Study On The Preparation And Modification Of Cartilage Tissue Engineering Scaffolds Based On Bioactive Glass

Osteoarthritis is a chronic progressive bone and joint disease that seriously affects people’s normal life.Clinically,it is usually treated with autologous cartilage transplantation or allogeneic cartilage transplantation.However,due to the limited sources and immunogenicity of these two types of bone repair materials,more and more studies have been conducted to repair bone injury by preparing bone tissue engineering scaffolds.Bioactive glass has higher bioactivity,also has pro-angiogenic and antibacterial properties,and is able to form a strong interfacial bond with surrounding tissue.In this paper,the bioactive glass prepared by sol-gel method was compounded with chitosan and sodium alginate,and the cartilage tissue engineering scaffold was prepared by freeze-drying method.Finally,the scaffold was modified with graphene oxide to explore the effect of graphene oxide on the performance of the scaffold.（64-x）Si O₂-36Ca O-x P₂O₅（x=0,2,4,6,8mol%）was prepared by sol-gel method using ethyl orthosilicate,triethyl phosphate and calcium nitrate tetrahydrate as raw materials.The effect of phosphorus content on the microstructure and in vitro mineralization properties of bioactive glass was analyzed.The results show that the prepared bioactive glass is mainly amorphous.With the increase of phosphorus content,the percentage of bridging oxygen in the silicon-oxygen tetrahedron in the bioactive glass first increases and then decreases.Among them,the silicate network structure of the 4mol%P₂O₅ group was the densest.After immersing the bioactive glass in simulated body fluid（SBF）for 3 days,irregular cauliflower-like hydroxyapatite particles appeared on the glass surface,indicating that the addition of phosphorus enhanced the in vitro mineralization performance of the bioglass.Bioactive glass/chitosan/sodium alginate（BCS）composite scaffolds were prepared by freeze-drying method using 60Si O₂-36Ca O-4P₂O₅ group bioactive glass with good in vitro mineralization properties as active material.The results showed that the prepared BCS composite scaffolds had a connected three-dimensional porous structure,the overall pore size of the scaffolds in the BG1 group was larger,and the compressive modulus was the lowest,which was 1.083±0.002 MPa.With the increase of bioglass content,the porosity of the composite scaffold gradually decreased,and the swelling ratio and degradation rate decreased.After soaking in SBF for 3 days,cauliflower-like hydroxyapatite was formed on the surface of BCS composite scaffolds,indicating that the scaffolds had good in vitro mineralization properties.Adding bioglass to the scaffold could improve the relative cell viability of MC3T3-E1osteoblasts to a certain extent,and the BG1 group composite scaffold had the strongest ability to promote the proliferation of osteoblasts.Finally,in order to improve the mechanical properties of the BG1 group scaffolds,graphene oxide/bioactive glass/chitosan/sodium alginate（GBCS）composite scaffolds with different content of graphene oxide were prepared by freeze-drying method on the basis of the BG1 group composite scaffold formula.The results showed that the prepared GBCS composite scaffolds had a three-dimensional porous structure.With the increase of graphene oxide content,the swelling ratio and degradation rate of the scaffolds in PBS buffer decreased,and the compressive modulus increased from 1.049±0.004 MPa to 2.266±0.015 MPa.After soaking in SBF for 3 days,cauliflower-like hydroxyapatite was formed on the surface of GBCS composite scaffolds,indicating that the composite scaffolds had good in vitro mineralization properties.After MC3T3-E1 osteoblasts were cultured in the leaching solution of the composite scaffold for 3 days,some dead cells appeared in the scaffold containing graphene oxide,indicating that the graphene oxide doped in this formula can effectively improve the mechanical properties of the scaffold,but not conducive to cell proliferation.