Chemiluminescence immune luminols and acridinium esters

Chemiluminescence immuno-CLIA analysis was born in 1977. According to the basic principles of radioimmunoassay, a highly sensitive chemiluminescence technique is combined with a highly specific immune response to establish a chemiluminescence immunoassay. CLIA has the characteristics of high sensitivity, strong specificity, wide linear range, easy operation, and does not require very expensive equipment. CLIA has a wide range of applications. It can detect antigens, haptens and antibodies of different molecular sizes, as well as nucleic acid probes. Compared with radioimmunoassay (RIA), fluorescence immunoassay (IFA) and enzyme immunoassay (EIA), CLIA has the advantages of no radiation, long validity period of markers and full automation. 

Chemiluminescence immunoassay contains two systems: immunoassay and chemiluminescence analysis. The immunoassay system uses chemiluminescent substances or enzymes as markers, which are directly labeled on antigens or antibodies, and react with antigens and antibodies to form antigen-antibody immune complexes. The chemiluminescence analysis system adds an oxidant or enzyme's luminescent substrate after the immune reaction is over. The chemiluminescent substance is oxidized by the oxidant to form an excited intermediate, which emits photons to release energy to return to a stable ground state. Luminous intensity can be detected by a luminous signal measuring instrument. According to the relationship between the chemiluminescence label and the luminescence intensity, the standard curve can be used to calculate the content of the analyte.

Chemiluminescence immunoassay is a type of immunoassay method in which antibodies or antigens are directly labeled with chemiluminescence reagents. At present, common markers are mainly luminol and acridine ester chemiluminescent agents.

1 Chemiluminescence immunoassay of luminol label: The luminescence of luminol is oxidation reaction luminescence. In alkaline solutions, luminol can be oxidized to emit light by many oxidants, of which H2O2 is the most commonly used. Due to the slow speed of the luminescence reaction, some enzymes or inorganic catalysts need to be added. The main enzymes are horseradish peroxidase (HRP), and the inorganic ones include O3, halogen, Fe3, Cu2, Co2 and their complexes. In the early days, it was mainly used for the determination of inorganic and organic biological small molecules, and the sensitivity was reduced due to the decrease of luminescence intensity after labeling. It has been found that the addition of certain phenols and their derivatives, amines and their derivatives and phenylboronic acid derivatives to the luminescence system has a significant enhancement effect on the luminescence of the system, the luminescence intensity can be increased by 1000 times, and the "background" luminescence Significantly reduced, the light-emitting time has also been extended. The use of these enhancers makes chemiluminescence immunoassays widely used in the field of protein and nucleic acid analysis.

2 Chemiluminescence immunoassay labeled with acridine esters: Acridine esters are used in CLIA because of their poor thermal stability, and a more stable acridinium ester derivative has been synthesized after research. Under the conditions of H2o2 and OH, acridine ester compounds can emit light rapidly with a high quantum yield. For example, the quantum yield of acridine aromatic ester can reach 0.05. Acridine ester is used as a marker for immunoassay, and the luminescence system is simple , Fast, no need to add catalyst, and high marking efficiency, low background. These characteristics arouse great interest of the majority of analysts and diagnostic workers.