The Study On Performance Of Chitosan/Nano-Hydroxyapatite Composite Scaffold Modified With Reduced Graphene Oxide

At present,bone transplantation materials have become the second largest transplantation materials in the world,and the demand for bone continues to increase due to diseases such as tumors,infections,and arthritis.However,due to limitations such as insufficient autologous bone transplantation donors and secondary injuries,as well as rejection reactions of allogeneic bone transplantation,surgical treatment options are severely limited.Therefore,the development of biological scaffolds to support bone regeneration has become a key area in Bone Tissue Engineering(BTE).Chitosan(CS)has the advantages of a wide range of sources,good biocompatibility,and strong plasticity.It can also further simulate the structural characteristics of the extracellular matrix(ECM),but its strength is low and its degradation rate is fast.Therefore,inorganic materials are usually combined with CS to overcome the limitations of CS and improve performance.Nano hydroxyapatite(nHA)is an inorganic material,whose structure is closest to the composition of natural bone.A large number of studies have proved that CS/nHA composite scaffold has excellent physical and chemical properties and biological properties.As a promising multi-purpose nano material,reduced graphite oxide oxide(rGO)has been widely studied.It has been used in many biomedical fields due to its good conductivity,large specific surface area and other excellent and unique properties.At present,a single material cannot fully replicate the characteristics of bones.In order to further enhance the physicochemical and biological properties of CS/nHA composite scaffolds,this experiment intends to introduce different concentrations of rGO into CS/nHA to optimize its performance,and study the cell adhesion,proliferation,osteogenic differentiation,and mechanical properties of composite scaffold materials with different rGO contents.Objective:The research objective is to screen the appropriate rGO concentration,optimize the biological and mechanical properties of CS/nHA composite scaffolds,and provide suitable bone tissue engineering scaffolds for repairing bone defects in clinical practice by detecting the physicochemical and biological properties of scaffold materials.Methods:First.graphite oxide Oxide(GO)was prepared by the improved Hummers method.The green and environmentally friendly ascorbic acid(L-AA)with strong reducibility was used as the reducing agent to achieve the reduction of GO and eliminate a large number of hydroxyl,carboxyl,carbonyl and epoxy groups in the structure of GO.Characterization and detection of GO and rGO were performed using scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),transmission electron microscopy(TEM),Raman spectroscopy(Raman),X-ray photoelectron spectroscopy(XPS),X-ray diffractometer,and universal tensile testing machine;Then,rGO/CS/nHA composite scaffolds were prepared by mixing different concentrations of rGO with CS and nHA,and the pore size,porosity,degradation rate,swelling rate,and mechanical strength of rGO/CS/nHA composite scaffolds with different rGO contents were investigated.Finally,the ability of human dental pulp stem cells(hDPSCs)to adhere,proliferate,grow,and differentiate into osteoblasts on the scaffold was tested.This study successfully prepared rGO through chemical reduction method.Results:The surface of the chemically prepared rGO showed a distinct laminar structure,the fold was more pronounced and dense,and the oxygen-containing groups were reduced.rGO/CS/nHA composite scaffolds with an rGO concentration of 0.1 mg/ml had a porosity of 73.87±4.72%,pore size of 194.71±47.45μm,elastic modulus of 1.47±0.21MPa,and scaffold pore walls were roughly wrinkled under SEM with a solubility of 725.52±15.56%and a 21-day degradation rate of 9.53±0.56%.Inoculate hDPSCs in rGO/CS/nHA stents with an rGO concentration of 0.1 mg/ml and cell vaccination rates,cell proliferation rates,and ALP activity levels were measured.Conclusions:The study proved that rGO has good biocompatibility,and a 0.1mg/ml concentration of rGO modified CS/nHA composite scaffold is conducive to cell growth and osteogenic differentiation.At the same time,the mechanical strength of the scaffold has been significantly improved,achieving the goal of optimizing the biological and mechanical properties of the composite scaffold,which has great potential for application in the field of bone tissue engineering.