Preparation and characterization of porous β-tricalcium phosphate/collagen composites with an integrated structure

Porous ββ-tricalcium phosphate (TCP)/collagen composites with different ββ-TCP/collagen weight ratio were prepared. The influences of the preparation conditions on the microstructure of porous composite and the joint status of ββ-TCP particles with collagen fibrils were characterized by X-ray diffractometer, scanning electron microscopy and transmission electron microscopy. The results showed: (1) an acid treatment could effectively disassemble collagen fibrils; (2) in the resulting porous composites, ββ-TCP particles homogenously existed on the skeleton of the collagen fibril network and bonded tightly to both the fibrils and themselves. The tight bonding formation could be due to the reaction between Ca ions in the particles and carboxyl groups in collagen polypeptide chains and due to the reprecipitation of partially dissolved ββ-TCP during synthesis. The tight bonding between ββ-TCP particles and collagen fibrils in the composites demonstrated an integrated structure, which was reproducible when ββ-TCP/collagen ratio ranged from 2 to 4. Such integrated structure would make significant contributions in reliably tailoring properties of the porous composites by varying ββ-TCP content. In addition, the porous composites had large porosity (∼95%) and appropriate pore size (∼100 μm), showed no negative impact in cytotoxicity assay and complete bone tissue regeneration after 12 weeks in animal test.