Self-oriented assembly of nano-apatite particles: a subunit mechanism for building biological mineral crystals.

摘要

The organized precipitation of calcium phosphate and its I crystallization into a calcium hydroxyapatite are the central events in the development of skeletal and dental tissues. To bring calcium phosphates out of solution and generate crystals of hydroxyapatite, it is necessary to exceed the solubility product of the precipitating phase in the mineralizing compartment. While the final product is an apatite of some description, the precise nature of this initial phase-and indeed transitional phases-is still a matter of debate. It may be apatitic, but amorphous material has also been detected (Posner, 1969). Such precipitation can be achieved by elevating the local concentration of calcium and/or phosphate ions. Removing water or reducing the dielectric constant of the solution, for example, with organic molecules will have a similar effect. The solubility product itself may also be reduced by the addition of other ions that may be incorporated in some way into the apatite structure; fluoride is an important case in point.