Space explorers in future human missions to the moon or Mars will need more than just a regular sunscreen to protect themselves from the sun's harmful rays. A new bioengineered material presents an answer to that problem in the form of selenomelanin, a combination of melanin and selenium.
Humans, once we cross the Earth's protective magnetic field, are exposed to many types of harmful radiation, according to NASA. This includes X-rays, ultraviolet radiation, and gamma rays from the sun, as well as superfast subatomic particles, called galactic cosmic rays that originate outside our solar system.
Exposure to radiation causes DNA breakage than can lead to cancer, radiation poisoning, and death. This is where melanin comes in handy, a pigment that's naturally found in plants, animals, bacteria, and fungi. Humans have melanin, and this helps protect us against the sun's UV rays.
"Melanin is ubiquitous and enigmatic," Nathan Gianneschi, a biochemist at Northwestern University in Evanston, Illinois, told Live Science. "We don't fully understand it."
According to a paper published in the New Journal of Science, animal melanins come in two main forms: pheomelanin and eumelanin. Eumelanin is the component that makes hair and skin color dark, while pheomelanin contains the element sulfur and tends to be reddish or yellowish, and is found in red or auburn hair and in the human lips.
Between the two, pheomelanin absorbs X-rays better. With this fact, Gianneschi, along with a team of researchers, took pheomelanin samples from red rooster feathers and made some tests to see if they can make it even more protective.
The researchers incorporated the element selenium instead of sulfur. Selenium is just right below sulfur on the periodic table of elements and has been found to prevent cancer. They combined the two to form selenomelanin, a new element that nature has never seen before.
Tested on skin cells, selenomelanin showed success in shrugging off high doses of X-ray radiation. According to Gianneschi, the cells absorbed selenomelanin, a process that he termed "microparasols," or tiny shields around the cells' nuclei, where DNA is stored. When the cells absorbed selenomelanin, they took on a naturally tanned or brown color, which he noted on the paper.
Further testing showed that engineered bacteria fed selenium could produce selenomelanin, which means there's a potential it can be manufactured in space.
Additional tests demonstrated that engineered bacteria fed selenium could produce selenomelanin, meaning the substance could be manufactured in space.
The paper has been published in the Journal of the American Chemical Society.