Insect-inspired Material That Could Solve Our Plastic Problem

"Shrilk," made from proteins found in crustacean and insect shells, is strong, stretchy, and fully biodegradable. It may be how you carry your groceries home in the future.

What if you could come back from the store, extract your haul, and throw your grocery bag in the garden to compost away? Scientists have created a sturdy, versatile, completely biodegradable alternative to plastic that could just make this crazy dream real. And it’s made from insect skeletons.

Javier Fernandez, a Spanish materials scientist, and his collaborators at the Wyss Institute, have created the material they’re calling "Shrilk," which mimics the architecture of arthropod exoskeletons. Grasshoppers and other similar bugs have an exoskeleton that is strong enough to support their innards, but light enough to allow the insect to fly. Shrilk, made from the proteins in these natural materials, also adopts a similar duality: It has the strength of an aluminum alloy, but is half its weight. It’s also completely biodegradable.

Fernandez was experimenting with chitin—found in insect shells— for use in bio-compatible microelectronics. When he recreated the complete micro architecture of the shell, with proteins layered like plywood, the result was Shrilk: strong, light, supple, surprising. "We got mechanical properties that were completely crazy and very unexpected," Fernandez tells Co.Exist.

Fernandez found that Shrilk’s elasticity changed from stretchy to stiff depending on how it was hydrated. And in addition to its spectacular strength and lightness, Shrilk biodegrades completely in a matter of months when in presence of moisture, breaking down into compounds that can be used as nitrogen fertilizer.

Shrilk is a shoe-in for use in medicine, Fernandez says. In the human body, the material has a lifetime of a few months. This makes it an excellent candidate for use in surgical sutures, or as a scaffold for regenerating tissues. Synthetic materials usually go through rigorous and lengthy tests before the FDA approves them for use in people. But, both the materials that form the Shrilk microstructure—chitosan and fibroin—are already individually approved.

Shrilk could also be sold as an eco-conscious stand-in for disposable plastics. If appropriately hydrated, its structure can vary from stretchy to stiff, so it could be used as either the shell of your cellphone or to replace the ubiquitous and wasteful grocery bags.

There are still several next steps that Fernandez and his colleagues must go through before Shrilk is ready to be manufactured commercially. But if it does hit the market, it would require a huge supply of the raw material that goes into it. Extracting the components from natural sources wouldn’t keep up. So, Fernandez and his team are researching ways to genetically engineer bacterial farms to mass-produce the necessary proteins. "If we want this to be realistic, we need to do the next step."

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