Hapten-Carrier Conjugation

Hapten-Carrier Conjugation

As a leading drug conjugation service provider, BOC Sciences is committed to offering hapten small molecule conjugation services. With advanced equipment and professional expertise, we provide comprehensive solutions for hapten-carrier conjugates.

Hapten-Carrier Conjugates

Haptens are small molecular compounds with a molecular weight below 1000 Da that cannot be effectively recognized by the immune system to induce an antibody response, such as toxins, hormones, pharmaceuticals, and pesticides. However, haptens can be chemically modified at specific sites by attaching active group-bearing linkers, and then they can be combined with carriers to create hapten-carrier conjugates, also known as artificial antigens. These conjugates can indirectly induce the proliferation and differentiation of B cells, resulting in the production of specific antibodies by utilizing T cell epitopes.

The preparation of hapten-carrier conjugates with good immunogenicity is the most critical step in establishing immunoassay methods for small molecular compounds. Immunoassays are sensitive analytical methods based on the specific recognition and reversible binding reactions between antigens and antibodies and have found extensive applications in biological analysis. Immunoassays for detecting small molecules mainly refer to indirect competitive enzyme-linked immunosorbent assay (IC-ELISA). For instance, in the case of small molecular toxin haptens, they are conjugated to carrier proteins, inducing an immune response in animals, and then tested using IC-ELISA.

DHapten protein conjugate used for IC-ELISAFig. 1 Hapten protein conjugate used for IC-ELISA1

BOC Sciences provides one-stop services for hapten-carrier conjugates, including synthesis, characterization, and commercial production. We offer comprehensive support to various clients in the field of drug development.

  • Hapten Protein Conjugate
    Proteins are commonly used carriers to induce a strong immune response. Hydrophilic carriers like bovine serum albumin, with its large reactive groups, stable properties, and solubility in aqueous or some organic solvents, are often used.
  • Hapten Conjugate Vaccine
    When small molecule targeted drugs are not effective treatment options, immunotherapy can be used as an alternative strategy. Since small molecules are not inherently immunogenic, hapten conjugate vaccines are used to produce antibodies against these small molecule haptens, such as several abused drugs like morphine haptens and cocaine haptens.
  • Hapten-Labeled Nucleotides
    Hapten-labeled nucleotides can be used to prepare DNA probes, such as fluorescence in situ hybridization (FISH) probe.

Hapten Conjugation Services

  • Hapten Small molecule Modification
    Haptens have multiple potential modification sites. Different hapten modifications result in differences in antibody affinity, specificity, and efficacy. We synthesize various modified haptens based on different sites and choose the one that maintains the most complete hapten structure when connecting to the carrier for high affinity and strong specificity antibody production. Alternatively, we can select modifications that do not preserve the complete structure of the hapten molecule for establishing highly sensitive IC-ELISA.
  • Linker Selection
    The linker should avoid attaching near functional groups of the target hapten and its length should be appropriate, allowing the immune system to recognize the characteristic structure of the hapten.
  • Conjugation
    It involve using coupling agents to link haptens to carriers at functional groups like -COOH, -NH2, or -SH. We select appropriate conjugation methods based on the specific hapten being used. Additionally, we have the capability to control the molar ratio of hapten to carrier.
    • Carboxyl groups: carbodiimide, mixed anhydride, and active ester
    • Amino groups: glutaraldehyde, isocyanate, nitrophenyl, isourea, isocyanate chloride, and diazotization
    • Hydroxyl groups: succinic anhydride, diazotized benzoic acid, and sodium chloroacetate
    • Thiol groups: S-acetylthioethyl succinimide ester reaction using a disulfide bond

Hapten Carrier System

Carrier systems allow haptens to activate the immune system and generate antibodies. BOC Sciences can provide custom hapten-carrier conjugation services, selecting appropriate carrier systems to meet your needs.

  • Proteins: Globulin fractions, bovine serum albumin (BSA), ovalbumin (OVA), keyhole limpet hemocyanin (KLH), rabbit serum albumin (RSA), human serum albumin (HSA), thyroglobulin, and others.
  • Peptides: Synthesized polylysine, polyglutamic acid, mixed amino acid polymers, and more.
  • Polymers: High-molecular-weight organic compounds such as polyvinylpyrrolidone, carboxymethyl cellulose, poly(methyl methacrylate) particles, and others.

Our Advantages

  • Hapten small molecule phage display
  • Hapten conjugate linker optimization
  • Multiple hapten conjugation methods
  • In vitro immunoassays such as ELISA and IC-ELISA
  • Advanced analysis techniques such as LCMS/MS, GC/MS, Prep-Chromatography


  1. Ertekin, Ö., et al., Biological Activity of the Carrier as a Factor in Immunogen Design for Haptens, Molecules, 2018, 23(11), 2977.
* Please kindly note that our services can only be used to support research purposes (Not for clinical use).
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