Graphene Oxide-A Tool for the Preparation of Chemically Crosslinking Free Alginate-Chitosan-Collagen Scaffolds for Bone Tissue Engineering

Developing a biodegradable scaffold remains a major challenge in bone tissue engineering. This study was aimed at developing novel alginate chitosan collagen (SA CS Col)-based composite scaffolds consisting of graphene oxide (GO) to enrich porous structures, elicited by the freeze-drying technique. To characterize porosity, water absorption, and compressive modulus, GO scaffolds (SA CS Col GO) were prepared with and without Ca2+-mediated crosslinking (chemical crosslinking) and analyzed using Raman, Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy techniques. The incorporation of GO into the SA CS Col matrix increased both cross linking density as indicated by the reduction of crystalline peaks in the XRD patterns and polyelectrolyte ion complex as confirmed by FTIR. GO scaffolds showed increased mechanical properties which were further increased for chemically crosslinked scaffolds. All scaffolds exhibited interconnected pores of 10-250 mu m range. By increasing the crosslinking density with Ca2+, a decrease in the porosity/swelling ratio was observed. Moreover, the SA CS Col GO scaffold with or without chemical crosslinking was more stable as compared to SA CS or SA-CS-Col scaffolds when placed in aqueous solution. To perform in vitro biochemical studies, mouse osteoblast cells were grown on various scaffolds and evaluated for cell proliferation by using MTT assay and mineralization and differentiation by alizarin red S staining. These measurements showed a significant increase for cells attached to the SA CS Col GO scaffold compared to SA CS or SA CS Col composites. However, chemical crosslinking of SA CS Col GO showed no effect on the osteogenic ability of osteoblasts. These studies indicate the potential use of GO to prepare free SA CS Col scaffolds with preserved porous structure with elongated Col fibrils and that these composites, which are biocompatible and stable in a biological medium, could be used for application in engineering bone tissues.