Phosphate biominerals

Phosphate occurs widely in biology as organic when it is bonded to a nucleic acid base or sugar and as inorganic when it is present as a biomineral. As a biomineral, it can occur as both amorphous and crystalline forms. 

Crystalline hydroxyapatites are the major mineral of bones and teeth in a matrix of the protein collagen. The hydroxyls reside in chaimels running along the crystal c-axis which provide easy access to the external environment. Hydroxyapatites in vivo are usually described as poorly crystalline, calcium deficient and containing carbonate substitutions. The carbonate substitutions can occur at both the hydroxyl and the phosphate 

This is a striking example of the specificity of INS the spectrum in Fig. 10.34c that clearly shows the presence of hydroxyls was the same 

The study of soft condensed matter (polymers, biopolymers and biological materials) is likely to be the area of INS spectroscopy that sees the largest growth in the next decade. The study of model compounds is a thriving area, where the analysis follows the routes described in this book the use of the isolated molecule approximation where intermolecular interactions are weak and ab initio codes for periodic systems where the interactions are significant. Re-analysis of older data is an activity that can yield further insights into the systems. 

In principle, crystalline polymers will yield to the same types of analyses. In practice, significant dispersion, even in the internal modes, is often present and calculations across the complete Brillouin zone are needed. These are still rare even for the simplest systems such as polyethylene, but are an obvious next step. 

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Elliott JC (2002) Calcium phosphate biominerals. Rev Mineral Geochem 48 427-453 England P, Molnar P (1990) Surface uplift, uplift of rocks, and exhumation of rocks. Geology 18 1173-1177 Estes RD (1991) The Behavior Guide to African Mammals, University of California Press, Berkeley Fremd TJ, Bestland EA, Retallack GJ (1997) John Day Basin Paleontology, Northwest Interpretive Association, Seattle, WA, p 80... 

Elliott J. (2002) Calcium phosphate biominerals, la Phosphates Geochemical, Geobiological and Materials Importance, Reviews in Mineralogy and Geochemistry (eds. M. J. Kohn, J. Hughes, and J. Rakovan). Mineralogical Society of America, Washington, DC, vol. 48, pp. 427-454. 

Macintyre I. G., et al. (2000) Possible vestige of early phosphatic biomineralization in gorgonian octocorals (Coelenterata). Geology 28, 453-458. 

One conclusion seems to emerge organisms, or their metabolic products, influence the formation of biominerals to the extent that straightforward physical-chemical calculations are inadequate to account for what actually takes place in natural systems. This statement, while expressed in general terms, is particularly true for phosphatic biominerals. Equilibrium seems to obtain very slowly, and it is suspected that many of these systems do not attain equilibrium because of kinetic factors. That is, before equilibrium can be effected under a particular set of circumstances, there is a change in the circumstances (ionic activities, pH, Eh, temperature, catalytic agents, etc.), thus creating new phase boundaries if, indeed, not an entirely different system. 

Gorobets BS (1981) Luminescence Spectra of Minerals, (in Russian) Moscow. 153 p Gotze J, Heimaim RB, Hildebrandt H, Gburek U (2001) Micro structural investigation into calcium phosphate biominerals by spatially resolved cathodoluminescence. Mater Wissen Werkstofflechnik 32 130-136... 

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