Enhanced mechanical properties and anti-washout of calcium phosphate cement/montmorillonite composite bone-cement for bone-repair applications

Calcium phosphate cement (CPC) has received extensive attention as a filler for heteromorphic bone defects owing to its excellent biocompatibility, self-curing property, and degradability. However, the low strength and poor anti-washout properties still restrict the use of CPC in the clinical application. In this study, montmorillonite (MMT) was introduced into CPC to prepare CPC/MMT composite bone-cement. The compressive strength of the composite cement was synergistically enhanced by increasing intermolecular bonding and the impeding crack propagation . Owing to its unique lamellar structure , viscosity, and hydrophilicity, CPC bound to MMT via the bridging effect of water molecules and the electrostatic interaction between MMT and Ca 2+ . When subjected to an applied load, crack propagation was further hindered by MMT pull-out, load transfer, crack deflection, crack branching, and crack bridging, which consuming more fracture energy, significantly improving the compressive strength of the cement strength. At 50 wt% MMT addition, the compressive strength of the composite bone cement (CPC+50%MMT) was 48.5 MPa, which is 227.04% higher than that of CPC alone (14.83 MPa). Surprisingly, the anti-washout ability of CPC was significantly improved, as indicated by the decrease in the mass loss of the composite bone cement from 71.25 to 6.48%, overcoming the trade-off between strength and anti-washout properties. The final setting time was shortened from 22 to 11.37 min, and the injectability exceeded 90%. In addition, the composite bone cement demonstrated outstanding cell adhesion and proliferation abilities, making it a promising material for bone-repair therapy.