THE BIOMIMETIC SYNTHESIS AND BIOCOMPATIBILITY OF SELF-ORGANIZED HYDROXYAPATITE/COLLAGEN COMPOSITES

Self-organized nanocomposites of hydroxyapatite (HAp) and collagen were prepared by controlling temperature and pH on the basis of a biomimetic process. Transmission electron microscopic observations indicated that the composites prepared at pH 8-9 and 40°C had the bone-like structure in which the c-axes of HAp nanocrystals aligned along collagen fibers forming bundles of about 20μm in length and 1μm in diameter. The mechanical strength of the composites obtained was dependent on the degree of self-organization: the maximum 3-point bending strength was 39.5±0.88MPa and Young’s modulus 2.50±0.38GPa. When implanted in Wister rats’ craniums and beagles’ bilateral radii, osteoblasts and osteoclasts were induced near the composites after two weeks, and the composites were covered with a newly formed bone after 12 weeks.