The effect of carboxylic acids and phosphate salts additives on the properties of chondroitin sulfate calcium phosphate cements

Abstract

The use of liquid phase additives is a strategy to improve the physicochemical, mechanical, and biological properties of calcium phosphate cements. In this study, TTCP and α-TCP particles were synthesized using the solid-state reaction method. Apatite cements were prepared by mixing TTCP/DCPD/α-TCP powders and liquid phases containing chondroitin sulfate with various additives of carboxylic acids and phosphate salts. The formation of hydroxyapatite and consumption of raw materials as well as the acceleration and deceleration periods through cementation process were investigated by XRD and DSC experiments, respectively. In addition, the morphology, setting time, porosity, compressive strength, degradation, in-vitro bioactivity and cytotoxicity were studied. The results showed that the approximate amount of hydroxyapatite resulting from the cementation process was divergent in the presence of liquid phase additives. The use of phosphate salt additives presented better results compared to carboxylic acid ones regarding hydroxyapatite cement product formation, compressive strength, hardening, setting, and cytotoxicity. All cements showed, generally a similar tendency to form dense hydroxyapatite on their outer surfaces through immersion in the simulated body fluid. The cement containing Na2HPO4 salt exhibited the lowest cytotoxicity and highest strength. The ALP assay and the morphological behavior of MG63 cells indicated the good activity and proper cell adhesion of this cement.