Monday, December 05, 2022

Soft yet strong: bio-hybrid material works like cartilage

Producing biomaterials that match the performance of cartilage and tendons has been an elusive goal for scientists, but a new material created at Cornell demonstrates a promising new approach to mimic natural tissue.

The results were published on July 8 in the Proceedings of the National Academy of Sciencesand provide a new strategy to synthesize clinical solutions for damaged tissue.

The fabric must be soft enough to bend and flex, but strong enough to withstand prolonged loading, for example, the weight of a tendon in the knee. When tissue becomes worn or damaged, collagen hydrogels and synthetic materials have the potential to serve as replacements, but neither alone possesses the correct combination of biological and mechanical properties of natural tissue.

Now Cornell researchers have designed a biohybrid composite material with the essential characteristics of a natural tissue. The material consists of two main ingredients: collagen, which gives the material its softness and biocompatibility, and a synthetic zwitterionic hydrogel, which contains positively and negatively charged molecular groups.

“These charge groups interact with the negatively and positively charged groups in collagen, and this interaction is what allows the materials to dissipate energy and achieve high levels of toughness,” said Lawrence Bonassar, Daljit S. and Elaine Sarkaria Professor of Engineering. Biomedical. in the Faculty of Engineering and co-lead author of the study.

The biohybrid composite approaches the performance of articular cartilage and other biological tissues, possessing 40% more elasticity and 11 times the fracture energy (a measure of durability) of the zwitterionic material on its own.

Nikolaos Bouklas, assistant professor at the Sibley School of Mechanical and Aerospace Engineering and co-lead author of the study, said the material’s biocompatibility means it can recruit cells and keep them alive.

“Ultimately, we want to create something for regenerative medicine purposes, like a scaffold that can take some initial loads until the tissue fully regenerates,” Bouklas said. “With this material, you could 3D print a porous scaffold with cells that could eventually create the actual tissue around the scaffold.”

In addition, the biohybrid material self-assembles once the two ingredients are mixed, Bouklas said, creating “the same interconnected network of collagen seen in natural cartilage, which would otherwise be extremely difficult to produce.”

The research brought together four research labs from three different departments thanks to a seed grant from Cornell’s Center for Materials Research. The collagen used in the biohybrid composite had already been in development in Bonassar’s lab, while the zwitterionic hydrogel was developed by study co-authors Robert Shepherd, associate professor at the Sibley School, and Emmanuel Giannelis, Walter R. .Read. in the Department of Materials Science and Engineering.

The study authors continue to investigate the material and the molecular processes behind its synthesis. Bonassar said the material is well suited to the kind of bioprinting he pioneered in his lab, and the authors have begun experimenting with using it as a 3D printing material.

Story Source:

Materials provided by Cornell University. Originally written by Syl Kacapy, College of Engineering, courtesy of Cornell Chronicle. Note: content can be edited for style and length.

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