The imprinting method is to transfer the biological macromolecular substance to the solid phase carrier through different routes, and the transferred solid phase carrier is treated with the quenching reagent, rinsed with an appropriate solution, and incubated in a solution containing the substrate or the probe. It can react with the corresponding probe to reveal a specific band. Common blotting methods are Southern, Northern, Western blotting, which are used to detect DNA, RNA and proteins, respectively. Among them, Western blotting is also called immunoblotting.

Immunoblotting is a method of detecting a certain protein in a complex sample based on the specific binding of an antigenic antibody. Western blot is a new immunochemical technology developed on the basis of gel electrophoresis and solid phase immunoassay. Since immunoblotting has high resolution of SDS-PAGE and high specificity and sensitivity of solid phase immunoassays, it has become a conventional technique for protein analysis. Immunoblots are commonly used to identify certain proteins and to perform qualitative and semi-quantitative analysis of proteins.
The basic principle of the immunoblotting method is that after the polyacrylamide gel electrophoresis, the protein sample separated by PAGE is transferred to a solid phase carrier (for example, a nitrocellulose membrane), and the solid phase carrier adsorbs the protein as a non-covalent bond, and The type of polypeptide that maintains electrophoretic separation and its biological activity are unchanged. The protein or polypeptide on the solid phase carrier is used as an antigen, and the corresponding antibody is immunoreacted, and then reacted with an enzyme or an isotope-labeled secondary antibody, and the specific purpose of electrophoretic separation is detected by substrate color development or autoradiography. Protein component of gene expression. This technique is also widely used to detect expression at the protein level.

Western blotting is performed in three stages. The first stage is electrophoresis, SDS-PAGE separates each protein component; the second stage is imprinting, which transfers the protein from the gel to the solid phase carrier; the third stage is immunoassay, which in turn reacts with the primary antibody and the labeled diabodies. The color is excited by the substrate or the excitation light to observe the presence or absence of the target band. This method is used as a confirmatory test in HIV infection. After the antigen is transferred to the nitrocellulose membrane by electrophoresis, the membrane is cut into strips, and the kit made of the enzyme-labeled antibody and the chromogenic substrate can be conveniently used for testing in the laboratory. The presence or absence of specific antibodies against the virus can be determined based on the position of the colored lines.

Recombinant immunoblot assay (RIBA) differs from immunoblotting in that specific antigens are not separated by electrophoresis separation, but are directly stripped onto a solid phase membrane. RIBA has been used for the determination and analysis of serum anti-HCV antibodies. RIBA adsorbs various antigen components in a horizontal line on the membrane strip of nitrocellulose membrane, and puts it in a special long groove reaction plate to incubate and wash with the specimen (primary antibody) and the enzyme-labeled secondary antibody. After the substrate is developed, the color band indicates that there is a specific antibody against the adsorbed antigen in the serum. The antibody titer can also be roughly estimated based on the thickness of the strip and the depth of coloration. RIBA is well suited for the analysis of pathogen antibodies containing complex antigenic components and, in addition to anti-HCV, is also successfully used for anti-HIV anti-assay assays.