Phil Messersmith Writes Perspectives Piece For Science

March 28, 2008

If anyone knows Dopa, it’s Phil Messersmith. Messersmith, professor of biomedical engineering at McCormick, used a mimic of the amino acid Dopa (officially called 3,4-L-dihydroxyphenylalanine) in creating Geckel, an adhesive that mimics the properties of both a gecko and a mussel in order to stay sticky underwater.

Messersmith has now used his Dopa expertise to write a Perspectives piece in the March 28 edition of Science, where he comments on new research and potential uses for the amino acid. In the piece, Messersmith writes about research performed by Frank Zok and others at the University of California-Santa Barbara that shows how Dopa participates in building structural tissues.

The group studied squid beaks, which a squid uses to penetrate the soft tissue of its prey. After measuring the amount of Dopa in different tissues around the beak, the group found that Dopa is intimately involved in the formation of mechanical gradients in tissues.

The beak, like many other materials in nature, utilizes a gradient of rigidity between a hard tissue and a soft tissue. The gradient solves a common material problem: If you try to match up a rigid tissue with a soft tissue without blending the hardness of the tissue in between, the interface is very weak. So nature uses gradients to make those connections stronger.

A common example is the tooth — the outside of a tooth, the enamel, is very hard. But the inside of the tooth, the dentin, is soft. In between, there is a very small gradient where the materials blend in order to bind the two materials together. A squid’s beak isn’t as hard as a tooth, but it is made up of a very rigid material. That beak is supported by the soft tissue of the squid through a large gradient of tissue.

“What’s new is what role the protein that contains Dopa has in forming this mechanical property gradient,” Messersmith says. The hardest part of the beak tissue contains the most protein content, while the softest part contains the least. What role Dopa plays in forming the tissue’s mechanical properties still needs to be determined. But what’s interesting to Messersmith is how information from such studies can be used in designing materials.

“There seems to be a rapidly growing interest in the use of Dopa and Dopa-like compounds to build materials in a variety of ways,” he says. “If you look at the literature in the last five years, there’s an emergence of papers on material applications of Dopa, and a lot of them are inspired by research like this.”

Besides Messersmith’s Geckel, Dopa has been used to coat materials, to add medicine to nanoparticles, and to create synthetic polymers for use as industrial or medical adhesives. “I think it was the right time to write a perspective on these uses and the possibilities that come around from new research,” Messersmith says.