Carbon nanotube-collagen@hydroxyapatite composites with improved mechanical and biological properties fabricated by a multi in situ synthesis process.

A novel carbon nanotube-collagen@hydroxyapatite (CNT-Col@HA) composite with good mechanical and biological properties was fabricated successfully by a multi in situ synthesis process, which can be used to repair or replace the damaged bone tissues. The carbon nanotube (CNT)/hydroxyapatite (HA) composite powders were firstly synthesized by the in situ chemical vapor deposition method. After the acidification of CNTs, the collagen (Col) molecules were covalently grafted onto the surface of CNTs in situ by the formation of amide linkages, obtaining Col-encapsulated CNTs powders. And then, a HA layer was deposited in situ onto the Col-encapsulated CNTs to form HA- and Col-encapsulated CNTs, consequently the ideal CNT-Col@HA composite was fabricated by the powder metallurgy method, and its mechanical and biological properties were investigated. The results showed that, the multi in situ synthesis process ensured the homogeneous dispersion of CNTs in HA matrix, and via the intermediate layer of Col, the close chemical bonding between CNT reinforcements and HA matrix was obtained, thereby the flexural strength and fracture toughness of the in situ synthesized 3 wt.% CNT-Col@HA composite were increased by approximately 74.2% and 274.6% compared with those of pure HA bulk, and better cell adhesion, spreading and proliferation were also observed on the in situ synthesized CNT-Col@HA composites. Therefore, the obtained composites in this work have great potential to be applied as implant material in clinic.