Nanoporous biocompatible layer on Ti-6Al-4V alloys enhanced osteoblast-like cell response

Background: The surface properties of Ti-6Al-4V (Ti64) alloys extensively affect the biological responses in a physical environment. To enhance the surface biocompatibility of Ti64 specimens, in the present study, electrical discharge machining (EDM) was performed to produce the modified layer on the surface of the Ti64 specimen. Methods: The EDM-functionalized surfaces were obtained at three different pulse durations, which varied from 10μs to 60μs. The surface properties of the EDM-functionalized specimen were characterized with scanning electron microscopy and X-ray photoelectron spectroscopy. The properties of adhesion and proliferation of MG-63 cells were evaluated for the interactions between the EDM-functionalized layer and cells. Results: The incorporation of oxygen roughened the EDM-functionalized surface on a microscale, where the nanoscale pores were superimposed. The EDM-functionalized layer, which can generate the thick anatase TiO2 on the Ti64 surface, afforded a cytocompatible environment. In cell culture, alkaline phosphatase activity could be enhanced on the EDM-functionalized surfaces as compared to the untreated surface. In addition, the increase in pulse durations to the EDM functionalization led to the enhancement of multiple osteoblast functions. Conclusion: The present study revealed that the chemistry and crystallinity of the EDM-functionalized layer played important roles in affecting osteoblastic responses to the specimens, thereby providing insight into the development of new biomedical implant surfaces.