Gadolinium-doped injectable magnesium-calcium phosphate bone cements for noninvasive visualization

Injectable bone cements are used in minimally invasive surgical techniques including vertebroplasty and kyphoplasty. This work is devoted to the development of magnesium-calcium phosphate cements (MCPCs) doped with gadolinium ions (Gd³⁺) for bone defect repair. Interaction between cement powders and a cement liquid resulted in the formation of newberyite and brushite phases, which gave mechanical strength up to 17 MPa without a thermal effect. The introduction of Gd³⁺ into the lattice was confirmed by electron paramagnetic resonance spectroscopy; the doping increased injectivity while giving rise to antibacterial properties against Escherichia coli. Assays of the cement samples soaking in Kokubo's simulated body fluid revealed the formation of calcium phosphate coatings on the cements’ surface. The cements manifested biocompatibility with the MG-63 cell line and significantly enhanced contrast when Gd-MCPC was placed into a bone defect and examined by X-ray micro–computed tomography. For the first time, visualization of a Gd-doped cement material was achieved in a model of a bone defect analyzed by MRI.