A material that mimics bone could be used to simultaneously mend and numb the pain of broken limbs, say scientists in South Korea.

Jeong Ho Chang at the Korea Institute of Ceramic Engineering and Technology, Seoul, Kyung Sik Oh at Andong National University, Kyunbuk, and colleagues created the material, which is a polymer–ceramic composite. 

The hydroxyapatite material (left) once coated with the polymer (right) could be used to mend and numb the pain of broken limbs.

The base of the material is hydroxyapatite, a calcium phosphate ceramic, which is a major component of bones and teeth. It is already used to make artificial bones and as a coating in hip replacement operations to encourage bone to grow onto the implant and help fix it in place.

The team coated the hydroxyapatite with a porous silica gel, which was then impregnated with a heat-sensitive polymer and hardened. Crucially, the polymer does not block the pores of the ceramic; in clinical use this should mean that the movement of bone-forming and bone-absorbing cells is not restricted. 

By adding the polymer, Chang explained, the composite could be used not only as a scaffold for regenerating damaged bone, but also as a reservoir for controlled drug release. 

The team tested the drug delivery properties of the material using indomethacin, a painkiller and anti-rheumatism drug. At low temperatures the polymer is swollen, trapping the drug within the pores of the material. As the temperature is raised above 34–36 °C, the polymer shrinks, gradually releasing the drug. By adjusting the amount of polymer in the material, Chang expects to be able to alter the rate of drug release.

Cytotoxicity tests showed that the material is not toxic to living cells and so should be safe for clinical use.

Chang plans to develop the work further by creating ‘smart scaffolds,’ tailored to work efficiently in a particular environment.

Nicola Burton