UChicago, Yale scientists look to living cells to develop novel self-actuating materials

Scientists from the University of Chicago and Yale University will collaborate on a new $6.25 million project intended to create novel, biologically inspired synthetic materials that can generate and respond to forces in the same way that cells do. Such materials could autonomously stiffen, change shape or self-heal in response to mechanical forces.

The five-year project will look closely at how biological cells sense mechanical cues from their environment and respond to those cues chemically. The team will use its findings to create, for example, a synthetic material that uses molecules from cells to move, compress or stretch itself in response to force.

“For over 50 years, cellular and molecular biologists have investigated what molecules are important to cells generating and measuring force,” said Eric Dufresne, PhD’00, associate professor of mechanical engineering and materials science at Yale and co-principal investigator. “We’re taking the next step by investigating how these molecules work together, and then we’re building artificial materials that could be used, say, for wound healing or for soft actuators in robots.”

According to the researchers, such materials would have unique ways of responding to force, with one potential material able to change shape and self-assemble in response to mechanical forces.

“Consider, for example, a rubber band, which will break if you stretch it too far,” said Margaret Gardel, associate professor in physics at UChicago and principal investigator of the research. “But if you stretch this material like that, it would respond to the force by converting more molecules into polymers, thereby growing in length.”

In addition to developing the proposed synthetic materials, the team also will further the scientific understanding of how cells sense mechanical forces and respond to those forces with chemical activity, a process known as mechanotransduction. According to the researchers, the process—which is the basis for our sense of touch, balance and hearing—is not fully understood, despite years of interest.

The team will examine mechanotransduction through a specific focus on integrin, a type of protein receptor in the cell membranes that facilitates communication between the cell and the outside world. Integrin plays a key role in helping a cell adhere to the structural proteins outside the cell that provide scaffolding for the body’s organs, bone and cartilage. Integrin also communicates inside the cell with actin, a protein that is essential for cell motility and cell division.

“We still have lots of unanswered questions about actin and actin-binding proteins,” said David Kovar, associate professor of molecular genetics and cell biology at UChicago and co-principal investigator. “I’m particularly excited about applying forces to the cell’s actin filaments, something that we will be able to do through this collaboration.”

The benefits of such collaboration were recognized by the team’s funding award from the U.S. Department of Defense’s Multidisciplinary University Research Initiative, a program that seeks to accelerate both research progress and translational application by supporting teams of investigators that intersect more than one traditional science and engineering discipline.

“Collaborative science, while always wonderful, often emerges out of need,” said Enrique De La Cruz, professor of molecular biophysics and biochemistry at Yale and co-principal investigator. “But this project resulted from common interests and desires. The goals of this research would be unattainable working in isolation.”

Ultimately, the researchers will construct materials with targeted chemical responses in response to force. In addition to the material that grows when stretched, the researchers will also develop a material with force-activated chemical pathways that respond differently to different modes of force, such as pulling versus compressing. The result would be a chemically driven, on/off switch that could be used in cutting-edge robotics.

“The targeted mechanical activation observed in biology would bring an exciting level of control to synthetic material systems that is unattainable using current approaches,” said David Stepp, chief of the Army Research Office’s Materials Science Division. “The research effort needed to realize this new control regime requires a coordinated and comprehensive program that spans biology, biochemistry, chemistry, materials science, computer science and synthetic biology.”

“Understanding the basic principles of mechanotransduction will be a major contribution not only to biology but to science as a whole,” said Martin Schwartz, the Robert Berliner Professor of Medicine at Yale and co-principal investigator. “I'd be pretty excited if we only uncovered new principles, but we’re in fact going beyond that to see if these principles can be applied to creating a new material.”

Gregory Voth, the Haig P. Papazian Distinguished Service Professor in Chemistry at UChicago, is also a co-principal investigator for the research.