Scientists create artificial nanoparticles that mimic melanin and protect cells in the epidermis from ultraviolet radiation.
In the summer heat, many people feel the need to use more sunscreen to prevent ultraviolet radiation from damaging their skin. Now scientists may have found a new way to block these dangerous rays: nanoparticles that mimic melanin and protect skin cells from the inside. If proven effective, the method may lead to the development of better topical protection and even treatments for certain dermatological disorders.
Melanin, a dark colored pigment, is one of our body's main natural defenses against damage induced by ultraviolet radiation. Under the surface of the skin, certain cells secrete melanosomes, the organelles that produce, store and transport melanin. These structures are then absorbed by the keratinocytes, the cells of the epidermis, and form around the nucleus a protective shell that blocks ultraviolet radiation. Those suffering from diseases such as albinism or vitiligo suffer from a defective production of melanin and are extremely sensitive to ultraviolet rays.
In order to create synthetic versions of melanosomes, a group of researchers from the University of California at San Diego bathed molecules of the neurotransmitter dopamine in an alkaline solution. Thanks to this they were able to produce nanoparticles similar to melanin but made of polydopamine, a polymer based on dopamine. When incubated in a Petri dish with human keratinocytes, the synthetic particles were absorbed by the cells and distributed around their nuclei, such as natural melanin.
The skin cells "are able to process [the synthetic nanoparticle] and turn it into a kind of" cap "around the nucleus, explains biochemist Nathan Gianneschi, one of the authors of the study, now at the Northwestern University of States United. Like melanin, the synthetic material functions as a pigment that darkens the skin. However, the synthetic pigment "not only filled the cells and made them dark. I really structured them, "says Gianneschi.
In fact, nanoparticles were not only transported and distributed through the skin cells in the same way as natural melanin, they also protected the DNA. To verify, the researchers incubated keratinocytes with nanoparticles and then exposed them for three days to ultraviolet radiation. Fifty percent of the cells that had absorbed the nanoparticles survived, compared with 10 percent of those who did not. The findings were recently published in ACS Central Science.
Once nanoparticles have been shown to behave in the same way as natural melanin and to effectively protect cells, the next step will be to determine the mechanism of absorption.
Reference: http://pubs.acs.org/doi/full/10.1021/acscentsci.6b00230