ISSN:
0021-9304
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
,
Technology
Notes:
Features controlling the initiation of matrix calcification have been investigated in a model system. Two major influences which dominate nucleation are the matrix integrity and the location of certain chemical binding sites. It has been shown that chemical chelating groups can, and do, promote calcification under simulated physiological conditions. Organically bound phosphate does not appear to promote nucleation, suggesting that it is chelation of calcium or other cations which is the initial step in tissue calcification. In the sequence of compounds investigated for nucleation catalysis, those possessing at least three chelating groups and a stereopsecific configuration were effective. The mineral phase forming first in association with the organic matrix is a soft non-apatitic calcium phosphate of Ca/P ratio approximately 1.5. This is the same phase that forms in the absence of organic matrices at physiological pH and is probably the precursor to hydroxyapatite in biological calcification. It is suggested that nucleation catalysts exist both within and outside the collagen fibrillar framework. A possible location of the internal site has been proposed, based on the availability of a capillary channel and chelating ligands, and this postulate is supported by electron microscopic evidence which shows that bone crystals lie within the fibrils, occupying space which terminates in the polar 640 A staining area.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jbm.820010305
