Research On Nano-Hydroxyapatite/Chitosan Electro-compatible Composite Biomaterial

Chitosan and hydroxyapatite were widely used in biomedical application, especially bone reparation materials due to their biocompatibility and bioactivity. In present research, bone was chosen as the prototype to design nano-hydroxyapatite particle/Chitosan (nHAp/CS) electro-compatible composite biomaterial via in-situ compositing and in-situ precipitation methods.The crystal structure of nHAp/CS composites was analyzed by X-ray diffraction (XRD). The dispersion of nano-HA particles in the composite was observed through transmission electron microscopy (TEM). The effects of the different amounts of HA on the mechanical and bio-electrical properties of the composite were investigated in comparison with natural bone. As well as the relationship between microstructure and performance of the composite was discussed.The results indicate that in-situ compositing method improves the dispersion of nano-HA particles in the chitosan matrix but decreases the crystallinity and grain size of HA. With the increasing HA content, the flexural strengths of nHAp/CS composites, prepared via both in-situ compositing and in-situ precipitation methods, initially increase and subsequently decrease, as well as the compressive strengths increase non-linearly, whereas the modulus of in-situ composited specimen shows a milder changing tendency than the in-situ precipitated one. Meantime, the dielectric constants and the piezoelectric constants decrease to a certain degree.When the mass ratio of HA and CS is 0.1, the flexural strength and modulus of the composite are 75.9MPa and 3.3GPa, the compression strength and modulus are 47.5MPa and 2.2GPa, respectively. With the same composition, the dielectric constant of nHAp/CS is 12 under 1MHz, as well as the piezoelectric constant d33 is 9.0pC/N which is comparable with natural bone. In brief, this nHAp/CS composite material is of potential application as bone substituent in hard tissue reparation due to its similarities of both mechanical and piezo-electrical performances to natural bone.