Researchers at the University of California, San Diego have created a sunscreen that both mimics and enhances the skin's natural protective abilities.

A team of chemists, materials scientists and nanoengineers were able to tap into the skin's defense mechanisms using nanoparticles of oxidized dopamine. Tests showed the particles mimic melanosomes, the organelle in skin cells that synthesizes, stores and transports melanin.

Researchers first developed the nanoparticles two years ago while studying the behavior of melanins in bird feathers.

"We hypothesized that synthetic melanin-like nanoparticles would mimic naturally occurring melanosomes and be taken up by keratinocytes, the predominant cell type found in the epidermis, the outer layer of skin," Nathan Gianneschi, a professor of biochemistry, materials science and engineering at UC San Diego, said in a news release.

Researchers believe their breakthrough could yield treatments for vitiligo and albinism, diseases caused by defects in the body's melanin production system. Patients diagnosed with vitiligo and albinism are at a much higher risk of skin cancer.

"The widespread prevalence of these melanin-related diseases and an increasing interest in the performance of various polymeric materials related to melanin prompted us to look for novel synthetic routes for preparing melanin-like materials," Gianneschi said.

Melanosomes are produced by cells called melanocytes, found among the bottom layers of the epidermis. The organelles deliver melanin to keratinocytes, skin cells in the upper layer of the epidermis. There, melanin goes to work protecting skin cells from ultraviolet radiation.

In lab tests using tissue culture, researchers showed the nanoparticles are absorbed and distributed throughout keratinocytes just like natural melanin. The nanoparticles also protected skin cells from DNA damage caused by ultraviolet radiation.

Researchers described their breakthrough in the journal ACS Central Science.

"Considering limitations in the treatment of melanin-defective related diseases and the biocompatibility of these synthetic melanin-like nanoparticles in terms of uptake and degradation, these systems have potential as artificial melanosomes for the development of novel therapies, possibly supplementing the biological functions of natural melanins," the scientists wrote in their paper.

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