A variety of surface modification methods are applied to modify titanium implants to improve their biological activity. Micro-arc oxidation (MAO) can relatively simply and efficiently produce porous coatings with high bioactivity and bond strength on titanium surfaces. However, there is no conclusion about the effect of coatings with different pore sizes produced by MAO on bone marrow mesenchymal stem cells (BMSCs). To study the effect of different pore sizes on BMSCs, rat BMSCs were applied to detect the effect of different pore sizes prepared by MAO on cell adhesion and osteogenic differentiation. Three groups of coatings with different pore sizes were successfully prepared, and the pore size was within the range of 3-10 mm. Importantly, the expression of adhesion-related protein integrin b1 and osteogenic-related proteins OSX and ALP increased along with the increase in pore size. This study showed that the porous coating prepared by MAO promotes BMSCs adhesion and osteogenic differentiation. It reveals that the pore size is in the range of 3-10 mm and the larger pores are more beneficial for BMSCs adhesion and osteogenic differentiation. This study is instructive for optimizing the design of biomedical implant surfaces.

Good biological properties for titanium implants will shorten the treatment cycle and improve patient comfort, which are also the main goals of dentistry and orthopaedics. At present, the biological properties of titanium implants are mainly enhanced in two aspects: their surface chemistry and surface morphology. In this study, a surface modification strategy combining bioactive trace elements with surface micromorphology modification was used to enhance the biological properties of pure titanium. A new coating incorporating silicon micropore/microsphere topography was prepared on a titanium plate by micro-arc oxidation (MAO) technology. The properties of the coating and its effects on the adhesion and osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) were further analyzed. The experimental results show that a coating doped with amorphous silicon with micropore/ microsphere topography was incorporated onto the titanium surface and the surface roughness in the treated groups was obviously higher than that in the Ti group. In vitro, the presence of a silicon-incorporating coating with a micropore/microsphere topography on the titanium surface significantly enhanced the initial adhesion, proliferation and osteogenic differentiation of BMSCs. These results indicate that the silicon-incorporating coating with micropore/microsphere topography has potential applications in dentistry and orthopaedics.

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To control the degradation of magnesium alloy and enhance its osteoinduction activity and antibacterial properties, we proposed the addition of Zn and Sr ions in the process of surface modification of the magnesium alloy (ZK60) by a one-pot hydrothermal process. We found that, after surface modification, the surface of the materials formed a cluster crystal structure coating layer, and the successful incorporation of Zn and Sr ions in the surface coating did not affect the morphology of the microstructure. The corrosion resistance of the surface of the modified magnesium alloy was significantly improved, and cells grew well on the modified material surfaces. Zn and Sr ions released from the coating layer promote cell osteogenic differentiation, and Zn ions also provide a good antibacterial effect. Thus, the combined use of Zn and Sr offers antibacterial effects and promotes osteogenic differentiation of cells. To summarize, we have developed a controllable and degradable magnesium alloy material that offers both osteoinduction and antibacterial effects. The development of this material provides ideas about the preparation of a novel biodegradable magnesium alloy with better bioactivity for clinical application.