A lot of manufactured glass today made from sand and sodium carbonate (碳酸钠) can be reused or melted down and recycled into new items, but it doesn't break down in the environment and will sit in landfills for thousands of years. A team of Chinese scientists aimed to deal with this environmental concern by developing an eco-conscious alternative.
In a study published recently in the journal Science Advances, a team at the Chinese Academy of Sciences' Institute of Process Engineering describe how they engineered biodegradable glass made from amino acids (氨基酸). That glass would have a smaller impact on the environment and can break down in a few weeks or in several months.
In a test, glass beads made out of amino acids were placed under the skin of mice, and the breakdown of the bead and the skin healing process were observed for 30 days. A diagram from the study shows how the mice's bodies broke down the beads. In that month, the glass implant degraded beneath the skin, the wound site healed, and fur grew back. "Throughout the experimental period, no mice exhibited any pain-related behavior that may have been caused by the glass implantation, and none of them experienced obvious weight loss," the researchers wrote in their paper.
Although amino acids do degrade over time in the environment this biodegradable glass is not as durable as traditional glass, because amino acids can break down quickly in heat. To overcome this problem, the researchers chemically modified amino acids using the heating-cooling process tailored for manufacturing the new glass. This is when materials for the glass are heated to become soft and then rapidly cooled so as to make the glass tougher.
"It's important to point out that this biodegradable glass is currently in the lab stage, and far from large-scale commercialization," emphasized Yan Xuehai, a professor involved in the study, in a press release.