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Optimized Fluorescence Labeling Solutions

Fluorescence is the result of a three-stage process that occurs in certain molecules (generally polyaromatic hydrocarbons or heterocycles) called fluorophores or fluorescent dyes. A fluorescent probe is a fluorophore designed to localize within a specific region of a biological specimen or to respond to a specific stimulus. Fluorescent probes enable researchers to detect particular components of complex biomolecular assemblies (including live cells) with exquisite sensitivity and selectivity. In general, the preferred bioconjugates should have high fluorescence quantum yields and retain the biological activities of the unlabeled biomolecules.

There are a number of fluorescent dyes developed and commercialized for labeling biomolecules. Among them FITC might be the most popular one although it has certain limitations, e.g., pH dependence, low photostability and short wavelengths etc. Alexa Fluor® dyes have been used for labeling proteins and other biomolecules with improved properties over the classic dyes such as fluorescein and rhodamine molecules. However, the extraordinary high costs of Alexa Fluor® dyes keep them from the certain applications that require using a large amount of dyes such as labeling peptides and oligos. In addition, Alexa Fluor® dyes do not provide a significant benefit for labeling peptides, oligo and other small molecules.

AAT Bioquest offers a complete set of fluorescent labeling dyes that are tiered and optimized for a variety of particular applications with significantly reduced cost. Our iFluor® dyes are a series of excellent fluorescent labeling dyes that span the full UV-visible spectrum. iFluor® dyes are optimized for labeling antibodies and other biopolymers including nucleic acids and carbohydrates. They demonstrate strong fluorescence, high photostability and pH independence on proteins and other biopolymers. All the iFluor® dyes have excellent water solubility. Their hydrophilic property makes the protein conjugation to be readily performed in aqueous media, minimizing the use of organic solvents. The resulting conjugates are resistant to precipitation during storage. The iFluor® dyes also have much better labeling performance than the classic fluorescent labeling dyes such as FITC, TRITC, Texas Red®, Cy3®, Cy5® and Cy7®. Some of our iFluor® dyes significantly outperform Alexa Fluor® labeling dyes on certain antibodies.

iFluor® dyes are the products of our recent R&D efforts. AAT Bioquest is rapidly expanding our product lines to meet your constantly changing research needs. We have been developing dyes to solve various limitations with the existing fluorescent labeling reagents while offering classic fluorescent labeling reagents which have high purity and competitive pricing to help you to get more research done with fewer funds.

Key Features of iFluor™ Dyes:

  • Versatile, available in a variety of reactive forms.
  • Bright, iFluor® conjugates exhibit more intense fluorescence than other spectrally similar conjugates of classic fluorescent dyes such as FITC, TAMRA and ROX under similar excitations.
  • Photostable, iFluor® dyes are more photostable than the classic fluorescent dyes such as FITC, Cy3® and Cy5®.
  • Well excited, iFluor® dyes have absorption spectra that match the principal output wavelengths of common excitation sources (such as 488 nm, 555 nm, 633 nm and 647 nm).
  • Multicolor, iFluor® dyes and their conjugates are available in a variety of distinct fluorescent colors.
  • pH-Insensitive, iFluor® dyes are robust and highly fluorscent over a broad pH range with little pH sensitivity.


Rapid Labeling of Proteins with ReadiLink™ Kits

The emission spectra of iFluor™ Goat Anti-Rabbit IgG conjugates.
ReadiLink™ iFluor® protein labeling kits provide a convenient way to label proteins using the succinimidyl ester (SE) reactive form of the iFluor® dyes. The succinimidyl ester shows good reactivity and selectivity with the aliphatic amines of proteins and forms a carboxamide bond, which is identical to, and is as stable as the natural peptide bond. iFluor®-protein conjugates may be used for immunofluorescent staining, fluorescent in situ hybridization, flow cytometry and other biological applications.

Each ReadiLink™ iFluor® protein labeling kit provides all the essential components for performing the conjugation reaction with a simple mixing step. The labeling kits require minimal hands-on time.

Table 1. Dye Selection Guide for iFluor® Fluorescence-Labeling Dyes

iFluor® Dye
Ex (nm)
Em (nm)
Features and Benefits
Ordering Information
iFluor® 350345442
  • Alternative to Alexa Fluor® 350 and DyLight™ 350
  • Much stronger absorption
  • Much stronger fluorescence
  • Less environment-sensitive
Cat# 1060 (maleimide, SH-reactive)

Cat# 1020 (SE, NH2-reactive)

iFluor® 405401420
  • Alternative to Cascade Blue®, Alexa Fluor® 405 and DyLight™ 405
  • pH-insensitive fluorescence
  • Photostable
Cat# 1021 (SE, NH2-reactive)$217
iFluor® 488491514
  • Alternative to Alexa Fluor® 488 and DyLight™ 488
  • pH-insensitive fluorescence
  • High labeling efficiency
  • Photostable
Cat# 1062 (maleimide, SH-reactive)

Cat# 1023 (SE, NH2-reactive)

iFluor® 555559569
  • Alternative to Cy3®, Alexa Fluor® 555 and DyLight™ 550
  • Strong fluorescence
  • More photostable than Cy3®
Cat# 1063 (maleimide, SH-reactive)

Cat# 1028 (SE, NH2-reactive)

iFluor® 594592614
  • Alternative to Texas Red®, Alexa Fluor® 594 and DyLight™ 594
  • Strong fluorescence
  • Photostable
Cat# 1029 (SE, NH2-reactive) $217
iFluor® 633638655
  • Alternative to Alexa Fluor® 633
  • Strong fluorescence
  • Photostable
Cat# 1030 (SE, NH2-reactive) $217
iFluor® 647654674
  • Alternative to Cy5®, Alexa Fluor® 647 and DyLight™ 650
  • Strong fluorescence
  • More photostable than Cy5®
Cat# 1065 (maleimide, SH-reactive)

Cat# 1031 (SE, NH2-reactive)

iFluor® 680682701
  • Alternative to Cy5.5®, IRDye® 700, Alexa Fluor® 680 and DyLight™ 680
  • Strong fluorescence
  • More photostable than Cy5.5®
Cat# 1066 (maleimide, SH-reactive)

Cat# 1035 (SE, NH2-reactive)

iFluor® 700693713
  • Alternative to Alexa Fluor® 700
  • Strong fluorescence
  • Good photostability
Cat# 1067 (maleimide, SH-reactive)

Cat# 1036 (SE, NH2-reactive)

iFluor® 750753779
  • Alternative to Alexa Fluor® 750 and DyLight™ 750
  • Strong fluorescence
  • More photostable than Cy7®
Cat# 1068 (maleimide, SH-reactive)

Cat# 1037 (SE, NH2-reactive)


Table 2. ReadiLink™ Rapid iFluor® Antibody Labeling Kits

ReadiLink™ Antibody Labeling Kit
Fluorophore Equivalent
Ex/Em (nm)
Flow Cytometry
Cat No.
ReadiLink™ Rapid iFluor® 350AMCA, Alexa Fluor® 350344/448Yes 1220
ReadiLink™ xtra Rapid iFluor® 350AMCA, Alexa Fluor® 350344/448Yes 1950
ReadiLink™ Rapid iFluor® 488FITC, Alexa Fluor® 488491/516YesYes1255
ReadiLink™ xtra Rapid iFluor® 488FITC, Alexa Fluor® 488491/516YesYes1955
ReadiLink™ Rapid iFluor® 555Cy3, Alexa Fluor® 555556/569Yes 1227
ReadiLink™ xtra Rapid iFluor® 555Cy3, Alexa Fluor® 555556/569Yes 1958
ReadiLink™ Rapid iFluor® 594Texas Red®, Alexa Fluor® 594587/603Yes 1230
ReadiLink™ xtra Rapid iFluor® 594Texas Red®, Alexa Fluor® 594587/603Yes 1960
ReadiLink™ Rapid iFluor® 633Cy5, Alexa Fluor® 633638/655YesYes1260
ReadiLink™ Rapid iFluor® 647Cy5, Alexa Fluor® 647654/669YesYes1235