Surface Induced Calcium Phosphate Nucleation and Growth

AbstractCalcium phosphate nucleation on colloidal oxide surfaces, such as TiO2, SiO2 and Al2MO3, has been studied as a model system to understand the role of surface chemistry on crystal nucleation kinetics and phase formation. The nucleation induction times have been measured using Constant Composition (CC) technique and calcium phosphate phases formation have been determined mainly by X-ray diffraction. The results indicated TiO2 not only significantly reduces the nucleation induction time and interfacial energy but also stimulates octacalcium phosphate formation over dicalcium phosphate dihydrate. SiO2 and Al2O3 have little effect on both nucleation kinetics and phase formation.

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Effects of citrate and NaCl on size, morphology, crystallinity and microstructure of calcium phosphates obtained from aqueous solutions at acidic or near-neutral pH

Journal of Dairy Research ◽

10.1017/s0022029912000076 ◽

2012 ◽

Vol 79 (2) ◽

pp. 238-248 ◽

Cited By ~ 5

Author(s):

Omar Mekmene ◽

Thierry Rouillon ◽

Sophie Quillard ◽

Paul Pilet ◽

Jean-Michel Bouler ◽

...

Keyword(s):

Calcium Phosphate ◽

Calcium Phosphates ◽

Octacalcium Phosphate ◽

Inhibitory Effect ◽

Particle Sizes ◽

X Ray Diffraction ◽

Phosphate Dihydrate ◽

Constant Ph ◽

Starting Solutions ◽

Calcium Phosphate Precipitation

Precipitation of calcium phosphates occurs in dairy products and depending on pH and ionic environment, several salts with different crystallinity can form. The present study aimed to investigate the effects of NaCl and citrate on the characteristics of precipitates obtained from model solutions of calcium phosphate at pH 6·70 maintained constant or left to drift. The ion speciation calculations showed that all the starting solutions were supersaturated with respect to dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and hydroxyapatite (HAP) in the order HAP>OCP>DCPD. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses of the precipitates showed that DCPD was formed at drifting pH (acidic final pH) whereas poor crystallised calcium deficient apatite was mainly formed at constant pH (6·70). Laser light scattering measurements and electron microscopy observations showed that citrate had a pronounced inhibitory effect on the crystallisation of calcium phosphates both at drifting and constant pH. This resulted in the decrease of the particle sizes and the modification of the morphology and the microstructure of the precipitates. The inhibitory effect of citrate mainly acted by the adsorption of the citrate molecules onto the surfaces of newly formed nuclei of calcium phosphate, thereby changing the morphology of the growing particles. These findings are relevant for the understanding of calcium phosphate precipitation from dairy byproducts that contain large amounts of NaCl and citrate.

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Microwave-Assisted Fabrication of Mesoporous Silica-Calcium Phosphate Composites for Dental Application

Polymers ◽

10.3390/polym13010053 ◽

2020 ◽

Vol 13 (1) ◽

pp. 53

Author(s):

Adrian Szewczyk ◽

Adrianna Skwira ◽

Marta Ginter ◽

Donata Tajer ◽

Magdalena Prokopowicz

Keyword(s):

Calcium Phosphate ◽

Mesoporous Silica ◽

Octacalcium Phosphate ◽

Precipitation Method ◽

X Ray Diffraction ◽

Coating Solution ◽

X Ray ◽

Microwave Assisted ◽

Calcium Orthophosphates ◽

Different Types

Herein, the microwave-assisted wet precipitation method was used to obtain materials consisting of mesoporous silica (SBA-15) and calcium orthophosphates (CaP). Composites were prepared through immersion of mesoporous silica in different calcification coating solutions and then exposed to microwave radiation. The composites were characterized in terms of molecular structure, crystallinity, morphology, chemical composition, and mineralization potential by Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX). The application of microwave irradiation resulted in the formation of different types of calcium orthophosphates such as calcium deficient hydroxyapatite (CDHA), octacalcium phosphate (OCP), and amorphous calcium phosphate (ACP) on the SBA-15 surface, depending on the type of coating solution. The composites for which the progressive formation of hydroxyapatite during incubation in simulated body fluid was observed were further used in the production of final pharmaceutical forms: membranes, granules, and pellets. All of the obtained pharmaceutical forms preserved mineralization properties.

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Unveiling the self-association and desolvation in crystal nucleation

IUCrJ ◽

10.1107/s2052252521003882 ◽

2021 ◽

Vol 8 (3) ◽

pp. 468-479

Author(s):

Danning Li ◽

Yongli Wang ◽

Shuyi Zong ◽

Na Wang ◽

Xin Li ◽

...

Keyword(s):

Density Functional ◽

Interaction Strength ◽

Solution Chemistry ◽

The Self ◽

Crystal Nucleation ◽

Nucleation Kinetics ◽

Molecular Conformations ◽

Self Association ◽

Induction Times ◽

The Relationship

As the first step in the crystallization process, nucleation has been studied by many researchers. In this work, phenacetin (PHEN) was selected as a model compound to investigate the relationship between the solvent and nucleation kinetics. Induction times at different supersaturation in six solvents were measured. FTIR and NMR spectroscopy were employed to explore the solvent–solute interactions and the self-association properties in solution. Density functional theory (DFT) was adopted to evaluate the strength of solute–solvent interactions and the molecular conformations in different solvents. Based on these spectroscopy data, molecular simulation and nucleation kinetic results, a comprehensive understanding of the relationship between molecular structure, crystal structure, solution chemistry and nucleation dynamics is discussed. Both the solute–solvent interaction strength and the supramolecular structure formed by the self-association of solute molecules affect the nucleation rate. The findings reported here shed new light on the molecular mechanism of nucleation in solution.

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Role of Aspartic and Polyaspartic Acid on the Synthesis and Hydrolysis of Brushite.

Journal of Functional Biomaterials ◽

10.3390/jfb10010011 ◽

2019 ◽

Vol 10 (1) ◽

pp. 11 ◽

Cited By ~ 5

Author(s):

Katia Rubini ◽

Elisa Boanini ◽

Adriana Bigi

Keyword(s):

Aspartic Acid ◽

Octacalcium Phosphate ◽

Physiological Solution ◽

Cooperative Action ◽

Phosphate Dihydrate ◽

Mineral Phases ◽

Carboxylate Groups ◽

Hydrolysis Of ◽

Thermal Stability Of

Dicalcium phosphate dihydrate (DCPD) is one of the mineral phases indicated as possible precursors of biological apatites and it is widely employed in the preparation of calcium phosphate bone cements. Herein, we investigated the possibility to functionalize DCPD with aspartic acid (ASP) and poly-aspartic acid (PASP), as models of the acidic macromolecules of biomineralized tissues, and studied their influence on DCPD hydrolysis. To this aim, the synthesis of DCPD was performed in aqueous solution in the presence of increasing concentrations of PASP and ASP, whereas the hydrolysis reaction was carried out in physiological solution up to three days. The results indicate that it is possible to prepare DCPD functionalized with PASP up to a polyelectrolyte content of about 2.3 wt%. The increase of PASP content induces crystal aggregation, reduction of the yield of the reaction and of the thermal stability of the synthesized DCPD. Moreover, DCPD samples functionalized with PASP display a slower hydrolysis than pure DCPD. On the other hand, in the explored range of concentrations (up to 10 mM) ASP is not incorporated into DCPD and does not influence its crystallization nor its hydrolysis. At variance, when present in the hydrolysis solution, ASP, and even more PASP, delays the conversion into the more stable phases, octacalcium phosphate and/or hydroxyapatite. The greater influence of PASP on the synthesis and hydrolysis of DCPD can be ascribed to the cooperative action of the carboxylate groups and to its good fit with DCPD structure.

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Nucleation and Glass Formation

MRS Proceedings ◽

10.1557/proc-57-99 ◽

1985 ◽

Vol 57 ◽

Cited By ~ 1

Author(s):

D. R. Uhlmann ◽

M. C. Weinberg

Keyword(s):

Glass Formation ◽

Nucleation Theory ◽

Crystal Nucleation ◽

Oxide Glass ◽

Classical Nucleation Theory ◽

Nucleation Kinetics ◽

Formation Behavior ◽

Homogeneous Crystal ◽

Exponential Factors

AbstractThe role of nucleation kinetics in affecting glass formation behavior is discussed. Also considered are measurements of homogeneous crystal nucleation in a variety of liquids. For a number of oxide glass-forming liquids, available data indicate pre-exponential factors which are larger than those predicted from classical nucleation theory by factors of 1017 to 1049. Possible sources of this discrepancy are discussed.

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Role of dynamic heterogeneities in crystal nucleation kinetics in an oxide supercooled liquid

The Journal of Chemical Physics ◽

10.1063/1.4964674 ◽

2016 ◽

Vol 145 (21) ◽

pp. 211920 ◽

Cited By ~ 20

Author(s):

Prabhat K. Gupta ◽

Daniel R. Cassar ◽

Edgar D. Zanotto

Keyword(s):

Supercooled Liquid ◽

Crystal Nucleation ◽

Nucleation Kinetics

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Reactive phase formation in sputter-deposited Ni/Al multilayer thin films

Journal of Materials Research ◽

10.1557/jmr.1997.0021 ◽

1997 ◽

Vol 12 (1) ◽

pp. 133-146 ◽

Cited By ~ 93

Author(s):

K. Barmak ◽

C. Michaelsen ◽

G. Lucadamo

Keyword(s):

Phase Formation ◽

Molar Ratio ◽

X Ray Diffraction ◽

Nucleation Kinetics ◽

Scanning Calorimetry ◽

Calorimetric Analysis ◽

Transmission Electron ◽

Nial Phase ◽

Magnetron Sputter ◽

Sputter Deposited

We have investigated reactive phase formation in magnetron sputter-deposited NiyAl multilayer films with a 1 : 3 molar ratio and various periodicities, L, ranging from 320 nm down to a codeposited film with zero effective periodicity. The films were studied by x-ray diffraction, differential scanning calorimetry, electrical resistance measurements, and transmission electron microscopy. We find that Ni and Al have reacted during deposition to form the B2 NiAl phase and an amorphous phase. The formation of these phases substantially reduces the driving force for subsequent reactions and explains why nucleation kinetics become important for these reactions. Depending on the periodicity, these reactions result in the formation of NiAl3 or Ni2Al9 followed by NiAl3. Detailed calorimetric analysis reveals differences in the nucleation and growth behavior of NiAl3 compared with other studies.

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Effect of Ceria Additive on Microstructure and Properties of Laser-Cladded Bioceramic Coating

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.434-435.586 ◽

2010 ◽

Vol 434-435 ◽

pp. 586-589

Author(s):

Min Zheng ◽

Ding Fan ◽

Jian Bin Zhang ◽

Xiu Kun Li

Keyword(s):

Corrosion Resistance ◽

Rare Earth ◽

Calcium Phosphate ◽

Rare Earth Oxide ◽

Resistance Testing ◽

X Ray Diffraction ◽

Microstructure And Properties ◽

Transverse Flow Co2 Laser ◽

Precursor Powders

The calcium phosphate bioceramic coating was fabricated on titanium alloy (Ti-6Al-4V) substrate by a 5kW continuous transverse flow CO2 laser. Due to the peculiar role of rare earth oxide in laser cladding, the effect of ceria additive on the microstructure and properties of laser-cladded bioceramic coating was investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), microhardness and corrosion resistance testing. The results indicate that the appearance of rare earth oxide ceria in the precursor powders has an impact on the microstructure and properties of the laser-cladded bioceramic coating. Calcium phosphate bioceramic such as hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) are synthesized on the top surface of laser-cladded specimens. And the addition of rare earth oxide ceria in pre-placed powders has an influence on the formation of calcium phosphate bioceramic phases. Furthermore, it reveals that the laser-cladded bioceramic coating of ceria additive in pre-placed powders has more favorable microhardness and corrosion resistance compared with the coating without rare earth oxide.

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Effect of pH Values on Conversion of Calcite Crystals into Calcium Phosphate Phases in Buffer Solutions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.2183 ◽

2007 ◽

Vol 353-358 ◽

pp. 2183-2186 ◽

Cited By ~ 2

Author(s):

Ya Ping Guo ◽

Bao Qiang Li ◽

Yu Zhou ◽

De Chang Jia

Keyword(s):

Calcium Phosphate ◽

Ph Value ◽

Octacalcium Phosphate ◽

Precipitation Reaction ◽

X Ray Diffraction ◽

Buffer Solution ◽

Effect Of Ph ◽

X Ray ◽

Buffer Solutions ◽

Ph Values

Calcium phosphate phases with laminar-plate structure were converted from calcite powders after soaking in phosphate buffer solutions of pH’s 6.0-8.0 at 37 °C for 9 days. The effect of pH values on the conversion of calcite crystals was investigated by X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy. If the pH value of a buffer solution is kept at 6.0, calcite powders are converted mainly to dicalcium phosphate dehydrate (DCPD) or octacalcium phosphate (OCP). If the pH value is kept at 6.4 or 7.0, calcite powders are converted mainly to OCP. Hydroxyapatite (HAP) with poorly crystalline can be obtained from calcite powders both by treatment of a basic buffer solution, and by treatment of an acid buffer solution without regulating its pH value during the reaction. The conversion mechanism of calcite crystals is a dissolution-precipitation reaction.

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