By Suherman Candra Maholtra 
In a significant advancement for dermatological 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 daily sun protection: the unsightly, chalky residue known as "white cast." By re-engineering the physical structure of zinc oxide—a common and safe UV filter—into microscopic, four-armed "tetrapods," the team has created a formula that provides robust protection against ultraviolet radiation while remaining virtually invisible on a wide range of skin tones. The study, led by the UCLA Health Jonsson Comprehensive Cancer Center, represents a intersection of materials science, cosmetic chemistry, and preventative medicine, offering a potential solution to long-standing disparities in skin cancer outcomes.
The Public Health Crisis of Skin Cancer and Sunscreen Non-Compliance
Skin cancer remains the most prevalent form of malignancy in the United States, with more than 9,500 people diagnosed every day. According to the American Academy of Dermatology, one in five Americans will develop skin cancer in their lifetime. While most cases are highly treatable if caught early, the disease remains a significant public health burden, largely because ultraviolet (UV) radiation exposure is a cumulative and often preventable risk factor.
Dermatologists have long advocated for the daily application of broad-spectrum sunscreen with an SPF of 30 or higher. However, adherence to these recommendations remains low across many demographic groups. One of the most frequently cited reasons for avoiding mineral sunscreens is their aesthetic profile. Traditional mineral sunscreens rely on inorganic filters like zinc oxide and titanium dioxide. While these ingredients are highly effective at reflecting and scattering UV rays, they are notorious for leaving a thick, white, or grayish film on the skin. This effect is particularly pronounced on individuals with darker skin tones, often leading to "sunscreen hesitancy" or the total avoidance of sun protection.
The UCLA study, published in the journal ACS Materials Letters, posits that the "white cast" problem is not an inherent flaw of the chemical itself, but rather a consequence of the physical shape of the particles used in current manufacturing processes.
Engineering the Tetrapod: A Breakthrough in Materials Science
Standard zinc oxide particles used in commercial sunscreens are typically produced as spherical nanoparticles. While these particles are small, they have a high tendency to aggregate or "clump" together within the sunscreen emulsion. When these clumps reach a certain size, they begin to scatter visible light rather than just absorbing or reflecting UV light. This scattering of visible light is what the human eye perceives as a white or chalky residue.
The UCLA research team, led by senior author Paul S. Weiss, a distinguished professor of chemistry, biochemistry, and bioengineering, took a different approach. Instead of using spherical particles, they utilized a patented high-temperature flame process to create zinc oxide in the shape of tetrapods—microscopic structures with four distinct arms extending from a central point.
"Because of their unique geometry, these tetrapod-shaped particles have built-in ‘standoffs,’" explained AJ Addae, the study’s first author and a UCLA chemical biology doctoral candidate. "Unlike spheres, which can pack tightly together and form large, light-scattering aggregates, tetrapods form porous, interconnected networks. They simply cannot collapse into the dense clumps that cause the white cast. This allows the particles to remain evenly distributed throughout the lotion."
The structural integrity of the tetrapods ensures that the sunscreen remains stable over time. In laboratory tests, the tetrapod formulations showed significantly less separation and thickening compared to traditional spherical formulas, suggesting a longer shelf life and more consistent application for the consumer.
Performance Metrics: SPF 30 and Visual Clarity
To validate the efficacy of the new structure, the researchers conducted comparative analyses between the tetrapod-shaped zinc oxide and conventional nanoparticles. The results demonstrated that the tetrapod formula achieved an SPF (Sun Protection Factor) of approximately 30 when used at the same concentration as standard zinc oxide. This level of protection is the "gold standard" recommended by the Skin Cancer Foundation for daily use.
Beyond UV protection, the visual results were striking. In controlled applications on various skin types, the tetrapod-based sunscreen produced a "warmer" appearance that blended naturally with the skin’s pigment. Unlike many "tinted" sunscreens that use iron oxides to mask the white cast, the UCLA formula achieved transparency through structural engineering alone, without the need for added pigments or specialized coatings that can sometimes irritate sensitive skin.
"The very first formulations already showed a visible difference," said Weiss, who also serves as an investigator in the UCLA Health Jonsson Comprehensive Cancer Center. "This isn’t just a cosmetic improvement; it is a fundamental shift in how we approach the materials used in preventative healthcare."
Addressing Healthcare Disparities and the "Skin of Color" Gap
The implications of this research extend far beyond the beauty industry. There is a critical need for sun protection solutions that serve diverse populations. While melanoma—the deadliest form of skin cancer—is less common in Black, Hispanic, and Asian populations than in White populations, the mortality rates for these groups are disproportionately high.
Research indicates that Black patients are significantly more likely to be diagnosed with melanoma at a late stage, when the cancer has already metastasized. One contributing factor is a lack of awareness regarding sun safety in communities of color, compounded by a lack of products that are aesthetically compatible with darker skin.
For AJ Addae, who is also a cosmetic science entrepreneur, the project was born out of personal necessity. "I started thinking about this because I was frustrated by how mineral sunscreen looks on my own skin," Addae said. "That frustration became the starting point for this work. If we can make a product that people actually enjoy wearing, we can bridge the gap in skin cancer prevention."
The research team is now collaborating with the UCLA Health Skin of Color Clinic to further refine the formula. This partnership aims to ensure that the next generation of sunscreens is developed with the specific needs of diverse dermatological profiles in mind.
The Regulatory and Environmental Context
The UCLA innovation arrives at a pivotal moment for the sunscreen industry. In recent years, the U.S. Food and Drug Administration (FDA) has tightened its oversight of sunscreen ingredients. In its 2019 and 2021 proposed rules, the FDA identified only two ingredients as "generally recognized as safe and effective" (GRASE): zinc oxide and titanium dioxide. Many chemical filters, such as oxybenzone and octinoxate, are currently under further study due to concerns about systemic absorption and potential endocrine disruption.
Furthermore, environmental concerns have led several jurisdictions, including Hawaii and the U.S. Virgin Islands, to ban certain chemical sunscreens believed to contribute to coral bleaching. As a result, consumer demand for "mineral" or "reef-safe" sunscreens has surged. However, the "white cast" of mineral options has remained the primary hurdle to widespread adoption. By solving the aesthetic issue of zinc oxide, the UCLA team is clearing the path for a safer, more environmentally friendly, and more inclusive sun protection market.
Future Research: The Skin Microbiome and Commercialization
While the initial results are promising, the UCLA team notes that the tetrapod technology must undergo further rigorous testing before it hits consumer shelves. The next phase of research will focus on how these unique particles interact with the skin microbiome—the complex ecosystem of bacteria and fungi that live on the skin’s surface and play a role in immune function.
"We want to ensure that by changing the shape of the particle, we aren’t inadvertently affecting the skin’s natural defenses," Weiss noted.
The researchers are also exploring the scalability of the high-temperature flame process used to create the tetrapods. For the technology to be viable, it must be cost-effective for large-scale manufacturing. However, because the process utilizes existing materials (zinc oxide) and a known industrial method (flame spray pyrolysis), the path to commercialization may be shorter than that of a entirely new chemical entity.
Conclusion: The Best Sunscreen is the One People Use
The UCLA study serves as a reminder that sometimes the solution to a complex medical problem lies not in discovering a new drug, but in redesigning the delivery of an existing one. By applying the principles of materials science to the field of dermatology, Weiss, Addae, and their colleagues have addressed a practical barrier that has hindered skin cancer prevention for decades.
As the global community continues to face rising temperatures and increased UV exposure due to environmental changes, the importance of accessible, effective, and aesthetically pleasing sun protection cannot be overstated. "The best sunscreen is the one people will actually use," Addae concluded. "If we can make zinc oxide look better on more skin tones without sacrificing protection, we have the potential to save lives through better compliance and earlier prevention."
The study was supported by the National Science Foundation, the Challenge Initiative at UCLA, and a Sigma Xi IFoRE Grant-in-Aid. Other contributors to the research include Jennifer Uyanga and Professor Justin Carman of UCLA, as well as Professor Yogendra Kumar Mishra of the University of Southern Denmark. Together, their work marks a new chapter in the evolution of sun care, where science and inclusivity work hand-in-hand to protect public health.
