Graphene oxide-reinforced alginate/gelatin hydrogel via Schiff-base bond and thiol-Michael addition for bone regeneration

The poor mechanical properties of hydrogels limit their application as scaffolds to provide support for bone regeneration. Inspired by the superior mechanical properties of nanocomposites-reinforced hydrogels and the double network (DN) structure of hydrogels, the current study investigated the fabrication of graphene oxide (GO) reinforced DN hydrogels for bone regeneration. To this regard, aldehyde methylene sodium alginate (AMSA), amino gelatin ( amino G), and dithiothreitol modified graphene oxide (DGO) were initially synthesized, and subsequently were employed in the preparation of AMSA/ amino G (AG) and DGO/AMSA/ amino G (GSG) DN-hydrogels, while imposing different mass ratios of the reacting components. The physicochemical and biological properties of the prepared hydrogels were subsequently assessed using several tests such as Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, nuclear magnetic resonance, cell compatibility and in vivo experiments. The compressive strengths of the prepared AG and GSG hydrogels were conversely correlated with their porosity characteristics. This study showed that although AG and GSG hydrogels had favorable cell viability and cell proliferation characteristics, GSG hydrogels presented an improved osteogenic capacity compared to AG hydrogels. This study was, therefore, able to demonstrate the functionality of employing novel GSG hydrogels in tissue engineering via their use as scaffolds for mechanical support and cell proliferation to promote bone regeneration.