Effect Of Cu/Mg Doped Calcium Silicate Bioceramics And Nano-hydroxyapatite Composite Porous Scaffold On Osteogenesis

Objective:Hydroxyapatite（HA）is often used as scaffold material for bone tissue engineering because of its good biocompatibility and good bone conductivity.The mechanical properties and osteogenic properties of simple HA scaffolds are limited to some extent.At present,the composite scaffolds made of bioceramics and HA are more preferred to improve their mechanical properties and bone repair ability.The oxygen supply limit of microvessels is between 100 and 200μm.In bone defect repair,when tissue growth exceeds this range,new vessels are needed to supply oxygen and nutrients to discharge metabolites.Compound in the middle of the scaffold material in bone tissue engineering seed cells may be due to a lack of sufficient oxygen and nutrients and active growth factors,such as physiological functions such as cell proliferation,secretion and differentiation is blocked the phenomenon of death,even cause the failure of tissue engineering bone graft to repair,so early microvascular formation and is to address the large pieces of bone tissue engineering bone ingrowth build the core of the problem.Mg²⁺and Cu²⁺have the ability to promote angiogenesis in the early stage.Therefore,this study prepared the composite scaffold of Mg/Cu-doped silicate bioceramics and HA,and detected its physical and chemical properties,biological effects on osteoblasts and the formation of new bone in animals,so as to discuss the bone repair ability of the composite scaffold.Methods:In this experiment,silicate bioactive ceramics were prepared by sol-gel method,and then mixed with hydroxyapatite,porous scaffolds were prepared by using wax balls as pore-forming agent（groups:Mg+Cu group,Mg group,Cu group,CS group,HA group）,and the porosity and mechanical properties of composite porous scaffolds were detected.The surface morphology,pore size and inner connection diameter of the scaffold were observed by scanning electron microscopy.The phase and chemical composition of the scaffold were analyzed by XRD,EDS and FTIR.In vitro experiments,the effects of scaffolds in 5 groups and MC3T3-E1 co-culture on osteoblast toxicity,activity and proliferation were detected by Live/Dead staining,CCK-8,ATP content,ALP activity and Alizarin red staining.In vivo experiment,the bone repair performance of porous scaffolds was evaluated by HE staining,Goldner staining and Micro-CT 8 weeks after implantation in SD rats.Results:1.Silicate bioceramics containing Cu and Mg can be prepared by sol-gel method.The composite porous scaffolds with porosity of 70%,pore size of 300-400μm and compressive strength of 6-7MPa can be prepared by using the wax ball as pore-forming agent.The mechanical properties of the scaffold can be improved with the addition of silicate bioceramics.2.In the in vitro experiment,after co-culture of each group of porous scaffolds with MC3T3-E1,early detection of Live/Dead staining and ATP showed that the scaffolds had no obvious toxicity to osteoblasts in the early stage;scaffolds and MC3T3-E1 were co-cultured for 1,3,5,7 days detected by CCK-8,and the proliferation rules were as follows:Mg+Cu=Mg>Cu=CS>HA.After 1,7 and 14 days co-culture,the ALP activity of osteoblasts and each group of porous scaffolds was as follows:Mg+Cu=Mg>Cu=CS>HA.After 1,7 and 14 days of co-culture with osteoblasts in each group,alizarin red staining showed that the formation of calcium nodules was as follows:Mg+Cu>Mg>Cu=CS>HA.3.In the in vivo experiment,8 weeks after the porous scaffold was implanted into SD rats,the results of HE,Goldner staining and micro-CT showed that the rules of scaffold new bone and mineralized bone formation were as follows:Mg+Cu>Mg=Cu>CS>HA.Conclusion:The composite scaffolds with a porosity of 70%,a pore diameter of 300-400μm,a compressive strength of 6-7MPa and a stable composition can be successfully prepared by using sol-gel method and using wax balls as pore-forming agent.With the addition of silicate bioceramics,the mechanical properties and bone repair ability of scaffolds were significantly improved,and the Mg+Cu group was the best,indicating that the addition of Mg and Cu could further improve the bone repair ability of scaffolds,providing an experimental basis for the clinical application of porous composite scaffolds.