Methods: Surface morphology and composition of the specimens were analyzed by SEM and EDS. Surface roughness and contact angle were measured using a surface profilometer and a contact angle measuring system, and surface energy was calculated based on Owens-Wendt-Rabel-Kaelble theory. Cell adhesion and proliferation were assayed by MTT method. Alkaline phosphatase (ALP) activity was assessed with a commercial kit. The mRNA level of several integrin subunits was surveyed by Semi-quantitative RT–PCR.
Results: A porous bioactive oxide layer was grown on TLM, and the diameters of holes was larger when higher voltage applied. Both Ca and P were incorporated into the oxidized surfaces. Surface roughness was enhanced on the micro-arc oxidized surfaces. After MAO treatment, Water contact angles became smaller and surface energies of the TLM surfaces were increased, especially the polar component. Cell culture experiments demonstrated an enhanced initial osteoblasts adhesion on the micro-arc oxidized surfaces. Higher initial cell proliferation was observed on the micro-arc oxidized surfaces. Nevertheless, the ALP activity of the cells was lower on the micro-arc oxidized surfaces than on the polished one. RT-PCR demonstrated a lower mRNA level of integrin subunit â1 of the cells on the micro-arc oxidized surfaces than on the polished surface.
Conclusion: MAO process can enhance surface roughness, wettability and surface energy of TLM, and incorporate Ca/P into the surface, which are dependent on the MAO voltage. Initial cell adhesion and proliferation are enhanced, while initial cell differentiation is inhibit by MAO. Integin â1 expression level seems to play minor role in these cell behaviors. This work is supported by National High Technology Research and Development Program of China, grant number: 2002AA326070.