The core principle of colloidal gold reagent is colloidal gold technology, and China's colloidal gold technology has already reached the world leading level, with high technology popularization and many manufacturers. Many world-famous brand colloidal gold products are produced in China or directly provided by Chinese companies. The formation of this situation is precisely because China has already mastered the core production process of colloidal gold.

The first application of immunogold staining occurred in 1971. Taylor and Faulk combined nano gold particles with anti Salmonella antiserum, detected Salmonella surface antigen by immunocytochemistry, and created nano gold immunolabeling technology.

In 1978, geoghega discovered the application of colloidal gold markers at the light microscope level. Other scholars further confirmed that colloidal gold could adsorb proteins stably and rapidly, but its biological activity did not change significantly. It can be used as a probe to accurately locate biological macromolecules such as cell surface and intracellular polysaccharides, proteins, peptides, antigens, hormones and nucleic acids. It can also be used in daily immune diagnosis and immunohistochemical localization. Therefore, it has attracted extensive attention in clinical diagnosis and drug detection.

After years of development, colloidal gold labeling has developed into an important immunolabeling technology. Colloidal gold immunoassay has been widely used in drug detection, biomedicine and other fields, and has attracted more and more attention in related fields.

For example, in early 2020, China's colloidal gold method for testing COVID-19 products has passed the emergency examination and approval, and the relevant technology has been applied to the application level. This product breaks through the limitation of the existing testing technology sites and operators, and can detect the results in about 15 minutes. Therefore, it is widely used in medical and health institutions at all levels to promote the forward and sinking of diagnosis, which plays a key role in effectively controlling the epidemic situation.