7789-77-7Relevant articles and documents
Peroxo derivatives of hydroxyapatite and calcium hydrophosphate
Skogareva,Pilipenko,Shabalova,Tripol'Skaya
, p. 673 - 679 (2011)
Hydroxyapatite and calcium hydrophosphate peroxo solvates were synthesized and characterized by IR spectroscopy, powder X-ray diffraction, and TGA to be used as biocompatible and antibacterial medicaments in manufacturing calcium phosphate bioceramics for implantations in orthopedics and dentistry. A wide range of hydrogen peroxide percentages in stable mixtures of mCa 5(PO4)3(OH) + nCaHPO4 ? H 2O2 ? H2O (ranging from 0.5 to 18%) allows composites to be prepared with a tailored active oxygen content.
Di- tert-butylphosphate Derived Thermolabile Calcium Organophosphates: Precursors for Ca(H2PO4)2, Ca(HPO4), α-/β-Ca(PO3)2, and Nanocrystalline Ca10(PO4)6(OH)2
Murugavel, Ramaswamy,Verma, Sonam
, p. 13233 - 13244 (2020)
Thermally and hydrolytically unstable di-tert-butyl phosphate (dtbp-H) has been used as synthon to prepare discrete and polymeric calcium phosphates that are convenient single-source precursors for a range of calcium phosphate ceramic biomaterials. The reactivity of dtbp-H toward two different calcium sources has been found to vary significantly, e.g., the reaction of Ca(OMe)2 with dtbp-H in a 1:6 molar ratio in petroleum ether forms a mononuclear calcium hexa-phosphate complex [Ca(dtbp)2(dtbp-H)4] (1), whereas the change of calcium source to CaH2, in a 1:2 molar ratio under otherwise similar reaction conditions, yields the calcium phosphate polymer, [Ca(μ-dtbp)2(H2O)2·H2O]n(2). Compounds 1 and 2 have been extensively characterized by various spectroscopic and analytical techniques. The solid-state structures of both 1 and 2 have been determined by single-crystal X-ray diffraction studies. In discrete molecule 1, the central calcium ion is surrounded by two anionic dtbp and four neutral dtbp-H ligands in an octahedral coordination environment. Compound 2 is a one-dimensional polymer in which adjacent calcium ions are connected through double dtbp bridges. Solid-state thermolysis of bulk 1 in air leads to the exclusive formation of calcium metaphosphate β-Ca(PO3)2 in the entire temperature range of 400-800 °C. Thermal decomposition of polymer 2, however, can be fine-tuned to produce either α-Ca(PO3)2 or β-Ca(PO3)2 depending on the thermolysis conditions employed. Although the sample sintered at 600 °C produces exclusively α-form of Ca(PO3)2, the sample annealed at 800 °C or above produces β-form. Both α- and β-forms can also be successively formed one after other by a slow heating of a freshly prepared 2 on the powder diffractometer sample holder. Additional forms of ceramic phosphates have been prepared by solvothermal conditions because of the highly labile nature of the tert-butoxy groups of dtbp in 1 and 2. Solution decomposition of either 1 or 2 in boiling toluene at 140 °C in a sealed tube produces calcium dihydrogen phosphate [Ca(H2PO4)2·H2O] as the only product in the form of single crystals. Solution thermolysis of 2 in protic solvents such as water and methanol can be biased to produce other calcium phosphate biomaterials such as hydroxyapatite [Ca10(PO4)6(OH)2]and calcium monohydrogen phosphate [Ca(HPO4)] in the presence of additional calcium precursors such as CaO and Ca(OMe)2, respectively.
Biocompatibility of apatite-containing implant materials
Malysheva,Beletskii
, p. 180 - 183 (2001)
Thermochemical decomposition of hydroxyapatite in phosphoric acid was studied with the aim of producing polymineral gradient-resorptivity composites. The procedure was tested on the BAK-1000 glass-apatite composite. The results indicate an enhancement of resorptivity, without changes in the performance parameters or crystal structure, thereby suggesting a new approach to controlling the bioactivity of apatite-containing bioceramics.
Effect of phase transformations during synthesis on the chemical composition and structure of calcium-deficient hydroxyapatite
Kitikova,Shashkova,Zonov,Sycheva,Rat'ko
, p. 1119 - 1127 (2007)
The chemical and phase changes during the precipitation of calcium-deficient hydroxyapatite from a solution of natural chalk in a mixture of phosphoric and nitric acids, with the use of aqueous ammonia as the precipitant, have been studied by potentiometric titration and physicochemical analysis. The initial solution concentration and precipitation time are shown to have a significant effect on the composition and structure of the precipitate. The processes in the solution and precipitate are interpreted in terms of thedegree of protonation of phosphate ions under various conditions.
Analysis of the effects of thermal treatments on CaHPO4 by 31P NMR spectroscopy
Louati,Hlel,Guidara,Gargouri
, p. 13 - 18 (2005)
The compound CaHPO4 was obtained by slow evaporation at room temperature. The sample was characterised by X-ray diffraction, differential scanning calorimetry and 31P MAS NMR spectroscopy at different annealing temperature. At room temperature, the observed values of the 31P NMR chemical shift for the title compound are found to be -1.6, -0.4 and 1.4 ppm with the proportions 1/4, 1/2 and 1/4, respectively, revealing the presence of three non-equivalent phosphorus sites in the structure. The 31P NMR investigation at different annealing temperatures points to a conversion of (HPO42-) into (P2O 74-) at high temperature.
Insight into shape control mechanism of calcium phosphate nanoparticles in reverse micelles solution
Lai, Chen,Tang, Shaoqiu,Wang, Yingjun,Wei, Kun,Zhang, Shiyin
, p. 717 - 725 (2005)
The present experiment demonstrates a systematic morphosynthesis of calcium phosphate crystals with controlled morphology in reverse micelles solution of CTAB/n-pentanol/ water/cyclohexane. Well-defined morphologies of calcium phosphate particles, such as nanowires, tablets, brushlike particles, and fiber bundles, can be prepared. The microstructural characteristics of the CTAB/n-pentanol/water/cyclohexane reverse micelles solution has been investigated by FTIR spectroscopic, 31P NMR, and UV-visible absorption spectra techniques, demonstrating that the molar ratio of water to surfactant (Wo) and n-pentanol to surfactant (Po) showed significant effects on the morphology of the resulting particles. At lower Wo and Po, CTAB played a role in guiding the growth direction. With increasing Wo and Po, crystal growth lost the direction-guiding capability of CTAB. However, as crystal growth modifiers, water and cosurfactants follow different mechanisms. The solubility of water causes a decrease in bound water layer, resulting in a decrease in interactions between CTA+ and PO43- which invalidates the shape control of surfactant molecules. The loading of cosurfactant (n-pentanol) results in decreasing the rigidity of the reverse micelles interface. This in turn favors the shape fluctuations of reverse micelles, inducing crystal development. Copyright
Chemical processing of CaHPO4·2H2O: Its conversion to hydroxyapatite
Tas, A. Cuneyt,Bhaduri, Sarit B.
, p. 2195 - 2200 (2004)
The aim of this paper is to develop a robust chemical process to synthesize Na- and K-doped brushite (DCPD: dicalcium phosphate dihydrate, CaHPO 4·2H2O), a potential starting material for bone substitutes. The powders were synthesized by using sodium phosphate and potassium phosphate and aqueous solutions containing calcium chloride at room temperature, followed by drying at 37°C. DCPD powders thus formed were found to contain 460 ppm K and 945 ppm Na. On calcination in air, these powders readily transformed into monetite (DCPA: dicalcium phosphate anhydrous, CaHPO4) first, and then into Ca2P2O7 (calcium pyrophosphate). Na- and K-doped DCPD powders were shown to completely transform, in less than 1 week, into poorly crystalline carbonated apatite on immersion in an acellular simulated/synthetic body fluid (SBF) solution at 37°C. The Tris (i.e., tris(hydroxymethyl)aminomethane) buffered SBF solution used in this study had a carbonate ion concentration of 27 mM equal to that of human plasma. DCPD powders of this study displayed a notable apatite-inducing ability. This finding suggests the use of these DCPD powders as the starting materials for potential bone substitutes, which can be easily manufactured in aqueous solutions friendly to living tissues, at temperatures between room temperature and 37°C.
A Comparative study of the synthesis of calcium, strontium, barium, cadmium, and lead apatites in aqueous solution
Flora, Natalie J.,Hamilton, Keith W.,Schaeffer, Richard W.,Yoder, Claude H.
, p. 503 - 521 (2004)
The aqueous syntheses of the hydroxy and halo apatites of calcium, strontium, barium, lead, and cadmium were explored. Because these cations represent the main group s- and p-fillers and a transition metal, they present different synthetic challenges. The alkaline earth cations and lead form hydrogen phosphates at slightly acidic and slightly basic conditions, the alkaline earths form the fluorides (MF2) in the preparation of the fluoroapatites with excess fluoride, and ammonia is required for the preparation of the cadmium apatites through decomplexation. A variety of reagents were utilized with most of the derivatives, but, in general, the source of the cation was its nitrate or halide, and the phosphate is best provided as ammonium hydrogen phosphate. The requirements for pH, heating, and reaction time were also explored. A number of literature syntheses for pure phase apatites could not be reproduced: calcium iodoapatite, strontium fluoroapatite, and cadmium hydroxyapatite. Several apatites were prepared for the first time in aqueous solution: barium fluoroapatite, lead bromoapatite, and cadmium chloroapatite. The relative ease of formation of the compounds is rationalized with arguments based upon lattice and hydration energies.
Synthesis and thermal characterization of copper and calcium mixed phosphates
Da Silva Filho,Da Silva, Oberto G.,Da Fonseca, Maria G.,Arakaki, Luiza N. H.,Airoldi
, p. 775 - 778 (2007)
A series of compounds with composition of Ca1-xCu xHPO4, where x varied from 0.05 to 0.5 were synthesized by precipitation method. The compounds were characterized by elemental analysis, X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and thermogravimetry. The chemical stabilities of solids were investigated at several pH. Elemental analysis of copper, calcium and phosphorus are in agreement with the proposed composition. The formation of lamellar phosphates was evidenced. The stability of the set of compounds was better for samples with high copper content. Springer-Verlag 2007.
Transformation of Brushite (CaHPO4·2H2O) to Whitlockite (Ca9Mg(HPO4)(PO4)6) or Other CaPs in Physiologically Relevant Solutions
Tas, A. Cuneyt
, p. 1200 - 1206 (2016)
Brushite (dicalcium phosphate dihydrate, DCPD, CaHPO4·2H2O) and whitlockite [WH, Ca9Mg(HPO4)(PO4)6] are usually found in the mammalian metabolism in the form of diverse pathological calcifi
