Novel method for the obtainment of nanostructured calcium phosphate cements: Synthesis, mechanical strength and cytotoxicity

The calcium phosphate cements have a large number of advantages regarding its use in orthopedics and traumatology, being the most prominent its biocompatibility and bioactivity, which allows the osteoconductive of bone tissue and in situ hardening, allowing greater ease of handling. However, the use of conventional synthesis methods, e.g. solid state reactions, brings great difficulty to the obtainment of highly pure α-tricalcium phosphate phase. In this work, the use of the solution combustion synthesis method allowed to synthesize nanostructured α-tricalcium phosphate with high purity. Further studies on pH influence, fuel nature (urea or glycine) and fuel ratio (0.75, 1.0, 1.5 and 2.0) allowed to define the best synthesis parameters (pH 1.5 and urea fuel content in two times higher than the stoichiometric). After choosing the best parameters to the obtainment of highly pure α-tricalcium phosphate, we studied the feasibility of their use as calcium phosphate cement (CFC) by studying the influence of particle size by increasing the milling time from 30 to 180 min. The better results were found for the milling time of 180 min. Compressive strengths up to 30.4 MPa were obtained for this formulation. However, after soaking the calcium phosphate cements in simulated blood plasma (SBF), in growing times up to 28 days, a decrease in compressive strength was noticed, which is an indicative of the high solubility of the α-tricalcium phosphate powders obtained by solution combustion synthesis. The synthesized powder did not show any cytotoxicity to the tested cells.