Effect of micropores and citric acid on the bioactivity of phosphorylated chitosan/chitosan/hydroxyapatite composites

The phosphorylated chitosan/chitosan/hydroxyapatite (PCS/CS/HA) bio-composite was synthesized by the coprecipitation method, and the effect of micropores and citric acid on its bioactivity was studied via simulated body fluid (SBF). The PCS had been successfully prepared by introducing the phosphate groups into CS. After the aging process, the crystallinity of HA became higher. The CO32− groups in PCS/CS/HA composite showed that the HA obtained in this study was carbonate apatite. After soaking in SBF for 21 days, the Ca/P molar ratios of unpolished PCS/CS/HA sheet increased from 1.28 to 1.53, which was closer to that of HA. In addition, the unpolished composite sheet soaked in SBF with citric acid presented a better bioactivity.