Fluorophores, Enzymes, and Biotin/Streptavidin Conjugations

Human PBL stained with CD3 and CD20 conjugated to RPE and DyLight488.

Human PBL stained with CD3 and CD20 conjugated to RPE and DyLight488.

Bio-Rad offers two complimentary easy-to-use antibody conjugation kits, in a wide range of labels suitable for use in most applications. Readilink fluorophores have been optimized for flow cytometry whereas Lynx kits, in addition to common fluorophores include enzymes and biotin conjugations. Save valuable time by quickly conjugating your label of choice using these kits with minimal hands on time.


LYNX Rapid and Rapid Plus Conjugation Kits® are available in a wide range of options including common fluorophores, enzymes and biotin/streptavidin conjugations, suitable for use in flow cytometry, ELISA, western blotting, immunohistochemistry and immunofluorescence. Identical protocols for small scale and large scale conjugations allow conjugation of up to milligram quantities of antibody. Conjugate your antibodies in 3 easy steps with only 30 seconds hands-on time and no purification required.

Readilink™ Kits

Readilink Antibody Conjugation Kits offer 12 unique fluorescence conjugation options for small volumes. Quickly label your antibody of interest in two easy steps in just over an hour with the unique chemistry of Readilink Dyes. The excitation wavelengths and narrow emissions spectra of the fluorophores ranging from violet to far red are ideal for multicolor flow cytometry. The infrared excitable conjugations are suitable for westerns, ELISA and in-vivo imaging.

Want to know how much fluorophore is conjugated to your antibody?

Easily calculate the fluorophore:protein (F:P) ratio using these 4 steps.

You may need to know the amount of fluorophore conjugated to your antibody for control purposes. To determine the fluorophore : protein ratio you will need to calculate the molar concentrations of both the fluorophore and the protein based on absorbance at known wavelengths in a spectrophotometer and then express this as a ratio. This ratio will be an indication of the average number of dye molecules conjugated to your antibody in your solution.

  1. Remove any excess fluorophore. Excess fluorophore will interfere with the absorbance measurement.
  2. Determine the concentration of protein. Measure the absorbance of the protein at A280 nm. Divide this value by the molar extinction coefficient for your protein.
    (e.g. mouse IgG has an extinction coefficient of 203,000 M-1 cm-1).
  3. Determine the fluorophore concentration. Measure the absorbance of the fluorophore at the wavelength of maximal excitation (e.g. for FITC use 495 nm wavelength). Divide this value by the molar extinction coefficient for the dye.
    (e.g. FITC has an extinction coefficient of 75,000 M-1 cm-1).
  4. Determine the labeling. Divide the fluorophore concentration by the protein concentration to calculate the F/P ratio.

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