Researchers win MURI award to develop new biomaterials

They may be tiny, but leafhoppers have a super power: they secrete a substance that makes their bodies water-repellant and anti-reflective, which may help them blend in with their surroundings and escape surface tension. Symbiotic bacteria living in the leafhoppers appear to assist in producing the substance and its soccer-ball-shaped nanostructures called brochosomes, but the process is something of a mystery.

The U.S. Army has awarded researchers in Materials Science and Engineering at Illinois support for a major new interdisciplinary initiative that aims to learn more about this process so as to yield new biomaterials, inspired by the brochosomes. The award is part of the Department of Defense's highly competitive Multidisciplinary University Research Initiative (MURI) program, which supports research that intersects more than one traditional scientific or engineering discipline.

The researchers aim to synthesize new materials by "hacking" the brochosome production process with engineered versions of the symbiotic bacteria. The work includes new design and characterization methods for bioinspired materials. The team of researchers at the University of Illinois includes materials science professor Charles Schroeder, entomology assistant professor Marianne Alleyne, postdoctoral researcher Dr. Gabriel Burks, and entomology graduate student Elizabeth Bello.

The Illinois team aims to understand how leafhopper diversity contributes to brochosome structure and properties, including the role of charge interactions in assembling complex brochosome structures. Ultimately, this work will enable the design and creation of new functional materials inspired by brochosomes, with applications including anti-reflecting coatings, camouflage, and water purification.

The collaborative MURI team includes researchers from the University of Texas at Austin, molecular biosciences professor Jeffrey Barrick, integrative biology professor Nancy Moran, chemical engineering professors Benny Freeman and Delia Milliron, along with Michael Jewett of Northwestern University.

"The project does have an aim," Moran said, "which is to understand and engineer the production of interesting materials. But as part of getting to that aim, there will be some basic biology. Initially we'll need to survey this diversity of leafhoppers to find a good model."

Leafhoppers, like humans, need 20 amino acids to make proteins. But leafhoppers can only produce 10 themselves. For the rest, they rely on symbiotic bacteria, single-celled organisms that live inside leafhopper cells and co-evolve with the bugs, to produce these molecules.

Moran plans to sequence the genomes of the leafhoppers and their symbionts to try and untangle which genes are needed in each to make brochosomes. Barrick, who leads the team, says the group will apply this, and a host of other techniques to try and puzzle out how symbionts and their host insect combine to make the molecules.

Together with the work of other members of the team, the result would be a start-to-finish understanding of the brochosome production process – information that the scientists can later use to insert symbionts that sneak in slight changes and lead to new properties.

To better understand these behaviors, researchers at Illinois will characterize the physical and chemical properties of brochosome materials. Dr. Gabriel Burks, a postdoctoral researcher in the Schroeder group, comments that “This award is a tremendous opportunity to expand our fundamental knowledge on brochosome chemistry, morphology, and properties. We will use cutting-edge characterization tools at Illinois to understand how these proteinaceous nanomaterials are formed and assembled to yield such extraordinary macroscale properties.”

The Department of Defense grant, which provides $3.75 million over three years, with an option for a two-year extension plus an additional $2.5 million in funding, supports a multidisciplinary approach.

“The MURI award provides an ideal opportunity to pursue fundamental research in biomaterials with a highly collaborative team,” said Schroeder. 

“I am extremely excited to work together with this outstanding team of scientists and engineers.” Alleyne agrees: “Plants and animals use a myriad of mechanisms that result in functionalities such as anti-reflectance and hydrophobicity. By describing the structure and formation of brochosomes in different leafhopper species, we will develop new and innovative ways to make engineered materials with desired properties. An extra bonus of this work, especially for an entomologist, is an improved understanding of leafhopper physiology.”

The research conducted at Illinois is part of an emerging field of bioinspired materials, with an overall goal of designing and building new materials with enhanced properties. Such research could play a role in emerging technologies ranging from anti-wetting or anti-fouling surfaces or new materials for chemical separations.