The Fabrication And Antibacterial Behavior Of Nano-featured And Micro-nano-featured Surfaces On Pure Titanium For Biomedical Applications

Titanium（Ti）and its alloys are widely used as implant materials owing to their excellent mechanical properties and biocompatibility.However,clinically,bacterial-related infection（BRI）usually occurs in the implantation of titanium-based materials,which leads to infection or even failure of the metallic implant.BRI should be mainly attributed to the early adhesion of bacteria on implants,followed by the formation of a mature biofilm.Once a mature biofilm has formed on the surface of implants,it is difficult to eradicate with traditional treatments.Besides,considering the ever-increasing bacterial resistance to the antibiotic,the developmennt of a physical antibacterial surface on Ti-based implants to prevent the formation of mature biofilms by inhibiting the early adhesion of bacteria or killing bacteria directly is of great value.In this study,highly ordered self-assembled titania nanotube（TNT）arrays with different nanotubular diameters are fabricated on Ti by electrochemical anodization.The results of E.coli viability assay,bacterial morphology,bacterial live/dead staining and RT-q PCR show that compared with the typical polished surface of biomedical commercially pure Ti,TNT arrays exhibit remarkable inhibition behavior against the early adhesion of Escherichia coli（E.coli）,and the ones with larger nanotube diameter seem to be more effective.The underlying anti-bacterial mechanisms of TNT samples may include: 1)the anti-initial-attachment effect;2)damage of the membrane function resulting in the death of E.coli.Specifically,the anti-initial-attachment effect at the lag phase;the anti-attachment and bactericidal effects at the logarithmic phase,while,the former plays a more signif icant role than the latter;the reduced anti-bacterial properties probably due to the overgrowth of bacteria on TNT arrays at the stationary phase.Besides,previous studies have shown that compared with pure titanium,a micron-scaled roughness surface is beneficial to osseointegration.However,the micron-scaled surface roughness and the presences of pores can promote the adhesion and proliferation of bacteria,leading to infection.The nanotube structure could solve this problem.Therefore,in order to promote cell adhesion and proliferation,which leads to good osseointegration while inhibiting the adhesion and proliferation of bacteria on the surface of the material,the micron-nano-featured structure surface were fabricated.In this study,a micron-nano-featured surface is obtained on a micron-scaled surface by powder metallurgy,followed by electrochemical anodization treatment.And the effect on cell behavior and initial adhesion process of bacteria are studied.And the results show that the micron-nano-featured structure surface not only presents improved cell adhesion and cell proliferation,but also displays a significant antibacterial effect within 8 hours.