Extreme stability unlocks new possibilities

A team led by Pochan, Ph.D. candidate Yao Tang and postdoctoral researcher Tianren Zhang developed computationally designed peptides that come together to form particles they call “bundlemers.” 

Consisting of four peptides, each bundlemer is shaped like a tiny barrel, with a carefully arranged pattern of positive and negative charges on its surface. That precise pattern makes the bundlemers extremely stable over the entire pH range, from the strongest acids to the strongest bases. At very low or very high pH, the particles form liquid crystals, while at neutral pH, they assemble into lattice-like clusters.

“Being so stable across the entire pH range is really unique and powerful,” Pochan said. This stability, combined with the ability to switch between different ordered states, paves the way toward new kinds of advanced materials, he explained. 

For example, Kevlar, the material used in bulletproof vests, is made by processing liquid crystal polymers into an extremely strong solid. By harnessing the strength and adaptability of bundlemers, researchers may be able to create similar materials with precisely designed properties.

Programming assembly through surface design

“The surface patterning of chemistry is what’s so important about these building blocks,” Pochan noted. “This is something we’re going to explore for the next decade: how we can use that patterning to give these particles very specific behavior.”

In this case, the researchers designed surface charge patterns that allow the peptide particles to assemble into ordered structures across the entire pH range. Even small changes to this surface chemistry can lead to large changes in behavior, shifting how the bundlemers interact with each other and what kinds of structures they form.

This level of molecular precision is common in biology but rare in materials science. Changing a single amino acid on the surface of a protein can completely alter its structure and function. In contrast, conventional soft materials, such as plastics, are inherently disordered, making it difficult to leverage surface chemistry to control their properties.

“Combining tools from biology with materials science allows us to achieve an extraordinary degree of precision,” Pochan said. “Because we have exact control over the surface display of our bundlemers, we can explore in-depth how to direct their assembly into ordered materials.”

From fundamental discovery to real-world impact

For the current study, Pochan’s team built the bundlemers in the lab using standard chemical synthesis techniques. But because they are protein-based materials, they potentially could be produced inexpensively and at large scale using biological methods. 

To explore paths toward scalable production, Pochan is collaborating with Pierre Rouviere, former Dupont scientist and entrepreneur with experience in engineering bacteria to produce protein and peptides for large-scale industrial applications. The collaboration is supported by a Delaware Bioscience Center for Advanced Technology grant for Entrepreneurial Proof of Concept.

Pochan also plans to launch his own startup on UD’s STAR Campus, further embedding this work within Delaware’s growing innovation ecosystem and extending insights that emerged from fundamental research into new directions. 

Other UD co-authors of the paper include graduate student Jacob Schwartz and professor Christopher J. Kloxin. Postdoctoral researcher Dai-Bei Yang and professor Jeffery G. Saven, both of the University of Pennsylvania, are also co-authors. Major sources of support include the National Institute of Standards and Technology, part of the U.S. Department of Commerce, and the National Science Foundation through UD’s Materials Research Science and Engineering Center. UD central facilities and their scientific staff were also critical in performing the research. These include the Keck Center for Advanced Microscopy and Microanalysis, the Advanced Materials Characterization Lab, the Peptide and Protein Materials Center and the Delaware Biotechnology Institute.