Tough webs

What do you get when you cross goat's milk and spiderproteins? Bullet-proof biosteel

Published: Tuesday 15 December 1998

Biosteel: tougher than spiderm IT is tough, non-toxic and green. It is Biosteel. By borrowing a little from genetic as well as plain engineering, researchers in Quebec, Canada, have developed this incredibly light fabric that is both biodegradable and strong enough to stop bullets. If all goes as planned, biosteel - made by lacing goat's milk with specially-synthesised proteins found in spiders - could soon become a green alternative to high-strength plastics.

But right now, there is one catch. Jeff Turner, president of Quebec's Nexia. Biotechnologies, says the biodegradable fabric would have to be sealed off from the environment if in critical applications, such as body armour or spacecraft. Otherwise, he warns, bacteria could get in and 'eat' it up.

Turner's team has already taken the first step towards creating biosteel by transferring the spider gene for the protein into goat mammary cells and collecting soluble protein from the milk. And they expect genetically engineered goats to start producing the protein in the next few months.

While nobody has yet made a fabric from biosteel, Turner is convinced the protein can be turned into a super material because of its natural role in the silk of a spider's web. "When you think of what a web has to do, its extreme strength makes perfect sense," he says. The silken threads of the web must be nearly invisible to prey and yet be able to bring a fly to a screeching halt.

Evolution came up with a two-pronged solution. First came a rock-solid protein, capable of making many bonds with its neighbours. Then, the spider developed a unique way of spinning the protein into a whisper-thin thread. As the spider secretes the protein solution, the silk dries and pulls taut, transforming the proteins into nearly crystalline and completely insoluble cable. This explains why webs do not dissolve in the rain.

Turner and his team members decided to mimic the spider's own method of production by using goat's mammary cells. It turns out that the way mammals produce milk proteins and spiders make silk proteins are broadly similar. Both are produced in skin-like epithelial cells, then held in a space, or lumen, where shear stresses on the pro Biosteel toughen the Spider web. Biosteel goats is large enough for Nexia's scientists to collect the protein they need to start making fabric. Then they will face the next great hurdle: how to match the spider's spinning skill. "Nature probably took a long time to get this process right," he says. "And I think the same will be true for us."

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