Soft but tough: Biohybrid materials work like cartilage

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

The results are published July 8 in the Proceedings of the National Academy of Sciences, and provide a new strategy for synthesizing clinical solutions for damaged tissue.

The tissue must be soft enough to bend and flex, but durable enough to withstand prolonged loads – for example, the loads that the knee tendons have to support. When tissues are worn or damaged, collagen hydrogels and synthetic materials have the potential to serve as substitutes, but they do not have the right combination of biological and mechanical properties of natural tissues.

Now, Cornell researchers have engineered a biohybrid composite material with essential characteristics of natural tissue. It consists of two main ingredients: collagen – which provides softness and biocompatibility to the material – 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 it is this interaction that allows the material to dissipate energy and achieve high levels of toughness,” said Lawrence Bonassar, Daljit S. and Elaine Sarkaria Professor in Biomedical Engineering. in the College of Engineering and co-author of the study.

The biohybrid composite approximates the performance of articular cartilage and other biological tissues, having 40% more elasticity and 11 times the fracture energy – a measure of durability – than the zwitterionic material itself.

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

“Ultimately, we wanted to create something for regenerative medicine purposes, like a piece of scaffolding that can withstand some of the initial load until the tissue regenerates completely,” Bouklas said. “With this material, you can 3D print a porous scaffold with cells that can eventually create a real network around the scaffold.”

In addition, biohybrid materials can self-assemble once the two materials are mixed, Bouklas says, creating “the interconnected network of collagen seen in natural cartilage, which otherwise would be very difficult to produce.”

This research brings together four research laboratories from three different departments thanks to an initial grant from the Cornell Materials Research Center. The collagen used in the biohybrid composite has been developed in Bonassar’s laboratory, while the zwitterionic hydrogel was developed by study co-authors Robert Shepherd, professor at the Sibley School, and Emmanuel Giannelis, Walter R. Read Professor of Engineering in the Department of Materials Science and Engineering.

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

Syl Kacapyr is associate director of marketing and communications for the College of Engineering.

/ Public Release. Material from this original organization/author may be timely, edited for clarity, style and length. The views and opinions expressed are those of the author. See more here.

#Soft #tough #Biohybrid #materials #work #cartilage