May 15, 2008
Nano-encapsulation gives UV protection
Topical creams and gels are a convenient way of administering various pharmaceutical and cosmetic treatments, but particles sitting on the skin surface are vulnerable to photo-degradation. Supason Wanichwecharungruang and her colleagues at Chulalongkorn University, Thailand, think that they've found the answer – chitosan nanocontainers – a UV-resistant formulation with controlled release properties.
nanotechweb.org (NTW) catches up with Supason Wanichwecharungruang (SW) to discover more about the technology.
NTW: How do cosmetic and pharmaceutical developers protect their topical products at the moment?
SW: Various encapsulation systems such as liposomes, microemulsion, multiple emulsions and solid lipid particles have been used in cosmetic formulations. These encapsulation systems not only provide a controlled release property for the encapsulated active ingredients, but also can partially help to protect the encapsulated materials. For example, by reducing the amount of contact with oxygen or other entities.
What are the limitations of the current technology and where does your nanoformulation fit in?
Since existing capsules are not made of material that can filter out light, the encapsulated materials are still prone to photodegradation. During storage, a light-proof-container can help to prevent or slow down the photodegradation of active materials. However, one cannot prevent this degradation after the cosmetics have been applied onto the skin. This is where our UV-absorptive-nanocontainer will be very useful.
For example, if you apply a retinol containing cosmetic formulation onto your face, the retinol molecules will start to degrade on your skin once you encounter sunlight. However, if retinol molecules are encapsulated into UV-absorptive-nanocontainers, the photo-degradation will be prevented or at least significantly reduced.
It is important to emphasize that the UV-absorptive chitosan nanospheres are more than just a light filter. The material also controls the release of the encapsulated active material.
What systems are you working on right now?
Two systems are being developed in our group; UV-absorptive chitosan derivatives (PPLC and PCPLC) and UV-absorptive poly(vinylalcohol) derivatives. We are just finishing the encapsulation of various photo-unstable compounds, such as retinyl acetate, retinyl palmitate, ascorbyl palmitate, astaxanthin and coenzyme Q10.
Together with a local company (Greater Pharma Group of Companies), we are working on the application of the chitosan derivative system. Only hydrophobic materials can be encapsulated into the PPLC and PCPLC particles, but a system that can encapsulate hydrophilic compounds is under investigation.
We have also developed a high capacity and high stability nano-encapsulation system for cosmetics. This will provide a way of dispersing hydrophobic active compounds into water at a very high concentration (up to 8–10% w/v) without the use of an emulsion, which removes the worry of emulsion breakdown.
The researchers presented their work in Nanotechnology.
About the author
James Tyrrell is editor of nanotechweb.org.