What is a magnetic bead?
Magnetic beads are formed by wrapping Fe3O4 core with a certain tissue, which can be adsorbed by magnet, and there are small beads that adsorb (combine) the target material through the surface coating. The reason why it is magical is that it has many uses! What are the details?
1. Cell isolation
The surface of magnetic nanoparticles is connected with bioactive adsorbents or other ligands, such as antibodies and exogenous coagulant. Using their specific combination with target cells and the action of external magnetic field, cells can be separated and classified conveniently and quickly. Compared with the commonly used cell separation methods, it is simple, fast, efficient and safe. The following figure is a schematic diagram of the principle of separating cells with magnetic nanoparticles.
Immunoassay is an important method in modern biological analysis technology. It plays a great role in the quantitative analysis of proteins, antigens, antibodies and cells.
Macromolecular magnetic nanoparticles are used for immunoassay. The principle is to graft antibodies adsorbed on bacteria on the surface of macromolecular magnetic nanoparticles, mix and settle them with stock solution, separate and purify them under the action of magnetic field, and obtain living bacteria adsorbed on macromolecular magnetic nanoparticles.
Macromolecular magnetic nanoparticles can be coupled with antibodies to separate immune cells with specific antigens. Using the antigens or antibodies combined with macromolecular magnetic nanoparticles for immunoanalysis has the characteristics of high specificity, fast separation and good reproducibility. This method has been applied to some immunological function tests, such as the typing of human major histocompatibility complexes before human organ transplantation. Antibodies corresponding to different antigens can be coupled to polymer magnetic nanoparticles, the corresponding cells can be separated, and then micro cytotoxicity test can be carried out for typing and cross matching.
In addition, the proportion of various types of cells in peripheral blood can be known by coupling polymer magnetic nanoparticles with antibodies against different cell subtype marker antigens, enriching cells, observing and counting.
3. Enzyme immobilization
The enzyme has – COOH, – Oh, – NH2 and other active functional groups, which can be combined with magnetic nanoparticles by physical adsorption, cross-linking, covalent coupling and embedding. The specific implementation methods include adsorption cross-linking, covalent binding, covalent bond coupling, etc. Magnetic biopolymer microspheres immobilized enzyme can improve the biological compatibility, immune activity, hydrophilicity and stability of the enzyme. It is easy to separate the enzyme from the substrate or product. The operation is simple and easy. The external magnetic field can be used to control the movement mode and direction of the immobilized enzyme of magnetic materials and improve the catalytic efficiency of the immobilized enzyme.
4. Magnetic control detection
In the process of usual interventional therapy, ectopic embolism and infarction will occur and cause serious complications, which is a thorny problem to be solved urgently in clinic. Interventional therapy using magnetic nano particle carrier for embolization in magnetic control vessel has the advantages of magnetic control guidance and target embolization, which provides a way to solve the above problems.
5. Targeted drugs
The particle size of nanoparticles is relatively small and can pass through capillaries. Therefore, magnetic nano materials can be used as directional carriers. Under the external magnetic guidance system, drugs can be delivered to specific lesion sites for release, which can enhance the curative effect, reduce the side effects of drugs on human normal tissues and have good biocompatibility, that is, magnetic targeted drug delivery system technology.
6. Gene therapy
At present, virus vectors and liposome vectors are commonly used. Virus vectors have some disadvantages, such as difficult preparation, limited loading size, inducing host immune response and potential tumorigenicity. Liposomes, which are widely used at present, have the advantages of virus vector, but have no disadvantages of virus vector. However, the large particles of liposomes affect the transfection efficiency, and the emergence of magnetic nanoparticles overcomes their shortcomings. The preparation of magnetic Fe3O4 biological nanoparticles is simple, the diameter can be less than 10 nm, has very large surface energy, and has multiple binding sites, so the carrying capacity is better than other vectors, and the transfection efficiency is also higher than the currently used vectors. Therefore, magnetic biological nanoparticles can become a better gene carrier and be used in gene therapy.
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