Effects of phosphate solution pH on the setting behavior and hemocompatibility of α-tricalcium phosphate granular cement

Calcium phosphate granules can set when mixed with acidic phosphate solutions, forming an interconnected porous structure suitable for bone regeneration. However, the high acidity of these formulations may compromise their biocompatibility. This study investigates the feasibility of using less acidic phosphate solutions for α-tricalcium phosphate (α-TCP) granular cement to improve biocompatibility while ensuring sufficient setting. α-TCP granules were mixed with sodium phosphate solutions adjusted to pH 1, 2, 3, 5, and 7. Raising the solution pH prolonged the setting time while simultaneously reducing the hemolytic potential of the granular cement. Notably, no hemolysis was observed at pH≥3. All the granules set, forming interconnected porous structures and exhibiting partial conversion to calcium-deficient hydroxyapatite and octacalcium phosphate. These results demonstrate that using phosphate solutions with pH≥3 is an effective approach to optimize both the setting behavior and biocompatibility of α-TCP granular cement for clinical applications.