Granick Casts A Wide Research Net

Schematic representation that single-particle fluorescence tracking shows surprisingly non-classical, non-Gaussian statistics combined with mundane Fickian displacement when colloidal beads diffuse not only on phospholipid tubes but also when they diffuse through networks of actin filaments. Image courtesy of Rui Lu and Bo Wang.

Steve Granick is a professor in four different departments at the University of Illinois, a member of the Beckman Institute’s 3-D Micro and Nanosystems group, and leads a research group that embodies the term interdisciplinary. Yet his research has a very simple theme: “To understand everyday life.”

The Granick Research Group has a multidisciplinary membership and addresses a wide variety of scientific problems, but its methods, solutions, and even its mission as described by group leader Steve Granick often have the element of simplicity.

For example, a 2011 Nature paper from the group reported on the development of a new class of complex, self-assembling materials called Janus spheres that were described by Granick as “a big step forward in showing how to make non-trivial, non-obvious structures from a very simple thing.”

The Granick Research Group includes Ph.D. students from materials science, chemistry, physics, and engineering, coming together to study problems that are, as Granick writes, “at the interface” of these areas, especially as they apply to soft materials and surface level molecular interactions. Maintaining research interests in these varied areas and investigating topics involving polymers, water, complex fluids, thin films, lipids, and other soft materials certainly appears multifaceted.

“It’s all over the place,” Granick said with a smile. Perhaps, but he also says there is a simple, unifying theme underlying the research pursued in his interdisciplinary lab: “To understand everyday life.”

Those everyday life questions and their sometimes simple solutions are part of work in Granick’s group that has often been remarkable. They have challenged the physics textbooks when it comes to Brownian motion, framed the discussion around hydrophobicity, and created those self-assembling spheres that have the ability to form useful structures. It’s a varied research environment in their lab – which is just how Granick likes it.   

“To me it’s like travelling around the world,” he said. “Some people just like to go to a different country every few years, and I feel that way about scientific problems.”

To me (research is) like travelling around the world. Some people just like to go to a different country every few years, and I feel that way about scientific problems.
– Steve Granick

Granick, who came to Illinois in 1985 for his first faculty position, is a professor in the departments of Chemistry, Chemical and Biomolecular Engineering, Physics, and Materials Science and Engineering. He is also a member of the Beckman Institute’s 3-D Micro and Nanosystems group. He earned a Ph.D. in physical chemistry from the University of Wisconsin-Madison, and had a postdoctoral position with Nobel Laureate in Physics Pierre-Gilles de Gennes in France; both experiences, he said, continue to influence his work to this day.   

The Granick group’s research interests are in the areas of single-molecule methods, polymers, complex fluids, and biomaterials, using methods of physical, analytical, and materials chemistry to study molecules at surfaces. There is more uniting this group, however, than trying to gain an understanding of everyday life. There are the properties of the materials systems that the group works on, as well as the students and others from different disciplines in the lab who come together to make the research happen.

“What ties it together is that the rules of complicated systems with interactions are not so different in all those different systems, and having students who are curious about the world,” Granick said. “It’s very productive to have students working on what seem like different projects but come to the lab together, drink coffee together, have lunch together, watch what the others are doing, and then comment and push each other forward because of that interdisciplinary environment.”

Granick said teaching and mentoring young scientists is central to his work. 

“I enjoy seeing people live up to their potential,” he said. “Sometimes you feel that, because they were in the right situation, they take a different path, and then go forth and make contributions to the world that might not have happened otherwise.”

It is an approach to doing research that has led to notable discoveries in theoretical physics, materials science, and chemistry, among other areas.

“That’s always there, but it doesn’t come from me sitting in the office and giving work orders to a team of workers who will then carry them out,” Granick said. “It’s much more effective and fun when everyone contributes.”

Those contributions have resulted in many important papers and discoveries over the years. Several of those have revolved around the lab’s research involving hydrophobic (water repellent) and hydrophilic (water attracting) surfaces. Beginning with a paper published in Science in 2002, followed by another in that publication in 2008 and again this year, Granick and his collaborators have provided new insight into the hydrophobic effect while also developing a new class of “smart materials” based on their findings.

Granick and his co-authors wrote in the 2002 paper about the Janus effect (based on the Roman dual-nature God with two faces pointing in opposite directions), in which water was confined between hydrophobic and hydrophilic surfaces, and about their finding of a fluctuating effect that is peculiar to water in that environment compared to other fluids. They eventually took advantage of the Janus effect (as reported in the 2011 Science paper) in the development of helical “supermolecules” based on small latex spheres dubbed Janus spheres. The ability of these spheres to attract water on one side and repel it on the other enabled self-assembly into clusters, or supramolecules, that are useful for creating small-scale structures.    

“We found a way to take something that everybody knows about – everybody has a raincoat and an umbrella and knows about hydrophobicity – and take it beyond that qualitative state,” Granick said. “Since then we have taken advantage of this hydrophobic attraction to make non-trivial, beautiful structures between small particles.

“We use the hydrophobicity not as a problem to understand, but as a tool to provide a weak attraction. What you find is that very simple motifs can form structures that you would have thought would be hard to make.  If you start with these building blocks, we discovered that this weak attraction, which we knew from the other work, was enough to guide the structures into these complicated patterns.”

 The group also reported in that Nature paper in 2011 on their development of triblock Janus spheres with three stripes of reactivity and a simplicity that makes them ideal for manufacturing purposes. They used the triblock Janus spheres to create lattice structures that could potentially be used as filters.

Much of his group’s recent success, Granick says, can be traced to advances in microscopy and other imaging modalities they use, thanks to teaming with research scientist Chul Bae. An example involved a discovery about the protein actin that gave new insight into the “Conga line” movements of this protein and the role it plays in cellular structure and in important processes such as cellular signaling and transport. They reported their findings in Physical Review Letters, along with co-author Kenneth Schweizer from Materials Science and Engineering.

By using single-molecule fluorescence imaging, and a sparse fluorescent labeling technique, they created a simple, direct method for following the movements of the molecules as they formed filaments critical to cell structure and processes. They discovered that the filaments behaved much differently than previously thought, forming long chains that moved like a conga line, rather than the snakelike movement that had been previously used to describe their actions in forming the matrix needed for cell structure. The researchers tagged individual links in the molecular chain with a fluorescent dye and tracked their motion as they would individual dancers in a conga line. What they found was the filaments moved not as though they were in a cylinder as previously thought but more freely and sometimes more tangled up through the empty spaces of the matrix, illuminating cellular biology as well as issues such as polymer entanglement that are found in the manufacturing of plastics.

Another project provided new thinking on a famous theory of Albert Einstein. In a 2008 paper with Bo Wang, Stephen M. Anthony and Bae from his lab, Granick wrote about Brownian motion and its role in the movements of a liquid as its diffuses through another material. They showed that Brownian motion can best be described with greater extremes than the traditional bell-shaped curve model.

Granick has also collaborated with other Beckman faculty members over the years, including Paul Braun, Jeff Moore, and John Rogers. Granick said the ability to have the kinds of working partners he has had at Illinois is one reason he has spent his entire career as a faculty member here.

“It’s a great research university. What has kept me here is its breadth and its depth,” Granick said. “It continues to attract great people in a lot of areas, which is very stimulating.”

And he plans to keep on working at the interface of those areas

“It’s a lot of fun to work in different areas,” Granick said. “Sometimes it makes more work because you have to talk to more people, read more journals and go to different kinds of meetings. But the bonus makes it all worthwhile.”