Nanomaterials in Personal Care: Opportunities and Safety Considerations

By: Julian Hewitt and Mindy Goldstein, PhD

Posted: November 26, 2008, from the December 2008 issue of Cosmetics & Toiletries.

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Here, nano-scale is being defined as approximately 1–100 nm.

It also is important to recognize that some materials can exist as particles that have an external size greater than the nano-scale but that consist of aggregates or agglomerates of smaller particles or crystals that are within the nano-scale range. The DIN/ISO proposal describes these as nano-structured aggregates or nano-structured agglomerates. The terms aggregate and agglomerate are often confused or used interchangeably but they are in fact quite distinct and are defined as follows:²

• Aggregate: A particle comprising strongly bonded or fused particles wherein the resulting external surface area may be significantly smaller than the sum of calculated surface areas of the individual components.
• Agglomerate: A collection of loosely bound particles or aggregates or mixtures of the two wherein the resulting external surface area is similar to the sum of the surface areas of the individual components.

Applications in Personal Care
Many modern cosmetic products contain nano-sized components. Examples include the following.
Nanoemulsions: These emulsions typically have a droplet size of 50–100 nm that, due to this size, are usually transparent or at least translucent in appearance. Nanoemulsions also provide pleasant texture and/or skin feel.

Liposomes, niosomes, nanosomes and nanocapsules: Liposomes and niosomes are globular vesicles that can vary from 25 nm to 5000 nm in size and are used to encapsulate active ingredients in order to improve their stability or skin delivery (and thus efficacy). Nanocapsules represent a similar concept except that they have rigid walls.

Fullerenes: A number of prestige cosmetic products have been developed that contain C60 fullerene molecules, which have unique antioxidant properties.