Chemiluminescence immunoassay

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Chemiluminescence immunoassay (CLIA) is an immunoassay technique which combines the specific and sensitive CLIA of antigen and antibody. It was first established in 1976.
(1) Principles
Chemiluminescence immunoassay belongs to labelled antibody technology. It labels antibodies or antigens with chemiluminescent agents, catalytic luminescent enzymes or products indirectly participating in the luminescent reaction. When labelled antibodies or labelled antigens are combined with corresponding antigens or antibodies, the luminescent substrates are activated by luminescent agents, catalytic enzymes or products. Redox reaction, which releases visible light or stimulates the luminescence of fluorescent substances, is finally detected by luminescence spectrophotometer.
(2) Markers
1. Luminol and its derivatives are directly labeled by luminescent agents. They belong to cyclohydrohydrazines and can react with many oxides such as oxygen, hypochlorite, sulfur and peroxide to emit light. Therefore, luminol or its derivatives can be directly labeled with antibodies or antigens for CLIA. This method is specific, but it often affects the properties of luminescent materials and reduces the sensitivity due to cross-linking.
2. Luminescent catalytic enzymes are commonly used to label antibodies or antigens such as horseradish peroxidase, pyruvate kinase and glucose oxidase. The difference between CLIA and ELISA is that CLIA is an indicator reaction with luminescent substrates, which is called ELISA.
3. The labeled products participate in the reaction markers and do not directly catalyze the luminescence reaction, but the reaction products can make the reaction system luminescent. For example, oxalic acid labeled antibodies or antigens can produce dioxins under the action of hydrogen peroxide, which can stimulate the luminescence of Rubrene.
(3) Application
CLIA has high specificity and sensitivity, and can detect 10-5 mol/L of antigen. Fast, usually in tens of minutes or 1-3 hours. It is easy to operate and can be used for solid phase and homogeneous analysis. The test has good repeatability and the reagent is easy to standardize and commercialize. At present, it has been used for the determination of many drugs, hormones, pathogenic microorganisms and their metabolites, antibodies and other bioactive substances.