Harvard University engineers have created a tough, extremely stretchy artificial gel that may soon be used to replace damaged cartilage in human joints and spinal discs.
The new “hydrogel” – developed by a team of mechanics, materials science specialists and tissue engineers – stretches to 21 times its length, recoils, and can heal itself, according to a report on the material published in the journal Nature. Tests of the gel found it is also “biocompatible” – meaning the body’s immune system won’t reject or attack it – and it is much tougher than human cartilage.
"Conventional hydrogels are very weak and brittle – imagine a spoon breaking through jelly," explained lead researcher Jeong-Yun Sun, with the Harvard School of Engineering and Applied Sciences.
"But because they are water-based and biocompatible, people would like to use them for some very challenging applications like artificial cartilage or spinal disks. For a gel to work in those settings, it has to be able to stretch and expand under compression and tension without breaking."
Called a hydrogel, because its main ingredient is water, the new material is a hybrid of two weak gels that were combined to create a stronger one. The primary component is polyacrylamide, used in soft contact lenses, and alginate, a seaweed extract used to thicken food.
Beyond artificial cartilage, the researchers suggested that the new hydrogel could be used in soft robotics, optics, artificial muscle, as a tough protective covering for wounds, or "any other place where we need hydrogels of high stretchability and high toughness."
The research was funded, in part, by the U.S. Army Research Office, the National Science Foundation, the Defense Advanced Research Projects Agency, and the National Institutes of Health.