Solid phase membrane immunoassay
2021-02-11 11:19:02
The solid phase membrane-based immunoassay is similar to the solid phase enzyme immunoassay (ELISA) and is characterized by a microporous membrane as a solid phase. The label can be used with enzymes and various colored fine particles such as colored latex, colloidal gold, colloidal selenium, and red colloidal gold zui. The solid phase membrane is characterized by its porosity. Like filter paper, the solid phase membrane can be passed through by the liquid, and the liquid can also migrate forward through the capillary. Two different types of fast detection methods have been established using this capability.
In the solid phase membrane immunoassay, the flow-through form is called immunofiltration assay (IFA); the cross-flow form is called immunochromatographieassay (ICA). Because of the commonly used colloidal gold as a marker, the domestic literature refers to the former as the immunogold sol spot method and the gold immunoassay, etc., and the latter is called colloidal gold immunochromatography, etc., collectively referred to as "golden standard".
The solid phase membrane is the main raw material of the solid phase membrane immunoassay reagent and plays a decisive role in the quality of the reagent. A commonly used film is a nitrocellulose membrane. The nitrocellulose membrane itself is hydrophobic, and a surfactant is added during the production process of the membrane to become hydrophilic and has strong adsorption properties for proteins. The following characteristics should be noted when selecting a suitable nitrocellulose membrane.
1. The pore size can be expressed in microns (Atm) by the size of the particles. The film used for the flow-through method is generally selected to be about 0.4 μm, and the film for the cross-flow method may be selected from 5 to 10 μm.
2. The flow rate is expressed in ml/(cm2·min). The flow rate has a certain relationship with the pore size. The larger the pore size, the faster the flow rate. When selecting a suitable membrane in the cross-flow method, the flow rate is more valuable than the pore size.
3. Protein binding is expressed in ug/cm2.
4. Uniform quality membranes should have good homogeneity to ensure homogeneity within the reagent lot number.
In the solid phase membrane immunoassay, the flow-through form is called immunofiltration assay (IFA); the cross-flow form is called immunochromatographieassay (ICA). Because of the commonly used colloidal gold as a marker, the domestic literature refers to the former as the immunogold sol spot method and the gold immunoassay, etc., and the latter is called colloidal gold immunochromatography, etc., collectively referred to as "golden standard".
The solid phase membrane is the main raw material of the solid phase membrane immunoassay reagent and plays a decisive role in the quality of the reagent. A commonly used film is a nitrocellulose membrane. The nitrocellulose membrane itself is hydrophobic, and a surfactant is added during the production process of the membrane to become hydrophilic and has strong adsorption properties for proteins. The following characteristics should be noted when selecting a suitable nitrocellulose membrane.
1. The pore size can be expressed in microns (Atm) by the size of the particles. The film used for the flow-through method is generally selected to be about 0.4 μm, and the film for the cross-flow method may be selected from 5 to 10 μm.
2. The flow rate is expressed in ml/(cm2·min). The flow rate has a certain relationship with the pore size. The larger the pore size, the faster the flow rate. When selecting a suitable membrane in the cross-flow method, the flow rate is more valuable than the pore size.
3. Protein binding is expressed in ug/cm2.
4. Uniform quality membranes should have good homogeneity to ensure homogeneity within the reagent lot number.
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