Study Of 3D RGO/PPY Composite Scaffolds With Sr And Their Osteogenesis In Vitro

Objective:To construct a strontium-modified 3D rGO/PPY composite scaffold and evaluate its osteogenic activity in vitro,which provides a certain experimental basis for its clinical application.Materials and methods:Based on the three-dimensional reduction of graphene oxide/polypyrrole?3D rGO/PPY?composite scaffold,which was studied in the previous research group^[1],polydopamine?PDA?was used as cross-linking agent,and strontium?Sr?was coupled to the surface of the scaffold by soaking method.The modification of Sr was completed by socking method.The structure,chemical composition and element distribution of the 3D rGO/PPY scaffold before and after modified with Sr were characterized by SEM,XPS and EDS,respectively.The effects of the composite scaffolds on the early adhesion and proliferation of MC3T3-E1 cells were evaluated by MTT,AO/EB fluorescence double staining and SEM experiments.The alkaline phosphatase?ALP?activity assay and alizarin red staining assay were used to evaluate the ability to induce osteoblastic differentiation.Results:1.Physical characterization:SEM observed 3D rGO/PPY composite scaffold is a three-dimensional cross-linked macroporous structure with a pore size of100-300?m.The Sr is uniformly distributed on the surface of 3D rGO/PPY scaffold,and make no difference to the structural morphology of the scaffold.EDS and XPS results indicate that Sr is uniformly distributed on the surface of the substrate scaffold.2.In vitro osteogenic performance evaluation:MTT results show that the number of cells on the surface of the modified 3D rGO/PPY composite scaffold increased.The SEM show good cell spreadability and well-extended pseudopodia.AO/EB double staining also indicate that the number of cells in the 3D rGO/PPY modified with Sr group>3D rGO/PPY/PDA group>3D rGO/PPY group.There is no significant difference in the expression of ALP activity between 3D rGO/PPY and 3D rGO/PPY/PDA groups after 7 and 14 days coculture,but the OD values of ALP activity in Sr modified 3D rGO/PPY group are 1.95 and 3.46,higher than the 3D rGO/PPY/PDA group,1.08 and 2.3?P<0.01?,3D rGO/PPYgroup 0.94 and 2.10?P<0.01?respectively.The results of alizarin red staining show that the Sr modified 3D rGO/PPY group have a large range of red stained areas,and a large number of calcium nodules are observed.Conclusions:The Sr modified 3D rGO/PPY composite scaffold is successfully prepared,which promote the adhesion and proliferation of MC3T3-E1 cells and induce osteogenic differentiation of MC3T3-E1 cells.