Cosmetics

For most consumers, the most obvious applications of nanotechnology have been in the cosmetic industry. New formulations of vitamins and anti-ageing chemicals, such as retinol, have been packaged inside liposomes and micelles in the form of creams. These are made up of fatty acid molecules which do not dissolve in water, but instead assemble into nanoscale globes that can contain the vitamin or anti-ageing chemical, either dissolved in the fat itself or in a separate enclosed water droplet. The advantage of applying such creams is that liposome or micelle is easily absorbed by cells in the skin, and so increases the amount of active ingredient where it is needed. In a similar way, liposome and micelle formulations are now being used to increase the nutritional quality of packaged foods. The fatty globes, instead of delivering vitamins to the skin, help vitamins, minerals and other nutrients (collectively known as nutriceuticals) to be absorbed by the digestive system.

Diagram shows a micelle containing “nutriceuticals”. The hydrophilic (or water loving) head groups of the fatty acid are exposed to the water, the hydrophobic (or water hating) tail groups keep close together and in the interior of the micelle.

Other cosmetics employ a more straightforward approach, for example suncreams. Zinc oxide has been used as a sunblock for several decades, however in its normal formulation it is a white paste (which is not very attractive!). By reducing the size of the zinc oxide particles to the nanoscale, the optical properties are changed (they are now transparent to visible light), however their other properties remain the same (they can still absorb and block UV light) and so an effective and attractive product is made.