Saving your skin

Gregory Nemec

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The sunscreens we use today, essential as they are for reducing cancer risk, can work their way into our skin—potentially causing other health problems. A team of Yale researchers decided to see if they could find something better.

The result: a new sunscreen that coats the skin without entering the body. Bioengineering professor Mark Saltzman and School of Medicine dermatology professor Michael Girardi ’92MD haven’t tested it on humans yet, but that’s coming soon. Their findings were published in the September 28 online edition of Nature Materials.

Currently, commercial sunscreens come in two types. The UV-absorbing type is highly effective, but it penetrates the skin and may show up in breast milk and fatty tissue. It can also generate reactive oxygen molecules when UV hits it—molecules that may damage DNA. The other major type uses zinc or titanium oxide to reflect sunlight; the most widely used versions of these use nanoparticles, which can work their way into the skin, with unknown effects.

To keep their novel sunscreen on the skin’s surface, the Yale researchers used nanoparticles that include surface aldehydes—a class of sticky molecules. The aldehyde-laden nanoparticles cling to the skin’s outer layer. If they’re not wiped off, they simply wear away as the skin naturally renews itself.

The researchers encapsulated a UV-filtering chemical found in ordinary sunscreen within these nanoparticles. They tested the formula on mice and found that it works at least as well as the standard kind. Yet it uses just 5 percent as much of the UV-filtering chemical—essentially eliminating concern about DNA damage from reactive oxygen molecules.

If human studies go well, the new sunscreen could show up in beach bags in two to three years.