Looks Like Jello, Works Like Cartilage

Replacement Part?

March 21, 2008 -- It may not look like much, but a slippery, Jello-like material developed by scientists in the United States and Japan could soon be improving everything from artificial joints to contact lenses.

The material is a hydrogel, and as the name implies, is made mostly of water. But it's also surprisingly resilient.

"Most hydrogels are like gelatin; you touch them and they break into pieces," said Wen-li Wu, a scientist at the National Institute of Standards and Technology and an author of the new study.

"What we are talking about is a gel that you can squeeze as hard as you can, but it's still slippery," he said.

Produced from materials that are cheap and readily available, the hydrogel is held together by two polymers. The first is a charged solid that clings to a second, uncharged liquid polymer. If a crack develops in the solid polymer, the liquid polymer flows into the defect and essentially heals it.

The hydrogel is clear and as slippery as natural cartilage -- an improvement over current materials used in artificial joints. The hydrogel is also softer and more resistant to wear than current materials, say its makers.

"It will definitely absorb more shocks than current materials," said Wu.

The research builds on a 2003 study from the lab of study collaborator Jian-Ping Gong at Hokkaido University in Japan.

Since it is resistant to the build-up of proteins, the hydrogel could also be used for contact lenses and artificial corneas, among other applications.

Studies in animals have proved promising, but there are currently no clinical trials underway to evaluate the hydrogel's use in humans.

"It's an excellent material, very tough," said Curt Frank, a scientist at Stanford University who works on hydrogels but was not involved in the NIST work.

"The hydrogel's properties are very comparable to human tissues and have the potential to create a device that could replace human tissue," he said.

The research was presented at the March meeting of the American Physical Society.

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