Colloidal gold is a kind of nanomaterial widely used in immunolabeling technology. Colloidal gold technology is a commonly used labeling technology, which is a new type of immune labeling technology that uses colloidal gold as a tracer marker for antigens and antibodies, and has its unique advantages. In recent years, it has been widely used in various biological research. Almost all the immunoblotting techniques used in the clinic use its markers. At the same time, it can be used in flow, electron microscopy, immunology, molecular biology and even biochip.

Colloidal gold is negatively charged in a weak alkali environment, and can form a firm bond with the positively charged groups of protein molecules. Because this bond is electrostatic bond, it does not affect the biological properties of protein.

In essence, the labeling of colloidal gold is the encapsulation process in which proteins and other macromolecules are adsorbed to the surface of colloidal gold particles. This spherical particle has a strong ability to adsorb proteins and can bind non-covalently to staphylococcal A protein, immunoglobulin, toxin, glycoprotein, enzyme, antibiotic, hormone, and bovine serum albumin polypeptide conjugates.

In addition to protein binding, colloidal gold can also bind to many other biological macromolecules, such as SPA, PHA, ConA, etc. According to some physical properties of colloidal gold, such as high electron density, particle size, shape and color reaction, coupled with the immune and biological properties of the binder, colloidal gold is widely used in immunology, histology, pathology and cell biology and other fields.