200730 bigfin reef squid prev

Self-heal like a squid

US and German researchers have developed a self-healing material inspired by squid ring teeth protein. Yes, you read that correctly.

Not your usual inspiration for new technology – a bigfin reef squid (Sepioteuthis lessoniana). Credit: Sirachai Arunrugstichai / Getty Images

The biosynthetic polymer could, they say, be used to repair materials that are under continual repetitive movement such as robotic machines, prosthetic legs, ventilators and personal protective equipment like hazmat suits.

Squid ring teeth are circular predatory appendages on the suction cups of squid that are used to grasp prey. If the teeth break, they can heal themselves. The soft parts in the proteins help the broken proteins fuse back together in water, while the hard parts help to reinforce the structure and keep it strong.

The researchers – from Penn State University, US, and the Max Planck Institute for Intelligent Systems – produced high-strength synthetic proteins that mimic nature by using a series of DNA tandem repeats made up of amino acids produced by gene duplication.

Tandem repeats are usually short series of molecules arranged to repeat themselves any number of times. The researchers manufactured the polymer in standard bacterial bioreactors.

“If you cut this polymer in half, when it heals it gains back 100 percent of its strength,” says Penn State’s Melik Demirel, co-author of a paper in the journal Nature Materials.

Self-healing materials aren’t new but current strategies have significant limitations, the researchers say, including loss in functionality and long healing times.

“We were able to reduce a typical 24-hour healing period to one second, so our protein-based soft robots can now repair themselves immediately,” says Max Planck’s Abdon Pena-Francelsch. “In nature, self-healing takes a long time. In this sense, our technology outsmarts nature.”

The polymer heals with the application of water and heat, but the researchers say light would also work.

And it will biodegrade, just like a squid. Or, with the addition of an acid like vinegar, it could be recycled into a powder to manufacture more soft, self-healing polymer.

The Royal Institution of Australia has an Education resource based on this article. You can access it here.

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