Researchers at the University of California, Los Angeles (UCLA) have recently developed a new mineral sunscreen that successfully solves the long-standing problem of traditional zinc oxide sunscreen products leaving a thick white coating on the skin. Zinc oxide has always been considered one of the best sunscreen ingredients because it can block both UVB and UVA ultraviolet rays. However, its white effect after application discourages many consumers, which has become one of the main reasons why people are reluctant to use sunscreen.
The zinc oxide particles in traditional sunscreens have a round structure similar to platelets and tend to aggregate into clusters, thereby scattering visible light and forming an obvious white or gray coating on the skin. This phenomenon is particularly noticeable on dark skin. AJ Addae, lead author of the study, said: "The best sunscreen is the one that people actually want to use. If zinc oxide can look better on more skin tones without sacrificing protection, it could help protect more people from the sun's most dangerous damage."
Rather than reinvent the wheel and develop a new chemical formula, the research team chose to change the shape of the zinc oxide particles themselves. They used a process called "flame synthesis" to heat materials containing zinc ions to a high temperature of 900 degrees Celsius, causing the zinc ions to evaporate and decompose. Then during the cooling process, the free zinc combines with oxygen to form zinc oxide crystals. More importantly, these zinc oxide crystals exhibit a tetrapod-like "tetrapod" structure, with four "legs" radiating out from the center, similar to a children's game of checkers. This unique shape prevents the particles from aggregating into clumps.
Addae explains: "Due to their structural properties, these tetrapod-shaped particles have supporting points and form a porous network rather than packing into clumps. They are unable to pack tightly and agglomerate, so they remain evenly distributed in the sunscreen." The new sunscreen achieves an SPF 30 protection rating and visually reduces the white coating because the particles no longer clump, an effect that has been confirmed by a series of color science indicator tests.
Addae, who is Ghanaian-American, noticed an immediate difference when she tested it on her own skin: "When I put it on my skin, I didn't see that white coating that I used to have with zinc oxide. That's when I realized this could really work." Part of the impetus for the study, she admits, was traditional sunscreen. Poor performance on her own skin: "I started thinking about this because I was frustrated with how mineral sunscreen looked on my skin. The white coating and other unsightly issues I encountered with mineral sunscreen led me to avoid using sunscreen altogether. That frustration really became the starting point for this work."
Currently, Addae and her team are working with UCLA Health's Skin of Color Clinic to study the effects of this new zinc oxide particle on the skin microbiome, a first step toward bringing the product to market. The research results have been published in the journal ACS Materials Letters. Since skin cancer is one of the main preventable types of cancer and the use of sunscreen is the best way to prevent it, this innovative technology is expected to increase people's willingness to use sunscreen products, thus more effectively protecting the public from UV rays.