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Custom Conjugation & Labeling Services

Custom Conjugation & Labeling Services

CST has 1,500+ ready-to-ship antibody conjugates for flow cytometry, immunofluorescence, immunohistochemistry, high-content screening, and other immunoassays. Our direct conjugation experts can also build specific antibody-label combinations so that you can sidestep the time-sink and pitfalls of do-it-yourself kits.


Conjugated antibodies are analyzed using size exclusion chromatography to verify their physical integrity and ensure preparations are free of contaminants, such as antibody aggregates or fragments, that may interfere with your experiments. Testing in key applications using biologically relevant cell systems and controls is also available.


Stringent purification to remove free dye/label and antibody, optimization of bio-conjugation chemistries, and identification of optimal degree of labeling ensures the best signal-to-noise ratio and the highest quality product.


Extensive technical support and consultation are provided by the same scientists who produce and validate our commercially available antibodies.

Order Guarantee

Antibody loss occurs during every conjugation and cleanup process. We account for varying labeling efficiencies, absorb the cost of excess antibody required to manufacture your conjugate, and ensure you receive exactly the amount of antibody you requested.


Multiple tiered options are available to match your needs and budget—from basic antibody conjugation to full validation and stability testing.

Basic conjugations typically ship in 10-12 days, complex conjugations may take 3-4 weeks.


Choose from a Broad Offering of Conjugation Types

Our general conjugation offering includes fluorescent dyes, HRP, beads, biotin/haptens and oligonucleotides. For more details and additional labels, see our services offered table.

Custom Conjugation & Labeling Services

Superior Performance Over Do-it-Yourself (DIY) Conjugation

CST Custom Conjugation vs. Other Vendors

CST Custom Conjugation vs. Other Vendors: Analysis of FGF Receptor 1 (D8E4) XP® Rabbit mAb #9740 conjugated using CST methods compared to DIY kits from two other vendors via via Ultra-High-Performance Liquid Chromatography (UHPLC). The optimization of bio-conjugation chemistries and stringent purification to remove free dye and antibody performed by CST results in a higher quality product, compared to other vendors’ products that contain higher levels of free dye and debris which can interfere with assay results.

Optimization of Degree of Labeling (DOL) Ensures Specific Signal Intensity

Custom Conjugation Labeling Services 4

DOL Service Option for Fluorophores: Conjugation to certain fluorescent dyes (Alexa Fluor® and Pacific Blue™) is optimized by DOL testing to identify the optimal antibody:dye molecular ratio, resulting in conjugates with maximum specific signal intensity. In the data shown, the DOL of 4.28 provides the most optimal signal-to-noise compared to higher DOLs.

Request a Custom Conjugation

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Standard Conjugation Services Offered

If you don’t see the label you’re interested in, just ask us! In many cases, we can accommodate your request.


Conjugation Type: Examples Service Tier Service Includes
Fluorophores Type I: Alexa Fluor®, Cyanine (CyDye®), Pacific Blue, mFluor, and iFluor dyes Basic Conjugation + Removal of Free Dye
Tier I Degree of Labeling (DOL) + Basic Service
Tier II Validation1 + Tier I Service
Tier III Stability Testing + Tier II Service
Fluorophores Type II: Phycoerythrin (PE), PE-CyDye® Tandems (e.g. PE-Cy®7), and Allophycocyanin (APC) Basic Conjugation + Purification
Tier I Validation1 + Basic Service
Tier II Stability Testing + Tier I Service
Haptens: Biotin, Digoxigenin (DIG), Dansyl, and others Basic Conjugation + Removal of Free Biotin
Tier I Validation2 + Basic Service
Beads: Sepharose® and Magnetic Basic Conjugation + Removal of Free Antibody
Tier I Validation3 + Basic Service
Enzymes: Horseradish Peroxidase (HRP) Basic Conjugation + Purification
Tier I Validation2 + Basic Service
Oligonucleotide: Including Akoya PhenoCycler Barcodes and 10x Genomics Feature Barcodes 4 Basic Conjugation + Purification
Tier I HPLC Analysis + Basic Service


1 Standard validation application method is Flow Cytometry. Alternatives may increase timeline and pricing.

2 Standard validation application method is Western Blot. Alternatives may increase timeline and pricing.

3 Standard validation application method is Immunoprecipitation. Alternatives may increase timeline and pricing.

4 Oligonucleotide conjugation offerings may be limited for certain Intellectual Property (IP)-protected technologies.

Oligonucleotide Conjugation Services

  • Biophysical characterization checks integrity, size, and confirms no aggregation, free antibody or free oligo, and is typically performed by analytical size exclusion chromatography (SEC).
  • Tier 1 includes a Certificate of Analysis (COA) with HPLC results.

Regarding Alexa Fluor conjugation, this product is provided under an intellectual property license from Life Technologies Corporation. The transfer of this product is conditioned on the buyer using the purchased product solely in research conducted by the buyer, excluding contract research or any fee for service research, and the buyer must not (1) use this product or its components for (a) diagnostic, therapeutic or prophylactic purposes; (b) testing, analysis or screening services, or information in return for compensation on a per-test basis; or (c) manufacturing or quality assurance or quality control, and/or (2) sell or transfer this product or its components for resale, whether or not resold for use in research. For information on purchasing a license to this product for purposes other than as described above, contact Life Technologies Corporation, 5781 Van Allen Way, Carlsbad, CA 92008 USA or [email protected]. Alexa Fluor is a registered trademark and Pacific Blue is a trademark of Life Technologies Corporation. Cy and CyDye are registered trademarks of GE Healthcare. All other trademarks are the property of their respective owners. Visit for more information.