Design and Synthesis of Compound-specific Haptens for β-Lactams

Anti-antibiotics antibodies have emerged as powerful tools for the detection of antibiotics in immunoassays. The key step to developing an immunoassay for the specific antibiotic is to synthesize artificial antigens with good immunogenicity. Careful design of immunizing antigens can lead to the production of compound or class selective antibodies. Nowadays, based on chemical criteria, theoretical studies, and molecular modeling assisted hapten design, Creative Biolabs provides mature strategies and perfect techniques for the modification, design, and synthesis of compound-specific haptens for β-Lactams.

Compound-specific β-Lactams Hapten Design

Since β-Lactam antibiotics share a 6-aminopenicillanic acid structure (a β-Lactam ring structure coupled to a thiazolidine ring) and differ in their acyl-side chain, the key point for compound-specific β-Lactams hapten design is the acyl-side chain. Concerning compound-specific β-Lactams hapten design, more attention should be paid to the side chain structure and the coupling sites. To prepare compound-specific monoclonal antibodies (mAbs) or polyclonal antibodies (pAbs), the first requirement is that the modified hapten should have a certain degree of complexity or rigidity. Otherwise, the β-Lactams hapten would be difficult to produce antibodies or the antibody titer is very low. The second important requirement is to maintain the original molecular structure of the antibiotics itself and to make the hapten to be exposed to the surface of the carrier as much as possible, so that after immunization, the hapten can be maximally recognized by the immune cells of the immunized animal, stimulating the animal to produce specific immune response and generate high affinity and high specificity antibodies against the hapten.

Examples of Compound-specific Haptens for β-Lactams

Synthesis of the artificial antigen and mAb development for Cefalexin (CEX) have been conducted successfully. Complete antigens of CEX-BSA and CEX-OVA were prepared by glutaraldehyde method and BALB/c mice were immunized with them. The high-titer, sensitive and specific anti-CEX pAb had been produced. The rate of cross-reaction of CEX mAb with Cefradine was 0.969%, and there was no cross-reactivity to Cefazolin, Cefathiamidine and Cefuroxime.

Fig.1 Schematic diagram of CEX-BSA synthesis by glutaraldehyde method.

Compound-specific β-Lactams Haptens Conjugation Strategy

The choice of which conjugation chemistry to use depends on the functional groups available on the β-Lactams antibiotics, the required hapten orientation and distance from the carrier, and the possible effect of conjugation on biological and antigenic properties. Creative Biolabs provides the following conjugation methods for the generation of compound-specific β-Lactams hapten.

• Glutaraldehyde-mediated reaction
• Carbodiimide-mediated reaction
• NHS ester-mediated reaction
• NHS ester-maleimide heterobifunctional cross linker-mediated reaction
• Active-hydrogen-mediated hapten-carrier conjugation
• Reductive Amination-mediated hapten-carrier conjugation

General Guidelines for Immunizing Hapten Synthesis

• Distal to important haptenic determinants
• Avoid attachment to functional groups
• Appropriate length of handle
• Compatibility of reaction with target molecule functional groups
• Solubility of hapten
• Stability of hapten under coupling conditions and subsequent use
• Ease of synthesis
• Appropriate coupling ratio determines the strength and specificity of the immune response

Depending on the availability, source, and nature of a given β-Lactams hapten, several approaches might be evaluated in the design of antigen, as well as strategy to develop high quality antibodies by Creative Biolabs. Often, upfront consultation will be of benefit to design an appropriate approach for the design and synthesis of compound-specific β-Lactams hapten. For class-specific haptens design, see the section entitled Design and Synthesis of Class-specific Haptens for β-Lactams. If you are interested in our services, please feel free to contact us for more information.