Billions of eggshells are thrown away as waste by food processing industries. The abundance and natural source of the eggshell have attracted the attention of scientists at Russia’s National University of Science & Technology Center for Composite Materials (NUST MISIS.) Now, the NUST MISIS team is developing a bioactive polymer-ceramic composite extracted from eggshells that can help treat surgical bone procedures such as skull injuries.
For more than a century of intense effort, scientists have tried developing a synthetic version of a bone for surgical applications that work as well as the original. However, none are really up to the job. For example, when a skull is fractured or suffers a congenital disability that leaves a part of the cranium ultra-thin, the usual procedure involves replacing the defective or damaged section of bone with one made of ceramic, plastic, or metal.
There are a few mechanical problems to these replacements such as:
- The artificial plate is either too soft
- Too stiff
- Too brittle
- Too pliable
- Responsible for altering its shape as temperatures change
- Hard to shape and fit accurately
Another problem is that these materials are biologically inert, or bioinert, which means they don’t interact with living tissue. While such materials can prevent infections or tissue rejection, it also negates the implant from becoming a part of the body as a natural component.
To resolve these issues, the NUST MISIS team turned to a synthetic polymer called polymethylmethacrylate (PMMA) that’s commonly used as a bone cement because of its self-curing properties and strength. However, PMMA is not ideal because it’s bioinert, so, the team modified it by adding a silicate bioceramic material known as diopside that’s extracted from eggshells.
The team claims that the diopside is relatively biodegradable, nontoxic, and can stimulate bone tissue growth in its vicinity. That means the implant can eventually fuse with the bone rather than being just cemented to it.
Inna Bulygina, an author of the study and Ph.D. student at NUST MISIS, said:
Eggshells have health benefits such as bone mineralization and growth, treatment of osteoporosis, and are therefore used as a bone graft. We have adopted a cost-effective approach to recycling biowaste to improve the quality of life for patients with bone disease. For the production of composites, diopside obtained from eggshells was used.
The scientists used a solvent casting method to produce a porous composite PMMA/diopside material. The process involves forming a thermoplastic polymer by repeatedly dipping a mold into a solution of the polymer, leaving layers of film behind. The team produced different samples of the material with 75, 50, and 25 percent proportions of diopside added.
Rajan Choudhary, a postdoc student, and the study’s lead author said:
The samples containing 50% diopside have shown the best result – they have demonstrated a four-fold increase in compressive strength, and after four weeks of in vitro testing have shown a good ability to deposit bone minerals on their surface. At the same time, we have found that the mechanical properties of the obtained porous composites correspond to the properties of the spongy bone of the human body.
The NUST MISIS team published the research on July 20 in the Journal of Asian Ceramic Societies.
