UCLA Researchers Develop Mineral Sunscreen to Reduce White Cast

A new mineral sunscreen formulation developed by UCLA researchers aims to address a common barrier to sun protection: the noticeable white cast left on skin, particularly for people with darker skin tones. The breakthrough centers on reshaping zinc oxide particles, a key ingredient in mineral sunscreens, to improve their aesthetic appeal without compromising effectiveness.

The Problem with Traditional Mineral Sunscreens

Dermatologists consistently recommend daily sunscreen use to protect against harmful ultraviolet (UV) radiation, the leading preventable cause of skin cancer in the United States. Although, many individuals avoid mineral sunscreens containing zinc oxide due to the white or gray cast they often leave on the skin. This is especially problematic for people with darker complexions.

A New Shape for Zinc Oxide

Researchers at the UCLA Health Jonsson Comprehensive Cancer Center discovered that altering the shape of zinc oxide particles, rather than the chemical composition, could significantly reduce this cosmetic drawback. The team engineered zinc oxide into microscopic, four-armed structures known as tetrapods.

How Tetrapods Improve Sunscreen Appearance

Conventional zinc oxide particles are typically round and tend to clump together, scattering visible light and creating the unwanted white cast. The tetrapod shape, with its “legs,” prevents this clumping. According to AJ Addae, a UCLA chemical biology doctoral candidate and first author of the study, “Because of their structure, these tetrapod-shaped particles have standoffs and form porous networks instead of collapsing into clumps. They can’t pack tightly and aggregate, so they stay evenly distributed in the sunscreen.”

Performance and Stability

Testing revealed that the tetrapod-based sunscreen achieved a sun protection factor (SPF) of approximately 30, comparable to standard mineral sunscreens. The formulations also demonstrated improved stability over time, with less separation or thickening. Importantly, the tetrapod sunscreens reflected visible light differently, appearing warmer and closer to natural skin tones in both laboratory tests and controlled applications, without the need for coatings or pigments.

Implications for Skin Cancer Prevention

Paul S. Weiss, a senior author of the study and a distinguished professor at UCLA, emphasized that improving the aesthetic appeal of sunscreen could lead to more consistent use, potentially having a significant impact on skin cancer prevention. This is particularly relevant for individuals with darker skin tones, who are often diagnosed with skin cancer at later stages and have a higher mortality rate from the disease.

Personal Motivation and Future Research

Addae’s personal experience with the challenges of finding a cosmetically acceptable mineral sunscreen fueled the research. “The best sunscreen is one that you’ll wear, and that’s really all where my motivation is for this,” she stated. The research team is now collaborating with the UCLA Health department of dermatology, including the Skin of Color Clinic, to further investigate how these particles interact with the skin microbiome and pave the way for real-world application.