Potential as a Smart Material

Photo: A pea pod

Amy Shen, Ph.D., assistant professor of Mechanical and Aerospace Engineering, and colleagues are trying to understand a novel plant protein structure called forisome. Shen and Pickard are probing the biomechanical properties of the forisome, which, in a variety of plants, responds to injury by swelling up in reaction to an increase of calcium. The swelling of the proteins within transport cells protects the plant from hemorrhaging nutrients. Once the danger passes, the forisomes go back to their original shapes.

The goal is to understand the system well enough to enable future collaborators to develop a chemically stable artificial forisome - a non-living system that can integrate functions such as sensing, acting and logic in response to external stimuli. Such a smart material would be biomimetic. One of the best examples of a natural system whose behavior researchers would like to synthesize - a biomimetic - is the famed Venus flytrap.

Forisome is particularly attractive as a biomimetic smart material because, unlike most protein motors, it is not dependent on adenosine triphosphate (ATP) for its activation, making it more flexible. Shen used a microfluidic device - a soft lithography system of micro-channels embedded in fluids, so small it fits in the palm of a hand - to see how the forisome proteins would react to changes in calcium, pH and the hydrodynamic environment itself.

Shen and her collaborators found that they could induce swelling easily as well as reverse the swelling in the device, rather more easily than other systems used previously to study the proteins. "We're interested in the kinetics of the forisome proteins," Shen said. "We wanted to see how fast they change shape and also their potential as a smart material. We intend to do other experiments that might reveal the durability and actuation kinetics of forisomes."

COMPAMED.de; Source: Washington University in St. Louis