Colloidal Gold Test Kit: An Indispensable Detection Tool in Modern Medicine

In the expansive field of modern medicine, a diagnostic tool is gradually emerging—it is the colloidal gold test kit. With its unique technology and advantages, it is playing an increasingly important role in clinical diagnosis, bringing numerous conveniences to doctors and patients. When it comes to colloidal gold, you might not be unfamiliar, as it is widely used in COVID-19 testing and pregnancy testing. Colloidal gold chromatography technology, with its instant detection characteristics, occupies a significant position in the field of rapid testing.

Immuno-colloidal gold technology is a novel immunolabeling technology that uses colloidal gold as a tracer and colorimetric medium. It utilizes the principle that antigens and antibodies can specifically bind in immunology, completing this reaction during the chromatography process to achieve detection purposes.

What is colloidal gold?

Colloidal gold method is derived from chloroauric acid (HAuCl₄) which, under the action of reducing agents such as white phosphorus, ascorbic acid, sodium citrate (sodium citrate), tannic acid, etc., can aggregate into gold particles of a certain size, and due to electrostatic effects, form a stable colloidal state. This colloidal state forms a negatively charged hydrophobic colloidal solution, hence called colloidal gold.

Because its size ranges between 1-100 nanometers, it can also be termed gold nanoparticles. The term "colloid" or "sol" here is a conventional term and does not imply any glue; rather, it refers to a state where particles are finely dispersed like smoke.

Why use gold?

Gold possesses very stable chemical properties. Another characteristic of colloidal gold is that only a minimal amount is required to display a deep color.

Is it expensive? Gold is indeed quite costly, but the amount of nanometer-sized gold particles is minimal. For example, a COVID-19 antigen test kit for 20 individuals contains only microgram levels of gold, which is worth less than a cent!

Colloidal gold labeling adsorbs macromolecules like proteins onto the surface of colloidal gold particles. Under pH conditions close to the protein's isoelectric point or slightly alkaline, the negative charge on the surface of the gold particles tightly binds with the positively charged groups on the protein surface due to electrostatic adsorption. This allows the color to be seen with the naked eye and does not denature biomacromolecules, making colloidal gold an excellent label.

Key applications and prospects

The key points of clinical application are: 

• Rapid diagnosis is needed for treating acute and severe conditions. For instance, acute myocardial infarction markers assisting in the diagnosis of acute heart attacks are a good example (such as Hotgen's Cardiac Rapid Test Kit).

• Screening and epidemiological investigations: such as various infectious diseases (viral hepatitis, HIV, sexually transmitted diseases, and other epidemics) and epidemiological investigations (like Hotgen's Infectious Disease Rapid Test Kit);

• Screening and preventive checks for certain tumors (e.g., prostate cancer, colon cancer, liver cancer, breast cancer);

• Perinatal health screenings (such as Hotgen's Preterm Birth Prediction Rapid Test Kit).

Colloidal gold kits can serve as rapid preliminary screening tools, with positive and suspicious results warranting further detailed and reliable investigations.

With continuous technological advancements, the application fields and accuracy of colloidal gold test kits will keep expanding, providing more possibilities for the development of modern medicine.