Silk can be used in place of microplastics in certain applications. (Image Credit: ivabalk/pixabay)
Bees aren’t the only insect that lives a brutal life thanks to human intervention. Silkworms might have it worse.
Silk, sourced from silkworm cocoons, could have even more applications in the future! MIT and chemical corporation BASF researchers developed a silk-based, biodegradable replacement for microplastics, which have been showing up everywhere, including mountaintops, the seafloor, and the human bloodstream. Their study is crucial for companies presented with stricter regulations for using microplastics.
Many microplastics are created due to object degradation. However, small amounts of these particles are intentionally placed in products containing active ingredients, such as agriculture and cosmetic sprays. Discovering alternative materials for microplastics provides researchers with more control over microplastic pollution.
Silk production, called sericulture, involves silkworms consuming mulberry tree leaves once every few hours for 20 to 35 days, allowing them to grow. When they’ve finished the feeding process, the silkworms lift their head to signify they’re ready to spin the cocoon. Then, the silkworm attaches to a tree, rotating 300,000 times to spin the silk cocoon, which takes three to eight days. Then, the silkworms place themselves within the cocoon, at which point the extraction process begins.
These cocoons are added to boiling water, which softens and dissolves the gum that binds the cocoon. This step essentially ensures that the thread doesn’t sustain any damage. Afterward, the threads are reeled from the cocoon in long threads that go on a reel.
Silk works as an ideal substitute because the material is non-toxic, survives processing, and can be used from low-quality fiber disposed of by textile companies. Other compounds could also serve as an alternative to microplastics, but they do not have all the advantages that silk offers in this case.
So the team retrofitted today’s manufacturing equipment to produce microcapsules using fibroin containing concentrated solid forms of an herbicide and Vitamin C. The microcapsule was drenched in ethanol for certain lengths of time, manipulating the way the silk’s long protein folded and stuck together. As a result, the microcapsules dissolved and released active ingredients.
Silk-based microcapsules must perform better or be similar to nonbiodegradable solutions. Sprayed herbicides gradually release, helping to eliminate weeds without affecting live crops. Spraying silk-based microcapsules on plants for six days caused less damage compared to other spraying products.
However, silk-based microcapsule sprays may not work with every application, but it still has potential versus other alternatives that BASF studied. BASF also says that silk-based microcapsules could be commercially available in a few years. Next, the researchers plan to encase active ingredients that rely on a different manufacturing technique, like those that must stay in a liquid or gas state.
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