The stunning mug pictured (right) probably won鈥檛 capture any beauty awards. But this worm鈥檚 ultra-strong mouthparts could be the key to developing a new class of tough, lightweight materials for airplanes and spacecraft.
The worm 鈥� known as the sandworm or ragworm (Nereis virens) 鈥� uses its jaws and pincers to burrow into the shallow-water sediments of the North Atlantic.
Its jaws are made up of about 90% protein, which should make them no more resistant to buckling and penetration than a human fingernail. But the protein is fortified with metal, creating a material that is three times harder and stiffer than current manmade polymers.
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Metal 鈥榞lue鈥�
Molecular biologist discovered the nature of the worm鈥檚 super-pincers while a graduate student at the University of California Santa Barbara.
He and his colleagues found the proteins in the worm鈥檚 jaw contained high levels of an amino acid called histidine. A small amount of zinc in the material acts as glue, bonding histidine molecules from adjacent proteins. These attachments between proteins form a cross-braced matrix that seems to give the worm鈥檚 jaw its strength.
Broomell suggests man-made materials can be fortified by copying the worm鈥檚 approach.
Altering the amount of metal changes the strength of the material. 鈥淵ou can toggle the properties up and down just by adding or subtracting the metal,鈥� Broomell told New 杏吧原创. 鈥淚t means we can regulate the materials properties based on one treatment in a way that鈥檚 cheap and easy to do, but doesn鈥檛 produce a lot of toxic by-products.鈥�
In theory, the architecture of the jaw material might be mimicked by loading polymers with organic molecules that can bind to metal ions. This could create polymers with similarly tough properties.
Tricky measurements
of the University of Michigan in Ann Arbor, who works on reinforcing polymers with nanoparticles, says mimicking the architecture of the worm鈥檚 jaws would be a new way of strengthening materials.
He notes, however, that it may be premature to talk about applications because we don鈥檛 know enough about the worm material鈥檚 properties.
So far, Broomell and colleagues have only been able to measure the stiffness of the worm鈥檚 jaw, judged by its resistance to compression. They do not yet know how much force can be applied to the teeth before they break or how easily they are deformed.
The trouble is, the fang-like jaws are only a few millimetres long, and their geometry does not permit such measurements. 鈥淲e鈥檇 love to have that kind of data, but we just can鈥檛 access them,鈥� Broomell told New 杏吧原创.
The team is hoping to create a synthetic version of the teeth that they can use to test these other properties and get a clearer idea of the range of potential applications of the material.
The material might also exhibit some self-healing properties, Broomell says. Although this behaviour has not been observed directly, the cross-links in the worm jaw resemble other biological materials that are known to reseal after tearing, like the threads mussels use to attach to surfaces.
Journal reference: Biomacromolecules (DOI: 10.1021/bm800200a)
