Surface Modification Of Pure Magnesium And Its Biocompatibility Studies For Biomedical Applications

Biomaterials not only have important social effect in bettering the living quality of human beings, improving their health and saving their lives, but also become a new growth point in economic and scientific-technological areas. At present, though a variety of metallic biomaterials have been developed and widely used in clinic, none of them is ideal. Therefore, it is necessary and urgent to develop new metallic biomaterials.In this study, the alkali-heat treatment and heat-organic layers treatment techniques were studied to make the treated samples obtain bioactive surface when soaked in SBF. SEM, XRD, EDX and FTIR analysis were employed to examine the samples at various intervals. Biocompatibility tests, including cytocompatibility and hemolysis tests, were also conducted to testify the possibility of using magnesium in biomedical fields. The results showed that in alkali-heat treatment, the samples obtained a coating of light magnesium carbonate quickly after they were soaked in supersaturated NaHCO3-MgCO3 solution with the starting pH of 9.3. The coating became half-melted and denser when they were heat-treated. More important, an oxide layer with the thickness of 20nm was formed after heat treatment. The high corrosion resistance of treated sampled could be demonstrated by the fact that no specific mass loss was observed when they were soaked in SBF for 180d. Calcium-phosphate based apatites were also detected on the surface of samples subjected to 180d-soaking experiment in SBF.In the heat and organic layer-treatment, the treated samples showed good corrosion resistance and obtained HA and OCP precipitates in SBF within 24h. The biocompatibility test results showed that magnesium had no inhibitory effect on the proliferation of marrow cells; whereas heat-treated and heat-organic films-treated samples caused no hemolysis, untreated magnesium had obvious hemolytic effect.In the end, thermodynamic conditions for precipitating HA, interactions between the ions in the solution and substrate and possibility of employing magnesium in biomedical fields were discussed .