Biological Evaluation Of Composite Coatings On Pure Titanium Loading With Polydopamine-baicalin

Research Background:Since Professor Branmark first reported,dental implantology has been developed rapidly.The development of titanium-based implants with different designs and surfaces has always been a hotspot.Therefore,treatment on the surface of bone implants has become an important factor affecting osseointegration.Polydopamine is a multifunctional surface-modifying polymer,which is used in the biomedical field such as the surface modification of orthopedic/dental implants,drug delivery,and biosensing.Baicalin is a Chinese herbal component extracted from the dried roots of the plant Scutellaria baicalensis Georgi.It has a variety of pharmacological effects,can promote osteogenesis cells differentiate into bone,which makes it possible to be used as an ideal coating material.This study intends to prepare a composite coating rich in polydopamine and baicalin by the co-deposition method,and explore its effect on the biological activity of bone marrow mesenchymal cells,which can provide new ideas for constructing biologically active implant coatings.Research objective:1.To successfully prepare polydopamine-baicalin composite coating on titanium surface by co-deposition method.2.To investigate the effect of polydopamine-baicalin coating on bone marrow mesenchymal stem cells.3.Investigate the safety of the loaded polydopamine-baicalin coating in animals.Materials and Methods:1.The titanium sheets were soaked in the dopamine solution and baicalin solution,and the polydopamine-baicalin composite coating was loading on the surface by codeposition,and its physical and chemical properties were tested.2.The processed titanium sheets were divided into 4 groups:Ti group,BC group,PDA group,BC-PDA group,and rat bone marrow mesenchymal stem cells(BMSCs)was inoculated with good growth on the surface of each group for evaluation.Its influence on cell adhesion proliferation and osteogenic differentiation was assessed.3.The backs of male SD nude mice were implanted with titanium sheets in each group,and they were sacrificed 2 weeks later and the HE stained sections were observed to determine the biocompatibility of the titanium sheets in the experimental group.Result:1.The surface structure of each group of samples were observed through scanning electron microscope(SEM).The surface of the titanium sheet in the experimental group is more uniform,with a large number of microspheres and a denser mesh structure.XPS experiment proved that the PDA group and the BC-PDA group have chemical states such as R-NH2,R-NH-R,R=N-R,-N...H-O-,C-O-H and C=O.The contact angle experiment showed that the PDA group and the BC-PDA group had better hydrophilicity,with statistical differences(P<0.05).2.The CCK-8 experiment showed that BMSCs had the ability to adhere and proliferate on each group of titanium sheets.The number of cells in the BC-PDA group was more than that in the Ti group at 2h,and the number of adherent cells in the BC-PDA group was more than that in the BC group and the PDA group at 4h,with statistical differences(P<0.05).At 1,3,and 7 days,the proliferation rate of BC-PDA group was the fastest.DAPI staining and dead/live cell staining showed that there were live cells on the titanium plates in each group.The cells in the BC-PDA group were densely packed with more filiform pseudopods.Alkaline phosphatase(ALP)experiments showed that the ALP activity of the cells on the surface of the titanium sheets in each group increased with time.At 7d and 14d,the intracellular ALP activity of the BC-PDA group was higher than that of the Ti group(P<0.05).3.Two weeks after the titanium plates were implanted in nude mice,HE histological staining observed that the fibers of the titanium plates in each group grew circularly to form cysts,with a small amount of lymphocyte infiltration in the local area,and no other pathological changes.Conclusion:1.The co-deposition method was used to successfully prepare a polydopamine-baicalin coating with good hydrophilicity on the surface of the titanium sheet.2.The polydopamine-baicalin composite coating on the surface of pure titanium can improve the early adhesion,proliferation and differentiation of bone marrow mesenchymal stem cells.3.The safety test of the polydopamine-baicalin coating on the surface of the titanium sheet through the in vivo implantation experiment found that it has good biocompatibility.