Au Naturale Nanoparticle Sun Protection

By: Katie Schaefer, C&T magazine

Posted: September 1, 2010, from the September 2010 issue of Cosmetics & Toiletries.

page 2 of 3

The ability of English ivy nanoparticles to protect skin from UV also is enhanced by their size and smoothness. “We observed that the [English ivy nanoparticles] are uniform at 65.3 ± 8.04 nm, and they have a smooth surface. This smoothness will enhance absorption or scattering of light,” said Zhang.

Although it was important for Zhang to assess the UV protection of the English ivy nanoparticles, it was equally as important to assess their skin penetration and toxicity for comparison with metal-based nanoparticle UV filters. It was determined that nanoparticles with a diameter <10 nm could reach the deeper layers of the stratum corneum (SC), while nanoparticles larger than 40 nm could only reach 5–8 μm into the SC after 8 hr of application, and 8–13 μm after 20 hr of application. It was therefore concluded that English ivy nanoparticles could not penetrate the SC from cosmetic applications.

The team also tested for cytotoxicity by incubating 1 μg/mL of English ivy nanoparticles with HeLa cells for 24 hr. With propidium iodide staining, the researchers noted no toxicity of the cells treated with English ivy nanoparticles, compared with control cells.

Ongoing Work

In personal care, the adhesion properties of the ivy nanoparticles could enhance the durability of sunscreens, reducing the frequency of re-application. These adhesion properties are also viable for other industries.

“We have investigated nanoparticle enhanced adhesion for medical glue,” said Zhang, who added that his team is working with the National Science Foundation to examine the ability of the nanoparticles to interface with surfaces.