Effects Of Tantalum Boride Coating On Medical Titanium Alloy On Osteogenic Differentiation Of BMSCs In Vitro

Background:Orthopaedic biomaterials are materials that are used to repair or replace damaged bone tissue in humans,to reshape their anatomical structures and restore their function.The ideal orthopaedic biomaterials should not only meet certain mechanical support and antibody fluid corrosion performance,but also have good biocompatibility and biological activity.Medical titanium alloy?Ti6Al4V?is currently the most widely used orthopaedic biomaterials due to its good mechanical support and certain corrosion resistance,but there are some deficiencies of it.For example,Ti6Al4V is biologically inert material which lacks of the effect of induction osteogenesis,resulting in poor periprosthetic osseointegration and limited prosthetic lifespan.In addition,bone marrow mesenchymal stem cells?BMSCs?are the important source of osteogenic cells.Therefore,more researches are focus on the surface modification of Ti6Al4V to enhance its induction of osteogenic differentiation of BMSCs.Tantalum?Ta?is widely used in medicine due to its good biocompatibility.In order to further enhance the osteoinductivity of Ta,the non-metallic compound coatings of Ta have attracted wide attention.For example,it is confirmed that tantalum nitride?TaN?coating and tantalum carbide?TaC?coating have good corrosion resistance and biocompatibility,which can enhance cell adhesion and osteogenic differentiation.In addition,boron?B?plays an important role in human bone health.However,although tantalum boride?B-Ta?coating has been proved to have good corrosion resistance,there is no research on the biological properties of B-Ta coating.Objective:To investigate the effect of tantalum boride coating made by magnetron sputtering on the biological behavior and osteogenic differentiation of BMSCs in vitro.Methods:Pure Ta coating and B-Ta coating were deposited on the surface of medical titanium alloy?Ti6Al4V,TC4?and pure silicon by magnetron sputtering.The coatings were characterized by X-ray diffraction?XRD?and transmission electron microscopy?TEM?.Rabbit BMSCs were isolated and cultured in vitro.Then BMSCs were seeded on the surface of each coating.The adhesion,proliferation,and osteogenic differentiation of BMSCs on TC4,Ta coating,and B-Ta coating were detected and compared.LIVE/DEAD cell staining was used to analyze cytotoxicity of these materials;fluorescence staining was used to observe cytoskeleton and scanning electron microscopy was used to observe cell morphology,which were used to analyze cell adhesion;CCK-8 assay was used to detect cell proliferation;alkaline phosphatase?ALP?staining,ALP activity quantification and alizarin red staining were used to analyze osteogenic differentiation of BMSCs in vitro.Results:In this study,a pure Ta coating and B-Ta coating were successfully deposited on the surface of TC4 by magnetron sputtering.The characterization of B-Ta coating shows that the coating has the typical phase of Ta₃B₄.Cytotoxicity analysis showed that neither the Ta coating nor the B-Ta coating increased the cytotoxicity of the TC4.Cell adhesion showed that the cytoskeleton of BMSCs spread well on the surface of B-Ta coating,and BMSCs on the surface of B-Ta coating have abundant filopodia.Cell proliferation showed that BMSCs on the surface of B-Ta coating proliferated faster.Cell proliferation experiments showed that the number of cells on the surface of B-Ta coating was higher than that of the control group.ALP staining and ALP activity quantification showed that B-Ta coating can upregulate the expression of intracellular ALP.Alizarin red staining showed that the B-Ta coating promoted the deposition of calcium nodules.Conclusion:The present study demonstrates that the Ta₃B₄ coating successfully prepared on the surface of titanium alloy which completely covering the substrate by magnetron sputtering.This coating has less cytotoxicity and can effectively enhance the adhesion,proliferation and osteogenic differentiation of BMSCs.In summary,B-Ta coating is expected to become a new method for surface modification of orthopedic implants.