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RESEARCH PRODUCT

Bio-inspired Resorbable Calcium Phosphate-Polymer Nanocomposites for Bone Healing Devices with Controlled Drug Release

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description

In orthopedic research, increasing attention is being paid to bioresorbable composite materials as an attractive alternative to permanent metal bone healing devices. Typical composites consist of a biodegradable polyester matrix loaded with bioactive calcium phosphate ceramic particles (tricalcium phosphate, TCP or hydroxyapatite, HA) added to improve the biological response and mechanical properties of the neat polymer. The mechanical behavior of such particle-reinforced composites, however, falls far short of the expected performance in high-load bearing situations. Replicating some features of nacre—a strong and tough natural nanocomposite with a very high content of brittle inorganic phase, can pave the way for a new generation of high-strength resorbable bone implants. This chapter will concentrate on the processing of such “bio-inspired” nanocomposites with high calcium phosphate content where the strong ceramic skeleton is toughened by a small amount of continuously dispersed polymer component. To further improve the mechanical properties, manipulating the adhesion at the interface between the ceramic and polymeric nanoscale components was attempted. An original high pressure consolidation method was employed to fabricate dense bulk nanocomposites without exposing them to high processing temperatures. This allows for incorporation of biomolecules that can then be released from the implanted device to enhance bone regeneration (growth factors) or prevent infection (antibacterial drugs). Finally, it is important to evaluate how polymer addition to calcium phosphate influences cell-material or cell–cell interactions because of potential consequences for bone regeneration and vascularization. Towards this goal, CaP-polymer nanocomposites were assessed in monocultures of endothelial cells and osteoblasts and in co-culture thereof as an example of a more complex test system.