Fabrication of calcium phosphate-calcium sulfate injectable bone substitute using chitosan and citric acid

In this study, an injectable bone substitute (IBS) consisting of citric acid, chitosan solution as the liquid phase and tetra calcium phosphate (TTCP), dicalcium phosphate anhydrous (DCPA) and calcium sulfate hemihydrate (CSH) powders as the solid phase was prepared. Four groups containing different percentages (0–30%) of calcium sulfate hemihydrate (CSH, CaSO4 · 0.5H2O) were investigated. Initial setting times for IBS with CSH were longer than those without CSH. The setting times for all compositions were in the range of 25–45 min. The injectability was improved by the addition of CSH in the present system. Scanning electron microscopy images showed that fiber-like crystallization appeared in the cements. The enhancement of crystallinity was confirmed by XRD profiles where the peak intensity of HAp increased with incubation time and the addition of CSH. Also, the compressive strength increased with the addition of CSH. The maximum compressive strength obtained for IBS was with 20% CSH after 28-day incubation in 100% humidity at 37°C.