Intercalated chitosan/hydroxyapatite nanocomposites: Promising materials for bone tissue engineering applications

[Display omitted] •Hydroxyapatite (HA) nanoparticles were synthesized by a sol-gel process.•Stable chitosan/HA dispersions were prepared in formic acid.•SEM and XRD studies indicated formation of self-intercalated chitosan/HA nanocomposite films.•AFM and SEM images showed presence of HA nanoparticles on CS/HA film surface.•Thermal degradation of nanocomposites yielded 3D porous HA scaffolds. Preparation and characterization of chitosan/hydroxyapatite (CS/HA) nanocomposites displaying an intercalated structure is reported. Hydroxyapatite was synthesized through sol-gel process. Formic acid was introduced as a new solvent to obtain stable dispersions of nano-sized HA particles in polymer solution. CS/HA dispersions with HA contents of 5, 10 and 20% by weight were prepared. Self-assembling of HA nanoparticles during the drying of the solvent cast films led to the formation of homogeneous CS/HA nanocomposites. Composite films were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-rays (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, X-rays diffraction (XRD) analysis and thermogravimetric analysis (TGA). SEM and AFM confirmed the presence of uniformly distributed HA nanoparticles on the chitosan matrix surface. XRD patterns and cross-sectional SEM images showed the formation of layered nanocomposites. Complete degradation of chitosan matrix in TGA experiments, led to the formation of nanoporous 3D scaffolds containing hydroxyapatite, β-tricalcium phosphate and calcium pyrophosphate. CS/HA composites can be considered as promising materials for bone tissue engineering applications.