Insectoid material could replace plastic

Posted by Emma Woollacott

Researchers at Harvard University's Wyss Institute for Biologically Inspired Engineering have developed a new super-strong material based on the shells of creatures such as shrimps.

Shrilk is low-cost, biodegradable, and biocompatible, they say, and could one day replace plastics in consumer products and be used safely in medical applications such as sutures.

"When we talk about the Wyss Institute's mission to create bioinspired materials and products, Shrilk is an example of what we have in mind," says professor Donald Ingber.

"It has the potential to be both a solution to some of today's most critical environmental problems and a stepping stone toward significant medical advances."

Natural insect cuticle makes a good model, say the team: it's light, strong, and thin enough to be flexible. It consists of layers of chitin, a polysaccharide polymer, and protein organized in a laminar, plywood-like structure.

The Harvard team was able to engineer a thin, clear film with the same composition and structure, composed of fibroin protein from silk and from chitin, commonly extracted from discarded shrimp shells.

The end result is similar in strength and toughness to an aluminum alloy, but only half the weight. It's biodegradable, and can be produced at a very low cost, since chitin is readily available as a shrimp waste product.

It's also easily molded into complex shapes, such as tubes - and, by controlling the water content in the fabrication process, the researchers were even able to vary its stiffness, from elasticity to rigidity.

The applications are endless, they say. Shrilk could be used to make trash bags, packaging, and diapers that degrade quickly. Thanks to its strength and biocompatibility, it could also be used to suture wounds that bear high loads, such as in hernia repair, or form a scaffold for tissue regeneration.