Preparation and characterization of a hydroxyapatite–collagen composite as component for injectable bone substitute

The paper presents an improved sol–gel technique for the preparation of hydroxyapatite–atelocollagen composites suitable as precursor for osseous regeneration. This technique includes a premineralization step of atelocollagen providing a suspension of microfibrils in which the synthesis of the inorganic component was conducted at low temperature. The characterization of the composite was performed by FTIR spectroscopy, X-ray diffraction and scanning electron microscopy. The particle size distribution and the zeta potential were determined by Zetasizer measurements. The time stability of the composite was evaluated by turbidimetric measurements and macroscopic observation. The composites can be stored for a long time in sterile liquid media without a major risk of aggregation or sedimentation. From the final composite a slurry was obtained by sedimentation in centrifugal field and oscillatory rheological experiments were made to get information about its flow behavior. The slurry could be used as an injectable osteoconductive component, able to act as stock form in orthopaedic kits.