3D-printed hydroxyapatite/gelatin bone scaffolds reinforced with graphene oxide: Optimized fabrication and mechanical characterization

Recently, 3D-printing technology has been widely applied to precisely fabricate tissue-engineered scaffolds with designed shapes and porosity. Especially in bone tissue fabrication, bioceramic-based composites have been commonly proposed because of their favorable osteogenic ability. Among various materials, hydroxyapatite (HA) is frequently adopted to produce bioceramic-based composite scaffolds due to its major features such as osteoconductivity, bioactivity, and low toxicity. However, the intrinsically poor mechanical properties of pristine HA, including low fracture toughness and tensile strength, limit its application in clinical practice, thereby various improvement approaches have been introduced. In the present work, we fabricated graphene oxide (GO)-reinforced HA/gelatin composite scaffolds by extrusion-based 3D-printing under precisely optimized printing parameters. The various printing parameters such as printing temperature, extrusion pressure, and printing velocity were thoroughly investigated and optimized to evaluate the printability of GO-reinforced HA/gelatin composites. Moreover, the overall features of those composites, including physicochemical, rheological, morphological, mechanical, and biological properties were quantitatively analyzed and compared with controls. The overall results indicate that the proper addition of GO can efficiently reinforce the mechanical properties of HA/gelatin composite scaffolds. Specifically, the compressive and flexural strength value of the HA/gelatin composite scaffold was enhanced by 15% and 22% with the 0.5% GO incorporation, respectively. Based on the experimental results, this study suggests the great potential of using GO in the fabrication of composite bone scaffolds with improved mechanical properties for application in bone tissue engineering.