UCLA Researchers Develop Sunscreen that Reduces White Appearance

UCLA researchers have developed a mineral sunscreen formulation that significantly reduces the white, chalky cast that keeps many people from wearing sun protection daily. 

For decades, dermatologists have urged people to apply sunscreen daily to protect against ultraviolet radiation. Excessive exposure to ultraviolet radiation is the leading preventable cause of skin cancer, the most common cancer in the United States. 

Yet many Americans still skip it in part because mineral formulas with zinc oxide often leave behind a white, chalky cast. 

A new study led by researchers at the UCLA Health Jonsson Comprehensive Cancer Center suggests that these concerns may be fixable without inventing a new chemical ingredient. Instead, a simple change in the shape of zinc oxide particles could help solve one of sunscreen’s biggest cosmetic drawbacks. 

The researchers report that a newly engineered form of zinc oxide, shaped like microscopic four-armed structures called tetrapods, provides strong protection against harmful ultraviolet radiation while leaving less of the telltale white cast than conventional zinc oxide formulations that have long discouraged regular use. 

The findings, published in the journal ACS Materials Letters, could have implications for skin cancer prevention, particularly by encouraging more consistent sunscreen use across a wider range of skin tones.

Conventional zinc oxide particles tend to clump together, destabilizing sunscreen formulations and scattering visible light, creating a white or gray cast on the skin that is particularly noticeable on darker skin tones.

To overcome this issue, the researchers decided to look at altering its physical structure to see whether the particle shape made a difference. 

Most zinc oxide used in sunscreens is produced through chemical processes that create very small, roughly round nanoparticles. In the new study, the team tested zinc oxide made using a patented high-temperature flame process that produces much larger particles shaped like tiny tetrapods. 

These particles were then compared with conventional zinc oxide nanoparticles commonly used in sunscreens. The team found that sunscreens formulated with the tetrapod-shaped zinc oxide offered several practical benefits.

When formulated into test sunscreens at the same concentration as conventional zinc oxide, the tetrapod-based sunscreen achieved a sun protection factor (SPF) of about 30, which is comparable to standard mineral sunscreens. The lotions also remained more stable over time, with fewer signs of separation or thickening.

Most noticeably, the tetrapod sunscreens reflected visible light differently. Instead of producing a stark white or gray cast, they appeared warmer and closer to natural skin tones in laboratory tests and controlled skin applications, without relying on special coatings or added pigments to mask the white cast. 

The study was funded in part by the National Science Foundation, the Challenge Initiative at UCLA and a Sigma Xi IFoRE Grant-in-Aid.