Biohybrid material acts like cartilage — ScienceDaily

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

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

The fabric needs to be soft enough to bend and flex, but durable enough to withstand sustained loading—for example, the weight a knee tendon must support. When tissue wears out or is damaged, collagen hydrogels and synthetic materials have the potential to serve as substitutes, but none possess the right combination of biological and mechanical properties of natural tissue.

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

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

The biohybrid composite approaches the performance of articular cartilage and other biological tissues, possessing 40 percent more elasticity and 11 times the fracture energy—a measure of durability—of the zwitterionic material itself.

Nikolaos Bouklas, an assistant professor in the Sibley School of Mechanical and Aerospace Engineering and co-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 the purposes of regenerative medicine, such as a piece of scaffolding that can withstand some initial loads until the tissue fully regenerates,” Buklas said. “With this material, you can 3D print a porous scaffold with cells that could eventually create the actual tissue around the scaffold.”

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

The research brought together four research labs from three different departments thanks to a grant from the Cornell Center for Materials Research. The collagen used in the biohybrid composite was already under development in Bonassar’s lab, while the zwitterionic hydrogel was developed by study co-authors Robert Shepherd, an associate professor in the Sibley School, and Emmanuel Janelis, the Walter R. Read Professor of Engineering in the department in 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 type of bioprinting pioneered in his lab, and the authors have begun experimenting with using it as a 3D printing material.

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Materials provided by Cornell University. Original written by Syl Kacapy, College of Engineering, courtesy of Cornell Chronicle. Note: Content may be edited for style and length.

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