1、 Basic principles

The basic principle of ELISA kit is to bind antigen or antibody with enzyme to form enzyme-linked antigen or antibody. By reacting with the corresponding antibody or antigen in the sample, an antigen antibody enzyme complex is formed. This complex can catalyze substrate reactions and produce color changes. By the degree of color change, antigens or antibodies in the sample can be semi quantitatively or quantitatively detected.
 

2、 Experimental process

The experimental process of ELISA kit usually includes the following steps:

1. Envelope：Adsorb antigens or antibodies onto the surface of solid-phase carriers (such as polystyrene, nylon, etc.), and the carrier surface is specially treated to enhance binding ability.
2. sealed：Add blocking solution to block the unbound sites on the surface of the carrier to prevent non-specific binding.
3. Sampling：Add the sample to be tested and the enzyme-linked immunosorbent assay secondary antibody. If there is a target antigen or antibody in the sample, they will bind to the antigen or antibody on the solid-phase carrier to form an antigen antibody complex.
4. incubation：Incubate at a certain temperature for a certain period of time to fully bind the antigen antibody.
5. wash：Wash to remove unbound antigens, antibodies, and enzyme-linked secondary antibodies.
6. Add substrate：Adding substrate solution, the enzyme-linked antigen antibody complex catalyzes the substrate to undergo a color reaction, resulting in a color change.
7. termination：Add termination solution to stop the color reaction.
8. Detect and Analysis：Quantitatively analyze the concentration of antigens or antibodies in a sample by measuring the optical density value or fluorescence intensity.

3、 Classification

ELISA kits are mainly divided into two categories based on their application scope: indirect ELISA kits and direct ELISA kits. Indirect ELISA kits are suitable for detecting antibodies, while direct ELISA kits are suitable for detecting antigens.
 

4、 Advantages and limitations

advantage:

• high sensitivity：Capable of detecting extremely low concentrations of antigens or antibodies.
• high specificity：Antigen antibody binding is highly specific and can accurately recognize target molecules.
• Quantifiable：By measuring the degree of color change, antigens or antibodies in the sample can be quantitatively detected.

limitations:

• The operation is relatively complex and requires professional personnel to carry out the operation.
• Due to various factors such as sample processing and experimental conditions, there may be certain errors in the results.

5、 Precautions

• When using the ELISA kit, it should be operated strictly according to the instructions.
• Pay attention to the collection and storage conditions of samples to avoid sample contamination or degradation.
• Avoid exposing the reagent kit to high temperature, high humidity, or direct sunlight to avoid affecting its performance.
   

In summary, ELISA kit is a sensitive and specific biological analysis technique widely used in biomedical research and clinical diagnosis. By understanding its basic principles, experimental procedures, classifications, advantages and limitations, as well as precautions, this tool can be better used for scientific research and clinical diagnosis.