IN-VITRO CRYSTAL-GROWTH OF OCTACALCIUM PHOSPHATE ON TYPE-I COLLAGEN FIBER

Octacalcium phosphate (Ca8H2(PO4)6.5H2O, OCP) crystals grew on tendon collagen, which was sliced into a disk, in an experimental system where Ca2+ and PO4(3-) ions diffused into the collagen disk from mutually opposite sides. Crystal growth on collagen fibrils reflected the intrinsic property of the collagenous matrix: Ribbon-like OCP crystals with a length of about 10-30 mum grew on the Ca side of the collagen disk; small granules with about 50 nm diameter grew on the PO4 side of the disk; small rectangular shaped crystals of less than 1 mum in size grew inside the disk. The c-axis of the OCP crystal was on the whole parallel to the collagen fibril. These results indicate that the collagenous matrix modulates the ionic diffusion and therefore regulates the crystal growth.