Calcium phosphate, mineralization

Perkin, K.K., Turner, J.L., Wooley, K.L. and Mann, S. (2005) Fabrication of hybrid nanocapsules by calcium phosphate mineralization of shell cross-linked polymer micelles and nanocages. Nano Letters, 5,1457-1461. 

Calcium phosphate minerals in thermodynamically modelled MSW bottom ash leachate systems... 

The most intensively studied organelles have been the mitochondria. Various enzymatic functions require that intracellular calcium be kept at 10-6 to 10-7 M in the cytosol and there is firm evidence that mitochondria have an important role in fulfilling this function. Because mitochondria sequester calcium in muscle, kidney and liver, it has been postulated that mitochondria might serve as an apparatus to overcome the energy of activation necessary for forming a new calcium-phosphate mineral phase at calcifying sites47. ... 

However, methane-diphosphonate could not prevent the growth of apatite crystals in vitro on prepared sinews of rats tail out of a metastable solution with calcium and phosphate ions. On the contrary, the precipitated crystalline particles were bigger and better crystallized than those from control solutions. This is in surprising contrast to most of the information from the literature. No other calcium phosphate minerals besides apatite have been found by X-ray diffraction, whereas under comparable conditions brushite and octacalcium phosphate grow on collagenous sinews549. ... 

Cuervo, L. A., Pita, J. C., Howell, D. S. Inhibition of calcium phosphate mineral growth by proteoglycan aggregate fractions in a synthetic lymph. Calc. Tiss. Res. 13, 1 (1973)... 

Schnepp ZAC, Gonzalez-McQuire R, Mann S (2006) Hybrid biocomposites based on calcium phosphate mineralization of self-assembled supramolecular hydrogels. Adv Mater 18(14) 1869-1872... 

The major interest in calcium phosphate cements has always been in their potential for biomedical applications. This is because bone contains hydroxyapatite (Ca5(P04)30H), a calcium phosphate mineral. Any material that could be used to bond bone or produce an artificial graft should contain this mineral for compatibility. In fact, much of the research in producing calcium phosphate-based cements or sintered ceramics was motivated by their biomedical applications. We will discuss applications of calcium phosphate cements in detail in Chapter 18. This section describes their materials development. 

Among all the minerals used by organisms, three categories are widely dominant silica, calcium phosphates, and calcium carbonates. Calcium phosphate minerals are usually associated with vertebrates , where they form bone and the dentine and enamel of teeth. However, phosphate minerals are present in some invertebrate shells, such as Brachiopods, whereas vertebrates used calcium carbonate minerals in eggshells and otoliths. Calcium minerals represent about 50% of all biogenic minerals. 

The main part of the calcium phosphate minerals produced by organisms is crystalline and described as apatite. 

It has been proven over the years that the effect of fouling can be lessened to some extent for the application of whey concentration by pretreating the feed streams for the ultrafilters. Whey contains many insoluble solids such as casein fines, lipoprotein complex, mineral precipitates, free fats and microorganisms. Clarification of these debris helps reduce fouling potential during ultrafiltration. In addition, it is quite evident that calcium phosphate minerals in whey are not stable and their precipitation in the membrane pores often results in flux decline. Demineralization of whey before ultrafiltration helps maintain high permeate flux considerably [Muir and Banks, 1985]. 

In all vertebrates, including humans, the calcium phosphate mineralized endoskeleton is not only the basis of species identification, but plays two distinct major roles in this phylum. The skeleton is the scaffold with sites for muscle... 

Fig. 3.1.8. Sandy phosphorite from near Kursk, R.S.F.S.R. (so-called kurskite). The calcium-phosphate mineral forms both an anisotropic and apparently isotropic cement for the glauconitic sandstone. Magnification 67x. Reproduced with permission (McConnell,...

Phosphorite Sedimentary deposits of calcium phosphate minerals... 

Calcium and phosphorus are major minerals that are needed for the development of healthy bones and teeth. These two minerals are found in a crystalline calcium phosphate mineral known as hydroxyapatite, [Cajo(P04) (OH)2l, that makes up the mineral matrix of bone and teeth. In addition, calcium is required for normal blood clotting and muscle function. The RDA for calcium is 1200 mg/day for adults between nineteen and twenty-four years of age and 800 mg/day for adults over age twenty-five. Milk, cheese, canned salmon, and dark green leafy vegetables are all rich sources of dietary calcium. 

Jaynes WF, Moore PA Jr., Miller DM (1999) Solubility and ion activity products of calcium phosphate minerals. J Environ Qual 28 530-536... 

Sen Gupta PK, Swihart GH, Dimitrijevic R, Hossain MB (1991) The crystal stmcture of luenebuigite, Mg3(H20)6(B2(0H)s(P04)2). Am Mineral 76 1400-1407 Sergeev AS (1964) Pseudo-autunite, a new hydrous calcium phosphate. Mineral Geokhim 1 31-39 (in Russian)... 

Merrillite, an anhydrous calcium phosphate mineral often coexisting with apatite in lunar and meteorite samples, has been used for a number of fission track dating studies of extraterrestrial materials. Following a paper by Fuchs (1962) this mineral was most commonly identified in meteorites as whitlockite, but Dowty (1977) has shown that it exhibits significant differences to terrestrial whitlockite, (Ca,Mg)3(P04)2, and should be distinguished from it. As a result, earlier publications use whitlockite while later ones apply the name merrillite , for the same mineral. Merrillite is now the appropriate species name for the high-temperature phosphate mineral found predominantly in... 

In sulfate-dominated wetlands, production of sulfide (through biological reduction of sulfate) and formation of ferrous sulfides may preclude phosphorus retention by ferrous iron in regulating phosphorus bioavailability (Caraco et al., 1991). In iron- and calcium-dominated systems, Moore and Reddy (1994) observed that iron oxides likely control the behavior of inorganic phosphorus under aerobic conditions, whereas calcium phosphate mineral precipitation governs the solubility under anaerobic conditions. This difference is in part due to a decrease in pH under aerobic conditions as a result of oxidation of ferrous iron compounds, whereas an increase in pH occurs under anaerobic conditions as a result of reduction of ferric iron compounds. The juxtaposition of aerobic and anaerobic interfaces promotes oxidation-reduction of iron and its regulation of phosphorus solubility. 

---