Preparation Of Composite Microstructure And Silver-loaded Oxidation Layer On Titanium Alloy Surface And Its Osteogenic And Antibacterial Properties

Titanium and its alloys are widely used in the field of biomedical materials due to their excellent biocompatibility,mechanical properties,corrosion resistance and other comprehensive properties,especially in the repair and replacement of hard tissue implants.However,for the biological inertness of titanium,after implantation into the human body,it cannot be directly bonded with human tissues and cells.This may cause the loosening of the implant,which will lead to the decrease of the implant service process and cause failure to the implantation operation.At the same time,the titanium material does not have antibacterial properties.In the early stage after the implantation operation,bacterial infection is prone to occur,which will also cause the failure of the implant and bring pain and economic burden to the patient.After the titanium implant is implanted into the human body,it is the surface of the material that first contacts and directly reacts with human tissues and cells.Therefore,in order to improve the osteogenic and antibacterial properties of the implant material,it is necessary to conduct the material surface modification before the implantation operation.In this paper,the surface modification of the titanium alloy implant material was carried out by the compound modification method of micro milling,acid etching,and micro-arc oxidation.And the composited microstructure of"micro groove-micro hole-micro pit" was constructed to adjust the surface roughness,wettability and other physical and chemical properties of the implant material,which improved its biological activity and osteogenic properties of titanium.At the same time,the modification method of PLGA loaded silver coating was carried out to modify the implant to obtain an implant with both osteogenic and antibacterial properties.Firstly,the effect of osteoblasts of microgroove surfaces with different morphologies,prepared by the "micro milling and acid etching" method,on the growth was studied.By testing the surface morphology,roughness,and wettability of different groups of samples,it was found that the construction of the micro-grooves improved the surface roughness and the surface contact angle value also increased.After the acid etching,the milling burrs were cleared and the surface appeared a sub-micron pit morphology,and the contact angle decreased.Furthermore,the surface wettability of the cross micro grooves changed into the state of hydrophilicity.The cell morphology was observed via in vitro cell experiments,and it was found that the presence of microgrooves promoted the growth of osteoblasts on the surface of the materials,especially the cross micro grooves.Secondly,the influence of the micro-arc oxidation process parameters on the morphology of the porous oxide layer on the titanium surface was studied.Under the calcium and phosphate electrolyte system,by adjusting the process parameters of pulse voltage,pulse frequency,duty cycle and oxidation time in the process of micro-arc oxidation,the change trend of surface porous morphology was studied,and appropriate micro-arc oxidation process parameters(voltage 450V,pulse frequency 800Hz,duty factor 30%,oxidation time 10min)were selected for subsequent experiments.Then,a composited microstructure morphology of "micro grooves-micro holes-micro pits" was constructed on the titanium surface,using the method of "micro milling,acid etching,and micro arc oxidation".And its osteogenesis property was studied by in vitro cell experiments.The results showed that after the modification treatment,the surface showed a super-hydrophilic state,and a large amount of calcium phosphate oxide and rutile TiO2 were generated into the layer.The experimental results of cell adhesion,cell proliferation,and osteogenic differentiation showed that the modified surface promotes the growth,proliferation and differentiation of osteoblasts,and improved the osteogenic properties of the material surface.Finally,the surface of the titanium implant material was modified by the method of PLGA loaded silver coating based on the previous modification to improve the antibacterial properties.Through in vitro bacterial experiments,it was found that the modified sample surface had a good inhibitory effect on the growth of Staphylococcus aureus and Escherichia coli,and exhibited good antibacterial properties.Besides,the method was cellular nontoxic.A new method for surface modification of implants with both osteogenic and antibacterial properties was verified.