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The synthetic melanin that will act as a natural radiation filter

Dye-like nanoparticles may protect cells from the sun's harmful rays

Illustration: pixabay.
Illustration: pixabay.

By Matthew Sedka, the article is published with the approval of Scientific American Israel and the Ort Israel Network 29.10.2017

In the hot summer months, many people feel the need to apply large amounts of sunscreen on their skin to prevent the sun from damaging it. But scientists have found a new way to block this dangerous radiation: nanoparticles that mimic the action of melanin and protect the skin cells from the inside. If proven to work, this approach could be used to develop more effective topical protection and perhaps even treatments for certain skin diseases.

The use of color (pigment) Melanin, which gives our skin a darker color, is one of the body's main natural defenses against the damage that ultraviolet radiation can cause to DNA. Under the surface of the skin there are special cells that secrete Melanosomes, which produce melanin, store it and transport it. These structures are absorbed by skin cells called Keratinocytes, and create shells around the cell nuclei that block the ultraviolet radiation. But in people suffering from diseases like albinism או macula Melanin production is not normal, so they are very vulnerable to the damage of ultraviolet radiation.

Researchers from the University of California, San Diego sang dopamine, a substance involved in the transmission of signals in the brain and other parts of the body, in a basic (alkaline) solution, and by doing so they created a synthetic version of these melanosomes. The chemical reaction that occurred caused the formation of melanin-like nanoparticles with shells and cores made of polydopamine, a polymer based on dopamine. When they were added to Petri dishes containing human keratinocytes, the skin cells absorbed the synthetic particles, and the particles dispersed around the cell nuclei like natural melanin.

The cells "are able to process [the synthetic nanoparticle] and turn it into a sort of covering around the nucleus," said the study's author, Nathan Gianski, a biochemist now working at Northwestern University. Like melanin, the synthetic substance also functions as a color that darkens the skin, but according to him, "it didn't just fill the cells and darken their color. He really fit into their structure."

The melanin-like particles were not only transferred and dispersed between the skin cells like natural melanin, but also protected the DNA of the cells. The researchers grew skin cells with such nanoparticles and then exposed them to ultraviolet radiation for three days. 50% of the cells that absorbed the nanoparticles survived, compared to only 10% of the cells without the nanoparticles. The findings were published earlier in 2017 in the journal ACS Central Science.

Now that the research group knows that the skin cells treat melanin-like nanoparticles like natural melanin, and that they can successfully protect the cells, the next step is to find out how the absorption mechanism works.

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