Applications Abound for Nano Field
“If you ask 10 people what I study, you may get 10 answers,” says Krystyn Van Vliet. That’s because the general phenomenon she explores — how a material’s mechanical properties, such as stiffness, can affect its chemistry, and vice versa — is applicable to so many disciplines. Van Vliet’s work has already, for example, led to important insights on everything from the formation of blood vessels to the structural dynamics of cement.
Key to her approach: studying these chemomechanical interactions at the nanoscale, or billionths of a meter.
Van Vliet, the Paul M. Cook Career Development Associate Professor of Materials Science and Engineering and Biological Engineering, is at the forefront of a relatively new field called chemomechanics. The tools that can probe materials’ mechanical properties at the most basic level of atomic features have been around only since the early 1990s.
Van Vliet recalls needing to travel to Lawrence Livermore National Lab to run experiments for her MIT doctorate because the Institute didn’t have the equipment. Now, she’s faculty director of the Department of Materials Science and Engineering’s NanoMechanical Technology Laboratory, “which is filled with these machines.”
Van Vliet first used these tools, coupled with computer simulations, to show how a stress or force can initiate a defect in an otherwise perfect crystal of metal. Such work is important as devices get smaller and smaller — a seemingly minuscule flaw can compromise their performance.
She’d always had a strong interest in biology, however, so before joining the MIT faculty she spent her postdoc years in a lab at Children’s Hospital. “I felt that there were measurements I could take down at the nanoscale to explore how mechanics might affect cancer biology and
vascular biology,” she says. “I don’t pretend that I knew how I was going to do that, but it seemed like it should be possible.”
She succeeded, and biology is now a major focus of Van Vliet’s lab. “Small changes in the chemistry of the interface [between a cell and the material it is next to] can affect the mechanical adhesion of the cell to that material, for example,” says Van Vliet. Similarly, “small changes in the mechanics, like the fact that the periphery of a tumor is stiffer, can change the biochemistry — how quickly, for example, enzymes can affect the speed of certain reactions.
“It’s that back-and-forth between chemistry and mechanics that interests me,” she says.
Among other advances, she and colleagues have shown how certain cells surrounding capillaries may use mechanical forces — contractions — to initiate angiogenesis, or the growth of new blood vessels, a process key to wound healing and the growth of cancerous tumors. The team is currently exploring how these contractions affect the growth rate, shape, and chemical secretions of the cells key to angiogenesis.
Van Vliet emphasizes, however, the range of projects in her lab. These include not only studies of cells, but of inorganic materials like new scratch-resistant coatings for cars, and even polymer nanocomposites that replicate the mechanical response of real human tissues. So, for example, the Army could develop a new protective garment without testing on a live body.
“So many amazing discoveries have been made at MIT,” says Van Vliet. “It’s inspiring just to be around all that history of great thinking and enthusiasm for learning.”