Characterization of CO3Ap-collagen Sponges Using X-ray High-resolution Mic rotom ograp hy Departments of Preventive Dentistry and 2Biomaterials Science, Hiroshima University School of Dentistry, 1-2-3 Kasumi, Minamiku, Hiroshima 734-8553, Japan

For reconstruction and regeneration of hard tissues, scaffold biomaterials with large size pores and high porosity are important, in addition to their roles as supporting frames. To develop a new biodegradable scaffold biomaterial, CO3Ap, which has crystallinity and a chemical composition similar to bone, was synthesized at pH 7.4 and 60 C. Then, the CO3Ap was mixed with a neutralized collagen gel and the C03Ap-collagen mixtures with different kinds of CO3Ap contents and porosity were lyophilized into sponges. Scanning electron micrography (SEM) observation of C03Ap-collagen sponges showed favorable pores for cell invasion. Approximately 50-300 mm size pores appeared to continue through the bulk. Higher magnification of the sponge showed a better adhesion between CO3Ap crystals and collagen. X-ray high-resolution microtomography revealed a clear image of the 3D structure of the sponges. The porosity of 0, 70 and 90%(w/w) CO3Ap-collagen sponges was 79.272.8%, 72.672.4% and 48.976.1%, respectively. The 70%(w/w) C03Ap-coIlagen sponge appeared to be the most favorable biomaterial from the viewpoint of natural bone properties. Mouse osteoblast MC3T3-E1 cells were cultured in aMEM with 10% FCS for 2 weeks. Hematoxylin-eosin staining confirmed osteoblast cells invaded well into the C03Ap-collagen sponge. These sponges are expected to be used as hard tissue scaffold biomaterials for therapeutic uses.