UCLA Develops Innovative Mineral Sunscreen to Eliminate White Cast
Researchers at the University of California, Los Angeles (UCLA) have developed a new mineral sunscreen formulation designed to reduce the white or gray cast commonly left by zinc oxide. This innovation aims to address a primary reason many individuals avoid consistent daily sun protection, particularly those with darker skin tones, while maintaining the sunscreen's effectiveness against ultraviolet (UV) radiation.
Background on Mineral Sunscreens
Dermatologists recommend daily sunscreen application to protect against UV radiation, which is a primary preventable cause of skin cancer. Mineral sunscreens, also known as physical sunscreens, utilize active ingredients such as zinc oxide and titanium dioxide, creating a physical barrier on the skin's surface to block UV rays. Zinc oxide, in particular, is classified by the U.S. FDA as generally recognized as safe and effective, offering broad-spectrum protection against UVA and UVB rays and often recommended for sensitive skin types.
However, traditional mineral sunscreens, often made with small, spherical zinc oxide nanoparticles, can clump together on the skin.
This clumping scatters visible light, resulting in a noticeable white or chalky residue, a cosmetic concern that can deter consistent use.
Chemical sunscreens, conversely, absorb UV rays and convert them into heat, with some ingredients' long-term systemic absorption effects still under investigation.
The Tetrapod Zinc Oxide Innovation
The research team, led by chemical biology doctoral candidate AJ Addae and senior author Paul S. Weiss, engineered zinc oxide particles into a distinct, microscopic, four-armed structure referred to as tetrapods. This development was motivated in part by Addae's personal experience with existing chalky sunscreens.
The tetrapod particles are produced using a patented high-temperature flame-based process, resulting in larger particles compared to traditional nanoparticles. Their unique shape prevents them from clumping together, promoting even distribution within the sunscreen formulation.
This structure forms a loose, porous network on the skin, which reduces the reflection of visible light.
The approach focuses on altering the physical structure of zinc oxide rather than developing new chemical compounds.
The study, published in ACS Materials Letters, found that sunscreens formulated with these tetrapod-shaped zinc oxide particles achieved a Sun Protection Factor (SPF) of approximately 30, comparable to standard mineral sunscreens and consistent with recommended daily use guidelines. These new formulations also demonstrated improved stability over time.
Aesthetic and Health Implications
In laboratory tests and controlled skin applications, sunscreens utilizing the tetrapod zinc oxide appeared warmer and blended more closely with natural skin tones, effectively minimizing the visible white cast. This was achieved without requiring special coatings or added pigments.
This advancement holds potential implications for skin cancer prevention by encouraging more consistent sunscreen use, especially among individuals with darker skin tones.
Individuals with darker skin tones are sometimes diagnosed with skin cancer at later, more difficult-to-treat stages.
Future Development
While the research shows promising results, tetrapod zinc oxide sunscreens are not yet available commercially. Further testing is ongoing, including collaborations with the UCLA Health department of dermatology and the Skin of Color Clinic, to study how these particles interact with the skin microbiome and to facilitate real-world application of the technology. The research team is also exploring avenues for commercialization.