The Preparation And Properties Of Nanoplate-like Hydroxyapatite/Graphene Oxide/Sodium Alginate Composite Scaffolds

Tissue engineering consists of seed cells, scaffolds, and growth factors. Scaffolds play a key role in the field of tissue engineering. Sodium alginate(SA) is a kind of natural polysaccharides and can form hydrogels by cross- lingking in the presece of calcium ions. Due to its excellent biological compatibility, SA has been widely used in applications of tissue engineering. However, it still has several limitations when used in tissue engineering application, such as the poor mechanical properties, lack of biological activity and the weakness of osteoinduc tion. Therefore, it is essential to improve its performance by compounding with other materials.In order to improve the mechanical properties of SA scaffold, the GO/SA composite scaffold was prepared via the method of freeze-drying. The SEM, XRD, FTIR and TG were utilized to analyze the micro structure, crystalline structure, chemical structure and thermal properties of the composites. The porosity, water uptake ability, mechanical properties and biocompatibility properties of the GO/SA were also tested. The results showed that GO/SA composite scaffold had three-dimensional network structure, high porosity, increased water uptake ability, improved thermal properties and enhanced mechanical properties as compared to SA. In addition, the GO/SA composite scaffolds were cultured with the human osteosarcoma cells(MG-63) to evaluate their biocompatibility. The results showed that MG-63 cells proliferated and grew well on the composites, indicating that the GO/SA scaffolds were non-toxic and biocompatible.In order to increase the bioactivity of SA scaffold, the hydroxyapatite(HAp)/SA composite scaffold was prepared via the method of freeze-drying. Prior to preparation of the HAp/SA, surface modification of HAp with glucosamine(GlcN) was conducted due to the fact that nano-HAp tends to agglomerate,which decreases the interfacial bonding with polymers. The TEM, XRD, FTIR, TG and CCK-8 test were adopted to analyze microstructure, crystalline structure, chemical structure, thermal properties and biocompatibility of the surface modified HAp(denoted as GHAp). The results showed that GlcN was successfully grafted on the surface of HAp with improved cell proliferation. The GHAp was used to reinforce SA to fabricate GHAp/SA and GO/GHAp/SA composite scaffolds through the freeze-drying route. The SEM, XRD, FTIR and TG were conducted to characterize the microstructure, crystalline structure, chemical structure and thermal properties of the GHAp/SA and GO/GHAp/SA composites. The porosity, water uptake ability, mechanical properties and biocompatibility of the GHAp/SA and GO/GHAp/SA composite scaffolds were also determined. The results showed that GHAp/SA and GO/GHAp/SA composite scaffolds exhibited 3D network structure, high porosity, improved water uptake ability, enhanced thermal properties and improved mechanical properties as compared to SA, which was beneficial to their further applications. The cell studies implied that GHAp promoted the proliferation of MG-63 cells on the GHAp/SA and GO/GHAp/SA scaffolds.Compared with GO/SA and GHAp/SA composite scaffolds, GO/GHAp/SA composite scaffolds showed further improved mechanical properties and enhanced thermal properties, due to the fact that GO/GHAp/SA composites effectively combine the advantages of bioactive HAp and high-strength GO.