Firstly, the antigen coating was solid-phased, and the antigen to be tested was coated in the hole of the ELISA plate, and the antigen was incubated to adsorb onto the hole wall. A blocking solution is used to seal the space in the pore that is not occupied by the antigen to prevent nonspecific binding. Add the sample to be tested, which may contain antibodies. If the sample contains the target antibody, it will bind to the antigen. Clean the non-specific binding substances in the well and remove the unbound antibodies. Enzyme-labeled secondary antibodies ( usually secondary antibodies against the species or type of antibodies in the sample ) are added, and the secondary antibodies bind to the antibodies in the sample to form an immune complex. Clean again to remove unbound enzyme-labeled secondary antibodies. When the substrate solution is added, the enzyme-labeled secondary antibody catalyzes the substrate reaction to produce a color change or other signal. Results The signal intensity was read by microplate reader, and the concentration of antibody was calculated according to the standard curve.

The antibody coating was first immobilized, and a specific capture antibody was coated on the hole of the ELISA plate. The antibody usually maintains specificity with the antigen binding site. Then incubate for a certain period of time to fix the antibody to the pore wall. A blocking solution ( such as bovine serum albumin, BSA ) is used to close the gap in the pore that is not occupied by the antibody to avoid non-specific binding. Add a sample containing the target antigen to the well plate, and the antigen will bind to the capture antibody in the well plate. Wash the well plate with washing buffer to remove unbound substances. Another enzyme-labeled antibody ( usually an antibody different from the target antigen ) is added to detect the antibody, which forms a double binding with the antigen to form a sandwich structure. Wash again to remove unbound enzyme-labeled antibodies. The substrate solution is added, and the enzyme-labeled antibody catalyzes the substrate reaction to produce a measurable signal ( such as color change ). The optical density ( OD value ) was measured using a microplate reader ( such as a microplate reader ), and the concentration of the antigen was determined according to the standard curve.

First, the solid-phase antibody coating is coated with a specific capture antibody in the ELISA plate hole, and the antibody will bind to the target small molecule antigen. Blocking solution was used to block the space not occupied by the antibody to avoid non-specific binding. The sample containing the target antigen and the enzyme-labeled antibody were added, and the antigen in the sample competed with the enzyme-labeled antibody to capture the antibody. Clean the non-specific binding substances in the well, leaving the combined antigen-antibody complex. The substrate is added, and the enzyme catalyzes the substrate reaction to produce a measurable signal. The results showed that the intensity of the signal was negatively correlated with the concentration of the antigen in the sample. The weaker the signal, the higher the antigen concentration in the sample. The concentration of antigen in the sample was determined by measuring the optical density (OD value).