By Suherman Candra Maholtra 
In a significant advancement for both materials science and public health, researchers at the University of California, Los Angeles (UCLA) have developed a novel mineral sunscreen formulation that addresses one of the primary barriers to consistent sun protection: the unsightly, chalky residue known as "white cast." By re-engineering the physical structure of zinc oxide particles, the team has created a formula that provides robust ultraviolet (UV) protection while remaining nearly invisible on a diverse range of skin tones. This breakthrough, led by scientists at the UCLA Health Jonsson Comprehensive Cancer Center and published in the journal ACS Materials Letters, could fundamentally change the landscape of skin cancer prevention by encouraging more frequent and inclusive sunscreen use.
For decades, dermatologists have emphasized that daily sunscreen application is the most effective way to mitigate the risks of UV radiation, which is the leading preventable cause of skin cancer. Despite these warnings, adherence remains low across many demographics. One of the most cited reasons for this reluctance is the aesthetic performance of mineral sunscreens. Unlike chemical sunscreens, which absorb UV rays through organic compounds, mineral sunscreens utilize inorganic minerals—primarily zinc oxide and titanium dioxide—to reflect and scatter radiation. While these minerals are highly effective and generally recognized as safe by regulatory bodies, their tendency to leave a thick, pale film has long been a deterrent, particularly for individuals with darker skin tones.
The Physics of the White Cast: Why Traditional Zinc Oxide Fails
To understand the UCLA breakthrough, it is necessary to examine why traditional mineral sunscreens behave the way they do. Most commercial mineral sunscreens utilize zinc oxide nanoparticles that are roughly spherical in shape. Because of their high surface energy and chemical properties, these nanoparticles tend to aggregate, or clump together, within the sunscreen lotion. When these clumps reach a certain size, they begin to scatter visible light in a process known as Mie scattering. This scattering is what produces the opaque, white, or grayish appearance on the skin.
For individuals with more melanin, this scattering creates a stark contrast against the natural skin tone, often resulting in a "ghostly" or ashen appearance. This is not merely a cosmetic inconvenience; it is a significant public health hurdle. When a product is difficult to apply or results in an undesirable appearance, consumers are less likely to use the recommended amount or may skip application entirely.
The UCLA team, led by senior author Paul S. Weiss—a distinguished professor of chemistry, biochemistry, bioengineering, and materials science at UCLA—and first author AJ Addae, a doctoral candidate in chemical biology, sought to solve this problem by looking at the geometry of the particles rather than the chemistry of the ingredients.
Engineering the Tetrapod: A New Geometric Approach
The researchers departed from the standard spherical nanoparticle model, instead utilizing microscopic, four-armed structures called tetrapods. These tetrapods are created through a patented high-temperature flame process, which results in particles that are significantly larger than traditional nanoparticles but possess a unique branched architecture.
"Because of their structure, these tetrapod-shaped particles have standoffs and form porous networks instead of collapsing into clumps," explained AJ Addae. The four-armed shape prevents the particles from packing tightly together. In a liquid suspension, such as a sunscreen lotion, these tetrapods maintain a more uniform distribution. Because they do not aggregate into large, light-scattering clumps, they interact with visible light differently than spherical particles.
In laboratory testing, the tetrapod-based formula demonstrated a remarkable ability to provide sun protection factor (SPF) 30—the benchmark recommended by the American Academy of Dermatology—while maintaining a "warmer" and more translucent appearance on the skin. The researchers achieved this without the use of artificial tints, pigments, or specialized coatings that are often used in high-end cosmetic sunscreens to mask the white cast.
Addressing Public Health Disparities in Skin Cancer
The implications of this research extend far beyond the beauty industry. Skin cancer is the most common form of cancer in the United States, with millions of cases diagnosed annually. While individuals with lighter skin tones have a higher incidence of melanoma, the deadliest form of skin cancer, the mortality rates for people of color are disproportionately high.
According to data from the American Cancer Society, the five-year survival rate for melanoma is approximately 91% for white patients but only 66% for Black patients. A primary factor in this disparity is the timing of diagnosis. Because of a prevailing myth that darker skin is "immune" to sun damage, and because of the lack of inclusive sun protection products, skin cancers in people of color are often detected at much later, more advanced stages when treatment is less effective.
"This isn’t just about cosmetics," said Professor Weiss. "If improving how sunscreen looks leads to more consistent use, it could have real implications for skin cancer prevention." By creating a mineral sunscreen that is aesthetically compatible with all skin tones, the UCLA team is addressing a critical gap in preventative healthcare.
Comparative Data and Formula Stability
The study published in ACS Materials Letters provided rigorous comparative data between the new tetrapod formula and conventional zinc oxide preparations. The researchers found that at the same concentration of active ingredients, the tetrapod formula matched the UV-blocking capabilities of standard products.
Furthermore, the tetrapod structures offered superior formula stability. Traditional mineral sunscreens often suffer from "phase separation," where the heavy mineral particles settle at the bottom of the container or cause the lotion to become excessively thick and difficult to spread over time. The porous network formed by the tetrapods helps maintain the structural integrity of the lotion, ensuring that the active ingredients remain evenly suspended and effective throughout the product’s shelf life.
During controlled applications, the tetrapod sunscreen was noted for its "spreadability." Because the particles do not clump, the lotion glides more smoothly over the skin’s surface, allowing for a more even layer of protection. This is vital because the efficacy of any sunscreen is dependent on the thickness and uniformity of the application.
The Journey from Personal Frustration to Scientific Breakthrough
The project was born from a combination of entrepreneurial spirit and personal experience. First author AJ Addae, who is also a cosmetic science entrepreneur, noted that her own frustrations with mineral sunscreens were the catalyst for the research. Like many people with darker skin, Addae found that the available "safe" mineral options were unusable due to the white cast they produced.
"I started thinking about this because I was frustrated by how mineral sunscreen looks on my own skin," Addae said. "That frustration really became the starting point for this work."
The collaboration between Addae and Weiss represents a growing trend in "translational" materials science—where fundamental laboratory research is directly applied to solving real-world consumer and health problems. By combining Addae’s insights into cosmetic formulation with Weiss’s expertise in nanotechnology and surface science, the team was able to bridge the gap between academic theory and practical application.
Regulatory Context and Environmental Considerations
The timing of this discovery is particularly relevant given the shifting regulatory landscape for sunscreens. In recent years, the U.S. Food and Drug Administration (FDA) has increased its scrutiny of chemical sunscreen filters such as oxybenzone and octinoxate. These chemicals, while effective at absorbing UV, have been found to enter the bloodstream at levels that warrant further safety studies. Furthermore, several jurisdictions, including Hawaii and the U.S. Virgin Islands, have banned certain chemical filters due to their documented role in coral bleaching and the degradation of marine ecosystems.
In contrast, zinc oxide is one of only two ingredients (along with titanium dioxide) that the FDA currently classifies as "generally recognized as safe and effective" (GRASE). As consumers and regulators move away from chemical filters, the demand for high-performing mineral alternatives has surged. The UCLA tetrapod technology provides a path forward for mineral sunscreens to compete with the aesthetic elegance of chemical formulas without the associated health or environmental concerns.
Future Directions: Microbiome and Clinical Trials
While the initial results are promising, the UCLA researchers emphasize that more work is needed before the tetrapod sunscreen reaches retail shelves. The team has already begun collaborating with the UCLA Health Department of Dermatology and the UCLA Skin of Color Clinic to conduct further testing.
One area of particular interest is the interaction between tetrapod particles and the skin microbiome—the community of beneficial bacteria that lives on the human skin surface. Because the tetrapod particles are larger than traditional nanoparticles and have a different surface geometry, researchers want to ensure they do not disrupt the delicate balance of the skin’s natural defenses.
"The best sunscreen is the one people will actually use," Addae concluded. "If zinc oxide can be made to look better on more skin tones without sacrificing protection, it could help more people protect themselves from the sun’s most dangerous effects."
The study received support from several prestigious organizations, including the National Science Foundation and the Challenge Initiative at UCLA. As the team moves toward commercialization and larger-scale clinical trials, the focus remains on the ultimate goal: reducing the global burden of skin cancer through inclusive, science-driven design. This research serves as a testament to how the physical reshaping of existing materials can lead to profound improvements in human health and social equity.
