You probably don’t give a lot of thought to squid beaks, but they actually possess a pretty interesting quality. While the end of the beak is hard and sharp, the beak material gradually becomes softer as it nears the mouth. This means that there’s no abrupt boundary between the hard beak and the soft mouth, which could result in discomfort or injuries. Inspired by the squid, scientists at Ohio’s Case Western Reserve University have now developed a material with the same qualities, that could be used to create more comfortable, less harmful medical implants.
The natural squid beak is composed of a nanocomposite material, made up of “a network of chitin fibers embedded within increasingly cross-linked structural proteins from mouth to tip.” While that gradient is present even when the beak is dry, it’s particularly apparent when it’s wet – and squid beaks tend to be wet a lot.
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To make their beak-like material, the scientists started with another material that they had created previously. Based on the skin of the sea cucumber, that material is hard when dry, yet soft when wet.
They took some of that material, in film form, and added functionalized cellulose nanocrystals. Those nanocrystals form cross-links when exposed to light – the greater the exposure, the higher the number of links that form. By progressively exposing the film to more and more light along its length, they were able to make it rigid at one end, while gradually becoming softer towards the other end.
Like the natural squid beak and the artificial sea cucumber skin, the new material’s qualities turned out to be most pronounced when wet. Given that the inside of the human body is a wet place, it’s hoped that the material could be used in the creation of implants such as abdominal feeding tubes, prosthesis attachment points, and anything else in which body tissue presses against man-made material. Presently, the conflict between soft biological tissue and hard implants can lead not only to discomfort, but even to the breakdown of the biological tissue.
The research was led by Prof. Stuart J. Rowan, and is described in a paper published this week in the Journal of the American Chemical Society.
Source: Case Western Reserve University