Synthesis And Bone Repair Of Hydroxylated Boron Nitride/Chitosan/ Silver Nanoparticles Composite Scaffolds

Bone defects caused by trauma,infection and tumor resection are one of the biggest challenges facing orthopedics,which seriously affect human life and health.To meet the clinical needs,the development of scaffolds with osteogenic induction and antibacterial effects is a promising research direction in bone tissue engineering.Natural polymer chitosan?CS?,has good biocompatibility,biodegradability and low toxicity characteristics,can be processed into porous structure of scaffolds.However,one of the major disadvantages of CS is its poor mechanical strength and poor ability to control wound healing at the injured site,which makes it difficult to bear the load-bearing role of porous three-dimensional scaffolds in bone repair.Boron nitride?BN?,also known as the“white graphene”.Boron nitride materials and hydroxylated boron nitride?BN-OH?have the superior mechanical properties,high specific surface area,excellent chemical stability,and good biological compatibility,which are the ideal materials for biomedical composites materials.Silver nanoparticles?AgNPs?have good antibacterial properties,good biological security,long-term antibacterial effect,and AgNPs don't need light excitation characteristics.Low concentration of AgNPs have lower incidence of infection and the good cell compatibility,can promote the osteoblast proliferation and induce osteogenesis differentiation,which are suitable for tissue engineering scaffolds to inhibit infection and repair bone defects.In this study,CS/AgNPs mixture was synthesized by in-situ reduction using CS and AgNO₃ as raw materials,and BN-OH/CS/AgNPs mixture was synthesized by electrostatic interaction.They were further converted into four interconnected porous composite scaffolds with good biocompatibility and osteogenic ability,including CS scaffold,CS/AgNPs scaffold,BN-OH/CS scaffold and BN-OH/CS/AgNPs scaffold.The physical and chemical properties of the scaffolds were characterized by SEM,EDS and water contact angle.Using mouse osteoblasts?MC3T3-E1?and staphylococcus aureus?MRSA?as models,the biocompatibility and bone inducibility of scaffolds were studied by using thiazolam blue,alkaline phosphatase assay,alizarin red staining and other methods.The antibacterial activity of the scaffolds was measured by agar diffusion method.Taking SD IGS Rats bone defects as the models,the bone repair ability of scaffolds were demonstrated by animal experiments.The results showed that the scaffolds have interconnected porous structure and are suitable for the adhesion and growth of osteoblasts.The BN-OH/CS/AgNPs composite scaffold not only has significant biocompatibility and osteoinducibility,but also exhibits excellent antibacterial properties.The results of animal experiments showed that BN-OH/CS/AgNPs composite scaffold can significantly promote bone repair and accelerate bone healing.The results are of great significance to the development of bone tissue engineering.