Ochratoxins Hapten Design and Synthesis

Ochratoxin is a kind of mycotoxin secreted by genus Aspergillus and Penicillium, whose producers are extensively distributed in agricultural and food commodities such as cereals. Haptens are a class of small molecules that can’t elicit an immune response in the human body. Sometimes, it is necessary to stimulate immunity against hapten molecules since anti-hapten antibodies have no toxicity to organisms. As a leading provider in antibody production, Creative Biolabs offers sophisticated design and synthesis services for ochratoxin hapten-carrier conjugates and helps clients to understand the mechanism of antigen-antibody interaction as much as possible. To date, hapten products have been increasingly essential for the development of rapid and sensitive immunoassays.

Introduction to Ochratoxins

Ochratoxin is produced as a mold secondary metabolite by a variety of fungi species. It belongs to the group of a prominent three-member family of mycotoxins and is mainly made up of isocoumarin, linked to β-phenylalanine. Ochratoxin contains 9 major structural analogs which have been categorized into 4 types as A, B, C, and D. Among them, ochratoxin A (OTA) is undoubtedly the most toxic and common one, being ochratoxin B (OTB) and ochratoxin C (OTC) of lower relevance. The minute structural difference between them is the absence of the dihydroisocoumarin chlorine atom in OTB and the existence of the ethyl ester group in the L-phenylalanine format in OTC. They display teratogenicity, mutagenicity, hepatotoxicity, nephrotoxicity, and immunosuppression, thereby posing serious health threats for exposed humans and animals. Particularly, OTA has proven to be a strong carcinogen for rodents and is classified by the International Agency for Research on Cancer (IARC) as Group 2B (possibly carcinogenic to humans).

Tab.1 Basic information of ochratoxins. (Xu, 2019)

Basic information of ochratoxins.

Rational Hapten Design Services at Creative Biolabs

Immunoanalytical technologies are often exploited in the detection of hazardous small molecule compounds with low molecular weight. Antibody research and development for these molecule targets is a challenge, because they are haptens and have no ability to evoke a humoral immune response in laboratory animals. Immunogenic formats of haptens are generally prepared by conjugating them to a carrier protein, which is used to serve as an immune stimulator. Ochratoxin has an active group as a carboxy group and thus it can be directly coupled to the carrier protein without derivative progress. At Creative Biolabs, we have designed and developed ochratoxin haptens by selecting appropriate carrier proteins and appropriate conjugation strategy to enhance antibody production. There are several traditional methods used for antigen preparation.

Chemistry-assisted bioconjugates for OTA hapten immunodiagnostics. Fig.1 Chemistry-assisted bioconjugates for OTA hapten immunodiagnostics. (López-Puertollano, 2020)

  • The carbodiimide (EDC)/N-hydroxysuccinimide (NHS) coupling method: OTA is firstly dissolved into dimethylsulfoxide (DMF), and then EDC and NHS are added. The crosslinking system is processed under stirring at room temperature (37°C) in dark for hours. Next, the reaction solution is mixed with the carrier protein solution and the mixture system is reacted under stirring in dark for some time. The conjugated hapten is dialyzed in phosphate buffer solution (PBS) and ultimately is stored at -20°C for further usage.
  • The carbodiimide (CDI) method: OTA and CDI are firstly dissolved into anhydrous dimethylsulfoxide. The reaction system starts under stirring at 37°C in dark for several hours. Then ultrapure water is added to terminate the reaction, and the solution is dropped into the carrier protein solution and reacted at room temperature in dark for hours. The obtained hapten is dialyzed in PBS and finally stored at −20°C. Remarkably, the activated process should be performed in the anhydrous background as CDI is easy to decompose in water.

    Today, we have established advanced platforms to improve technologies on hapten design and carrier development. Our experts conjugate the ochratoxins to immunogenic carries (larger molecules) and evaluate its potential to induce antibody reaction with respect to ochratoxin conjugates. Afterward, polyclonal or monoclonal antibodies can be successfully developed with mice immunized with these hapten-carrier conjugates. Here, we’d like to provide custom design and synthesis services for different kinds of ochratoxins, including but not limited to:


  • One-stop, cost-effective methods to design and synthesize happens for different kinds of ochratoxins
  • Expertise in antibody production and antigen preparation, especially in small molecule haptens
  • Practiced technicians with more than 10 years of experience in custom projects for antigen development

Proper haptens to ochratoxins may be a simple and rapid detection for a wide range of samples in the immunology and manufacturing industry. With advanced platforms and extensive experience in the antibody market, Creative Biolabs is confident in providing customer-tailored design and synthesis services for various ochratoxins and other small molecular compounds. If you’re interested in our services, please don’t hesitate to contact us or directly send us an inquiry.


  1. Xu, C.L.; et al. Food Immunoassay. FOOD SCI NUTR. 2019.
  2. López-Puertollano, D.; et al. Click chemistry-assisted bioconjugates for hapten immunodiagnostics. Bioconjug Chem. 2020.
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