Stabilizing amorphous calcium phosphate phase by citrate adsorption

CrystEngComm ◽  
2014 ◽  
Vol 16 (10) ◽  
pp. 1864-1867 ◽  
Author(s):  
Yan Chen ◽  
Wenjia Gu ◽  
Haihua Pan ◽  
Shuqin Jiang ◽  
Ruikang Tang
Keyword(s):  
Calcium Phosphate ◽  
Amorphous Phase ◽  
Amorphous Calcium Phosphate ◽  
Surface Reaction ◽  
Phosphate Phase ◽  
Calcium Phosphate Phase

Citrate controls nucleation by association with a precursor amorphous phase, which inhibits the surface reaction for nucleation.

scholarly journals PRECIPITATION OF HYBRID HYDROXYAPATITE / AUTOFIBRIN NANOCOMPOSITES

2021 ◽  
pp. 818-828
Author(s):  
Илья Евгеньевич Глазов ◽  
Валентина Константиновна Крутько ◽  
Роман Алексеевич Власов ◽  
Ольга Николаевна Мусская ◽  
Людмила Викторовна Кульбицкая ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Simulated Body Fluid ◽  
Amorphous Calcium Phosphate ◽  
Body Fluid ◽  
Hybrid Composites ◽  
Model Solution ◽  
Hybrid Nanocomposites ◽  
Biomimetic Apatite ◽  
Phosphate Phase ◽  
Calcium Phosphate Phase

Синтезированы гибридные нанокомпозиты на основе гидроксиапатита и аутофибрина в форме фибринового сгустка либо цитратной плазмы путем осаждения при pH 9. «Мягкие» условия осаждения и быстрое выделение нанокомпозитов способствовали сохранению биополимерной матрицы аутофибрина. Дестабилизация дополнительной фазы аморфного фосфата кальция с образованием стехиометрического гидроксиапатита обусловлена влиянием макромолекул фибрина. Формирование кальцийдефицитного гидроксиапатита с x« 0,1 и Ca / P 1,65 происходило в среде цитратной плазмы, который после 800 °С превращался в смесь гидроксиапатит / 3 -трикальцийфосфат. Синтез композитов на основе биомиметического апатита осуществляли при добавлении 30 об.% модельного раствора Simulated Body Fluid (SBF). Влияние ионов Mg, CO~, входящих в состав SBF, способствовало стабилизации аморфного фосфата кальция и образованию карбонатзамещенного гидроксиапатита, устойчивого к термическим превращениям до 800°С. Совокупное влияние аутофибрина и ионов введенного SBF позволило управлять составом минеральной составляющей гибридных нанокомпозитов без разрушения биополимерной матрицы. Hybrid composites based on hydroxyapatite and autofibrin were synthesized by precipitation in a medium with pH = 9. Soft precipitation conditions and rapid isolation of the composite precipitates favored preservation of a biopolymer matrix of autofibrin. An effect of fibrin macromolecules contributed to destabilization of the amorphous calcium phosphate phase and formation of stoichiometric hydroxyapatite. The medium of the citrated plasma stimulated precipitation of calcium-deficient hydroxyapatite with x « 0,1 and the Ca / P ration of 1,65 which transformed into the mixture of hydroxyapatite / 3 -tricalcium phosphate at 800 °С. Biomimetic apatite composites were synthesized with an addition of 30 vol. % of a Simulated Body Fluid (SBF) model solution. The effect of Mg, CO~ ions of SBF promoted the stabilization of amorphous calcium phosphate and formation of carbonated hydroxyapatite that exhibited thermal stability up to 800 °С. The cummulative effect of autofibrin and ions of induced SBF provided controlling composition of the mineral part of hybrid nanocomposites without disruption of an autofibrin matrix.

Synchrotron X-Ray Microanalysis and Imaging of Synthetic Biological Calcium Carbonate in Comparison With Archaeological Samples Originating from the Large Cave of Arcy-sur-Cure (28000-24500 BP, Yonne, France)

2013 ◽  
Vol 19 (6) ◽  
pp. 1523-1534 ◽  
Author(s):  
Emilie Chalmin ◽  
Ina Reiche
Keyword(s):  
Calcium Carbonate ◽  
Calcium Phosphate ◽  
Formation Process ◽  
Amorphous Calcium Phosphate ◽  
Analytical Methods ◽  
X Ray ◽  
Phosphate Phase ◽  
Carbonate Formations ◽  
Calcium Phosphate Phase ◽  
Case Based

AbstractBiosynthetic calcite samples were investigated using combined synchrotron X-ray microspectroscopy mapping. These samples were prepared with bacteria isolated from the Large cave of Arcy-sur-Cure in which prehistoric figures are masked by an opaque calcite layer. The biotic or abiotic origin of this layer is the issue of the present work. As previously known, a large community of bacteria may be involved in the CaCO3 formation in caves. A mixture of calcite/vaterite was obtained from bacteria isolated from the cave. Therefore, we can offer conclusions on their calcifying capability. The rare presence of vaterite in cave environments may be treated as a marker of biotic carbonate formations. Moreover, an amorphous calcium phosphate phase was present in the form of a calcite/vaterite mixture in the biotic model samples. This mixture of phases could be used as a tracer of the biotic process of CaCO3 formation. These biotic tracer phases were not identified using the applied analytical methods in the natural samples taken from the opaque calcite layers that covered the prehistoric figures of the Large cave. In this case, based on the obtained results, the biotic calcite formation process is likely to be considered as an undetectable effect at minimum.

Evidence of calcium phosphate supersaturation in the loop of Henle

1996 ◽  
Vol 270 (4) ◽  
pp. F604-F613 ◽  
Author(s):  
J. R. Asplin ◽  
N. S. Mandel ◽  
F. L. Coe
Keyword(s):  
Calcium Phosphate ◽  
Calcium Concentration ◽  
Loop Of Henle ◽  
X Ray ◽  
Ion Interactions ◽  
Collecting Ducts ◽  
Phosphate Phase ◽  
Dietary Phosphate ◽  
Calcium Phosphate Phase

We have used published rat micropuncture data to construct a matrix of ion concentrations along the rat nephron. With an iterative computer model of known ion interactions, we calculated relative supersaturation ratios in all nephron segments. The collecting ducts and urine showed expected supersaturation with stone-forming salts. Fluid in the thin segment of the loop of Henle may be supersaturated with calcium carbonate and calcium phosphate under certain conditions. Because calculations cannot predict the actual course of crystallization, we made solutions to mimic, in vitro, presumed conditions in the loop of Henle. The solid phases that formed were analyzed by X-ray powder diffraction, electron microprobe, and infrared spectroscopy. All samples were identified as poorly crystallized or immature apatite. The descending limb of Henle's loop creates a unique condition as it extracts water but not sodium, bicarbonate, calcium, or phosphate, giving a calcium concentration at the bend of 3 mM, pH 7.4, and a phosphate concentration that varies from 0.8 to 48 mM, depending on parathyroid hormone and dietary phosphate. We conclude that conditions in the thin segment potentially could create a solid calcium phosphate phase, which may initiate nucleation of calcium oxalate salts in the collecting ducts, potentiating nephrolithiasis and nephrocalcinosis.

The uptake of strontium by calcium phosphate phase formed at an elevated pH

1996 ◽  
Vol 204 (2) ◽  
pp. 363-370 ◽  
Author(s):  
S. Raičević ◽  
Ž Vuković ◽  
T. L. Lizunova ◽  
V. F. Komarov
Keyword(s):  
Calcium Phosphate ◽  
Phosphate Phase ◽  
Calcium Phosphate Phase

Probable Phase Composition of the Mineral in Bone

1980 ◽  
Vol 35 (5-6) ◽  
pp. 357-362 ◽  
Author(s):  
F. C. M. Driessens
Keyword(s):  
Phase Composition ◽  
Calcium Phosphate ◽  
Bone Mineral ◽  
Experimental Error ◽  
Human Bone ◽  
Apatite Structure ◽  
Phosphate Phase ◽  
Limits Of Error ◽  
Calcium Phosphate Phase ◽  
Citrate Ions

Abstract Formulas proposed for the mineral of bone were reviewed. Literature data were collected where Ca, P, Na, Mg and CO3 are determined in the same samples. These data were analyzed for their conformity to the above mentioned formulas. According to this analysis Mg is contained in a phase having the Ca/P of magnesium whitlockite within the limits of error. Na is contained in a carbonated calcium phosphate phase which in analogy with synthetic systems must have the apatite structure. The Ca/P ratio of the remaining "rest phase" is 2. This is based on the composi­ tion of 101 bone mineral samples taken from fishes, reptiles, amphibians, birds and mammals. The CO3 content of the bone samples agrees with the formula Ca8 (PO4)4 (CO3) (OH)2 · x H2O for the "rest phase" within the limits of experimental error. Such a compound has, however, not been found in synthetic systems. Human bone contains about 15% magnesium whitlockite, 25% of the Na and CO3 containing apatite and the rest is the carbonated calcium phosphate with Ca/P = 2. It is presumed that this compound has a structure similar to that of octo calcium phosphate and that most of the citrate ions which always occur in bone mineral samples are in­ corporated in that phase.

scholarly journals In situ luminescence analysis: a new light on monitoring calcium phosphate phase transitions

2017 ◽  
Vol 4 (7) ◽  
pp. 1157-1165 ◽  
Author(s):  
H. Terraschke ◽  
M. Rothe ◽  
A.-M. Tsirigoni ◽  
P. Lindenberg ◽  
L. Ruiz Arana ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Calcium Phosphate ◽  
Synchrotron Radiation ◽  
Calcium Phosphates ◽  
High Sensitivity ◽  
Luminescence Analysis ◽  
Biologically Relevant ◽  
Phosphate Phase ◽  
Calcium Phosphate Phase

In situ luminescence measurements allow monitoring the phase transitions of biologically relevant calcium phosphates with high sensitivity, independent of synchrotron radiation.

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