A New Mineral Sunscreen Solution: Say Goodbye to the White Cast
For years, dermatologists have emphasized the importance of daily sunscreen use to protect against ultraviolet radiation, a major cause of skin cancer, the most prevalent cancer in the United States. However, many people still hesitate to apply sunscreen due to a common issue: the white cast it leaves on the skin.
Mineral sunscreens, particularly those containing zinc oxide, have been criticized for their tendency to create a white, chalky appearance, resembling a ghostly mask. This 'white cast' is a significant deterrent for regular sunscreen use, despite its invaluable protective benefits.
A recent study from UCLA Health offers a promising solution to this problem. Instead of developing new chemicals, scientists have discovered that reshaping zinc oxide particles can transform mineral sunscreens. By altering the physical structure of zinc oxide, they've created a new form that provides protection without the white, painted-on look.
The key to this innovation lies in the shape of the zinc oxide particles. Traditional sunscreens use tiny, round zinc oxide nanoparticles, which tend to clump together, causing instability and visible light scattering, resulting in the white or gray cast. In contrast, the new approach involves reshaping zinc oxide into microscopic four-armed 'tetrapods'. These tetrapod structures effectively block ultraviolet rays while minimizing the white cast.
The study's senior author, Paul S. Weiss, highlights the potential impact of this discovery. He emphasizes that improving the appearance of sunscreen is not just about aesthetics; it's about encouraging consistent use, which could significantly contribute to skin cancer prevention.
AJ Addae, a UCLA chemical biology PhD student and cosmetic science entrepreneur, shares a personal connection to this research. Frustrated by the white cast of mineral sunscreen on her own skin, she decided to tackle the issue. Addae's research led to the development of a patented flame-based process that produces larger, four-armed 'tetrapod' particles. These tetrapods don't clump, forming airy networks that remain evenly spread in the sunscreen, resulting in a smoother application and a significantly reduced white cast.
When tested at the same concentration as regular zinc oxide, the tetrapod-based sunscreen achieved an SPF of approximately 30, comparable to standard mineral sunscreens. However, it maintained its stability over time, avoiding separation or thickening. Most notably, the tetrapod sunscreens reflected light more gently, appearing warmer and closer to natural skin tones in lab and skin tests, without the need for additional coatings or pigments to conceal the cast.
Addae's experience with the new sunscreen was transformative. She noted that applying it to her skin didn't result in the usual white cast associated with zinc oxide. This realization fueled her belief in the potential of this innovation.
The research is not yet ready for market, as further testing is required. However, the scientists involved are optimistic about the future of this approach, envisioning a collaboration between materials science and cancer prevention. By reshaping zinc oxide, they've opened a pathway to sunscreens that offer robust protection while maintaining a natural appearance on the skin.
Journal Reference:
1. Ajoa J. Addae, Jennifer Uyanga, Yogendra Kumar Mishra, Justin Caram, and Paul S. Weiss. Flame-Synthesized Zinc Oxide Tetrapods for Photoprotection in Sunscreen Formulations. ACS Materials Letters. DOI: 10.1021/acsmaterialslett.5c01351 (https://doi.org/10.1021/acsmaterialslett.5c01351)
