Immunodiagnosis is a method to detect specific reactions of antigens and antibodies. Because it can amplify and display the detection signals by using isotopes, enzymes and chemiluminescent substances, it is often used to detect trace substances such as proteins and hormones.
Immunodiagnosis has undergone isotope radioimmunoassay (RIA), precise measurement of antigen-antibody binding by radioactivity of radioactive elements, colloidal gold technique (binding of chloroauric acid to protein macromolecules by electrostatic interaction in a specific environment), enzyme-linked immunoassay (EIA), and enzyme-linked immunoassay (ELISA), using active enzymes as markers. Immunoassay, time-resolved fluorescence assay (TRFIA) and chemiluminescence immunoassay (CLIA), which combines the principles of chemiluminescence with the principles of immune reaction, are used in the technical stages.
Radioimmunoassay has been basically eliminated due to environmental pollution. At present, the immunodiagnosis market in China is mainly composed of colloidal gold, enzyme-linked immunosorbent assay, time-resolved fluorescence and chemiluminescence. Among them, chemiluminescence immunoassay (CLIA) is an advanced immunodiagnostic technology recognized worldwide, which is widely used in the diagnosis of tumor markers, infectious diseases, endocrine function, hormones and so on.
The basic principle of chemiluminescence immunoassay (CLIA) includes two parts: immunoreaction and chemiluminescence. Chemiluminescence (CL) refers to the formation of an exciting intermediate by catalysis of a catalyst or oxidation of an oxidant. When the exciting intermediate returns to a stable ground state, it releases photons of the same energy level, resulting in the phenomenon of luminescence. Chemiluminescent immunoassay (CLIA) is a process in which luminescent substances or enzymes are first labeled on antigens or antibodies. After specific binding of antigens and antibodies, oxidants or luminescent substrates are added, and after oxidation or reaction with substrates, luminescent phenomena occur. Because the concentration of the substance to be measured in the chemical detection system is linearly and quantitatively related to the chemiluminescence intensity of the system under certain conditions, the content of the substance to be measured is determined by measuring the chemiluminescence intensity of the system with an instrument.
Technical classification - According to the different markers, chemiluminescent immunoassay can be divided into direct chemiluminescent immunoassay, chemiluminescent enzyme immunoassay and electrochemical analysis. According to the different coating methods of antigen or antibody, chemiluminescence can be divided into microporous plate type and particle type. Particle type can be divided into magnetic particle type and non-magnetic particle type. Among them, magnetic particle type is the most advanced chemiluminescence technology.
Microporous plate technology is actually a transitional product between ELISA and chemiluminescence. It is the main product form in the early stage of domestic chemiluminescence technology. It is also a unique product form of chemiluminescence detection technology in China's immune diagnosis industry. The manufacturers are mainly local manufacturers in China, and the luminescence base is used. Its sensitivity and specificity are low because of its substance and methodology.
Particle luminescence technology is also called tube luminescence technology. Samples can be tested on-the-spot without waiting for the sample collection, without the limitation of the time of consultation, sample collection and sample size, without background and cross-contamination between holes, and the results are reliable. The priority of inserting test in emergency projects at any time not only facilitates patients, but also saves the labor cost of department staff, and improves the examination. The efficiency of measurement.
Chemiluminescence technology of magnetic particles is a hot research topic in recent years. Solid-phase antibody is prepared by covalent bonding instead of physical adsorption. It has many advantages, such as large surface area, many active groups, strong bonding, fast immune response, etc. It has been rapidly developed and widely used in clinical diagnosis. At present, there are 21 manufacturing enterprises, a total of 512 batches of magnetic particle chemiluminescence products within the validity period. Domestic competition is white-hot, but also presents the characteristics of homogeneous rolling: most enterprises lack superior products, repeated layout in the same testing project.