Could silk solve humanity’s microplastic problem?


The prefix “micro” in the word microplastic might suggest that these tiny plastic particles, by definition less than 5 millimeters long, are harmless trifles. And while microplastics are sometimes made intentionally, more often than not these tiny shards are created by accidents or the ravages of time, ending their lives by polluting our environment. When this happens, they are far from harmless – rather, they pose a threat to most life forms on Earth.

This is partly because microplastics are linked to diseases ranging from cancer and infertility to inflammatory bowel disease. Unfortunately, they are so widespread in the environment that even remote Pacific island nations like Palau are not safe. Humanity desperately needs an alternative – and that’s where researchers from the Massachusetts Institute of Technology (MIT) come in.

As detailed in a recent paper published in the scientific journal Small, MIT researchers have developed a silk-based substitute for plastics for certain industrial products – specifically, industrial systems that currently use plastics for microencapsulation process. Microencapsulation is a process by which tiny particles or droplets are coated with a substance that transforms them into a pill-shaped object, which protects its core from degradation by elements such as exposure to air or humidity. While this silk-based substitute would not entirely solve the microplastic problem, it does indeed offer some companies a planet-friendly alternative to microplastic-producing products.

“We have successfully demonstrated that silk protein can be used as a technological material in agricultural products and cosmetics – it can protect and control the release of active ingredients, and it can be biodegraded,” said Benedetto Marelli, Professor of Civil and Environmental Engineering at MIT and a postdoctoral student. Munchun Liu told Salon via email. “Our technology can be applied to different active ingredients, whether water-soluble or not. We prepared the silk-based microcapsules using methods already widely adopted in the industry.”

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The MIT researchers believe their silk product can replace microplastics intentionally added to products, a group that the European Chemicals Agency currently estimates to represent around 10-15% of the global supply of microplastics. For convenience, the silk substitute should be refined with as much precision and care as the silk used in fine fabrics. To create high quality threads, silkworm cocoons are carefully unrolled; for the silk needed to replace microplastics, producers simply need to apply a simple and scalable water-based process. This means that it will be much cheaper and easier to produce the types of silk needed to save the world than those that helped fuel the economy of medieval Europe.

That said, that doesn’t mean it will be easy to replace microplastics with silk. Although the Silk Road no longer drives the global economy, there are unique economic challenges in the 21st century. Marelli and Liu told Salon that business stakeholders need to work “in concert” to encourage the use of technologies that offset negative environmental impacts.

“Engineering new solutions requires factoring planetary health into the equation so that we can all benefit from progress and innovation,” Marelli and Liu explained.

MIT researchers aren’t the only scientists trying to come up with creative solutions to the microplastics problem. Last month, a study published in the scientific journal Microbial Genomics revealed that the insect Zophobas morio has a bacterial enzyme in its gut that dissolves a class of plastics called polystyrenes, which exist in styrofoam, packing peanuts, bottles, and other common household products.

“Our results confirm previous suggestions that supervers can help reduce [polystyrene] waste,” the authors conclude.

Until there is a long-term solution to the microplastics crisis, Marelli and Liu noted that there are immediate steps individuals can take to do their part to alleviate the problem.

“Consumers can of course make a difference by limiting the use of take-out and throwaway products in favor of reusable ones,” Marelli and Liu wrote at Salon. “This includes obvious products such as plastic bags, utensils, durable clothing, long-lasting toys, tools, etc. At the same time, all stakeholders must find new solutions or define new policies that promote (or mandate) the adoption of circular materials, without compromising on performance.”

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