Mechanical properties, microstructure and histocompatibility of MWCNTs/HAp biocomposites

In this paper, the authors mainly investigated the mechanical properties, microstructure and histocompatibility of multi-wall carbon nanotubes/hydroxyapatite (MWCNTs/HAp) composite prepared by two techniques. Compared with pure hydroxyapatite, the bending strength and fracture toughness of the composite are all improved, especially the latter whose increment exceeded 200%. XRD shows that the primary crystal phase of the composite is HAp together with the diffraction peaks of carbon nanotube. By SEM we found that there are more carbon nanotubes in the composite sintered in Ar, but there are much pores in it and the interface between the carbon nanotube and hydroxyapatite is not very strong. In vacuum, the diameter of carbon nanotube became larger (reported before) than that in Ar, but the interface between MWCNTs and HAp is very strong and there are less pores in the composite. From a pathologic micrograph we can draw conclusions as follows. When MWCNTs/HAp composite was embedded into the striated muscle of a big white mouse it produced a little stimulation to the tissue around it and there was no serious inflammation reaction, implying better histocompatibility. Both MWCNTs/HAp and ZrO2/HAp composites can satisfy the condition of biomaterials but the histocompatibility of the former is much better than the latter.