Preparation And Osteogenic Activity Of Na₂Ti₃O₇/SrTiO₃ Nanowire Hybrid Coatings On Titanium

With the development of social productivity,and the improvement of medical and health conditions,the life expectancy per capita has increased significantly.Incidence of dental and orthopedic diseases and the medical demand for prosthetic replacement are increasing due to acceleration of global aging.The clinical application of titanium(Ti)implant materials has reconstructed the hard tissue function and greatly improved the patients'quality of life,but still faces implant failure due to long osseointegration time and poor osseointegration ability of the implants,causing patients to suffer double torture of physical and mental.The accompanying medical expenses have brought tremendous mental pressure and heavy financial burden to many families.Further enhancing the osteogenic induction ability of the implant to achieve early and long-term stable osseointegration are the fundamental way to solve the above problems.Nanostructured coatings fabricated on Ti have aroused great interest of researchers.The nanowire coating fabricated by alkali etching is not only cost-effective,but also could induce osteogenic differentiation by simulating the microenvironment of extracellular matrix(ECM),thus are promising to improve the success rate of the implants.Strontium(Sr),as a necessary trace element of human body,could improve bone formation of osteoblasts and inhibit bone resorption of osteoclasts during osseointegration,so it has been widely concerned.In the present work,Na₂Ti₃O₇/SrTiO₃ nanowire hybrid coatings on Ti are fabricated via one-step alkali etching in a mixed solution of Na OH and Sr(OH)₂·8H₂O to enhance its osteogenic activity.Scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,and transmission electron microscopy were used to characterize the samples.Biological experiments were conducted to evaluate the effect of continuous Sr²⁺release and nanowire morphology on the behavior and function of MC3T3-E1 and MG-63 cells.The main research results are as follows:(1)Nanowire hybrid coatings with Sr concentration ranging from 0 at.%to11.07 at.%are fabricated on pure Ti by alkali etching.(2)The main component of coating is Na₂Ti₃O₇.With the increase of Sr concentration,perovskite SrTiO₃ micro-spheres appear on the sample surfaces.Compared with Sr-free sample,Sr-containing samples change from three-dimensional network to cluster and compact nanowire structure.In addition,the noncumulative Sr²⁺release pattern from coatings shows a large amount and rapid release at the early stage followed by sustained and lower release.(3)Na₂Ti₃O₇/SrTiO₃ nanowire hybrid coatings significantly promote the spread of MC3T3-E1 and MG-63 cells.However,they have no effect on the adhesion,proliferation and viability of the two cells.(4)Na₂Ti₃O₇/SrTiO₃ nanowire hybrid coatings significantly promote osteogenic differentiation of MC3T3-E1 cells due to the synergistic effect of continuous Sr²⁺release and nanowire morphology.Sr²⁺could promote the osteogenic differentiation of MG-63 cells,but the nanowire structure has little effect on osteogenic differentiation.