Graphene and Synchrotron Light to Create Bone Graft

A group of Canadian researchers is using a high energy accelerator to accelerate bone tissue regeneration and, potentially, a remarkable new form of bone graft.

McGill University researchers are using the Canadian Light Source (CLS) at the University of Saskatchewan to use synchrotron light to alter the internal structure of graphene oxide in the hopes of making it more conducive to bone tissue regeneration.

The multidisciplinary group found that adding an emulsion of oil and water to the graphene oxide, then freezing it at two different temperatures, resulted in two different sizes of pores throughout the material.

Lead author Marta Cerruti, Ph.D., a professor of materials engineering at McGill, said that “when they ‘seeded’ the now-porous scaffolding with stem cells from mouse bone marrow, the cells multiplied and spread inside the network of pores, a promising sign that this novel approach could eventually be used to regenerate bone tissue in humans.”

“We showed that the scaffolds are completely biocompatible, that the cells are happy when you put them in there, and that they’re able to penetrate all through the scaffold and colonize the whole scaffold,” she stated.

Giving a bit of backstory, Dr. Cerruti told OTW, “We had a previous study on reduced graphene oxide scaffolds for bone tissue engineering, which showed promising results for this application and good biocompatibility. The potential of graphene materials in this application depends on the architectural structure of the final material. However, the reduced graphene oxide scaffolds we made have small pore size that would impede the cell infiltration. So, we tried to develop a method that can allow us to produce optimized structures for bone regeneration.”

Graphene scaffolds have long intrigued bioengineering scientists because they exhibit a porous morphology, great surface area, selective permeability of gases, excellent mechanical strength, good thermal and electrical conductivity, good optical properties, and biodegradability make them a highly attractive material for biologic scaffold design and engineering.

Synchrotron light is an electromagnetic wave similar to sunlight, but a million times brighter. What makes these waves brighter is that they are forced by “synchronized” application of strong magnetic fields to travel in a circular orbit inside synchrotron tunnels.

OTW asked the research team to explain how synchrotron light played a role in developing this new form of bone graft. Lead researcher Yiwen Chen, a Ph.D. student working under Dr. Cerruti, explained that it allowed the team of truly visualize the architecture of the bone graft.

“Based on our knowledge, it’s the first time synchrotron light has been used for this application”, said Chen. “Indeed, some techniques allow people to visualize the morphology of the pores of graphene porous materials. However, these techniques only enable people to see the surface of pores on a specific cross-section of the materials. In most of the articles, results from these techniques are sufficient for many applications. But for our purpose, visualizing the internal structure using synchrotron light was is critical.”

“We considered a conventional way to do that, microCT, and tried it. However, because graphene is based on carbon and oxygen, these light materials were transparent under microCT because of the low absorption of X-ray. At synchrotron, phase contrast imaging technique is a developed technology that has been successfully applied for biology samples, which are both mainly based on carbon and oxygen. Thus, our collaborator, Prof. Thomas Szkopek, proposed to apply this technique to visualize our graphene oxide scaffolds.”

As for what stands between now and the regular clinical application of this new approach, Dr. Cerruti added, “There are still many steps for future clinical application, such as extensive research in vivo, government approval, and clinical trial. Graphene is still a relatively new material, especially when we speak of biomaterials. Our study could offer a method to produce graphene oxide materials with a favorable structure for bone tissue engineering and move closer to the actual clinical application.”