Chromogen substrate, chemiluminescence substrate and fluorescent substrate
A very important class of protein preparations in the IVD field when diagnosing enzyme preparations. There are many enzyme substrates, which can be basically divided into chromogenic substrates, luminescent substrates, fluorescent substrates, etc. The more representative ones are TOOS, TMB, and Lu Minol, fluorescein, etc.
The difference between enzymatic detection and colloidal gold
The detection of enzyme-containing substrates is carried out through enzymatic reactions. The resulting product has a color change or produces chemiluminescence or fluorescence, and then uses the instrument to detect these changes, based on the relationship between these changes and the content of the analyte. analyze. This type of detection method is obviously different from the colloidal gold in the turbidimetric method. Colloidal gold is electrostatically bound to proteins or other biological macromolecules through colloidal gold particles (negative charge); while enzymatic detection is directly labeled with a substrate or Using enzymes to label the substance to be tested is combined in the form of chemical bonds, which is more stable.
Chromogen substrates, fluorescent substrates, and luminescent substrates in IVD
Features of chromogen substrate:
Chromogen substrates are commonly referred to as chromogenic reagents and chromogenic substrates. Commonly used are TOOS and MAOS in Trinder’s reagents, and TMB in ELISA. Since the color reaction is easier to detect, the application of this type of reagent is relatively early and common. Chromogenic substrates are commonly used to detect blood sugar, blood lipids, liver and kidney function and many other biochemical testing items; it can also be combined with immune response, but does not directly label the substrate, but uses peroxidase to label antibodies or antigens.
Features of fluorescent substrates:
The fluorescent substrate is the substrate of peroxidase developed after the chromogen substrate, and the detection sensitivity is higher than that of the chromogen substrate. Several fluorescent materials of different colors can be used at the same time, but the equipment is expensive and the detection cost is high. , It is also susceptible to interference from autofluorescence generated by cells or other molecules, and it is sensitive to light and unstable during observation and storage.
Features of chemiluminescent substrates:
Chemiluminescence is different from fluorescence. It means that the chemical energy generated in the process of chemical reaction is absorbed to excite the molecule and emit light. Fluorescence is the light emitted by absorbing the light energy to excite the molecule. Chemiluminescence does not require an external light source like fluorescence, with high detection sensitivity and low background, so it is more widely used. More commonly used are luminol, isoluminol, AMPPD and acridine esters.
The luminescence of acridinium ester does not require enzyme catalysis. In fact, it cannot be counted as a substrate, but it has more advantages than luminol, and it can be directly labeled, which has a very good development and application trend. In addition to fluorescent substrates, Desheng produces and develops a variety of Trinder’s reagents, luminol, acridine esters and enzyme preparations.
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