| Graphene is a novel two-dimensional one-atom-thick materials,because of its remarkable electronic character,exceptional thermal conductivity,superior mechanical properties and large specific surface area,and thus has aroused much attention in photolectric material,dye absorption and biomedical fields.However,the strong van der Waals force between graphene sheets makes it difficult to exist in monolithic layer or disperse homogeniously in the polymer matrix.In addition,graphene lacks specific biological activity,which limits its application in nanocomposites and biomedical fields.Hydroxyapatite(HA)is a natural inorganic salt,mainly in the animal's bones.It possess many advantages,such as stable in water,biodegradable and osteoinduction.HA,as an adsorbent and biomedical materials,are widely applied.However,the nano-HA is easy to aggregate,besides,its fragile and low fragmentation toughness also limits its practical application.Polylactic acid(PLA)is an important biodegradable materiasl,which has important application in tissue engineering.However,PLLA has low mechanical strength,poor toughness and low crystallization rate.An ideal bone tissue engineering scaffolds material,should not only has good bone conduction and osteoinduction,but also must have good biocompatibility,mechanical strength and plasticity.Based on the above problem,this work mainly focus two parts:1.At alkaline conditions,reduced graphene oxide-Hydroxyapatite(RGO-HA)hybrid was prepared via the in situ formation of hydroxyapatite on the surface of the graphene sheet.The hydroxyapatite on the surface of graphene sheets can effectively inhibit the ?-? stacking effect,realizing the synergistic dispersion of reduced graphene and hydroxyapatite.The structure of RGO-HA was characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),Raman spectroscopy,Transmission electron microscopy(TEM).Then the RGO-HA was used as an adsorbent,the effects of adsorption kinetics,isothermal adsorption and pH on adsorption were studied.The experimental results show:(1)The adsorption process of organic dyes on RGO-HA involves physical adsorption and chemical adsorption;(2)The adsorption capacity of RGO-HA disperse uniformly;(3)RGO-HA adsorbents are more suitable for the adsorption of cationic organic dyes,and the adsorption capacity is increasing sharply under alkaline conditions.2.Poly(D-lactide)grafted RGO-HA(RGO-HA-g-PDLA)hybrid material was prepared,and then RGO-HA-g-PDLA/PLLA composite nano-fiber scaffolds containing simvastatin(SIM)were prepared by electrospinning technology,and then the electrospinning membrane was rolled to cylindrical bioactive composite scaffold with increased simvastatin(SIM)concentration from the edge to the core.Collagen I(Col I)was fisrt adsorbed into the scaffolds and then crosslinked with glutaldehyde.In vitro mineralization experiments showed that the RGO-HA-g-PDLA/PLLA@SIM scaffold had better calcium deposition ability than PLLA,PLLA@SIM and RGO-HA-g-PDLA/PLLA.In vitro release experiments indicate that the SIM in the RGO-HA-g-PDLA/PLLA nano-fibers has a 30 days' effective release,much longer than that of PLLA,with 88% SIM released.In vivo experiments showed that RGO-HA-g-PDLA/PLLA scaffold material has a stronger ability to promote cranial defect repair. |
PDF Full Text Request