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Amorphous Calcium Phosphate (amorphous + calcium_phosphate)
Selected AbstractsOn the Stability of Amorphous Minerals in Lobster CuticleADVANCED MATERIALS, Issue 40 2009Ali Al-Sawalmih In situ X-ray diffraction during heating of lobster cuticle reveals three regions of thermally induced transformations: 1)Chitin decomposition, 2) amorphous calcium carbonate (ACC) , calcite transformation, and 3) amorphous calcium phosphate (ACP) , hydroxyapatite transformation. These results provide new insights into the stabilization mechanisms of amorphous biominerals based on ACC and ACP. [source] Preparation of Nano Carbonate-Substituted Hydroxyapatite from an Amorphous PrecursorINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2008Yanbao Li Carbonated amorphous calcium phosphate (CACP) precursors were precipitated by the wet chemical method at 5°C in the presence of poly(ethylene glycol) and carbonates. The nano carbonate-substituted hydroxyapatite (HAp) was obtained after heat treat CACP precursors at a low temperature (800°C) for 3 h. The calcium phosphates were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, inductively coupled plasma, thermal gravimetric and differential thermal analysis, transmission electron microscopy, and scanning electron microscopy. The results show that calcium phosphate particles with a Ca/P molar ratio of 1.73 are AB-type carbonate-substituted HAp with about 50 nm in diameter. [source] Effect of particle size of an amorphous calcium phosphate filler on the mechanical strength and ion release of polymeric composites,JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Soo-Young Lee Abstract The random clustering of amorphous calcium phosphate (ACP) particles within resin matrices is thought to diminish the strength of their polymerized composites. The objective of this study was to elucidate the effect of ball-milling on the particle size distribution (PSD) of ACP fillers and assess if improved dispersion of milled ACP in methacrylate resin sufficiently enhanced filler/matrix interactions to result in improved biaxial flexure strength (BFS), without compromising the remineralizing potential of the composites. Unmilled and wet-milled zirconia-hybridized ACP (Zr-ACP) fillers were characterized by PSD analysis, X-ray diffraction, thermogravimetric and chemical analysis, infrared spectroscopy, and scanning electron microscopy. Composite specimens made from a photoactivated, ternary methacrylate resin admixed with a mass fraction of 40% of un-milled or milled Zr-ACP were evaluated for the BFS (dry and wet) and for the release of calcium and phosphate ions into saline solutions. While having no apparent effect on the structure, composition, and morphology/topology of the fillers, milling significantly reduced the average size of Zr-ACP particulates (median diameter, dm = 0.9 ± 0.2 ,m) and the spread of their PSD. Better dispersion of milled Zr-ACP in the resins resulted in the improved BFS of the composites, even after aqueous soaking, and also gave a satisfactory ion release profile. The demonstrated improvement in the mechanical stability of anti-demineralizing/remineralizing ACP composites based on milled Zr-ACP filler may be beneficial in potentially extending their dental utility. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Protein dynamics of bovine dentin phosphophorynCHEMICAL BIOLOGY & DRUG DESIGN, Issue 2 2005K.J. Cross Abstract:, Bovine dentin phosphophoryn (BDP), a protein rich in aspartyl (Asp) and o -phosphoseryl [Ser(P)] residues, is synthesized by odontoblasts and believed to be involved in matrix-mediated biomineralization of dentin. The elucidation of the structure,function relationship of phosphophoryn has been a challenge because of its high-molecular weight, high negative charge, repetitive sequence, and lability. We have used the dynamic behavior of the 1H NMR signal at 600 MHz to provide insight into the molecular dynamics of phosphophoryn. Our results indicate that phosphophoryn is a molecule of uniformly high mobility, thus belonging to a recently identified class of intrinsically disordered proteins that are characterized by sequences of low complexity and rich in polar and charged residues. The significance of our results is that phosphophoryn, because of its uniform nature has the potential to be replaced by biomimetic synthetic peptide analogs that together with amorphous calcium phosphate may lead to the development of novel, nontoxic, apatite-based dental restorative materials. [source] | ||||||||||