Luminescent immunodiagnostic reagents are widely used in the fields of tumor markers, endocrine function, hormones, infectious diseases and other medical diagnosis, which is of great significance in disease diagnosis and adjuvant treatment. At present, there are mainly chemiluminescence (CLIA), electrochemiluminescence (ecli) and time-resolved chemiluminescence (TRFIA) methods. Each method has its own advantages and disadvantages. Below, Desheng will introduce the principles, advantages and disadvantages of these methods.
It mainly refers to the phenomenon that the luminescent agent of the substance participating in the chemical change radiates the absorbed chemical energy to produce light, mainly including direct chemiluminescence and enzymatic chemiluminescence. The most common direct chemiluminescence system is acridine ester / hydrogen peroxide system, which has relatively high sensitivity, but at the same time has the disadvantage of short luminescence time.
Enzymatic chemiluminescence mainly includes horseradish peroxidase (HRP) - luminol system, alkaline phosphatase (ALP) - amppd system and so on. Its advantage is that the luminous signal is strong and stable, and the luminous time is long, but the working curve may drift with time. Desheng can provide luminol, isoluminol, acridine ester and other chemiluminescence substrates.
Electrochemiluminescence is a combination of electrochemistry and chemiluminescence. It refers to the phenomenon that the excited state is generated by the electron transfer reaction on the electrode surface, and when it returns to the ground state, it produces light radiation. Electrochemiluminescence has two processes: electrochemical reaction and chemiluminescence reaction. Tripropylamine was used as electron donor and ruthenium tripyridine was used to label antibody (antigen). Compared with photoluminescence analysis, electrochemiluminescence is electrically activated, without excitation light source. Its luminescence signal is stable and the luminescence time is long, which effectively avoids the interference caused by stray light and impure light source, and greatly increases the sensitivity of analysis. But at the same time, there are some disadvantages, such as complex measurement method, high maintenance cost.
Time resolved fluorescence
Time resolved fluoroimmunoassay is a microanalysis method developed in recent ten years. The principle is to use trivalent rare earth ions (such as EU, EU, SM, SM, Te, TB, Dy) as tracers to label proteins, peptides, hormones, antibodies, nucleic acid probes or bioactive cells. After the reaction system (such as antigen antibody immune reaction, biotin avidin reaction, nucleic acid probe hybridization reaction, target cell and effector cell killing reaction, etc.) takes place, the target cells can be labeled, The fluorescence intensity of the final product was determined by time-resolved fluorescence immunoassay to determine the concentration of the substance in the reaction system.
Time resolved chemiluminescence has similar sensitivity to electrochemiluminescence and is more stable. However, the compatibility of the instrument is poor, the price is expensive, the operation is relatively complicated, and the requirements for reagents, water quality and environment in the production process are high.
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