Fabrication And Biological Properties In Vitro Of A Novel Functional Coating On Pure Titanium

Pure titanium and titanium alloys have been widely used in orthopedic and dental clinic attribute to their remarkable mechanical properties and bio-compatibility.However,implant related infection is still one of the more difficult postoperative complications,and titanium itself can not induce bone deposition,Therefore,the latest research focuses mainly on how to improve the surface treatment of the implant to promote early bone bonding,shorten the overall treatment time,and repair the bone defect which caused by inflammation,trauma and so on.We have successfully prepared double-layer nanoparticels loaded rhBMP-2 and SDF-1,which was proved to be with the excellent drug release characteristics and the in vitro biological properties of effectively inhibiting the activity of osteoclast,inducing bone marrow mesenchymal stem cells to migrate,and to mature to osteoblast,consequently inducing deposition of calcium salt,and forming bone tissue.Based on the nanoparticles,the novel coating was achieved by cross-linking the double-layer nanoparticles with gelatin on microarc-oxidized titanium.The release behavior of the functional coating was investigated,and the in vitro biological properties was also evaluated.The newly fabricated coating on titanium implant is expected to provide a new idea and method for early healing and repair of bone defect.Methods:1.The novel functional coating was achieved by cross-linking the double-layer nanoparticles loaded rhBMP-2 and SDF-1 with gelatin on microarc-oxidation coating on the titanium implant surface.The surface topography was observed by SEM.2.The release behavior of the coating was preliminarily investigated in vitro.3.The in vitro biological safety of the novel functional coating was evaluated by cytotoxicity test(Cell Counting Kit-8 method),oral mucous membrane irritation test and hemolysis test in vitro.4.Osteoclasts precursors and bone marrow mesenchymal stem cells were respectively co-cultured on the coating to evaluate its in vitro biological properties such as inhibiting osteoclast differentiation,promoting bone marrow mesenchymal stem cells to osteogenic differentiation.Transwell test was used to evaluated its effect to migration of BMSC.Results:1.The novel functional coating was successfully fabricated by cross-linking the nanoparticles loaded rhBMP-2 and SDF-1 with gelatin on microarc-oxidized titanium.The novel coating possessed excellent morphology,which is observed by SEM.The pores of the microarc-oxidized titanium were almost overlaid by nanospheres.The nanoparticles were well distributed in the pores of the microarc oxidization coating,and tightly cross-linked with each other and the walls of pores by gelatin.2.The release behavior of the novel functional coating in vitro showed the initial burst release and the lasting release,which is basically similar to the release behavior of double-layer nanoparticles,the initial burst release showed that about 15%-20% of the accumulate amount of three biological factor was respectively slowly released from the coating at the first 24 hours.The lasting release can remain at least 30 days,and with the down-regulation of pH,the release of drugs appeared more fast.3.Cytotoxicity test showed that no cytotoxicity,oral mucosa stimulation experiments showed that the coating is without mucosa irritation,hemolytic test showed that the coating is without hemolysis.To sum up,the coating material has good biocompatibility and safety in vitro.4.Co-culture of osteoclasts precursors and the fabricated coating revealed that the fabricated coating inhibited the differentiation and maturity of osteoclast to a certain degree.Besides,co-culture of BMSC and the fabricated coating revealed that the coating can promote osteogenic differentiation,promoting calcium deposition and forming bone tissue.Transwell test revealed that the coating can promote the migration of BMSC.Conclusion:The novel functional coating possessing excellent morphology was achieved on titanium.The release behavior in vitro can meet clinical requirement,the newly fabricated coating possessed good biological safety in vitro and the properties of inhibiting the differentiation of osteoclast and promoting BMSC migration and osteogenic differentiation.So it may has potential to be a new promising method to promote early-healing and repair bone defect.