Gold has been used throughout history, with Cleopatra being famed for sleeping in a gold mask. Alchemists referred to gold as the “Elixir of Life”. Gold was already being used by the Chinese as a medicine in 2500 B.C. In India, colloidal red gold was used in the form of ayurvedic medicine for rejuvenation and revitalization during old age, and was called “Swarna Bhasma”  Gold was for a long time used as a drug, called “nervin” for the revitalization of people who are suffering from nervous disorders. However, the modern scientific evaluation of colloidal gold did not commence until 1857, when Michael Faraday learned by experiment that the colour of gold solutions was due to the small size of gold particles. In the beginning of the 19th century, gold was used as a drug for the treatment of syphilis .
Therapeutic use of gold was established for the first time when Robert Koch discovered the bacteriostatic effect of gold cyanide on Mycobacterium tuberculosis, following which the medicinal use of gold for the treatment of tuberculosis was introduced in the 1920s . Gold and gold compounds are mainly applied as a drug for the treatment of rheumatic diseases including rheumatoid arthritis.
In the USA colloidal gold is simply listed as gold on the ingredient listing. You will find that many products containing gold are a golden colour, however colloidal gold is not golden in colour. Colloidal gold, also known as “nanogold”, is a suspension (or colloid) of sub-micrometer-sized particles of gold in a fluid – usually water. The liquid is usually either an intense red color (for particles less than 100 nm), or a dirty yellowish color (for larger particles). The nanoparticles themselves can come in a variety of shapes. Spheres, rods, cubes, and caps are some of the more frequently observed ones. The shape of gold nano particles is a major determinant of their uptake into cells . The intracellular uptake of gold nano particles was investigated, comparing different sizes and shapes. They have concluded that kinetics and saturation concentrations are highly dependent upon the physical dimensions of the nanoparticles. This finding will have implications in the chemical design of nanostructures for biomedical applications. The optical properties of nano particles of gold are also dependent on their shape 
Nano-Gold exhibit different colours at different sizes and concentrations
Colloidal gold has many studies showing benefits from both a medicinal perspective. Gold in cosmetics is used in two forms: as an ingredient of topical skin care (mask or cream) and as gold foil or gold leaf for direct application to skin.
What is the main properties of Nano Gold in beauty care compositions :
- It vitalizes the fiber tissues under the skin.
- It accelerates blood circulation.
- Releases the natural active ingredient transported by the surface of the nano particles
- Powerful antioxidant against free radicals
- Antiseptic and anti-inflammatory properties
- Reduces fine lines and wrinkles.
- Improves the firmness and elasticity of the skin.
- Vitalizes skin metabolism.
- Synergists in absorption of collagens, nutrients and essences of herbal and botanical extracts.
- Delays aging process and maintain skin youthful appearance
In 2010, an in vitro study showed that gold nanoparticles in an antiwrinkle face mask maximize contact of the active ingredients (L-ascorbic acid, retinoic acid, and collagen) with the skin, enhancing their skin permeation . In animal models, gold facial masks improve blood circulation and cutaneous elasticity, rejuvenate the skin, and reduce wrinkle formation .
Gold has unique electronic, optical, thermal, chemical and biological properties. They have potential catalytic applications in various fields such as biology, medicine, physics, chemistry, material science and other interdisciplinary fields  Gold is able to be used in diagnostic procedures. It is able to be radiolabelled and specifically target specific sites such as cancer.
How are Gold Nano Particles Made?
Gold nano particles are synthesized from the reduction of gold salts by various reducing agents such as gallic acid, H2O2, hydrazine, etc. 
Gold and Gold nano particles and toxicity
Although gold and gold compounds have been used as a potential drug for the treatment of Rheumatoid Arthritis, some adverse effects, such as skin irritation, dermatosis, contact allergy, and hypersensitivity reactions were associated with over exposure to gold and gold compounds.
According to McKenna et al. (1995), 278 consecutive patients with suspected contact dermatitis were patch tested. Around 13 patients (4.6%) were affected with a positive allergic response. The patients were female, with an average age of 37 years. The most affected sites of eczema (generic term for inflammatory conditions of the skin) were head and neck (62%); 46% of people had eczema on the limbs and 15% had a perianal rash.
Gold nanoparticles are being investigated as carriers for drugs such as Paclitaxel. The administration of hydrophobic drugs require encapsulation and it is found that nanosize articles are particularly efficient in evading the reticuloendothelial system.
Gold nanoparticles are used in a wide range of cosmetic and beauty care applications. Colloid gold is presently included in a large number of anti-aging formulas produced by various manufacturers all over the world. Colloidal gold cosmetic treatments can be used in association with very efficient collagen-based anti-wrinkle creams that regenerate the age-damaged tissue.
There are two main explanations for the use of colloidal gold as a skin care product: one is the fact that in the colloidal form, gold has some amazing anti-oxidant properties and the other relates to the capacity of this mineral to get electrically connected to the metal ions present in the cellular structure. Colloidal gold has a certain positive electrical charge that results from the specificity of the manufacturing process. The gold nano-particles in suspension have definitely a different impact at the cellular level than larger particles would; this allows colloidal gold to connect to the cellular structure at the most profound level.
About the Author
Jacine Greenwood is an internationally recognised educator who is known within the industry for her up to date knowledge and her ability to deliver training in an easy to understand method.
Jacine holds 6 Diplomas and a Bachelor of Nursing and her knowledge is well respected by her peers. With over 19 years experience in the industry and a background of cosmetic formulation, Jacine has an immense knowledge of current trends in research and new developments in the industry.
Jacine has been continually educating herself in all aspects of skin function and cosmetic chemistry for the past 21 years. Jacine’s knowledge is current and has a vast knowledge of the active ingredients that are being released onto the market.
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