Fabrication Ofmicro-nanostructure Ontitanium Surface And Its Effecton Loading And Releasing Offunctional Substance

Titanium(Ti)and its alloys are widely used in biomedical fields for hard tissue repairment and replacement due to their excellent biocompatibility and comprehensive mechanical properties.However,the bioactivity of Ti is poor,and it is combined with bone tissues in a mechanically locked manner in the human body,rather than effective bone bonding,thus long-term service may cause loosening of the implant and consequently implantation failure.Moreover,implant associated infection is also a serious problem,which affects the normal service of the implant in the human body and increases the suffering of the patient.In order to solve the above two problems faced by Ti-based implants,a bioactive micro-nanostructure was firstly prepared on Ti surface by blasting,acid etching and anodic oxidation,and then the antibacterial agent of silver(Ag)was loaded into the nanotubes on the micro-nanostructure by centrifugation and ultraviolet irradiation.The surface morphology,elemental composition,phase composition,structure and roughness of the obtained sample were characterized by SEM,EDS,XRD,XPS,TEM and AFM.The release behavior of Ag from the sample surface was explored by ICP-AES.The surface wettability was evaluated by contact angle experiments.The antibacterial property of the material was evaluated by bacteriostatic test such as colony number,absorbance,inhibition zone,bacterial activity and bacterial staining.The bioactivity was evaluated by simulated body fluid soaking experiment.The cytocompatibility was evaluated by cell co-culture experiments.The main conclusions obtained were listed as follows:(1)Microstructure was formed on Ti surface by blasting and acid etching.The residual sand blasting particles in microstructure can be removed by acid etching with 15%nitric acid and 1% hydrofluoric acid mixture and the acid treatment also made the surface structure more uniform.During the anodic oxidation,the water content in electrolyte had an important influence on the nanostructures formed on Ti surface.When the water content was 3%,the nanopore structure was obtained;when the water content was 5%,the nanotube structure with a diameter of about 100 nm was obtained;when the water content was 7%,the upper end of the nanotubes would be cleft to form the nanowire structure;when the water content was 9%,the splitting phenomenon of the nanotubes was intensifiedand more nanowire was formed.(2)In the Ag loaded micro-nanostructure,the diameter of the nanotubes was about100 nm,the thickness of the nanotube array layer was about 3 μm,and Ag was loaded into the nanotubes as a simple substance.The sample can release Ag under aqueous conditions for at least 30 days,and the loaded Ag had little influence on the surface roughness of the micro-nano structure,however,decreased the wettability to an extent.(3)The results of bacteriostatic test showed that the Ag-loaded micro-nanostructure had a long-term antibacterial activity against E.coli,showing good antibacterial property.(4)After soaking in simulated body fluid,bone-like apatite was formed on the Ag-loaded micro-nanostructure,indicating the good bioactivity of the sample surface.(5)Cell co-culture experiments showed that the Ag-loaded micro-nanostructure accelerated the proliferation of osteoblast MC3T3-E1,and the cells adhered to the surface and spread out fully,indicating the good cytocompatibility.