With summer quickly approaching, many of us are looking forward to beach vacations, picnics, and swimming at the local pool. But with increased sun exposure comes an increased risk of skin damage that sunscreen can’t always protect against.
Last week, researchers at the University of California, San Diego (UCSD) got a little bit closer to creating a solution.
In a study published in the American Chemical Society journal ACS Central Science, materials scientists and nanoengineers at UCSD created nanoparticles in the lab that copy the behavior of the melanin-producing cell structures, called melanosomes, that protect our skin from ultraviolet radiation.
These nanoparticles are a synthetic version of the naturally occurring particles in our skin that produce and hold onto melanin, and could have many practical applications, including a more effective topical sunscreen.
“There is potential that the nanoparticles could be formulated into a cream, however that needs to be studied in detail,” said Nathan Gianneschi, head of the research team and professor of materials science and engineering at UCSD.
“Our study showed that in cell culture, our materials are taken up by human skin cells,” he added. “The challenge now is to translate that to fully intact tissues, to see if it is possible to adapt it to a topical formulation.”
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Currently available topical sunscreens can help decrease the risk of sun exposure, like skin cancer, but must be applied in a very specific way: Broad-spectrum coverage above SPF 30 must be applied generously before going outside, and reapplied every two hours.
If the synthetic melanin nanoparticles created in this study were produced in a topical solution, it could mean a much more effective sunscreen.
“It would function as a natural tan,” Gianneschi said. “[It would] provide some mimic of our natural process for gaining protection from the sun and if it worked, it would be longer lasting than standard sunscreen, and would provide protection from within the tissue, rather than a coating on the outside,” he added.
In human skin, keratinocytes, the cells found in the outer layer of our skin known as the epidermis, soak up our naturally occurring melanosomes. Gianneschi and his team found that the synthetic melanin nanoparticles in their experiments were not only absorbed and distributed normally by the keratinocytes in the epidermis, but they also protected human skin cells from UV radiation damage.
Beyond the development of a more effective sunscreen, this discovery could have practical implications for the treatment of melanin-deficient disorders such as vitiligo and albinism. In both conditions, there is a lack of melanin produced in the skin, and because there are few treatments currently available, patients are at a higher risk of developing skin cancer.
In vitiligo and albinism treatments, according to Gianneschi, the synthetic nanoparticles might work like natural melanin. “It would provide a darkening of the skin, providing protection, as with a tan,” he said.
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Melanin particles are produced naturally by many different animals, in some cases, more effectively than in humans. The iridescent feathers of some bird species, as well as the skin of certain reptiles, produce melanin that fully protect them from the sun’s UV rays.
“Animals use [melanin] in the same way [as humans] to generate dark colors, but also to create structural coloration in the case of iridescence,” Gianneschi said. “Humans don’t have that kind of structural coloration, which is an evolution driven adaptation we did not adopt.”
In theory, it would be possible to extract these particles from animals for use in humans, but the process would likely be far more complicated than creating them synthetically in a controlled environment as Gianneschi and his team have done.
The next phase of Gianneschi’s research will look at how these synthetic melanin nanoparticles can be used in practical applications to protect against DNA damage caused by the sun’s UV rays.
“[We want to look at] optimizing the ability of these materials to absorb UV and what chemical structures are needed to increase protection beyond what is possible with the naturally occurring material,” Gianneschi said. “That would be an exciting direction.”
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