Preparation And In Vitro Bioactivity Of HA/CuO Gradient Bioceramic Materials

Titanium and its alloys have been widely used in medical implant materials such as artificial bones,artificial joints,and weight-bearing bones.Coated a layer of hydroxyapatite（HA）bioceramic coating on its surface can increase its biocompatibility and biological activity.However,due to the mismatch between the thermal expansion coefficients of HA and titanium,the coating is brittle and cracked during high-temperature calcination,which affects the mechanical properties of the coating.Meanwhile,The HA coating doesn’t possess bacteriostatic ability,and it is prone to bacterial infection and complications after implantation in the human body,which affects the postoperative recovery of patients.Therefore,it is an urgent problem to develop an HA bioceramic material with better mechanical properties and certainly bacteriostatic ability.In order to improve the bioactivity and other properties of HA bioceramic materials,a new series of HA/CuO bioceramic gradients were prepared by adding osteogenic trace element compounds and utilizing zonal electrophoresis/electrophoretic deposition using titanium as substrate.Composite materials,including HA/CuO/Sr CO₃,HA/CuO/Si O₂and HA/CuO/Zn O gradient composites,were tested by XRD,FT-IR,SEM,EDS,universal material testing machine,and electrochemical workstation respectively.The composition,crystal form,surface morphology,element content,bonding strength,and corrosion resistance were tested and characterized,and Staphylococcus aureus and Escherichia coli were used as probes to test the antibacterial properties of the coating powder.Cultured in HEPES simulated body fluid（H-SBF）,the osteoinductive ability of HA bioceramic composite coating was investigated.The results show that HA,CuO and other osteogenic trace element compounds are deposited successfully on Ti substrate,and all three gradient composites HA/CuO/Sr CO₃,HA/CuO/Si O₂and HA/CuO/Zn O have a certain gradient distribution in the radial direction.Compared with pure HA,the bonding strengths of the three gradient composite coatings and Ti substrate were increased by 20.8 MPa,6.86 MPa and 9.09 MPa;the corrosion resistance and biological activity in the simulated body fluid of HEPES were outstanding,and their self-corrosion potentials were 0.275 V,0.152 V and 0.145 V,the self-corrosion currents were 1.29×10^-9A·cm^-2,1.38×10^-10A·cm^-2and 3.24×10^-10A·cm^-2,respectively.The antibacterial rates of the three gradients composite coatings powder against Escherichia coli were 81.82%,77.27%and 79.55%,and the antibacterial rates against Staphylococcus aureus were 71.86%,70.31%and 82.29%,respectively.To sum up,the HA/CuO/Sr CO₃gradient composite exhibits the best mechanical properties,strong corrosion resistance,and excellent bacteriostatic ability,so it is expected to be developed into a new generation of artificial bone implant materials.