Degradation behaviour of non-sintered graphene/barium titanate/magnesium phosphate cement bio-piezoelectric composites

A sintering-free magnesium phosphate cement (MPC) with an arbitrary shape is potentially used as a bone implant material, especially with complex shapes. However, the high degradation rate of MPC may lead to the degradation of mechanical properties. In this study, graphene (G)/barium titanate (BT)/MPC composites were fabricated by introducing the piezoelectric phase BT and conductive phase G into MPC, which exhibited the piezoelectric effect after polarisation. The negative surface of the composite may attract Ca²⁺ and Mg²⁺ to mineralise rapidly, thereby reducing and improving its degradation rate and mechanical properties, respectively. The contents of additional G and BT were optimised. When BT and G contents were 50 mol% and 0.5 wt%, respectively, the piezoelectric coefficient of the composites increased to 6.31 pC/N, which is an increase of 421% without the addition of G. The results of in vitro degradation and mineralisation in simulated body fluids (SBF) showed that introducing BT and G could effectively slow down the degradation rate, promote mineralisation on the composite surface, and enhance the impact on bone integration.