Quinolones (QNs) Hapten Design and Synthesis

Creative Biolabs has many years of experience in antibody development. We not only have a good reputation in the development of antibodies against biological macromolecules, but also have a lot of experience and successful cases in designing, preparing haptens and developing small molecule antibodies.

The residues of quinolones (QNs), which are widely used in the prevention and treatment of animal diseases, in animal-derived foods have serious effects on human health. Therefore, the monitoring of QNs drugs has become a very necessary issue. The current detection methods for QNs are mainly instrument methods such as high-performance liquid chromatography and capillary electrophoresis. These methods can meet the requirements of sensitivity and accuracy, but it is difficult to meet the requirements of fast high-throughput processing due to the long time, high cost, and complicated processing steps. The immunoassay method based on the antigen-antibody reaction can meet the above needs, and the key to achieving the immunoassay is to obtain specific drug antibodies.

Quinolones (QNs)

Quinolones (QNs) are a class of synthetic drugs containing a 4-quinolone mother nucleus. They are a new generation of high-efficiency, broad-spectrum antibacterial drugs that have been rapidly developed in the past 30 years. The basic structure of QNs is 1,4-dihydro-4-oxopyridine-3-carboxylic acid. The two rings of the parent ring are basically in the same plane. Adding different groups to the 1, 5, 6, 7, and 8 positions of the mother core structure constitutes different QNs. Common QNs are marbofloxacin (MAR), norfloxacin (NOR), sarafloxacin (SAR), diflucloxacillin (DIF), enrofloxacin (ENRO), ciprofloxacin (CIP), etc. Using these QNs as haptens, researchers have prepared different antibodies to detect QNs residues. For example, using ciprofloxacin (CPF) as a hapten, coupling it to a carrier protein to prepare a complete antigen, and antibodies produced by immunizing animals with it has broad-spectrum specificity for fluoroquinolone (FQ), that is, 100% recognition of CPF, and recognition rates of 73.89%, 73.57%, 67.28%, 53.09%, 50.26%, 35.66%, 12.40%, and 3.23% for enrofloxacin ( ENF), norfloxacin, nadifloxacin, danofloxacin, pefloxacin, lomefloxacin, enoxacin, and sarafloxacin respectively. The subsequent establishment of an ELISA experiment also demonstrated the reliability of using this antibody to detect FQ in food.

Chemical structure of quinolones approved for use in animals. Fig.1 Chemical structure of quinolones approved for use in animals.

Design and Synthesis of Class-specific Haptens for Quinolones

In order to detect two or more related analytes in the same sample at the same time, it is necessary to design class-specific haptens to develop broad-spectrum antibodies. In the same class of drugs, they generally have a common parent structure and are called structural analogs. Drugs with the parent structure of the same class of compounds are selected for the rational design of haptens and prepared as complete antigens. The antibodies obtained after immunizing animals can recognize two or more structural analogs at the same time. Compared with the broad-spectrum immunoassay method of mixed antibodies, the antibodies produced by this class-specific hapten can reduce the subsequent workload and facilitate the operation. Existing studies show that the haptens based on ciprofloxacin and enrofloxacin can recognize more than 12 QNs.

Parent ring structure of quinolones Fig.2 Parent ring structure of quinolones.

Design and Synthesis of Compound-specific Haptens for Quinolones

Immunoassay technology that detects only one analyte in the same sample is also called specific immunoassay. The antibodies required for this test are generally highly specific and can only recognize the corresponding hapten. For QNs, gatifloxacin was once used as a hapten to prepare a complete antigen by coupling with serum albumin and ovalbumin through the activated ester method, and a polyclonal antibody was produced by immunizing the animal with it. In the ELISA experiment established in this way, the sensitivity of the antibody to gatifloxacin can reach 2.6 ppb, and cross-reaction with lomefloxacin is 3.0%. It has almost no cross-reaction with other drugs and has high specificity.

In response to customers' different requirements for test results, Creative Biolabs, with rich experience in antibody development, can provide customers with one-stop services such as class-specific and compound-specific hapten design, modification and synthesis, and subsequent antibody production and labeling.

If additional help is needed, please directly contact us and consult our technical supports for more details.

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