Fabrication and characterization of a biomimetic composite scaffold for bone defect repair

For successful bone tissue engineering, scaffolds with tailored properties are a basic requirement. The combination of different available materials not only appears to be desirable but also very challenging. In this study, a composite material consisting of hydroxyapatite and collagen was produced by a biomimetic precipitation method and characterized by X-ray diffraction (XRD) and thermogravimetry (TGA). Subsequently, a suspension-quick-freezing and lyophilization method was used to incorporate the hydroxyapatite into a polymeric matrix consisting of collagen and chitosan. Before physicochemical characterization, the highly porous scaffolds were consolidated by a dehydrothermal treatment (DHT). The main attention was focused on the particle size of hydroxyapatite, which should be in the nanometer range. This is relevant to achieve a homogeneous resorption of the material by osteoclasts. Small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), and environmental scanning electron microscopy (ESEM) were used to evaluate the outcome. The results suggest a successful polymeric embedding of nanoscaled hydroxyapatite particles into the matrix of the spongy construct.