Researchers at McGill University have developed a new way to manufacture complex materials that could offer a more environmentally sustainable alternative to conventional plastics and glues. The scientists used how mussels and mistletoe plants build natural fibers and adhesives as inspiration for their research.

“Living organisms are able to sustainably fabricate structurally complex, high-performance materials ‘bottom-up’ through self-assembly, which is still very challenging for humans using traditional material fabrication approaches,” said Matthew Harrington, a chemistry professor and lead author on the study.

Previous studies in the field focused on understanding how natural materials form. This research uses those insights to engineer entirely new composite materials in the lab. “In the older papers we were studying biological materials, while in the current paper we are making synthetic biologically inspired materials,” Harrington said.

To make the materials, the team drew inspiration from the protein-based adhesive structures produced by mussels combined with the cellulose fiber systems found in mistletoe berries. By mixing a laboratory-produced mussel protein with modified cellulose nanocrystals derived from wood pulp, the researchers created microscopic liquid droplets.

“Mussels make glues, fibers, and coatings using dense droplets of proteins, while mistletoe uses cellulose nanocrystals as a rigid building material in its stiff and sticky fibers,” said Hamideh Alanagh, a postdoctoral researcher and first, co-corresponding author on the study. “Combining these concepts, we set the stage for sustainable fabrication of advanced materials.”

Using a straightforward freeze-drying method, the droplets self-assembled into aligned porous scaffolds with layers of structure at different scales, where tiny building blocks organize into larger patterns similar to those found in biological tissues. “These droplets provide simple precursors for building complex materials.” said Theo van de Ven, a chemistry professor and senior author.

The scaffolds can also be dissolved back into droplets and reassembled into new structures, suggesting a manufacturing process that could reuse the same material multiple times. “The simple reversibility of droplet-based processing is highly appealing from a sustainability perspective,” said Alanagh. Laboratory tests also showed that the materials were not toxic to human cells, indicating potential biomedical uses such as tissue engineering.

Amin Ojagh, a postdoctoral researcher and co-first author on the study, noted that combining insights from both marine and plant materials was critical to the advance. “The new materials we created would not have been possible to make without the insights we acquired from both systems,” Ojagh said.

“The materials we use in our daily lives, such as plastics, glues and composites, are having a negative impact on our environment,” Harrington said. “By mimicking nature, we can develop new greener and more sustainable avenues for making materials with excellent properties.”

Mistletoe- and Mussel-Inspired Fabrication of Hierarchically Structured Protein-Cellulose Scaffolds From Biomolecular Condensates by Hamideh R. Alanagh, Seyed Mohammad Amin Ojagh, Theo G.M. van de Ven, Matthew Harrington, et al., was published in Advanced Materials. The research was supported by the Natural Sciences and Engineering Research Council of Canada, the New Frontiers in Research Fund, and the Fonds de recherche du Québec.