Natural wonders lead to new bio-inspired materials

Professor LaShanda Korley (left) imitated the architecture of the jaw-worm jaw system by adding a zinc coordinated supramolecular polymer in a covalently crosslinked polyethylene glycol network. Credit: Kathy F. Atkinson

A tiny hairworm, wriggling around the ocean, can extend his jaw beyond his mouth to trap his prey. The jaw-shaped shape, rigid at the base and flexible at the end, is made of a unique material containing the mineral zinc and the acid histidine, which together govern the mechanical behavior of the joint via the coordination chemistry of metals.

Scientists such as LaShanda Korley, a distinguished associate professor of materials science and engineering and chemical and biomolecular engineering at the University of Delaware, want to recreate these chemistries and build similar structures out of synthetic materials. In doing so, they can develop new and improved materials for sensors, health applications, etc. Such chemistries are ubiquitous in nature. The iron-protein interaction in human blood, for example, can be a determining factor of the disease.

In an article published in the July 2019 edition of the European Polymer Journal, Korley, accompanied by Chase Thompson, a PhD student in Materials Science and Engineering, and Sourav Chatterjee, Postdoctoral Fellow, explained how they had built a network of zinc materials and polymers. which mimicked the mechanical gradient of the jaw of a hair worm.

This project, the result of more than five years of work, was funded by a grant from the National Science Foundation. The goal is to use natural material systems to understand how to control the interaction of structural features, particularly mechanical properties, by combining dynamic and permanent structures, Korley said.

"The idea is: can you put in place two things that do not really like each other and use that idea of ​​dynamics as a way to control how energy is released into the system, which is related to mechanical behavior? "she said.

The team mimicked the architecture of the worm jaw system by adding a zinc coordinated supramolecular polymer in a covalently crosslinked polyethylene glycol network. With the right concentrations, they discovered that they could regulate the mechanical properties of the material. "The permanent network we use to host these dynamic interactions is a good platform for achieving these gradient structures," Thompson said. He then plans to study ways to influence the shape memory and other properties of these materials.

Korley is inspired by nature to design various materials. She is the principal investigator of EIRP: Bio-Inspired Materials and Systems, a $ 5.5 million five-year grant from the National Science Foundation.

As part of this project, Korley and collaborators from Case Western Reserve University, the University of California at San Diego, the University of Chicago, the University of Friborg, Switzerland and from the University of Strathclyde (UK) study and develop materials that can change hardness in response to their environment. , are safer and more effective biological implants, transmit nerve-like electrical signals and can react to the environment to initiate biological processes, all for use in soft robotic applications.

For example, researchers are investigating methods for making solid materials, such as spider silk, and materials that change shape depending on moisture, such as pine cones, which are Open in dry weather and close when they are wet. They also use the unique properties of the materials they discover to develop new 3D printed materials.

The study of flexible materials and polymers, which has long been the strength of UD, is developing, thanks in part to Korley's expertise. Korley and Thomas H. Epps, III, Senior Professor of Career Development Thomas and Kipp Gutshall in Chemical and Biomolecular Engineering and Materials Science and Engineering, have also established a new research center, the Soft Materials Research Center. and polymers (CRISP). Korley and Epps are collaborating with Chemours researchers and have recently published a review article on structure-property relationships in polymeric surface coatings in ACS Applied Polymer Materials.

Korley's research activity also includes outreach activities for undergraduate students, who can benefit greatly from the research experience that complements their classroom work.

"Research provides you with a platform to take this basic classroom training and apply it to a problem," she said. "In the lab, students learn to solve problems, to exhibit and communicate their work, and to become leaders and team players. We all have these aspects in our courses, but I think there is a comprehensive way to conduct undergraduate research to train students in this. "

Korley is also passionate about outreach activities that introduce high school girls to science and engineering. Students from his lab were involved in tutoring at Serviam Girls Academy in New Castle, Delaware.

"The most important thing for me is to have an impact, to be collaborative, to really engage with the community at large," she said. "It's important to me."