| [Object]This study is to evaluate the biocompatibility, physical and chemical property of Ti-6Al-4V alloy fabricated by electron beam melting and selective laser melting for bone tissue engineering[Method]Physical and chemical property:Ti-6A1-4V alloy specimens were fabricated by selective laser melting (SLM) and electron beam melting (EBM). A wrought form of Ti-6Al-4V alloy was used as a control. (1)Microstructure observation was detected through OM, SEM, TEM and EBSD tests. (2)Component analysis was detected by XRD, EDS, XPS and series of GB/T4698. Contact angle test was used to detect hydrophilicity.Hardness was observed using Vickers microhardness test. Electrochemical corrosion experiment, immersion test and cell culture medium analysis were operated to detect the corrosion resistance of Ti-6A1-4V alloy.Biocompatibility:Ti-6A1-4V alloy specimens were fabricated with selective laser melting (SLM) and electron beam melting (EBM). A wrought form of Ti-6A1-4V alloy was used as a control. EBM, SLM and wrought specimens were for experiment in vitro. EBM and wrought specimens were for experiment in vivo. (1) The morphology of cells and cell attachment and proliferation were observed by SEM and cell counting experiment. (2) The ultrastructure of cell, liver and kidney tissue were observed with TEM. (3) The DNA observation of liver and kidney tissue was operated using comet assay.[Result]Physical and chemical property:The microstructures of EBM, SLM and wrought specimens were different. Wrought specimen was basket-weave. EBM and SLM specimens had many fine acicular a laths. And the secondary a laths of EBM were coarser than SLM. Intermetallic compound was detected in EBM specimen and a’ phase was observed in SLM specimen. The surface topography of EBM and SLM specimens were similar, but were not the best for cell attachment. The content of C, H, O, N were almost unchanged. The surface component was a-Ti in three kinds of specimens. The components of Ti-alloy oxide film was detected in all kinds of the specimens. And segregation was not existed in all kinds of Ti-6Al-4V alloys. The result of roughness implied that the roughness of SLM and EBM specimens was suitable for cell attachment, but was not the best for cell attachment. Based on contact angle result, the character of SLM and EBM specimens was hydrophobic (>65°), which means it is not the best contact angle for cell attachment. The result of scanning electron microscope (SEM) suggested that the surface topography of EBM and SLM specimens were similar, but were not the best for cell attachment. The microhardness of SLM and wrought specimens was similar (P>0.05) and EBM was higher than that of SLM and wrought specimens (P0.05). The thermodynamic stability of EBM specimen was wrost in the group. The corrosion resistance of SLM specimen was the best, and EBM was the worst, when the electrode potential<1200 mV. However, when the electrode potential>1200mV, the result was the opposite. The content of Ti, Al, V ions of EBM and wrought specimens were very low and did not affect the cell attachment and proliferation.Biocompatibility:On the basis of SEM and cell counting results, the number of cells was similar in the three groups and increased obviously with the time prolonged. The shape of cells changed obviously from sphere to spindle. On the basis of the TEM result, the ultrastructure of cell and liver and kidney tissues was normal, and the cytomembrane was intact. Based on the general observation, the mesh scaffold showed thinner fibrous encapsulation and no sign of intolerance were observed. Histology showed that matured and slightly vascularized fibrous tissue was surrounding the specimen and struts. The result of comet assay showed that EBM and control group has very similar tail cells and the OTM value.[Conclusion]The Ti-6Al-4V alloy fabricated using the EBM and SLM had valuable properties for bone tissue engineering. However, it is better to do some further proper treatments, based on the application requirements. |
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