stable linkage
• Wide selection of bright & photostable CF® dye colors
CF®DI Aminooxy• CF®DI aminooxy dyes have matching charge & MW for 2D DIGE
• Green fluorescent CF®DI 488, red fluorescent CF®DI 555, and far-red fluorescent CF®DI 647
Cyanine Dye Aminoxy• Cyanine 555 is structurally identical to Cy®3, while Cyanine 647 is structurally identical to Cy®5
CF® Dye Hydrazide• Reacts with aldehydes & ketones
• Useful polar tracers
• Wide selection of bright, photostable, and highly soluble CF® dye colors
CF®DI Hydrazide• CF®DI hydrazide dyes have matching molecular weight and charge
• Green fluorescent CF®DI 488, red fluorescent CF®DI 555, and far-red fluorescent CF®DI 647
Other Aminooxy & Hydrazide Reagents• Selection of classic dyes and biotin
Aniline, 10X in Acetate Buffer• Catalyst for aminooxy & hydrazide reactions

Cy3 and Cy5 are registered trademarks of GE Healthcare

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Dyes with a free amine group

CF® Dye Amines can be used to conjugate CF® dyes to carboxylic acids groups in biological molecules. After activation with water soluble carbodiimides, carboxylic acids react with amine-functionalized dyes to form a stable amide bond.

Dyes or biotin with amine groups like Lucifer Yellow Cadaverine or Neurobiotin™ are also used as fluid phase markers for neuronal tracing, as well as gap junction connectivity and dye permeability studies.

Dyes with an Amine Group

CF® Dye Amine• Conjugate CF® dyes to carboxylic acids groups in biological molecules
• Selection of popular CF® dye colors
Other Dye and Biotin Amines• Selection of classic and biotin amines
• Polar tracers for neuronal injection or gap junction studies
EDC (EDAC)• Water soluble carbodiimide
• Activates carboxylic acids for reaction with amines

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Azides, alkynes, & BCN for bioorthogonal chemistry

Bioorthogonal labeling involves reactions between functional groups that do not react with native targets in the cell. Therefore bioorthogonal conjugation can be highly specific and controlled. We offer dyes with a variety of functional groups for bioorthogonal labeling. The original bioorthogonal chemistries require copper catalysis, which can cause oxidative damage to cells and proteins. Newer chemistries require lower copper concentrations or are copper-free, avoiding this problem.

Azide reacts with alkyne to form 1,2,3-triazole by copper(I) catalyzed 1,3-dipolar Huisgen cycloaddition. Picolyl azide undergoes the same reaction but at a much lower copper concentration, limiting copper-induced damage to cellular components. Azide reactive dyes also can undergo Staudinger ligation with phosphine containing compounds, while alkynes can be used as monomers to copolymerize with other monomers to form labeled polymers. BCN derivatives can be used for copper-free conjugation to azide groups. Methyltetrazine reacts with TCO (trans-cyclooctene) via a copper-free reaction.

Reagents for Bioorthogonal Labeling

Azides• Copper-catalyzed reaction with alkyne
• Copper-free reaction with BCN
• Staudinger ligation with phosphine
• Wide selection of CF® dye colors & biotin
Picolyl Azides• Reacts with alkyne at low copper concentrations
• Selection of popular CF® dye colors & biotin
Alkynes• Copper-catalyzed reaction with azide
• Polymer formation
• Wide selection of CF® dye colors or biotin
• Cyanine 555 (Cy®3) and Cyanine 647 (Cy®5 ) for 2D DIGE
BCN Reagents• Copper-free reaction with azide
• Wide selection of CF® dyes or biotin
• MTS-BCN allows conjugation of thiol groups to BCN
Methyltetrazine & TCO• Methyletetrazine reacts with TCO via copper-free reaction
• Wide selection of CF® dyes or biotin

Cy3 and Cy5 are registered trademarks of GE Healthcare.

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Dye Tyramides and TSA kits

Horseradish peroxidase (HRP) catalyzes the covalent reaction of tyramide to tyrosine residues. In the tyramide signal amplification technique, immunostaining is performed with HRP-conjugated antibodies or streptavidin. Subsequent reaction with fluorescent tyramide causes large numbers of fluorescent dye molecules to be deposited in the vicinity of the antibody,  generating dramatically stronger signal compared to conventional immunofluorescence.

Biotium’s Tyramide Amplification Kits feature our bright and photostable CF® dyes or biotin with anti-mouse, anti-rabbit, or HRP streptavidin conjugates. The kits offer benefits of high sensitivity and signal-to-background ratio, enabling the visualization of low-abundance targets that cannot be efficiently labeled using traditional immunostaining methods. Tyramide Amplification Kits can be used for multicolor signal amplification (see our Tech Tip to learn more). CF® dye, biotin, and other tyramides are also available separately.

Tyramides and Tyramide Amplification Kits

Tyramide Signal Amplification Kits• Choice of 6 bright & photostable CF® dyes or biotin
• Choice of goat anti-mouse, goat anti-rabbit, or streptavidin HRP conjugates
CF® Dye Tyramides• Choice of 15 bright & photostable CF® dyes
Other Tyramides• Other dyes, biotin, and DNP

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Free acid dyes

Near-IR CF® dye free acids are control dyes for studies that involve Near-IR CF® dye succinimidyl ester conjugated to antibody, protein or peptides.  We also offer a selection of classic dye free acids.


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Biotinylation Reagents and Other Biotin Compounds

Biotium offers biotinylation reagents with a full selection of reactive functional groups, as well as easy-to-use protein and antibody biotinylation kits.

Reactive Biotinylation Reagents

Biotin SE Protein Labeling Kit• Everything you need to label & purify 3 x 1 mg reactions
Mix-n-Stain™ Biotin Antibody Labeling Kits• Label your antibody in 30 minutes with no purification step
• Choose kits to label 5-20 ug, 20-50 ug, or 50-100 ug antibody
Biotin Succinimidy Ester (SE)• Amine-reactive biotin, label proteins on lysine residues
Biotin-X-SE• Amine-reactive biotin with longer linker
Biotin-XX-SE• Amine-reactive biotin with longer linker
Biotin-12-SE• Amine-reactive biotin with longer linker
Biotin-PEO4-propionate SE • Amine-reactive biotin with a long PEG spacer
Biotin-X-Free Acid• Can be converted to the mixed anhydride form, which is more amine-reactive than the SE form
Biotin-PEO4-Maleimide• Thiol-reactive biotin
Biotin-X-C5-Maleimide• Thiol-reactive biotin with a longer linker
Biotin MTSEA• Selective labeling of cell surface thiols under mild conditions
• Available with biotin, biotin-X, and biotin-XX linker lengths
Aminooxy Biotin• For stable labeling of carbonyls or carbohydrates
Biocytin Hydrazide• Fixable cytoplasmic tracer
• Also can be used to label carbonyls or carbohydrates
Biotin-PEO4-Hydrazide• Water soluble biotin for coupling to aldehydes or ketones
Biotin Alkyne• Bioorthogonal conjugation to azide or picolyl azide
• Polymer formation
Biotin Azide• Bioorthogonal conjugation to alkyne or phosphine
Biotin BCN• Copper-free bioorthogonal conjugation to azide
Biotin Picolyl Azide• Biorthogonal conjugation to alkyne at low copper concentrations
Biotin-PEO2-PPO2-Amine, TFA salt • Water soluble biotin derivative with a free amine for coupling to activated carboxylic acids
Biotin-PEO3-Amine • Water soluble biotin for coupling to activated carboxylic acids
Biotin-PEO4-Amine • Water soluble biotin for coupling to activated carboxylic acids
Biotin Cadaverine Free Base• Direct coupling to activated carboxylic acid groups without using an additional base
Biotin-X-Cadaverine, Free Base • Biotin-Cadaverine Free Base with longer linker
Biotin Cadaverine, Trifluoroacetate Salt• Coupling to carboxylic acids, DNA, and other biomolecules in the presence of base
Biotin-X-Cadaverine, TFA Salt• Biotin-Cadaverine TFA salt with longer linker
Biotin D(+)• Free biotin
Biotin-XX-Free Acid• Free acid biotin with a longer linker

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