Design And Manufacture Of Hierarchical Micro/Nano-structured Surface On Biomedical Titanium Alloy And Its Biocompatibility

Biomedical titanium alloys,due to their good mechanical properties,lower modulus of elasticity,corrosion resistance,and good biocompatibility,have been used to make artificial joint,dental implant and so on.However,titanium alloy implant in human body has a bad integration with surrounding bone tissue,which is easy to beloose and inflamed.Therefore,it is necessary to modify the implant surface before implantation in human body,in order to further improve its biocompatibility.The surface topographies of natural bone consist of macroscopic and microscopic structures.From the view of bionics research,the micro/nano-topography can improve the combination ability between implants and bone tissue,and improve the mechanical ability and biocompatibility of titanium alloy surface.At present,the micro/nano-topography modification has become one of the main methods to improvethe surface biocompatibility.In this paper,the biocompatibility and bone integration of titanium alloy were impro-ved by fabricating micro/nano-structured surfaces.Firstly,micro/nano-structured surface fabricated by micro-milling and alkali-hydrothermal reaction was evaluated through cell experiments.The surface features were characterized using laser scanning microscope,scanning electron microscope and contact angle goniometer.A series of cell experiments were used to evaluate biocompatibility of workpieces,including cell morphology,alkaline phosphatase activity,proliferation,osteopontin and osteocalcin expression,and mineralization.The results show that workpiece surface with micro/nano-structure contributed to MC3T3s spread,proliferation,and differentiation.Secondly,micro/nano-structured surface constructed by sandblasting,acid etching and alkali-hydrothermal treatment was evaluated through cell experiments.The surface characteristics were measured using X-ray diffraction,laser scanning microscope,scanning electron microscope and contact angle goniometer.A series of cell experiments were used to evaluate biocompatibility of workpieces,including cell counting,proliferation,morphology,osteocalcin expression,alkaline phosphatase activity and mineralization.The results show that workpiece surface with micro/nano-structure displayed better biocompatibility and improved MC3T3s proliferation and differentiation.Lastly,the micro/nano-topography was constructed via sandblasting,acid etching and alkali-hydrothermal treatment.Then Na⁺ in treated workpiece surface was replaced by Ca²⁺ and Mg2+ respectively through hydrothermal reaction.The diverse surface was measured by X-ray Photoelectron Spectroscopy,and Na⁺ on the surface was entirely replaced.A series of cell experiments were used to evaluate the synergistic effects of ions and micro/nano-topography on MC3T3 growth.The results indicates that Ca²⁺ and Mg2+ in workpiece surface promoted MC3T3s growth and differentiation.In addition,MC3T3s grown onto Ca²⁺ surface showed higher differentiation levels compared to that on mg²⁺ surface.