Diagnostic Test Kit
Antibody & Antigen

Do You Know How a Rapid Test Kit Works?

1. About the rapid detection kit

Immunology is a complex subject, which contains a lot of professional knowledge. This article aims to introduce you to the working principle of rapid detection kit.

In the field of rapid detection, colloidal gold method is usually used for rapid antibody detection at home.

Due to the affinity of sulfhydryl (-SH) group to gold surface, gold nanoparticles can easily combine with antibodies, peptides, synthetic oligonucleotides and other protein 3-5. Gold molecular conjugates have been widely used in diagnostic applications, and their bright red color is used for home and instant tests, such as home pregnancy tests.

Because the operation is simple, easy to understand, convenient, quick and accurate. Colloidal gold method is the main rapid detection method in the market at present.

Competition law and sandwich method are two main modes of colloidal gold method. They are generally accepted by the public because of their friendly user groups, short test time, little interference, low cost and easy operation by non-professionals. This technique is based on the biochemical interaction of antigen-antibody hybridization.

2. Working principle of rapid detection kit

Use two antibodies that bind different epitopes on diseased molecules. One (coated antibody) was labeled with colloidal gold nanoparticles, and the other (capture antibody) was immobilized on the surface of NC membrane. The coated antibody is dehydrated in the bonding pad. When the standard solution or sample is added to the sample pad of the test paper, the adhesive can instantly dissolve after contacting with the aqueous medium containing viruses. Then the antibody forms a complex with the virus in the liquid phase and keeps moving forward until it is captured by the antibody fixed on the surface of NC membrane, producing a signal proportional to the virus concentration. In addition, an additional antibody specific to the coated antibody can be used to generate a control signal. The absorption pad is located at the top and induced by capillary action, so that the immune complex is pulled onto the fixed antibody. Visible colors appeared in less than 10 minutes, and the intensity determined the number of viruses. In other words, the more viruses exist in the sample, the more obvious the red band appears.

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