Research On The Preparation And Properties Of Bioactive Glass-polymer Composite Scaffolds

Bone is an important part of the human body,it plays an important role in providing mechanical support,protecting vital organs,regulating calcium and phosphorus metabolism.Implanting bone repaired materials are widely used for clinical bone defect treatments.While,bone graft materials which are used in both study and clinical are inadequate.Therefore,to develop new graft materials which can fully meet the clinical needs has received extensive attention these days.In this study,firstly,the bioactive glass microspheres with high bioactivity were synthesized by sol-gel method combining template technology.Then the composite scaffolds with enough mechanical strength,high porosity and interconnected open-pore microstructure were prepared by freeze-drying combined the bioactive glass with gelatin and zinc oxide.We also studied the pore structure,mechanical properties,in vitro biomineralization activity and degradation performance of the composite scaffolds.The cell compatibility of the scaffolds was studied by using rat mesenchymal stem cells as the model.The main research work and conclusions are as follows:Firstly,the bioactive glass microspheres were synthesized by sol-gel method combining template technology.The powder particles were regular spherical,monodispersed and uniform-sized.The bioactive glass sphere with disordered mesoporous structure was assembled from nanoscale particles.In vitro mineralization test showed that the prepared bioactive glass particles had good apatite forming ability.Then,the bioactive glass/gelatin composite scaffolds with different mass ratio were successfully prepared by freeze-drying method.The composite scaffolds had the interconnected pore structure.When the mass fraction of the glass was less than 50%,the pore connectivity was excellent and the pore size with a wide distribution could be from several tens to hundreds of microns.When the mass fraction of the glass was more than 50%,the scaffolds' pore connectivity reduced,and most pores were larger than 200?m.The bioactive glass particles constituted the wall of obtained composite scaffolds,while the gelatin acted as binder.In vitro degradation test showed that the degradation rate of scaffold was accelerated with the increase of bioactive glass content in the composite scaffold.The degradation of pure gelatin scaffold was more uniform,and the scaffolds containing bioactive glass showed rapid weight loss at the beginning of degradation,which revealed the leaching of glass particles.In vitro mineralization tests showed that the pure gelatin scaffolds had no in vitro apatite forming activity,and the composite scaffolds containing bioactive glass showed different degrees of mineralization.With the increase of glass content,the mineralization effect was better.Finally,we combined tetrapod ZnO whiskers with the composite scaffolds which the content ratio of bioactive glass/gelatin was 7/3.Adding ZnO whiskers could enhance the mechanical behaviors of the scaffolds,and the composite scaffolds with 2 wt% ZnO had excellent integrated mechanical properties.The addition of ZnO had little effect on the pore structure of the scaffold,and the zinc oxide reduced the in vitro degradation rate of the scaffolds.In vitro mineralization tests demonstrated that the release of zinc ions delayed the mineralization process and resulted in reduced crystallinity and crystallite size of HC A.On the other hand,the scaffolds had good cell compatibility,and the composite scaffolds with zinc oxide showed better performance in promoting cell proliferation.