Fluorescein One-Shot Antibody Labeling Kit

SKU Unit Size Price Qty
F-9001-009K 1 Kit

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Fluorescein One-Shot Antibody Labeling Kit offers an efficient and reproducible method to label any antibody with fluorescein. The kit includes everything needed to make two fluorescein-antibody conjugates from 100 µg of any user-supplied antibody.


More Information
Conjugation Targets Antibody
Label/Modifier Type Fluorescein
Reactivity Amine
Recommended Storage 25°C
Applications Antibody Labeling, Antisense/RNAi, Aptamers, In Situ Proximity Ligation

Kit Components

  • NHS-Fluorescein (2 x 10.0 μg)
  • 10X Modification Buffer (1.5 mL)
  • Collection Tubes (8 x 1.5 mL)
  • Zeba™ Spin Columns (4 x 0.5 mL)
  • Fluorescein-IgG Control (100 μg)
  • Anhydrous DMF (500 μL)


Technical Information

a. Product Description

The Fluorescein Antibody Labeling Kit is designed to label a microscale quantity of antibody (100 μg) with 3 to 5 fluorescein molecules per antibody. The kit contains sufficient reagents to perform two labeling reactions, 100 μg of antibody per reaction. Fluorescein-labeled antibodies can be used for standard immunofluorescent staining and imaging of cells or tissues. This kit contains all the necessary components to label and purify an antibody in about 90 minutes.

b. Features and Benefits

The Fluorescein Antibody Labeling Kit uses an isomeric mixture of the 5- and 6-carboxyfluorescein N- hydroxysuccinimidyl ester (Figure 1) to modify antibody lysine residues. Reaction conditions have been optimized to provide a consistent level of fluorescein incorporation and maximal immunofluorescent signal output. The kit includes simple step-by-step instructions for labeling and quantification of incorporated fluorescein molecules. The Fluorescein Protein MSR Calculator is recommended that automatically determines antibody concentrations and fluorescein incorporation levels without the user having to perform complicated calculations. The kit can be used to attach fluorescein groups to all types of mammalian antibodies, including mouse, rat, rabbit, goat, sheep, horse, cow, hamster, or human IgG.


Figure 1. 5-(and 6-) carboxyfluorescein succinimidyl ester. Structure of 5-(and 6-) carboxyfluorescein succinimidyl ester used for labeling antibodies in the kit.

c. Fluorescein Procedure Diagram


Figure 2. Summary of Fluorescein labeling procecure.

d. Process Summary

  1. Sample Preparation: Adjust antibody to 1 mg/mL in 100 μL buffer

  2. Sample Analysis: Confirm initial antibody concentration with a spectrophotometer

  3. First Buffer Exchange: Equilibrate spin columns & buffer exchange antibody

  4. Label Antibody: Incubate antibody with NHS-Fluorescein

  5. Second Buffer Exchange: Remove excess labeling reagent

  6. Quantify Fluorescein Incorporation: Measure A280/A494 and use provided Fluorescein Protein MSR Calculator

e. Important Labeling Parameters to Consider

The Fluorescein Antibody Labeling Kit is specifically designed to add fluorescein groups to a single 100 microgram quantity of antibody. The kit provides consistent and reliable fluorescein incorporation by controlling the following reaction variables:

  • Initial antibody mass (100 μg) and volume (100 μL)

  • Reaction buffer ionic composition and pH

  • Reaction time (60 min)

  • Reaction stoichiometry

    A factor critical to labeling consistency is the accurate confirmation of initial antibody concentration. The procedure recommends the use of a spectral scan (220–350 nm)  rather than a single wavelength scan at 280 nm to measure antibody concentration. A spectral scan provides additional information that often reveals the presence of interfering additives or preservatives that will alter the sample’s A280. Common additives present in commercially obtained antibody preparations include preservatives such as sodium azide, thimerosal, protein stabilizers such as *BSA or gelatin, or other small-molecule additives such as glycine or trehalose. If a commercial source of antibody contains any of these additives, please refer to the Troubleshooting Guide section in the Appendix to determine how to proceed


Intellectual Property

SoluLINK® Bioconjugation For Research Use Only. Not for use in diagnostic procedures. For additional licensing restrictions, please see the license agreement at vectorlabs.com/solulink-research-license.

Products are for research use only, not for use in diagnostic or therapeutic procedures or for use in humans. Products are not for resale without express written permission of Seller. No license under any patent or other intellectual property right of Seller or its licensors is granted or implied by the purchase unless otherwise provided in writing.

TriLink does not warrant that the use or sale of the products delivered hereunder will not infringe the claims of any United States or other patents or patents pending covering the use of the product alone or in combination with other products or in the operation of any process. All and any use of TriLink product is the purchaser's sole responsibility.

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