Bioconjugates are those involving one molecule attached to another molecule, often by covalent bonds, to create a complex consisting of two molecules linked together. Bioconjugation technology has a wide range of applications in the development of new types of research on specific targeted derivatized proteins, DNA, RNA and carbohydrates, such as ligand discovery, disease diagnosis, and efficient screening. It is a research field with broad prospects.
Overview of Bioconjugation Technology:
Bioconjugation is the process of covalent bonding of two biomolecules. Common biochemical couplings include amine coupling of amino acid residues of lysine, sulfhydryl coupling of cysteine residues, and often photochemically initiated free radical reaction. The product of bioconjugation is a bioconjugate.
The most common biological conjugations are the coupling of small molecules, such as biotin to proteins; and the coupling of proteins to proteins, such as the coupling of antibodies to enzymes. Other uncommon coupling molecules such as oligosaccharides, nucleic acids, synthetic polymers: polyethylene glycol, carbon nanotubes. Bioconjugates include antibody-drug complexes (ADCs), pegylated proteins, siRNA complexes, and vaccine complexes.
Small molecules belong to haptens, which are only reactive but not immunogenic. They are immunogenic only after coupling with carriers (usually proteins, but also polypeptides) to form complete antigens, and antibodies will be produced after entering the body of animals. . Carrier proteins are macromolecules that can trigger immune responses by themselves. Many different types of carrier proteins can be conjugated with small molecules to prepare complete antigens. Commonly used carriers include bovine serum albumin, keyhole limpet hemocyanin, ovalbumin, bovine thyroglobulin and the like. The choice of carrier protein mainly involves factors such as its solubility, size, coupling group, immunogenicity, and cost. At present, the most widely used bovine serum albumin BSA on the market is mainly due to the stable chemical properties of BSA, not easy to denature, containing a variety of amino groups in the molecule, and high lysine content, cheap and easy to obtain. But BSA has limited its use as a blocking agent in some immunoassay experiments. The second choice is keyhole limpet hemocyanin KLH and ovalbumin OVA.
Coupling method of small molecule hapten and carrier:
1. For compounds with carboxyl or amino groups, use carbodiimide method and mixed acid anhydride method;
2. Compounds containing sulfhydryl groups, using the maleimide method;
3. For compounds with amino groups in the molecular structure, the glutaraldehyde method is the most commonly used method.
Applications of Bioconjugates:
1. Biochemical assessment:
Conjugated small molecules can be used as probes for rigorous biochemical analysis, and non-fluorescent small molecules such as biotin can also be used as mechanical probes.
2. Diagnostic application:
Qualitative and quantitative analysis of clinical samples is crucial for early disease diagnosis, and the high specificity of antibody-antigen interactions avoids sample purification and can be widely used.
3. Industrial application:
Bioconjugation can be used in many industries, and can be used in the food industry, such as isomerized fumaric acid and malic acid, for food residue detection; the pharmaceutical industry uses immobilized enzymes for drug synthesis, and can also be used for drug detection. agent detection, etc.