Preparation And Properties Of HA-coated Bone Scaffolds Based On Core-shell Hierarchical Porous Woven Structure

The scaffold is an important part of bone tissue engineering,and its key function is to provide temporary mechanical support at the defect site and provide a suitable environment for cell growth.With the in-depth research of artificial bone scaffolds,while meeting the basic requirements of degradability and biocompatibility,how to improve the mechanical properties of the scaffold,give it osteoinductivity and construct a low-density porous structure has become the focus of bone scaffold research.Among them,the biomimetic structure of natural bone apatite to prepare high bioactive hydroxyapatite(HA)biomaterial is an eternal topic in the field of bone tissue engineering.In response to the above problems,this study uses materials such as chitosan(CS),polyvinyl alcohol(PVA)and polylactic acid(PLA)to construct a coreshell scaffold with a textile structure.And on this basis,its performance is improved to prepare a degradable bone scaffold that not only meets the requirements of mechanical properties,but also has osteoinductive capacity and good cell compatibility.The main research contents are as follows:First,chitosan(CS)and hydroxyapatite(HA)of different mass ratios were mixed and injected into PVA/PLA multilayer composite braid,and a core-shell braided bone scaffold was obtained by freeze-drying technology.Through the cold atmospheric plasma(CAP)treatment of the scaffold,the scaffold obtains a hierarchical pore structure.The core of the scaffold added with HA produces a "fishbone"-like ordered structure with a pore size of 80-180?m,which can meet the needs of accommodating cells and forming blood vessels and new tissues.The surface of the bone scaffold has microscopic pores?10?m after being treated by CAP.The scaffolds with hierarchical pore structure have good mechanical properties and twice the degradation rate.In addition,the CAP-treated scaffolds precipitated more complete spherical HA crystals.Under the synergistic effect of HA and CAP treatment,compared with the pure CS scaffold,the scaffold achieved277.6% cell viability.In general,HA and CAP treatment could synergistically improve the performance of the bone scaffold.Then,on the basis of the hierarchical pore braided structure bone scaffold,PDA coating was deposited.When immersed for 12 hours,the scaffolds were well deposited with a PDA coating,and the microscopic pores on the surface can still be retained.Immersed the PDA-coated bone scaffold in 1.5 times the concentration of simulated body fluid(SBF)directly induced HA coating.PDA-induced HA-coated scaffolds precipitated clusters of intact spherical HA crystals in SBF.PDA coating and HA coating showed a synergistic effect on promoting cell growth and proliferation.Finally,PDA-coated bone scaffolds were coated with HA by pulse electrodeposition.The effect of PDA coating,the best deposition voltage and the best pulse width were explored.The SBF was used to evaluate the mineralization ability of the bone scaffolds in vitro,and the electrodeposited scaffold was precipitated with a uniformly clustered spherical HA crystal coating.According to MTT analysis,the cell proliferation and growth effect of the electrodeposited HA coating is better than that of the directly addition of HA nanoparticles and PDA-induced HA coating.The cells on the scaffold showed multiple elongated filopodia.And the biocompatibility of the scaffold increased to 347.1%.This PDA hierarchical pore bone scaffold with electrodeposited HA coating can potentially be used in bone tissue engineering.