Preparation and characterization of a novel hydroxyapatite/carbon nanotubes composite and its interaction with osteoblast-like cells

Hydroxyapatite (HA) and its based biomaterials could chemically bond directly to bone when implanted, resulting in the formation of a strong bone-implant interface. Carbon nanotubes (CNT) are believed to be very promising in the enhancement ceramic matrix and played an important role as reinforcement for imparting strength and toughness to brittle HA bioceramic. Here we demonstrate the potential use in reinforcing biomaterials through an attempt to use CNT strengthen brittle HA bioceramic. This work aims to study the optimum sintering conditions of CNT modified HA to get CNT–HA composite with improved mechanical properties using a rapid spark plasma sintering system. The microstructure, phases, chemical compositions and mechanical properties of the ceramic samples were characterized by various advanced methods. Though no obvious chemical reaction between CNT and HA has been detected, the physical crosslink caused by the presence of CNT resulted in that a CNT–HA composite with a relatively high value of modulus (~ 131.1 GPa) and hardness (~ 6.86 GPa) achieved at the sintering temperature of 1100 °C. In vitro cellular responses to the composites were assessed to investigate the proliferation and morphology of a human osteoblast cell line cultured on the various composites.