Organic nanoparticles secreted by English ivy rootlets absorb and scatter ultraviolet light thanks to large surface-to-volume ratio and uniformity.

Zhang, an associate professor of biomedical engineering at the University of Tennessee, Knoxville, along with his research team and collaborators, has found that ivy nanoparticles may protect skin from UV radiation at least four times better than the metal-based sunblocks found on store shelves today…

"Zhang speculated the greenery's hidden power lay within a yellowish material secreted by the ivy…It also has the ability to soak up and disperse light which is integral to sunscreens.

"'Nanoparticles exhibit unique physical and chemical properties due to large surface-to-volume ratio which allows them to absorb and scatter light,' Zhang said. 'Titanium dioxide and zinc oxide are currently used for sunscreen for the same reason, but the ivy nanoparticles are more uniform than the metal-based nanoparticles, and have unique material properties, which may help to enhance the absorption and scattering of light, and serve better as a sun-blocker.'" (EurekAlert! 2010)

"The concern for the biosafety and health risk for the metal-based and engineered nanoparticles in sunscreens has led to the search for alternative replacement nanoparticles. In this study, naturally occurring ivy nanoparticles were investigated to replace TiO2 and ZnO that are currently widely used in sunscreen products. Based on experimental data, we have demonstrated that ivy nanoparticles have the potential levels of UV protection necessary to warrant further investigation for uses in cosmetics.

The cell toxicity of ivy nanoparticles was next tested and it was determined that ivy nanoparticles exhibited much less toxicity than widely used TiO2 nanoparticles. Without obtaining the proper marker for experimental determination, a mathematical model was used to analyze the diffusion dynamics in the human skin, especially in the SC layer. Through this analysis, we found ivy nanoparticles with a diameter of 65.3 nm will not reach the bottom of SC layer in normal conditions for short periods of time after application. The biodegradability of these ivy nanoparticles further eliminates concerns regarding environmental contamination and in the case of entry into the body.

All of the above studies demonstrated that naturally occurring ivy nanoparticles could be a promising alternative for UV protection in cosmetics, especially with concerns regarding the safety of metal-based nanoparticles. With increased dangers associated with more UV passing through the atmosphere [56], the need to protect human from skin cancer elicits the need for safe and effective UV protective agents. The promising application of these ivy nanoparticles thus provides a better chance to help protect people from UV radiation." (Xia et al. 2010)