scholarly journals Pure hydroxyapatite synthesis originating from amorphous calcium carbonate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michika Sawada ◽  
Kandi Sridhar ◽  
Yasuharu Kanda ◽  
Shinya Yamanaka
Keyword(s):  
Calcium Carbonate ◽  
Calcium Phosphate ◽  
Room Temperature ◽  
Molar Ratio ◽  
Final Phase ◽  
Amorphous Calcium Carbonate ◽  
Phosphate Compound ◽  
Synthesis Strategy ◽  
Phosphorylation Reaction ◽  
Subsequent Calcination

AbstractWe report a synthesis strategy for pure hydroxyapatite (HAp) using an amorphous calcium carbonate (ACC) colloid as the starting source. Room-temperature phosphorylation and subsequent calcination produce pure HAp via intermediate amorphous calcium phosphate (ACP). The pre-calcined sample undergoes a competitive transformation from ACC to ACP and crystalline calcium carbonate. The water content, ACC concentration, Ca/P molar ratio, and pH during the phosphorylation reaction play crucial roles in the final phase of the crystalline phosphate compound. Pure HAp is formed after ACP is transformed from ACC at a low concentration (1 wt%) of ACC colloid (1.71 < Ca/P < 1.88), whereas Ca/P = 1.51 leads to pure β-tricalcium phosphate. The ACP phases are precursors for calcium phosphate compounds and may determine the final crystalline phase.

scholarly journals Calcium Phosphate Powder Synthesized from Calcium Acetate and Ammonium Hydrophosphate for Bioceramics Application

Ceramics ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 375-392 ◽  
Author(s):  
Tatiana Safronova ◽  
Valery Putlayev ◽  
Yaroslav Filippov ◽  
Tatiana Shatalova ◽  
Evgeny Karpushkin ◽  
...  
Keyword(s):  
Phase Composition ◽  
Calcium Phosphate ◽  
Room Temperature ◽  
Calcium Acetate ◽  
Molar Ratio ◽  
Composite Ceramics ◽  
Phosphate Powder ◽  
Starting Solution ◽  
By Products ◽  
Ammonium Hydrophosphate

Calcium phosphate powder was synthesized at room temperature from aqueous solutions of ammonium hydrophosphate and calcium acetate without pH adjusting at constant Ca/P molar ratio 1.5. Phase composition of the as-synthesized powder depended on the precursors concentration: At 2.0 M of calcium acetate in the starting solution, poorly crystallized hydroxyapatite was formed, 0.125 M solution of calcium acetate afforded brushite, and the powders synthesized from 0.25–1.0 M calcium acetate solutions were mixtures of the mentioned phases. Firing at 1100 °C led to complete elimination of the reaction by-products, yet the phase composition of the annealed compacted samples was the following: When 2.0 M solution of calcium acetate was used, the obtained ceramics consisted of β-Ca3(PO4)2, whereas at 0.125 to 1.0 M of calcium acetate, the ceramics was a mixture of β-Ca3(PO4)2 and β-Ca2P2O7. Synthesized calcium phosphate powders can be used as the powdered precursors for biocompatible bioresorbable composite ceramics production.

How similar are amorphous calcium carbonate and calcium phosphate? A comparative study of amorphous phase formation conditions

CrystEngComm ◽  
2018 ◽  
Vol 20 (1) ◽  
pp. 35-50 ◽  
Author(s):  
I. Buljan Meić ◽  
J. Kontrec ◽  
D. Domazet Jurašin ◽  
A. Selmani ◽  
B. Njegić Džakula ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Calcium Phosphate ◽  
Comparative Study ◽  
Amorphous Phase ◽  
Phase Formation ◽  
Amorphous Calcium Carbonate ◽  
Formation Conditions ◽  
Amorphous Phase Formation

Precipitation domains of ACP and ACP increase with the complexity of the system, the ACP one being always larger.

Morphology and Polymorph Selectivity Control in Calcium Carbonate Mineralization

2004 ◽  
Vol 847 ◽  
Author(s):  
Swaminathan Sindhu ◽  
Parayil K. Ajikumar ◽  
Subbiah Jegadesan ◽  
Suresh Valiyaveettil
Keyword(s):  
Thin Film ◽  
Calcium Carbonate ◽  
Low Temperature ◽  
Aspartic Acid ◽  
Polyacrylic Acid ◽  
Room Temperature ◽  
Amorphous Calcium Carbonate ◽  
Precipitated Calcium Carbonate ◽  
Selectivity Control

ABSTRACTThe present paper describes the mineralization of calcium carbonate at a low temperature (4 °C) and in presence of additives. Aspartic acid immobilized polyacrylic acid (PA-Asp) induced the nucleation of spherical vaterite polymorph at 4 °C. But at room temperature, a thin film of calcite was deposited. Moreover, stable amorphous calcium carbonate was precipitated in presence of magnesium at low temperature. The observed results show that low temperature and presence of additives influence the nucleation, polymorph selectivity and morphology of the precipitated calcium carbonate.

scholarly journals Nano-Hydroxyapatite Derived from Biogenic and Bioinspired Calcium Carbonates: Synthesis and In Vitro Bioactivity

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 264
Author(s):  
Francesca Cestari ◽  
Francesca Agostinacchio ◽  
Anna Galotta ◽  
Giovanni Chemello ◽  
Antonella Motta ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Calcium Carbonate ◽  
Inductively Coupled Plasma ◽  
Calcium Phosphates ◽  
Optical Emission ◽  
Molar Ratio ◽  
In Vitro Tests ◽  
Amorphous Calcium Carbonate ◽  
Calcium Carbonates

Biogenic calcium carbonates naturally contain ions that can be beneficial for bone regeneration and therefore are attractive resources for the production of bioactive calcium phosphates. In the present work, cuttlefish bones, mussel shells, chicken eggshells and bioinspired amorphous calcium carbonate were used to synthesize hydroxyapatite nano-powders which were consolidated into cylindrical pellets by uniaxial pressing and sintering 800–1100 °C. Mineralogical, structural and chemical composition were studied by SEM, XRD, inductively coupled plasma/optical emission spectroscopy (ICP/OES). The results show that the phase composition of the sintered materials depends on the Ca/P molar ratio and on the specific CaCO3 source, very likely associated with the presence of some doping elements like Mg2+ in eggshell and Sr2+ in cuttlebone. Different CaCO3 sources also resulted in variable densification and sintering temperature. Preliminary in vitro tests were carried out (by the LDH assay) and they did not reveal any cytotoxic effects, while good cell adhesion and proliferation was observed at day 1, 3 and 5 after seeding through confocal microscopy. Among the different tested materials, those derived from eggshells and sintered at 900 °C promoted the best cell adhesion pattern, while those from cuttlebone and amorphous calcium carbonate showed round-shaped cells and poorer cell-to-cell interconnection.

Rapid coating of Ti6Al4V at room temperature with a calcium phosphate solution similar to 10× simulated body fluid

2004 ◽  
Vol 19 (9) ◽  
pp. 2742-2749 ◽  
Author(s):  
A. Cuneyt Tas ◽  
Sarit B. Bhaduri
Keyword(s):  
Calcium Phosphate ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Room Temperature ◽  
Molar Ratio ◽  
Carbonate Content ◽  
Phosphate Solution ◽  
Phosphate Ions ◽  
Homogeneous Formation ◽  
Robust Process

In this paper, we report the utilization of high ionic strength (>1100 mM) calcium phosphate solutions in depositing 20–65-μm-thick, bonelike apatitic calcium phosphate on Ti6Al4V within 2–6 h, at room temperature. The super-strength solution used here multiplied the concentrations of calcium and phosphate ions in human plasma or simulated body fluid (SBF) by a factor of ten. The interesting features of the technique are given in the following. First, the solutions did not contain any buffering agents, such as Tris or Hepes. Second, during the process, homogeneous formation of calcium phosphate nano-clusters took place. However, their presence did not adversely affect the coating process. Third, other than simple surface treatments to begin with, no other additional intermediate steps were necessary. The only step needed after the preparation of the solution from reagents is the addition of proper amounts of NaHCO3 to raise the pH to 6.5 prior to the coating procedure. Fourth, there is no CO2 bubbling required, and hence, this is a robust process. Fifth, such a procedure led to a significant enhancement of coating rate enabling the formation in as little as 2–6 h. Coating proceeded with a linear rate. Sixth, the adhesion strength (12 ± 2 MPa) of the present coatings was comparable to coatings produced by soaking in 1.5× SBF solutions over a prolonged period of time, typically two to three weeks. Finally, the carbonate content (8 wt%) and Ca/P molar ratio (1.57) qualify the coating as bonelike.

scholarly journals Incorporation of Incompatible Strontium and Barium Ions into Calcite (CaCO3) through Amorphous Calcium Carbonate

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 270 ◽  
Author(s):  
Ayaka Saito ◽  
Hiroyuki Kagi ◽  
Shiho Marugata ◽  
Kazuki Komatsu ◽  
Daisuke Enomoto ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Room Temperature ◽  
Barium Carbonate ◽  
X Ray Diffraction ◽  
Amorphous Calcium Carbonate ◽  
Static Disorder ◽  
Ionic Radii ◽  
Barium Ions ◽  
Alkaline Earth Elements ◽  
Xrd Patterns

Calcite is a ubiquitous mineral in nature. Heavy alkaline-earth elements with large ionic radii such as Sr2+ and Ba2+ are highly incompatible to calcite. Our previous study clarified that incompatible Sr2+ ions can be structurally incorporated into calcite through crystallization from amorphous calcium carbonate (ACC). In this study, we synthesized Sr-doped calcite with Sr/(Sr + Ca) up to 30.7 ± 0.6 mol% and Ba-doped calcite with Ba/(Ba + Ca) up to 68.6 ± 1.8 mol%. The obtained Ba-doped calcite samples with Ba concentration higher than Ca can be interpreted as Ca-containing barium carbonates with the calcite structure which have not existed so far because barium carbonate takes the aragonite structure. X-ray diffraction (XRD) patterns of the Sr-doped and Ba-doped calcite samples obtained at room temperature showed that reflection 113 gradually weakened with increasing Sr/(Sr + Ca) or Ba/(Ba + Ca) ratios. The reflection 113 disappeared at Ba/(Ba + Ca) higher than 26.8 ± 1.6 mol%. Extinction of reflection 113 was reported for pure calcite at temperatures higher than 1240 K, which was attributed to the rotational (dynamic) disorder of CO32− in calcite. Our Molecular Dynamics (MD) simulation on Ba-doped calcite clarified that the CO32− ions in Ba-doped calcites are in the static disorder at room temperature. The CO32− ions are notable tilted and displaced from the equilibrium position of pure calcite.

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