Research On Biocompatibility Of N-HA/PA66 And Mg-Zn-Zr/HA Composite

Nanohydroxyapatite reinforced polyamide66 (n-HA/PA66) composite and magnesium-matrix material have been proposed as two promising biomaterials. In this study, biocompatibility of the two kinds of medical composites was investigated respectively.Osteoblasts were separated from the neonatal rat calvarias and co-cultured with n-HA/PA66, with PA66 as control. The cell attachment and morphology were studied using phase contrast light microscope (PCLM) and field-emission scanning electron microscope (FE-SEM). The osteoblasts attached very well to the composites with the shape of shuttle and/or triangular, and the cells were in a close contact with each other. The osteoblast proliferation was greater on the composites than on PA66 during the prescribed time periods, meanwhile, there were stastic differences (P<0.05) between the two groups after culturing for 1 and 3 days. Moreover, n-HA/PA66 pins, with PA66 pins as control, were implanted into the right and left shinbone shafts of the rabbits, respectively. High activity of osteoblasts and osteocytes were observed around the n-HA/PA66 pins as shown by hematoxylin and eosin (HE). The results of biocompatibility evaluation revealed that n-HA/PA66 had the acceptable biocompatibility as a new kind of bone implant material.Both the corrosion behavior and biocompatibility including blood compatibility and cytotoxicity were investigated on the following magnesium-matrix materials: Mg-2.5wt%Zn-0.5wt%Zr, Mg-2.5wt%Zn-0.5wt%Zr-1wt%HA before and after treated by immersion in hydrofluoric acid (40%HF, 12h, room temperature). We studied the corrosion resistance of the three materials by the electrochemical tests and immersion tests in simulation body fluid (SBF), the results showed that n-HA could improve the corrosion resistance of the magnesium alloy while the fluoride surface treatment did more obviously. The biocompatibility study on the three materials in vitro also revealed that the Mg-2.5wt%Zn-0.5wt%Zr-1wt%HA treated by immersion in hydrofluoric acid (40%HF, 12h, room temperature) did no harm to both blood and osteoblasts, which may be promising to be used as intravascular stent material.