Calcium phosphate-polymer

The structure of bone is even more complex. Bone consists of collagen fibrils imbedded in calcium phosphate polymer, Ca,Q(P04) (0H)2 (referred to as hydroxyapatite). The construction, analogous to that in reinforced materials, makes for very high physical strength. 

Klesing J, Wiehe A, Gitter B, Grafe S, Epple M. Positively charged calcium phosphate/ polymer nanoparticles for photodynamic therapy. J Mater Sci Mater Med 2010 21 887-92. 

Nickel halide complexes with amines give mixtures of linear polymer and cychc trimers (30). Nickel chelates give up to 40% of linear polymer (31). When heated with ammonia over cadmium calcium phosphate catalysts, propargyl alcohol gives a mixture of pyridines (32). 

The most commonly used scale inhibitors are low molecular weight acrylate polymers and organophosphoms compounds (phosphonates). Both classes of materials function as threshold inhibitors however, the polymeric materials are more effective dispersants. Selection of a scale control agent depends on the precipitating species and its degree of supersaturation. The most effective scale control programs use both a precipitation inhibitor and a dispersant. In some cases this can be achieved with a single component (eg, polymers used to inhibit calcium phosphate at near neutral pH). 

Polymeric Calcium Phosphate Cements. Aqueous solutions of polymers such as poly(acryHc acid), poly(vinyl alcohol), gelatin, etc, and/or autopolymerizable monomer systems, eg, 2-hydroxyethyl methacrylate, glycerol dimethacrylate, calcium dimethacrylate, etc, have been used as Hquid vehicles (41,42,76) for the self-setting calcium phosphate cement derived from tetracalcium phosphate and dicalcium phosphate [7757-93-9J. 

Related programs, such as phosphate-chelant and phosphate-polymer, are simply modifications of the basic phosphate-cycle, and they still rely on the precipitation of calcium (or other metal ions) as dispersible phosphate sludge. 

SS/MA may be structured in different ratios of sulfonated styrene to maleic anhydride. Typically, it is 3 1 (20,000 MW) or 1 1 (15,000 MW). The application rates of all calcium phosphate scale/sludge inhibitors or stabilizers vary, based on the amount of calcium present in the cooling system, with increased calcium hardness leading to higher levels of polymer required. 

The in situ precipitation route towards obtaining composites of polymer and calcium phosphate is similar to the strategy employed in naturally occurring biocomposites and well may prove a viable method for the synthesis of bone substitutes. 

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. 

Phosphate-polymer control, in industrial water treatment, 26 132-133 Phosphate recognition, 16 794 Phosphate refractory dental dies, compressive strength, 8 289t Phosphate rock, 11 119, 120 minerals in, 19 5, 14 recovery of fluoride from, 14 12-13 U.S. imports for consumption of, 19 15t U.S. production of, 19 17 Phosphates, 18 814-863 19 19. See also Phosphate Polyphosphates aluminum acid, 18 839 ammonium, 11 487 18 835-836 analysis of, 18 851-852 calcium, 18 836-839 condensed, 18 841-852 crystalline, 18 839 dispersants, 8 710t economic aspects of, 18 859-860... 

The selectivity is severely impeded if phosphate-based buffers are employed, since calcium-phosphate complexation occurs. In principle, the selectivity of a membrane-based ISE is constant, but contamination and degradation of the membrane s polymer component means that the selectivity decreases with usage. Contamination with biological samples can also be problematic. 

Low-molecular-weight carboxyl-containing polymers have been used to control the deposition of calcium phosphate (2-8). These polymers also function as... 

Evaluation of the Copolymers The polymer solutions were evaluated for their deposit control and dispersant activities. The tests included calcium phosphate inhibition, calcium carbonate inhibition, iron oxide dispersion, and clay dispersion. The procedures for these tests have been previously reported (12). A commercially available polyacrylic acid was also tested for comparison. The results are shown in Tables II to V. 

For methylcellulose, increased matrix material concentration did not affect the release profile (Table 4). The sustained action can be directly attributed to the formation of a hydration layer by this polymer. This hydration layer, however, did not resist attrition and remain intact. Consequently, attrition becomes more important than diffusion the hydrated layer dissolves away almost as rapidly as it is formed. On the contrary, the dibasic calcium phosphate dihydrate did not diffuse outward, but rather became entrapped within the matrix and effected an increase in release of drug because its presence necessarily decreased the polymer concentration. 

While the standard, modem chemical treatment programs used today almost always contain a synergistic blend of polymers and other organic inhibitors, they often may not contain a specific calcium phosphate deposit control agent (as it would increase the cost of the program). This situation reinforces the need for vigilance. 

Barrier layer Styrene butadiene, calcium phosphate, polysilicone, nylon, Teflon, polytetrafluoroethylene, halogenated polymers... 

One of the important fields where carbohydrate polymer/inorganic hybrids may be successfully applied is bioactive materials, e.g., artificial bones expedient for surgery to accelerate the recovery of living bones. There has been increasing interest in hydroxyapatite (HAp) deposition onto the matrix surface of cellulose or related polysaccharide. HAp is a form of calcium phosphate, a main constituent of the inorganic phase of human bone. This kind of study is also a step on the way to exploitation of new biomimetic mineralization methods. 

Casein monomers or small polymers — caseinate subunits + calcium phosphate — casein micelles... 

Sugawara A, Yamane S, Akiyoshi K (2006) Nanogel-templated mineralization polymer-calcium phosphate hybrid nanomaterials. Macromol Rapid Commun 27(6) 441—446... 

Nanocapsules calcium phosphate), gold Various polymers, e.g., Interfacial... 

Typically, bone has a solid outer portion called cortical bone and a porous inner part called cancellous bone. The amounts of each vary with location in the body. The cortical bone is a ceramic containing calcium compounds and viscous liquids, a protein called collagen , and an organic polymer. In addition to HAP, bone consists of calcium carbonate and calcium phosphate. HAP is 69 wt.% of total calcium phosphate compounds [4]. Part of the Ca in these compounds is substituted by Na, K, Mg, and Sr. Hydroxyl ions in the HAP are also substituted by F, CO3, or Cl, which makes the apatite a fluoroapatite, dahllite or chloroapatite, respectively. These substitutions are considered to play significant roles in the structure and mechanical properties of bones. 

---