University develops new plastic biomaterials for medical implants

Researchers from the University of Birmingham have developed a new thermoplastic biomaterial, which is tough and strong but also easy to process and shape.

A type of nylon, the material’s shape memory properties enable it to be stretched and moulded but able to reform into its original shape when heated. This makes it suitable for medical devices such as bone replacements, where minimally invasive surgery techniques require additional flexibility in implant materials.

The material was developed in the University’s School of Chemistry, by a team investigating ways to use stereochemistry, a double bond in the backbone of the polymer chain, to manipulate the properties of polyesters and polyamides (nylons). The study is published in Nature Communications.

Biocompatible polymers are widely used in medicine, from tissue engineering to medical devices such as stents and sutures. Although much progress has been made in the area of resorbable or degradable materials that are broken down by the body over time, there are still only a handful of non-resorbable polymers that can be used for longer-term applications.

Existing non-resorbable biomaterials, like nylons, currently commercially available suffer from a variety of limitations. Metal implants, for example, can wear poorly, leading to particle fragments breaking off, while composite materials can be difficult to process or extremely expensive.

The new material can be made using standard chemistry techniques and offers a stable, long-lasting option, with mechanical properties that can be tuned for different end products.

Senior researcher, Professor Andrew Dove, says: “This material offers some really distinctive advantages over existing products used to manufacture medical devices such as bone and joint replacements. We think it could offer a cost-effective, versatile and robust alternative in the medical device marketplace.”

A further advantage of the material is its amorphous structure.

Josh Worch, the postdoctoral researcher who led the work, explained: “For many plastics, including nylon, the toughness is often dependent on their semi-crystalline structure, but this also makes them harder to shape and mould. However, our new plastic is as tough as nylon, but without being crystalline so it is much easier to manipulate. We believe this is only possible due to the way we have used stereochemistry to control our design.”