材料期刊网

Magnesium (Mg) alloys have been demonstrated to be potential orthopedic implants due to their biodegradability in vivo. To enhance its corrosion resistance and improve its osteogenesis, beta-tricalcium phosphate (beta-TCP) was coated on a Mg alloy (Mg-3AI-1Zn) by phosphating process. In vitro, the human osteosarcoma cell line (SaOS-2) showed significantly good adherence and proliferation on the surface of the beta-TCP coated Mg alloy after 24-h incubation. The growth factor bone morphogenetic protein 2 (BMP-2) was highly expressed in SaOS-2 cultured with the beta-TCP coated Mg alloy by Western blot analysis (p < 0.05). In vivo, the newborn bone at the implant/bone interface was formed at week 1 and matured at week 4 postimplantation. Villous tissue was found at the implant/bone interface at week 12 postimplantation. The contents of phosphorus and calcium on the surface of the beta-TCP coated Mg alloy were decreased at week 4 and week 12 postimplantation, respectively. Immunohistochemical analysis of the experiment results demonstrated that the beta-TCP coated Mg alloy implants provided a high BMP-2 expression during the first 4 weeks postimplantation. Compared with the naked Mg alloy which was degraded for 33% in vivo, only 17% of the beta-TCP coated Mg alloy was degraded at week 12 postimplantation (p < 0.05). The in vitro cell tests showed that the beta-TCP coating provided the Mg alloy with a significantly better surface cytocompatibility, and in vivo results also confirmed that the beta-TCP coating exhibited greatly improved osteoconductivity and osteogenesis in the early 12 weeks postoperation period. Moreover, in vivo experiment demonstrated that the beta-TCP coating layer could slow down the degradation of the naked Mg alloy at the early stage of implantation. (C) 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.