Mechanical, tribological and biological properties of novel 45S5 Bioglass^® composites reinforced with in situ reduced graphene oxide

45S5 Bioglass^® (45S5) is one of the most widely used biomaterials in ceramic-based bone graft substitutes by virtue of its excellent biocompatibility and bioactivity. However, the fracture toughness and wear resistance of 45S5 have to be improved to extend its applications in load bearing orthopedic implants. The current study reports the first use of graphene nanoplatelet (GNP) to enhance the fracture toughness and wear resistance of 45S5. Composite powders with four different loadings of graphene oxide (GO), i.e. 0, 0.1, 0.5 and 1 wt%, were sintered by spark plasma sintering (SPS) at a relatively low temperature of 550 °C, during which in situ thermal reduction of GO took place. It was found that by adding 0.5 wt% GO to the 45S5 powder, the fracture toughness of the sintered pellets was increased by 130.2% while friction coefficient and specific wear rate were decreased by 21.3% and 62.0%, respectively. Furthermore, the viability of MG63 cells grown on the GNP-incorporated pellets was comparably high to that of the cells grown on the pure 45S5 pellets. As compared with the pure 45S5 leachates, the media conditioned by the GNP/45S5 pellets fabricated from the composite powder with 1 wt% GO could enhance both the proliferation and viability of MG63 cells. It is thus envisioned that the GNP-reinforced 45S5 is a highly promising material for fabricating mechanically strong and biocompatible load-bearing bone implants.