Preparation of chitosan/hydroxyapatite nanocomposite with layered structure via in-situ compositing

Chitosan(CS)/hydroxyapatite(HA) nanocomposite with high strength were synthesized via in-situ compositing at room temperature. The key of in-situ compositing is that a pre-precipitated CS membrane was used to obstruct the CS/HA precursor from NaOH aqueous solution. The CS membrane controlled the process of CS precipitation and transformation of HA from the precursor simultaneously and tardily. XRD, TEM and SEM were performed to investigate CS/HA nanocomposite. Results shown that the in-situ formed calcium phosphate in CS was exactly HA, and that nano-size HA granules were dispersed in CS matrix uniformly, and that the structure of CS/HA composite prepared by in-situ compositing is layered structure. The bending strength and modulus of CS/HA (100/5, wt/wt) were 86MPa and 3.4GPa, which is much higher than that of cancellous bone, 22MPa and 1.4GPa, respectively.