Hydroxycarbonate apatite

Bone is an extremely dense connective tissue that, in various shapes, constitutes the skeleton. Although it is one of the hardest structures in the body, bone maintains a degree of elasticity owing to its structure and composition. It possesses a hierarchical structure and, as most of the tissues, is nanostructured in fact, it is a nanoscaled composite of collagen (organic extracellular matrix) and hydroxycarbonate apatite, (HCA, bone mineral). This nanostructure is in intimate contact with the bone cells (several microns in size), which result (at the macroscopic level) in the bone tissue. Figure 12.2 shows the bone hierarchical ordering from the bone to the crystalline structure of HCA. 

Vallet-Regi, M., Arcos, D. and Perez-Pariente, J. (2000) Evolution of porosity during in vitro hydroxycarbonate apatite growth in sol-gel glasses. Journal of Biomedical Materials Research, 51, 23—28. 

Li P., Bakker D., van Blitterswijk C.A. The bone-bonding polymer Polyactive 80/20 induces hydroxycarbonate apatite formation in vitro. J. Biomed. Mat. Res. 1997 34 79-86... 

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