Now a ‘Natural Sunscreen’ With Melanin Like Cells Can Protect You from UV Rays

Highlights:

• Melanin cells provide skin, hair and eyes their characteristic color and have UV protectant effect.
• A research team from WC San Diego has developed nanoparticles that mimic melanin cells and protect skin cells from harmful UV rays.
• The use of these synthetic melanin nanoparticles in sunscreen is to offer protection which is closest to that provided by the naturally occuring melanin.

An ultimate ‘natural’ sunscreen has been developed by UC San Diego’s material scientists, chemists and nanoengineers. The nanoparticles used in the sunscreen mimic the naturally occurring melanosomes or the melanin producing cells, that protect the cells of the body from damage that can be caused due to the sun’s UV rays. The study that holds promise in protection against the UV rays was published in the journal ACS Central Science. UC San Diego’s professor of nanoengineering, chemistry, material science and biochemistry said that the scientists were successful in developing a synthetic version of the nanoparticles used by the body to synthesize and store melanin. Experimental studies showed that these nanoparticles mimicked the functions of the naturally occurring melanosomes. 

The production of melanin in the body is not only beneficial as a sun protectant but the defects in the production could lead to diseases like albinism and vitiligo. Vitiligo is a condition in which the immune system begins to treat the melanocytes as foreign and mounts an immune response. In albinism, however, genetic mutation results in improper secretion of tyrosinase, which is a copper containing enzyme associated with the synthesis of melanin. Vitiligo and albinism are both conditions that are found to increase the risk for cancer and there are no known treatment methods.

Dr. Gianneschi stated that the high prevalence of diseases associated with improper melanin production, along with an interest in developing polymeric materials that were similar to melanin, encouraged the research team to develop melanin like materials.

What is Melanin?

Melanin is responsible for the color of our skin, hair and eyes. This is produced by the body by different cells in different animals, for example in the skin of reptiles and in the feathers of birds.

We are constantly exposed to UV rays in our daily lives,, which affects the function and survival of cells in the body. Skin pigmentation is important for photoprotection, as melanin, besides being a UV absorbent, is also known to have an antioxidant with radical scavenging functions. Earlier studies have shown that people with darker skin have a lower incidence of skin cancer when compared with individuals who have lighter skin.

Though the benefits of melanin are well known, it is difficult to isolate melanin and it is easier to synthesize it. The research team led by Gianneschi, developed nanoparticles that were synthetic melanin, and which were found to mimic the natural melanin that were found in the feathers of birds. 

The scientists believed, that the novel melanin like nanoparticles would be taken up by keratinocytes, as they resembled the melanosomes that were found naturally. The keratinocytes are the most commonly found cells that are present in the outer layer of the skin, the epidermis.

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Under normal circumstances, the melanin that is produced by the body is secreted as melanosomes from the melanocytes and is transported to the keratinocytes. The melanin like nanoparticles that were developed by the research team from UC San Diego scientists using spontaneous dopamine oxidation, were synthetic analogues of melanosomes that occurred naturally. The scientists then focused on the following characteristics of the nanoparticles in tissue cultures:

• uptake
• transport
• spread
• UV protection

The study found that:

• the synthetic nanoparticles that were developed by the scientists were taken up by the keratinocytes
• they were distributed like normal melanocytes
• these nanoparticles protected the skin cells from DNA damage

The findings of the study showed that these specially designed nanoparticles have the potential to be used as artificial melanosomes. Diseases that are caused due to defective production of melanin could soon be treated using these synthetic melanin nanoparticles.

Differences in Skin Pigmentation

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The differences that occur in the skin pigmentation across ethnicities, are not due to the number of melanocytes that are present in the skin, but are based on

• the difference in the melanogenic activity
• the type of melanin produced in melanosomes
• the number and size of melanosomes
• the melanin content range from 17.9% to 72.3%

The number of melanocytes that are present in the skin of an individual are dependent on the race and vary across the different sites of the body. It varies between 2000m² in the head to 1000 mm² in the armpits. The total number of melanocytes that are present varies only about 2 fold between Asian and white skin, with dark skin having the highest levels of melanin.

Adapting the mechanism of UV protection afforded by the naturally occurring melanin into synthetically developed melanin, like nanoparticles, will ensure better protection against the harsh rays of the sun.

References:

1. The Protective Role of Melanin Against UV Damage in Human Skin - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/)
2. What gives skin its color? - (https://www.aad.org/public/kids/skin/what-gives-skin-its-color)

Source-Medindia