Calcium phosphate composites with

A urea-mediated mineralization technique was developed to enable the formation of pHEMA-based hydrogel-calcium phosphate composites with excellent polymer-mineral interfacial adhesion strength that is desirable for bone mimics. This mineralization method was also applied to generate more sophisticated composites containing functional hydrogels that possess anionic groups mimicking the extracellular matrix proteins in bone. 

In the field of metallic powder applications, a method of plasma spray coating suitable for biomedical materials has been developed using titanium and calcium phosphate composite powder. By means of the mechanical shock process, the appropriate composite powder was prepared, and plasma sprayed on Ti substrate under a low-pressure argon atmosphere. A porous Ti coating layer was obtained in which the surface and the inside of the pores were covered thinly with hydroxyapatite. This surface coating is expected to show excellent bone ingrowth and fixation with bone (21). 

The System Lime and Phosphoric Acid —Solubility of Calcium Phosphates— Conditions of Formation of Basic and Acid Calcium Phosphates—Composition of Solutions Saturated with Calcium Hydrogen Phosphates—Equilibria between Solid Phases and Solutions at Various Temperatures—Changes during Neutralisation—The Acid Phosphates—Manufacture of Superphosphate—Retrogression—Treatment of Special Ores—Phosphoric Acid— Commercial Preparation and Extraction from Rook—The History and Technology of Superphosphate Manufacture—Mixed and Concentrated Phosphorio Fertilisers—Potassium Phosphates—Ammonium Phosphates. 

These are generally made up of metabolic products present in the glomerular filtrate at levels close to their maximum solubility limit. Variation of the pH and composition of the urine or obstruction to urine flow may result in precipitation of substances in the kidney and contribute to calculi formation. Urinary calculi may be composed of calcium-containing stones such as calcium oxalate or calcium phosphate, both with and without magnesium ammonium phosphate, and stones containing either cystine, xanthine, or uric acid (21). The mucoprotein core around which the mineral salts precipitate account for 60% of the composition of the stone. 

Hydroxyapatite A calcium phosphate ceramic with a calcium to phosphorus ratio of 5/3 and nominal composition Cai0(PO4)6(OH)2. It has good mechanical properties and excellent biocompatibility. Hydroxyapatite is the mineral constituent of bone. 

Table 2.3 List of some non-setting non-allogenic pastes with indication of producer, product name, composition and form (pre-mixed or to be mixed). Denominations HA = Hydroxyapatite / -TCP = / -Tricalcium phosphate BCP = diphasic calcium phosphate (composite between HA and /3-TCP) CMC = carboxymethylcellulose H PMC hydroxypropylmethylcellulose... 

Hydroxyapatite calcium phosphate cement with composition of Caio(P04)6(OH)2 exhibits excellent mechanical properties and biocompatibihty major mineral constituent of the bone also finds use as a filler to replace amputated bone and/or as a coating to promote bone ingrowth into prosthetic implants. 

Park and Vasilos [42] fabricated carbon fiber reinforced calcium phosphate composites, made by hot pressing to give a ceramic with significantly improved ductility albeit with a slight decrease in ultimate flexural strength. The failure strains of the composites and the monolithic calcium phosphate ceramics were 0.36 and 0.21%, respectively. It was demonstrated that carbon fiber reinforced calcium phosphate composites would be good biomaterials for bone replacement. 

Among the composite, PLA or PLGA/calcium phosphate composites have been most extensively studied [89-93]. With the addition of calciiun phosphate in composites not only the mechanical strength is improved, but also a more stable pH value than that for plain PLA or PLGA can be achieved the acidic degradation byproducts of the PLA or PLGA is buffered by the calcium phosphate. 

Other inorganic materials, such as biphasic calcium phosphate (BCP) with CMC have been prepared for new classes of composite materials. Multiphasic materials such as bioceramic show high compressive properties in addition to containing water-soluble polymers and are considered good ionic carriers for the formation of ECM. This composite material provided adequate injectable properties and nontoxic responses, demonstrating its potential for the repair of AC (De Freitas et al., 2012). 

We can differentiate composites as bioresorbable or non-bioresorbable. The nonbioresorbable composites are the result of the combination of a non-bioresorbable calcium phosphate (HAP) with a non-bioresorbable polymer (PMMA, PE). In this case, we have to avoid the covering of ceramic grants of the sttrface, so as to preserve their biological activity. 

Tricalcium phosphate, Ca2(P0 2> is formed under high temperatures and is unstable toward reaction with moisture below 100°C. The high temperature mineral whidockite [64418-26-4] although often described as P-tricalcium phosphate, is not pure. Whidockite contains small amounts of iron and magnesium. Commercial tricalcium phosphate prepared by the reaction of phosphoric acid and a hydrated lime slurry consists of amorphous or poody crystalline basic calcium phosphates close to the hydroxyapatite composition and has a Ca/P ratio of approximately 3 2. Because this mole ratio can vary widely (1.3—2.0), free lime, calcium hydroxide, and dicalcium phosphate may be present in variable proportion. The highly insoluble basic calcium phosphates precipitate as fine particles, mosdy less than a few micrometers in diameter. The surface area of precipitated hydroxyapatite is approximately... 

Tricalcium Phosphate. Commercial tricalcium phosphate (TCP) is actually an amorphous basic calcium phosphate close to hydroxyapatite in composition. Because of its extremely low solubiUty in water, TCP is precipitated almost quantitatively from dilute phosphate solutions with a slurry of hydrated lime. TCP is separated by dmm-, spray-, or flash-drying the TCP slurry, with or without intermediate sedimentation or filtration steps. It is used as an industrial-grade flow conditioner and parting agent. 

Phospha.tes, Pentasodium triphosphate [7758-29-4] sodium tripolyphosphate, STPP, Na P O Q, is the most widely used and most effective builder in heavy-duty fabric washing compositions (see also Phosphoric acid and phosphates). It is a strong sequestrant for calcium and magnesium, with a p c of ca 6, and provides exceUent suspending action for soils. Because of its high sequestration power, it also finds extensive appHcation in automatic-dishwashing detergents. Sodium tripolyphosphate forms stable hydrates and thus aids in the manufacture of crisp spray-dried laundry powders. 

Chitosan scaffolds were reinforced with beta-tricalciiun phosphate and calcium phosphate invert glass [177]. Along the same line, composites of Loligo beta-chitin with octacalcium phosphate or hydroxyapatite were prepared by precipitation of the mineral into a chitin scaffold by means of a double diffusion system. The octacalciiun phosphate crystals with the usual form of 001 blades grew inside chitin layers preferentially oriented with the 100 faces parallel to the surface of the squid pen and were more stable to hy-... 

Silver white, relatively soft metal that is only applied in alloys. Oxygen and water attack pure Ca. The most prominent compound is the oxide (CaO) = burnt calcium, which hardens to calcium carbonate in mortar. Annual production of about 120 million tons. Burnt gypsum (CaS04 0.5 H20) hardens with water. A great step in evolution was the replacement of hard shells of brittle calcium carbonate by an internal skeleton of tough calcium phosphate (hydroxylapatite)-protein composite. Calcium is essential for all life forms. The daily requirement is 0.7-1.0 g. Humans (70 kg) contain 1 kg of calcium. Calcium silicate is the main component of cement. Marble is calcium carbonate in polycrystalline form and the favorite material of sculptors. 

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