UCLA scientists have innovated a mineral sunscreen formula that significantly reduces the pale, chalky residue typical of many sunscreens, encouraging daily use.
Dermatologists consistently emphasize the importance of daily sunscreen application to minimize UV exposure, a leading preventable cause of skin cancer, the most prevalent cancer in the United States.
Despite this advice, many individuals fail to apply sunscreen regularly, primarily due to the common complaint that mineral sunscreens with zinc oxide often leave a conspicuous white or gray film on the skin.
Innovating Zinc Oxide to Eliminate White Cast
A recent study from UCLA Health’s Johnson Comprehensive Cancer Center suggests a potential solution to this issue without the need for entirely new chemical compounds. Researchers modified the shape of zinc oxide particles, commonly utilized in mineral sunscreens.
By engineering zinc oxide into microscopic four-armed structures known as tetrapods, the team discovered that these particles leave less of a white cast than conventional zinc oxide formulations and offer enhanced protection against harmful UV rays.
The findings, published in ACS Material Letters, could encourage greater sunscreen use among individuals with diverse skin tones, contributing to skin cancer prevention.
“This is not just about aesthetics,” stated Paul S. Weiss, senior author of the study. With roles as a distinguished professor of chemistry and biochemistry, bioengineering, and materials science at UCLA, Weiss highlights the potential impact of improved sunscreen aesthetics on consistent usage and skin cancer prevention.
The Importance of Sunscreen Aesthetics
This research is especially critical for individuals with darker skin tones, who are less likely to use sunscreen consistently and are often diagnosed with skin cancer at a more advanced stage.
While melanoma, the deadliest skin cancer type, is less common among people with darker skin, studies indicate they are significantly more likely to succumb to the disease due to late diagnoses and treatment challenges.
Lead author AJ Addae, a PhD candidate in chemical biology at UCLA and a cosmetics science entrepreneur, was inspired by personal frustration with mineral sunscreen aesthetics. “My motivation stemmed from my experiences dealing with white casts from various mineral sunscreens, which led me to avoid using them altogether,” Addae shared.
Understanding the White Appearance of Mineral Sunscreens
Zinc oxide is widely esteemed in mineral sunscreens for its capability to block both UVA rays, which accelerate skin aging, and UVB rays, responsible for sunburn and increased skin cancer risk. The U.S. Food and Drug Administration recognizes zinc oxide as safe and effective.
Mineral sunscreens are generally recommended for sensitive skin, including acne-prone individuals or those with rosacea seeking non-chemical alternatives.
However, conventional zinc oxide particles often clump together, diminishing the sunscreen’s stability and resulting in visible white or gray residue, especially apparent on darker skin tones.
The UCLA team aimed to determine whether altering particle structure could prevent clumping and enhance sunscreen appearance.
Most zinc oxide used in sunscreens comprises tiny, roughly spherical nanoparticles created through chemical manufacturing processes. The recent study explored larger particles shaped like quadrupeds produced via a patented high-temperature flame process.
“These tetrapod-shaped particles create a porous network, preventing clumping and ensuring an even distribution within the sunscreen,” Addae noted.
SPF 30 Protection with Enhanced Stability
In comparing tetrapod-formulated zinc oxide with traditional nanoparticles prevalent in sunscreen, the quadrupedal formulation exhibited multiple advantages.
At comparable concentrations, the tetrapod sunscreen achieved a sun protection factor (SPF) of approximately 30, which aligns with standard mineral sunscreen efficacy.
Moreover, the tetrapod formulation demonstrated improved stability over time, showing minimal separation or thickening.
The most significant visible improvements were observed in how these particles interacted with light. Laboratory tests and controlled skin applications revealed that the tetrapod sunscreen delivered a warmer tone closer to natural skin shades, avoiding the stark white or gray hues associated with traditional zinc oxide.
This effect was achieved without additional pigments or specific coatings to mask the residue.
“Upon application, I noticed it didn’t leave a white cast typical with zinc oxide,” Addae reflected. “That was when I recognized that it truly worked.”
“What surprised us was the immediate visible difference in the first formulation,” added Weiss, a member of the UCLA California NanoSystems Institute and the Goodman Luskin Microbiome Center.
Advancing Materials Science for Skin Cancer Prevention
While this innovative sunscreen technology requires further testing before reaching commercial availability, the researchers underscore its potential in overcoming barriers to skin cancer prevention through materials science.
“The best sunscreens are the ones people actually use,” Addae asserted. “If we can enhance the appearance of zinc oxide for various skin tones without compromising on protection, we could significantly improve sun safety for many.”
Collaborating with UCLA Health’s Department of Dermatology and Skin of Color Clinic, the researchers are committed to exploring how tetrapod particles engage with the skin microbiome for practical applications.
Key Takeaways
- Mineral sunscreens containing zinc oxide traditionally leave a visible white or chalky layer on the skin.
- UCLA researchers have developed a method to reduce this effect by reshaping zinc oxide particles as four-armed tetrapods.
- Laboratory and skin application tests indicated that the tetrapod formula presents a warmer appearance, more akin to natural skin tones, without producing harsh white or gray tints.
The study also included contributions from Jennifer Uyanga, and co-advisors Professor Justin Carman at UCLA and Professor Yogendra Kumar Mishra from the University of Southern Denmark.
This research received partial funding from the National Science Foundation, the UCLA Challenge Initiative, and a Sigma Xi IFoRE Grant-in-Aid.
Source: www.sciencedaily.com