Our bodies build remarkably complex structures from tiny protein fibers, forming tissues, tendons, muscles, and organs. Scientists can recreate many of these biological building blocks in the lab, but controlling how they organize themselves into larger assemblies remains one of the most fundamental challenges in soft materials research.

Georgia Tech’s Itamar Kolvin is aiming to solve that problem using molecular motors powered by tiny chemical reactions, giving researchers a new way to guide how fibers assemble into larger structures in the lab. The work could open the door to advances in wound healing, artificial tissues, and organ repair.

Now, Kolvin, an assistant professor in the School of Physics, has been awarded a $747,000 CAREER grant from the National Science Foundation (NSF) to support this research.

The NSF Faculty Early Career Development Program is a five-year grant designed to help promising researchers establish a foundation for a lifetime of leadership in their field. Known as CAREER awards, the grants are NSF’s most prestigious funding for early-career faculty.

“The CAREER award is a crucial opportunity to push this research forward,” says Kolvin. “NSF plays a critical role in advancing science, and we wouldn’t be able to do our work without their support. I’m incredibly grateful for their commitment to advancing science.”

Microscopic Motorboats

While the body naturally assembles these fibers, their small size makes protein filaments difficult to control in a lab setting. Without guidance, the materials grow randomly, creating weak and disorganized structures. But Kolvin has found that exposing the filaments to controlled fluid flows can help them grow in predictable ways.

That’s where Kolvin’s molecular motors come in. He attaches the motors to rod-shaped particles called microtubules, transforming the otherwise inert particles into microscopic motorboats. Powered by chemical reactions, the microtubules move through the fluid and generate tiny currents. Those currents guide the suspended protein filaments, directing how they align and assemble.

Like sticks in a stream, the current helps the protein filaments align with the flow around them. When millions of filaments interact in this way, they can form bundles, clusters, and large-scale networks. 

“How do these rods align, when do they tangle, and when do they form networks?” Kolvin asks. “I’m interested in learning how we may be able to predict and ultimately control that behavior in order to direct the ways these structures can grow.”

Flexible Filaments

Kolvin’s earlier work has already shown success with actin, the filaments responsible for building muscles. When suspended in fluid, the molecular motors helped actin fibers bundle together and form a membrane-like structure. 

While that work demonstrated that molecular motors could influence assembly, Kolvin now aims to create a more dynamic, tunable system. Actin is limited, he explains, because of its simple rod-like shape, lack of rigidity, and because its bonds become permanent once the fibers bundle together.

He believes the more rigid, helix-shaped flagella in this new work will offer a wider range of opportunities. “The shape and rigidity of flagella expand the variety of patterns they can form,” he explains. “These new structures could have different applications.”

Toward Tunable Materials

Through molecular engineering, the Kolvin Lab creates flagella that are temperature-sensitive, meaning that they can make and unmake bonds at different temperatures. This property might be key in creating a system that could be assembled and disassembled on demand.

“This could make it possible to tune materials in real-time by warming or cooling the system," Kolvin explains.

By combining molecular motors with temperature-sensitive protein fibers, Kolvin aims to create systems that can be predictably shaped, assembled, and disassembled on demand, opening the door to new possibilities for tissue engineering and regenerative medicine. 

The work could also help answer long-standing problems in physics about active matter and collective behavior, revealing how flow and shape influence the way millions of microscopic building blocks align, pack, and assemble into complex materials.

“This CAREER award provides an exciting opportunity to pursue new ideas and tackle difficult, far-reaching questions,” Kolvin says. “I’m looking forward to seeing where this research leads in the years ahead.”