Fabrication And Biocompatibility Of Chitosan/Apatite Composite Coatings

Hydroxyapatite (HA) has been successfully applied in the reconstruction ofdentistry, orthopaedics and fades maxillaris due to the excellent biocompatibilityand osteoconductivity. However, the low fracture toughness and high brittlenessoften limit its extensive clinical applications. Based on the principle of in situtransformation, we have fabricated chitosan/apatite composite coatings bybiomineralization and hydrothermal method in the present work. Themorphologies and phases of the samples were studied by means of SEM, TEM,EDS, XRD, FTIR, TG-DTA and contact angle measurement techniques. SBFimmersion test has been employed to evaluate the in vitro apatite-forming abilityof the composite coatings. Besides，the biocompatibility of the specimens wasalso studied by using the human bone mesenchymal stem cells (hBMSC) as a cellmodel,BCHCs which prepared by biomineralization are composed of lowcrystallinity and plate-like apatite, macropores and network structures are formedamong the plates. However, HCHCs which prepared by hydrothermal methodcomposed by thicker and high crystallinity lfake apatite. The reaction time andCa/P ratio have no influence on the phase of BCHCs and HCHCs, while theyimpact much more on the morphologies. HA on the surface of BCHCs andHCHCs is calcium-deifcient apatite. Chitosan is distributed on the middle ofTi6A14V and HA, which would not only improve the adhesion of the coatings,but also reduce the toughness of HA.The SBF immersion test revealed that BCHCs and HCHCs have a highapatite-forming ability. After immersing BCHCs and HCHCs in SBF for3days，alayer of calcium-deficient HA were formed on the surface. The local degree ofC2a+supersaturation can be improved by the adsorption of C2a+in the SBF fromthe amino and hydroxyl of chitosan in the samples, so that accelerating thenucleation and growth of the calcium-deifcient HA.The cell culture test indicated that BCHCs and HCHCs have a favourable biocompatibility, hBMSCs showed a preferable viability, proliferation andspreadability on BCHCs and HCHCs than on Ti6A14V. The favourablebiocompatibility of BCHCs and HCHCs could be attributed to the excellentbiocompatible components of chitosan and calcium-deifcient HA, the certain porestructure, surface roughness and the good wettability, all above are suitable forcell adhersion, proliferation and spreadability.