'Smart' materials get smarter with ability to better control shap...( AUSTIN TexasA dynamic way to alter t...)

AUSTIN, TexasA dynamic way to alter the shape and size of microscopic three-dimensional structures built out of proteins has been developed by biological chemist Jason Shear and his former graduate student Bryan Kaehr at The University of Texas at Austin.

Shear and Kaehr fabricated a variety of detailed three-dimensional microstructures, known as hydrogels, and have shown that they can expand and bend the hydrogels by altering the chemistry of the environment in which they were built.

Hydrogels have been in development over the last couple of decades and are being used as parts in biology-based microdevices and medical diagnostic technologies, for drug delivery, and in tissue engineering. But the future utility of these "smart materials" relies on finding better ways to control their conformation.

Shear and Kaehr's work lays the foundation for more precise control of hydrogels. Among many applications, Shear says they will have the ability to better grow bacteria with the aim of understanding disease.

"This provides a significant new way of interacting with cultured cells," says Shear, an associate professor of chemistry and biochemistry. "The microstructures can be used to capture individual cells, and once isolated, clonal colonies of those cells can be grown and studied."

Their research appears in a paper published July 1 in Proceedings of the National Academy of Sciences.

As a proof of concept, the researchers built a rectangular house-like structure with a roof in which they trapped and then released E. coli bacteria. The bacteria blundered into the house through a funnel shaped door, where they found themselves trapped in a ring-shaped chamber. The funnel made it difficult to get out of the house.

Once inside, "they moved around the space like they were running around a racetrack," says Shear.

When the researchers increased the pH of the cell culture, the chamber changed vo
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