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Cheap, biodegradable, biocompatible "Shrilk" is a potential plastic replacement

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December 14, 2011

Arthropod cuticle, found in insects, spiders and crustaceans, has provided inspiration for...

Arthropod cuticle, found in insects, spiders and crustaceans, has provided inspiration for a new material that is strong, cheap, biodegradable and biocompatible (Photo: me'nthedogs via Flickr)

Web-slinging arachnids already have researchers toiling away looking to replicate the remarkable properties of spider silk. Now spiders, along with their insect and crustacean arthropod cousins, have provided inspiration for a new material that is cheap to produce, biodegradable, and biocompatible. Its creators say the material, dubbed "Shrilk," has the potential to replace plastics in consumer products and could also be used safely in a variety of medical applications, such as suturing wounds or serving as scaffolding for tissue regeneration.

Arthropods have an outer skeleton made up of a composite material called cuticle that consists of layers of a polysaccharide polymer called chitin and protein organized in a laminar, plywood-like structure. In its unmodified form, which can be seen in the body wall of a caterpillar, chitin is translucent, pliable, resilient and quite tough, but arthropods are able to modify its properties to make it tough and rigid, as seen in the body wall of a beetle, or to make it elastic, as seen in arthropod limb joints. Not only does cuticle protect the arthropod's internal components and provide structure for muscles and wings, it does so without adding weight or bulk.

It was this extraordinary strength, toughness and versatility that researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University claim to have replicated with the development of a Shrilk. By recreating the unique chemistry and laminar design of arthropod cuticle in the lab, Wyss Institute postdoctoral fellow, Javier G. Fernandez and Wyss Institute Founding Director Donald Ingber were able to engineer a thin, clear film that has the same composition and structure as arthropod cuticle.

Dubbed Shrilk because it is composed of fibroin protein from silk and from chitin, the material is similar in strength and toughness to aluminum alloy, but is only half the weight. Since chitin can be extracted from discarded shrimp shells it can be produced at very low cost. It is also biodegradable and can be molded into complex shapes. By controlling the water content in the fabrication process, the researchers were also able to vary the stiffness of the material, ranging from elastic to rigid.

The researchers say that these attributes make Shrilk suitable for a wide range of applications, including providing a cheap, environmentally safe alternative to plastic, and for making garbage bags, packaging, and diapers that degrade quickly. Since it is also biocompatible and strong, it could also be used to suture wounds that bear high loads, such as hernia repair, or as a scaffold for tissue regeneration.

"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," said 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."

The Wyss Institute team's research findings were published this week in the online issue of Advanced Materials.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
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7 Comments

If you're interested in the science behind the article, you can read the original paper for free at http://dx.doi.org/10.1002/adma.201104051 .

Dave Flanagan

Advanced Materials

Facebook User
15th December, 2011 @ 01:20 am PST

I'm surprised there aren't more companies trying stuff like this. I wish them the best of luck with their research. I hope this will actually end up in production, rather than just filling the pages of online design magazines.

mommus
15th December, 2011 @ 04:02 am PST

Hopefully this would not trigger shellfish allergies for people who have them.

Jon A.
15th December, 2011 @ 09:16 am PST

Useful concept, neat idea. Much like the idea of using cockroach exoskeleton material for making spacesuits, described five years ago in the high-tech sci fi novel "Building Up" (by J E D Cline) Blog post http://kestsgeojedc.blogspot.com/2011/12/welcome-feeling-when-ones-ideas-are.html or go to http://www.kestsgeo.com/2sciencefiction/buildingup.html to read the novel, particularly Ch 11, 12 and especially Ch 16. Although in the story, the insect exoskeleton material was utilized for making things like spacesuits only because of being in a desperate situation, the subject article points out advantages even in normal circumstances.

Jim Cline
15th December, 2011 @ 02:47 pm PST

I would be more trusting if it didn't come from Harvard or one of the other Ive league university.

Slowburn
15th December, 2011 @ 03:16 pm PST

"I want to say one word to you. One Word. Plastics"

Tom Phoghat Sobieski
16th December, 2011 @ 06:36 am PST

Twice as strong as aluminum, flexible or rigid, and biodegradable! I hope it does replace plastics because all the plastic junk floating in our oceans now does not degrade, it just breaks up into smaller and smaller pieces and is getting into the food chain. There is no nutrition in plastic so when animals eat it, their health goes down for various reasons. One reason, if not passed out of their system, like in the gullets of sea birds, they can starve because it takes up space. Another reason is the chemicals absorbed by the animals. Kudos to conscientious fishermen the world around that are picking up this flotsam and depositing it in containers provided by governments then disposed of properly.

Will, the tink
21st December, 2011 @ 04:54 pm PST
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