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Chemical and Biomolecular Engineering

Researchers at the University of Illinois and the University of Massachusetts, Amherst have taken the first steps toward gaining control over the self-assembly of synthetic materials in the same way that biology forms natural polymers. This advance could prove useful in designing new bioinspired, smart materials for applications ranging from drug delivery to sensing to remediation of environmental contaminants.

Proteins, which are natural polymers, use amino acid building blocks to link together long molecular chains. The specific location of these building blocks, called monomers, within these chains creates sequences that dictate a polymer’s structure and function. In the journal Nature Communications, the researchers describe how to utilize the concept of monomer sequencing to control polymer structure and function by taking advantage of a property present in both natural and synthetic polymers – electrostatic charge.

(from left) Charles Sing, professor of theoretical and computational polymer physics; graduate student Jason Madinya; and graduate student Tyler Lytle.
Inspired by the principles of natural polymer synthesis, Illinois chemical and biomolecular engineering professor Charles Sing, left, and graduate students Jason Madinya and Tyler Lytle co-authored a study that found they could create new synthetic materials by tuning the electrostatic charge of polymer chains. Photo by L. Brian Stauffer

“Proteins encode information through a precise sequence of monomers. However, this precise control over sequence is much harder to control in synthetic polymers, so there has been a limit to the quality and amount of information that can be stored,” said Charles Sing, a professor of chemical and biomolecular engineering at Illinois and a study co-author. “Instead, we can control the charge placement along the synthetic polymer chains to drive self-assembly processes.”

Sarah Perry, a study co-author and professor of chemical engineering at the University of Massachusetts, Amherst. She also is a Chemical Engineering alumnus (PhD ’10, Kenis) of Illinois.

“Our study focuses on a class of polymers, called coacervates, that separate like oil and water and form a gel-like substance,” said Sarah Perry, a study co-author and University of Massachusetts, Amherst chemical engineering professor, as well as an Illinois alumna. She received her PhD in 2010, advised by Dr. Paul Kenis.

Through a series of experiments and computer simulations, the researchers found that the properties of the resulting charged gels can be tuned by changing the sequence of charges along the polymer chain.

“Manufacturers commonly use coacervates in cosmetics and food products to encapsulate flavors and additives, and as a way of controlling the ‘feel’ of the product,” Sing said. “The challenge has been if they need to change the texture or the thickness, they would have to change the material being used.”

Sing and Perry demonstrate that they can rearrange the structure of the polymer chains by tuning their charge to engineer the desired properties. “This is how biology makes the endless diversity of life with only a small number of molecular building blocks,” Perry said. “We envision bringing this bioinspiration concept full circle by using coacervates in biomedical and environmental applications.”

The results of this research open a tremendous number of opportunities to expand the diversity of polymers used and the scale of applications, the researchers said. “Currently, we are working with materials on the macro scale – things that we can see and touch,” Sing said. “We hope to expand this concept into the realm of nanotechnology, as well.”

The National Science Foundation and the U. of I. Graduate College supported this research.

Written by Lois Yoksoulian, Physical Sciences Editor, University of Illinois News Bureau

To reach Charles Sing, call 217-244-6671; cesing@illinois.edu.

To reach Sarah Perry, call 413-545-6252; perrys@engin.umass.edu.

The paper “Sequence and entropy-based control of complex coacervates” is available online and from the U. of I. News Bureau. DOI: 10.1038/s41467-017-01249-1

Understanding various chemical reactions and transport phenomena from the molecular and electronic level; designing new synthetic pathways for radical forms of materials and medicines; characterizing and rationalizing the behavior of matter far away from equilibrium—these are just a few of the grand scientific and engineering challenges that the newest research group in the Beckman Institute aims to tackle.

By bringing together various research efforts across campus and leveraging outstanding resources at Illinois, such as the Computational Science and Engineering (CSE) program and the National Center for Supercomputing Applications (NCSA), the group plans to lead large-scale research efforts in the area of computational molecular science that would be beyond the capability of an individual research group.

The Computational Molecular Science (CMS) Group has been established within the Molecular and Electronic Nanostructures research theme at the Beckman. Yang Zhang, a professor of nuclear, plasma, and radiological engineering, is named the founding group leader.

Along with Zhang, the other nine faculty members of the group include Charles Schroeder and Charles Sing of the Department of Chemical and Biomolecular Engineering; Narayana Aluru, of the Department of Mechanical Science and Engineering; Paul Braun, Andrew Ferguson, and Kenneth Schweizer, of the Department of Materials Science and Engineering; and Martin Gruebele, So Hirata, Nancy Makri, of the Department of Chemistry.

“Our goal is to consolidate campus-wide expertise on computational molecular science to facilitate interdisciplinary research in several strategic areas at the Beckman Institute and Illinois, and eventually establish a world-leading thrust in the frontier of theory-driven computational molecular science,” Zhang said.

CMS is profoundly interdisciplinary. It embodies physics, which underpins the underlying fundamental principles; chemistry, which both explores higher-level emergent principles and creates novel synthetic routes of remarkable organic, inorganic, bio-molecular building blocks that can self-assemble to structures with unique properties; and molecular biology and medical science, which are imperative to improve our health and quality of life.

“This group is an intellectual powerhouse with ambitious aspirations to advance important problems in molecular design thinking. Their activities cut across a number of experimental projects in the institute and so, wisely, the new CMS group integrated key experimentalists into its faculty roster,” said Jeff Moore, director of the Beckman Institute.

“The unique aspect of the CMS group is the emphasis of statistical and quantum mechanical theories-driven method development and applications,” said Zhang. “Through these computations, our ambition is to significantly extend our understanding of the equilibrium and non-equilibrium properties of matter from the molecular and electronic level, along with the creation of simulation, visualization, and analysis software packages that would become the golden standards in the field of CMS.”

The research topics of the CMS group include first-principle and semi-empirical methods, large-scale molecular dynamics simulations, advanced rare event sampling techniques, intelligent coarse graining and dimensionality reduction, and big data analysis – all targeted to advance molecular science. The impact of the work is amplified through close collaborations with experimentalists, synthetic chemists, materials scientists, and engineers.

The CMS group will synergistically collaborate with other groups, such as the Theoretical and Computational Biophysics and the Autonomous Materials Systems groups, at Beckman Institute.

The National Science Foundation has awarded a $1.2 million, three-year grant to four professors in Chemical and Biomolecular Engineering for a project that has potential to advance the frontiers of 3-D printing. Drs. Charles Sing, Ying Diao, Damien Guironnet, and Simon Rogers intend to create a platform for designing advanced materials that allows makers to tune the structure and function of a material on-the-fly.

Not long after arriving on campus, the team of investigators, each an assistant professor with a different research background and set of skills, got together to brainstorm what intriguing challenges they could solve together. Take camouflage. Camouflage is only effective as long as the person wearing it remains crouched in the jungle or standing by a sand dune in the desert. What if you had a material that could provide camouflage in many different environments, and you control how it works? Chameleons change color by adjusting skin structure at nanometer-length scales. Could humans design something similar with advanced materials processing?

“What we’re talking about is making a device, an object, instrument, from ostensibly the same material. It has different properties in different parts of the material,” Rogers said. Imagine a Lego brick that has one transparent wall, but the brick is made from all the same material. There’s one material with different properties, and the maker controls the material’s properties.

The project has two overarching goals: develop a screening method for versatile, 3-D printable block copolymer materials, which are two or more different polymer chains linked together; and screen to optimize flow-based tuning of morphology in 3-D printed materials. That entails testing their hypothesis that tuning the flow in 3-D printing will allow for on-the-fly or on-demand manipulation. Insights gained from their research could have potential applications in camouflage, antireflection coatings, metamaterials and displays.

Professors Ying Diao, Damien Guironnet, Charles Sing and Simon Rogers

For this project, each faculty member brings a distinct set of skills and expertise. Charles Sing, who works in molecular simulation and theory, will provide what he described as a treasure map. His research will guide the synthesis that occurs in the lab of Damien Guironnet, the self-described “cook.” Because Sing will be predicting some of the molecule’s properties beforehand, Guironnet will be able to synthesize the molecules that will make the polymers with the unique structure needed for the process.

From there, the material is handed over to Simon Rogers and members of his lab, who carefully control different flow conditions and investigate how the structures reorganize. Rogers then feeds information gleaned from his experiments and analysis to Ying Diao’s group. Diao will take the novel molecule and, with the knowledge of how this material reacted to Rogers’ experiments, she will attempt to make a functional material using 3-D printing.

Rogers then feeds information gleaned from his experiments and analysis to Ying Diao’s group. Diao will take the novel molecule and, with the knowledge of how this material reacted to Rogers’ experiments, she will attempt to make a functional material using 3-D printing.

“One key issue we’re interested in is the assembly, how to direct the assembling of the materials because it’s critical to the function,” Diao said. “In this case, we’re interested in the photonic properties. Can we potentially make camouflage using this functional material by assembling the material into highly ordered structures? We’ll be able to sensitively modulate the structure over length scales predicted by Charles Sing.”

What they’re doing could be called a “high-risk, high-reward” type of project, Diao said, because proposing to physically change structure on the fly is a fairly new idea. “The challenge is, how the assembly of this novel class of materials respond to flow is previously unknown. Flow-directed 3D printing is also not demonstrated before and requires significant innovation to realize,” she said.

Faculty anticipate discoveries and some surprises along the way because the material they’ll be working with is new and the process, called non-equilibrium processing, is still a relatively new concept, they said.

The grant comes from the NSF’s Designing Materials to Revolutionize and Engineer our Future (or DMREF) program, which specifically funds projects that aim to develop advanced materials quickly and at a fraction of the cost.

What makes the project unique is each investigator has a role to play in each other’s research. Due to the iterative, multi-project investigator structure, there will be a lot of coordination involved and each faculty member will need to understand results from their colleagues to be able to apply it to their own research.

“It’s an exciting challenge,” Guironnet said. “We get the opportunity to understand each other’s work to increase the impact of our own research. And at the same time, I get to extend my expertise as well,” he said.

What’s also unique about the group is that each investigator is an assistant faculty member. They all joined the department within about a year of each other.

“Because we’re new professors, there’s been a focus on building our own reputations, our own lab expertise. This is our moment to do something bigger than that, and that is extremely exciting,” Sing said.

Thanks to the NSF funding, faculty also plan to expand their outreach projects in computation, characterization and synthesis, via the Girls’ Adventures in Math, Engineering and Science (GAMES) summer camp and the St. Elmo Brady STEM Academy, which exposes underrepresented elementary students to STEM fields.

More information about the grant can be found here.

 

Sing, Charles
Assistant Professor Charles Sing

Charles E. Sing, Assistant Professor of Chemical and Biomolecular Engineering at the University of Illinois, has received a 2017 National Science Foundation CAREER Award for his proposal, “Developing the design rules of charge sequence to inform polymer self-assembly.”

The National Science Foundation’s Faculty Early Career Development Program’s CAREER Awards are prestigious and competitive awards given to junior faculty who exemplify the role of teacher-scholar through outstanding research, excellent education, and the integration of education and research within the context of the mission of their respective organizations. The program will provide five years of support.

“I am incredibly honored by this award. I think it reflects the exciting ideas and hard work of my students, and I am excited to keep working with them to explore this new area of charged, patterned polymers. I hope we can live up to this recognition and push the field forward,” Sing said.

Dr. Sing aims to enable advances in materials that demand structural precision at the nano-level, such as fuel cell membranes, functional coatings and sensors, and drug delivery vehicles.

His research is inspired by the sophisticated precision of biological systems made from large molecules that specifically and exclusively interact using information encoded in patterns of electrostatic charge. He will investigate whether polymers—long chain-like molecules made of joined molecular units called monomers—that self-organize can be made to behave in a similar way. He and his research group will determine how patterns of electrostatically charged monomers along a polymer molecular chain can be designed to guide the self-organization of molecular structures at the nanometer length scale.

The NSF CAREER award will also support outreach efforts. Sing and his graduate and undergraduate students volunteer with the St. Elmo Brady STEM Academy, which aims to boost interest in STEM among underrepresented minorities. They teach elementary-age students about issues such as sustainability and the lifecycle of plastics and introduce them to interactive computer simulation activities.

Sing joined the Department of Chemical and Biomolecular Engineering faculty in 2014. He received his BSE/MS from Case Western Reserve University and his PhD from the Massachusetts Institute of Technology. His postdoctoral work was at Northwestern University’s International Institute for Nanotechnology.

Charles E. Sing, Assistant Professor of Chemical and Biomolecular Engineering at the University of Illinois, has received a 2017 National Science Foundation CAREER Award for his proposal, “Developing the design rules of charge sequence to inform polymer self-assembly.”

The National Science Foundation’s Faculty Early Career Development Program’s CAREER Awards are prestigious and competitive awards given to junior faculty who exemplify the role of teacher-scholar through outstanding research, excellent education, and the integration of education and research within the context of the mission of their respective organizations. The program will provide five years of support.

Sing, Charles
Charles E. Sing

“I am incredibly honored by this award. I think it reflects the exciting ideas and hard work of my students, and I am excited to keep working with them to explore this new area of charged, patterned polymers. I hope we can live up to this recognition and push the field forward,” Sing said.

Dr. Sing aims to enable advances in materials that demand structural precision at the nano-level, such as fuel cell membranes, functional coatings and sensors, and drug delivery vehicles.

His research is inspired by the sophisticated precision of biological systems made from large molecules that specifically and exclusively interact using information encoded in patterns of electrostatic charge. He will investigate whether polymers—long chain-like molecules made of joined molecular units called monomers—that self-organize can be made to behave in a similar way. He and his research group will determine how patterns of electrostatically charged monomers along a polymer molecular chain can be designed to guide the self-organization of molecular structures at the nanometer length scale.

The NSF CAREER award will also support outreach efforts. Sing and his graduate and undergraduate students volunteer with the St. Elmo Brady STEM Academy, which aims to boost interest in STEM among underrepresented minorities. They teach elementary-age students about issues such as sustainability and the lifecycle of plastics and introduce them to interactive computer simulation activities.

Sing joined the Department of Chemical and Biomolecular Engineering faculty in 2014. He received his BSE/MS from Case Western Reserve University and his PhD from the Massachusetts Institute of Technology. His postdoctoral work was at Northwestern University’s International Institute for Nanotechnology.

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