Materials that successfully replicate the necessary elasticity and strength of biological tissues, but which also biodegrade over an appropriate timescale, are difficult to engineer because a material’s mechanical properties typically govern the rate at which it degrades.
The team, from Birmingham University, UK, and Duke University, US, said that they have successfully enabled the rate at which the material degrades in the body and its mechanical properties to be controlled independently through the addition of succinic acid, a product found naturally within the body, to control the degradation rate.
In a new study published in Nature Communications, researchers showed how the polyester biomaterial degrades gradually over a period of four months, with healthy tissues growing into and eventually replacing the implant. Tests in rats were also carried out to confirm the material’s biocompatibility and safety.
Varying the amounts of succinic acid enabled the team to control the rate at which water penetrates the material, and hence the degradation speed.
Structural changes that increase degradation speed would usually cause loss of strength, but the material was designed with specific stereochemistry that mimics natural rubber, allowing its mechanical properties to be finely controlled. This allowed loss of strength to be compensated for by making stereochemical adjustments, an advance described as 'significant' by the researchers.
“Biological tissues are complex with varying elastic properties,” said the study’s co-author Prof. Andrew Dove. “Efforts to produce synthetic replacements that have the right physical characteristics and that can also degrade in the body have been ongoing for decades.
“Part of the challenge is that a ‘one-size-fits-all’ approach doesn’t work. Our research opens up the possibility of engineering biological implants with properties that can be fine-tuned for each specific application.”
Prof. Matthew Becker, Duke University, added that the tuneable nature of the biomaterial makes it suitable for a range of applications including replacement bone, vascular stents and wearable electronics.