Calcium phosphate soluble glasses

A. Baudrimont and J. Pelouze (1833) fused the sodium sulphate with galena or zinc blende and formed the alkali plumbate or zincate, and J. B. M. P. Closson boiled a soln. of sodium sulphate with milk of lime and lead oxide. The plumbate can be decomposed by sulphide, carbon dioxide, or by electrolysis. The St. Gobain Co. patented a process in which sand, coal, and sodium sulphate are heated together water-glass is formed and a soln. or suspension of that salt in water is decomposed by carbon dioxide or by milk of lime. J. Simpson (1890), J. C. Ody (1892), N. Basset and W. von Baranofi (1894) decomposed a soln. of sodium sulphate by calcium phosphate in dil. acid. The soluble sodium phosphate which is formed... 

Fused Calcium Magnesium Phosphate. In a process developed by TVA, a mixture of phosphate rock and olivine or serpentine (magnesium silicate) is fused in an electric furnace.21 The molten product is quenched with water and used in a finely divided state as a fertilizer. The product, a calcium magnesium phosphate (CMP) glass, contains about 20 percent P205 and 15 percent MgO. Over 90 percent of the product is soluble in citric acid. 

Solubilities of the Glasses of Calcium Phosphate-Silicates in Water in the Presence of Ion-Exchange Resin (36)... 

Kidney stones are solid materials that form in the urinary tract. Most kidney stones are composed of calcium phosphate and calcium oxalate, although they can be solid uric acid. The excessive ingestion of minerals and insufficient water intake can cause the concentration of mineral salts to exceed their solubility and lead to the formation of kidney stones. When a kidney stone passes through the urinary tract, it causes considerable pain and discomfort, necessitating the use of painkillers and surgery. Sometimes ultrasound is used to break up kidney stones. Persons prone to kidney stones are advised to drink six to eight glasses of water every day to prevent saturation levels of minerals in the urine. 

Biocompatibility is actually a major problem for implants and bioactive sol-gel glasses have been developed. They are typically made of a mixture of silica and calcium phosphate in order to show some affinity for the in vitro and in vivo nucleation of apatite (Hench, 1998). Such sol-gel glasses can also be used as implantable drug carriers. Experiments performed with ibuprofen, an anti-inflammatory drug, show that both processes, formation of an apatite layer and drug release, occur simultaneously. The release kinetics is mainly influenced by the solubility of the drug and the pore size of the bioglass (Ramila, 2003 Hall, 2003). 

The progress of precipitation is revealed by the concentration/time curves for zinc and phosphate, since both these species are present initially in solution. There should be maxima for the soluble aluminium, calcium and fluoride which are extracted from the glass, but because of the early onset of precipitation these are not observed. Precipitation is accompanied by an increase in pH when it reaches 1-8, at which juncture 50% of both zinc and phosphate have been precipitated, the cement paste gels (5 minutes after preparation). 

General Rules of Solubility as listed in Chapter 8 0.1 M solutions of the following compounds (these are the unknown solutions) Ag(N03) (silver nitrate), Ca(N03)2 (calcium nitrate), Cu(N03)2 (copper nitrate), NaOH (sodium hydroxide), KC1 (potassium chloride), Na2SC>4 (sodium sulfate), Nal (sodium iodide), and Na3PC>4 (sodium phosphate) eight small test tubes eight small disposable pipets pH paper one flame test wire in a cork glass plates a Bunsen burner and 3M HC1 (hydrochloric acid). 

Fusion of a phosphate with a silicate does not easily give a condensed polymer of Si04 and PO4 (12.62). Calcium metaphosphate fused with silica gel at 980°C (Si02 < 12.5%) gives a clear glass which is slowly but completely soluble in water. If the silica content is >12.5%, the resulting glass is turbid and not completely soluble in water. 

Based on observed tissue response, synthetic bone-graft substitutes can be classified into inert (e.g., alumina, zirconia), bioactive (e.g., hydroxyapatite, bioactive glass), and resorbable substitutes (e.g., tricalcium phosphate, calcium sulfate). Of these, resorbable bone-graft substitutes are preferred for bone defect filling because they can be replaced by new natural bone after implantation, p-tricalcium phosphate (Ca3(PO )2, p-TCP) is one of the most widely used bone substitute material, due to its faster dissolution characteristics. Preparation of magnesium-substituted tricalcium phosphate ((Ca, Mg)3(PO )2, p-TCMP) has been reported by precipitation or hydrolysis method in solution. These results indicate that the presence of Mg stabilizes the p-TCP structure (LeGeros et al., 2004). The incorporation of Mg also increases the transition temperature from p-TCP to a-TCP and decreases the solubility of p-TCP (Elliott, 1994 Ando, 1958). 

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