Research Of Antibacterial Coating On Titanium Alloy Prepared By Micro Arc Oxidation

Titanium and titanium alloy has been widely used clinically as preferred biological material for the manufacture of dental implants and other human hard tissue substitutes for its excellent bio-compatibility, comprehensive mechanical property and better corrosion resistance. But post-operation infection remains one of the most common and serious complications. It is believed that the forming of biofilms caused by adhesion and propagation of bacterias is one of the main reasons leading to this problem. The titanium alloy has no function of antibiosis itself as a kind of biomaterial. It would obviously make good sense if the alloy gains antibacterial capability through surface treatment.It is already proved that materials incorporated with silver had performances of wide-spectrum antibiotic ability, no drug tolerance and low virulence. The fact that coatings prepared by micro arc oxidation were of good quality is well accepted too. An MAO coating incorporated with silver is highly desirable in order to prevent implant associated infection.In this study, precoating technology was used to avoid changing component of the MAO electrolyte. The precoating on TA2alloy was prepared by anodic oxidation and low-voltage MAO. The Ag particles adhered to the wall of the nano tubes or micropore through immersion in a silver nitrate solution followed by ultraviolet light radiation. The ability of incorporating silver was contrasted between two kinds of precoating with SEM and EDS. The results showed that anodic oxidation coating with nano tubes was more suitable as precoating. At last, properties of the MAO coating incorporated with silver such as roughness, bonding strength between coating and matrix, silver releasing, valence of silver were detected with AFM, ICP-AES, XPS, SEM and so on. In order to value the antibiotic ability of MAO coating incorporated with silver, antibacterial assay using Staphylococcus aureus has been made.The results showed that the anodic oxidation nano-tube precoating (NT precoating) has higher ability of incorporating with silver for its higher surface energy. The NT-Ag-MAO coating prepared based on it had higher content of silver too. And also, the amount of Ag introduced to the NT-Ag-MAO coating can be varied by changing the concentration of nitrate solution and soaking time. It still showed that the preparing of precoating and silver incorporating treatment made no impact to Ca and P elements’entrance into MAO coating. So the MAO coating incorporated with silver would show more bio-compatibility. The bonding strength of NT-Ag-MAO coating incorporated with silver between coating and matrix was almost the same with common MAO coating. And it was far more stronger than bonding strength of the anodic oxidation coating. The antibiotic test showed the NT-Ag-MAO coating incorporated with silver had efficient antibiotic ability. Ninety nine percent of the Saphylococcus aureus were killed in first60mins and the antibacterial ratio was as high as seventy percent after7days’incubation. The NT-Ag-MAO coating showed better performances in roughness, silver releasing and thickness as well.In this research, silver particles adhered to the TA2surface successfully before MAO treatment through precoating technology. The precoating process is simple to operate and of low cost. The NT-Ag-MAO coating was of high silver content and antibacterial ability. Comparing with existing study for prepareing MAO coating incorporated with silver, this research made a lot of improvements.The method mentioned in this study is technically feasible. And it will provide a new idea for preparing antibacterial coating incorporated with silver on surface of titanium medical apparatus and instruments.