Surface Micro/Nanostructuring Of Titanium Implant And Research On Its Biocompatibility

Titanium and its alloys have been widely used to fabricate the hard tissue implants(e.g.teeth,bone-screws,and artificial joints)because of their low cost,excellent mechanical properties and biological characteristics.However,the binding capacity of machined titanium implants and bone tissues is poor due to the bio-inerness of titanium,which could lead to the loosening of implants and the failure of operation.Therefore,it is necessary to modify the surface of titanium-based implants for enhancing osteoinduction and osseointegration,improving the service time of the implant in the human body,and increasing the success rate of implantation.Surface morphology is an important parameter in the design and manufacture of implants,which plays an essential role in regulating the behaviors of cell.Natural bone tissue is a complex multiscale structure,including macro-scale,micro-scale,and nano-scale organizations.From the bionics point of view,implant with micro/nanostructure would be beneficial to improve the integration of an implant and bone tissue.Therefore,in this study,three novel methods have been proposed to fabricate the micro/nanostructure on the surface of titanium for improving the osseointegration of titanium implants.Firstly,a novel hybrid structure of micro-groove arrays combined with titania nanotubes was constructed on the surface of titanium by micro-milling and anodic oxidation.The surface morphology,surface roughness and contact angle of treated titanium were investigated.The results indicated that the micro/nanostructure enhanced the surface roughness and hydrophilicity of titanium substrates.In addition,cell experiments were carried out to investigate the biocompatibility of samples,including cell morphology,cell proliferation,and cell differentiation.The results showed that titanium surface with micro/nanostructure promoted the spreading,growing,and differentiation of cells.Secondly,micro/nanostructure was fabricated on titanium surface by the combination of sandblasting,acid etching,and chemical oxidation.The surface morphology and corrosion resistance of samples were investigated.The results demonstrated that micro/nanostructure comprising of micro-pits and nano-pits was successfully produced on titanium surface.And the micro/nanostructured titanium samples presented an excellent corrosion resistance.Moreover,the effects of different surface structure(micro-pits,nano-pits and micro/nano-pits)on the biocompatibility of implants were evaluated by cell culture experiments.The results demonstrated that the structure of micro/nano-pits was more beneficial to promote the adhesion,spreading,proliferation,and differentiation of cells than that of micro-pits or nano-pits.Lastly,micro/nanostructure containing zinc/strontium was produced on the surface of titanium by sandblasting,acid etching,alkali-heat treatment,and ion exchange.The surface morphology and contact angle of samples were investigated.The results demonstrated that ions exchange would not alter the surface topography of samples.In addition,the micro/nanostructured titanium surface with zinc/strontium ions presented an excellent hydrophilicity.Cell experiments indicated that the micro/nanostructured surface enhanced the spreading,prolifereation and differentiation of cells.More importantly,micro/nanostructured titanium samples containing zinc/strontium ions further improved the behaviors of cells compared to micro/nanostructured titanium samples due to the release of zinc/strontium ions.