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Journal ArticleDOI

Accurate characterization of pure silicon-substituted hydroxyapatite powders synthesized by a new precipitation route

TL;DR: The results, particularly those from infrared spectroscopy, raise serious reservations about the phase purity of previously prepared and biologically evaluated SiHA powders, pellets and scaffolds in the literature.
About: This article is published in Acta Biomaterialia.The article was published on 2013-06-01 and is currently open access. It has received 88 citations till now. The article focuses on the topics: Infrared spectroscopy & Fourier transform infrared spectroscopy.

Summary (1 min read)

1. Introduction

  • In order to correctly describe the physical, chemical and biological properties of SiHAs and to compare them to routinely implanted HA and β-TCP, well-characterized pure SiHAs powders first need to be prepared.
  • Therefore, this work was devoted to the development of a new route to synthesize monophasic SiHA powders with controlled stoichiometry.
  • To this purpose, a solution of soluble silicate was first prepared from TEOS via a sol-gel route, and then accurate powder analysis was carried out by means of ICP/AES, Xray powder diffraction, Rietveld refinement, high resolution electron transmission microscopy (HR-TEM) with energy dispersive spectroscopy (EDS) as well as infrared (FT-IR/ATR) and solid-state NMR spectroscopy.
  • Two pH levels of precipitation were studied, as well as six Si/P molar ratios.

2.1 Powder synthesis

  • The as-synthesized powders were heated under air using an alumina crucible.
  • The heating and cooling rate was fixed at 4°C min -1 .

2.2.1 X-ray powder diffraction and Rietveld refinement

  • Crystalline phases were identified by means of a Siemens D5000 θ/2θ X-ray diffractometer.
  • The evolution of the crystallinity of the samples after calcination at 1000°C for 15 h was evaluated by means of the full width at half maximum (FWHM) of the (211) peak at 2θ=31.8°, as it had the highest intensity and minimal overlap with neighboring peaks.

2.2.4 Electron microscopy (HR-TEM, SAED and EDX)

  • Gold was then distributed as crystallized nano-domains which were used as a reference in the selected area electron diffraction (SAED) patterns to calculate as precisely as possible the lattice parameters.
  • The SAED patterns obtained from regions with or without gold on the HA part were the same.

3.2.4 Electron microscopy

  • The results are the average of about ten intervals per pattern.
  • Moreover, other experimental patterns for different zone axes (not shown here) were obtained and compared to theoretical electron diffraction patterns calculated by means of the Java Electron Microscopy Simulation (JEMS) software [87] .
  • The results indicate that the experimental and simulated patterns are perfectly superimposed for 0.734 ≥ c/a ≥ 0.729.

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Citations
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Journal ArticleDOI
TL;DR: Tsangpoite and matyhite were identified from the D'Orbigny angrite meteorite by electron probe microanalysis, electron microscopy and micro-Raman spectroscopy as discussed by the authors.
Abstract: Tsangpoite, ideally Ca5(PO4)2(SiO4), the hexagonal polymorph of silicocarnotite, and matyhite, ideally Ca9(Ca0.5□0.5)Fe(PO4)7, the Fe-analogue of Ca-merrillite, were identified from the D'Orbigny angrite meteorite by electron probe microanalysis, electron microscopy and micro-Raman spectroscopy. On the basis of electron diffraction, the symmetry of tsangpoite was shown to be hexagonal, P63/m or P63, with a = 9.489(4) A, c = 6.991(6) A, V = 545.1(6) A3 and Z = 2 for 12 oxygen atoms per formula unit, and that of matyhite was shown to be trigonal, R3c, with a = 10.456 (7) A, c = 37.408(34) A, V = 3541.6 (4.8) A3 and Z = 6 for 28 oxygen atoms per formula unit. On the basis of their constant association with the grain-boundary assemblage: Fe sulfide + ulvospinel + Al–Ti-bearing hedenbergite + fayalite–kirschsteinite intergrowth, the formation of tsangpoite and matyhite, along with kuratite (the Fe-analogue of rhonite), can be readily rationalised as crystallisation from residue magmas at the final stage of the D'Orbigny meteorite formation. Alternatively, the close petrographic relations between tsangpoite/matyhite and the resorbed Fe sulfide rimmed by fayalite + kirschsteinite symplectite, such as the nucleation of tsangpoite in association with magnetite ± other phases within Fe sulfide and the common outward growth of needle-like tsangpoite or plate-like matyhite from the fayalite–kirschsteinite symplectic rim of Fe sulfide into hedenbergite, infer that these new minerals and the grain-boundary assemblage might represent metasomatic products resulting from reactions between an intruding metasomatic agent and the porous olivine–plagioclase plate + fayalite-kirschsteinite overgrowth + augite + Fe sulfide aggregates. Still further thermochemical and kinetics evidence is required to clarify the exact formation mechanisms/conditions of the euhedral tsangpoite, matyhite and kuratite at the grain boundary of the D'Orbigny angrite.

6 citations


Cites background from "Accurate characterization of pure s..."

  • ...Beyond the limit of y = 1–1.2, i.e. with ∼50% X site emptied, the hexagonal structure becomes unstable (e.g. Gomes et al., 2011; Marchat et al., 2013 and references cited therein)....

    [...]

  • ...In synthetic experiments of silicate-substituted hydroxylapatite at ∼1000–1200°C; i.e. Ca10(PO4)6–y(SiO4)y(OH)2–y, the maximum limit of Si substitution into the hexagonal apatite lattice was found to be y = 1–1.2 (Gomes et al., 2011; Marchat et al., 2013)....

    [...]

Journal ArticleDOI
TL;DR: Their biodegradability, good water dispersibility and drug-loading capacity, and sustained and pH-responsive drug release properties suggest that these synthetic Si-HAp nanoparticles have great potential applications as drug carriers.
Abstract: Silicon-containing hydroxyapatite (Si-HAp) nanoparticles with adjustable degradation rates were successfully synthesized via simple hydrothermal treatment of a precursor, calcium silicate hydrate powder, in trisodium phosphate aqueous solution. The degradation rate of the products could be facilely tailored by regulating the hydrothermal temperature, while the obtained Si-HAp nanoparticles exhibited high loading capacities toward doxorubicin (DOX) as well as sustained and pH-dependent drug release properties. HeLa cell culture results confirmed that the toxicity of DOX loaded in Si-HAp nanoparticles was more sustained than that of free DOX. Their biodegradability, good water dispersibility and drug-loading capacity, and sustained and pH-responsive drug release properties suggest that these synthetic Si-HAp nanoparticles have great potential applications as drug carriers.

5 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of molar ratios in the crystallochemical structure of biomimetic hydroxyapatite (BMHAP) on physicochemical characteristics of the product are presented.
Abstract: The results of the study of effects of molar ratios in the crystallochemical structure of biomimetic hydroxyapatite (BMHAP) on the physicochemical characteristics of the product are presented. With an increase in molar ratio in the range 1.50–1.67, there is an increase in the unit cell parameters a and c, while the average crystallite size increases from 7.52 to 70.30 nm. Particles of all samples in aqueous suspensions (pH 7) are negatively charged. The trend of the zeta potential of the synthesized powders in the range of investigated molar ratios is elucidated. The bioactivity of the samples is evaluated. All BMHAP samples have a higher bioresorbability as compared to unmodified stoichiometric hydroxyapatite, correlating well with the molar ratio in the structure of the products

5 citations

Journal ArticleDOI
TL;DR: In this paper, the sol-gel method was used to add MgO and SrBr2 to biografts containing Ca(NO3)2·4H2O, SiO2, P2O5, H3BO3 and AgNO3.
Abstract: In this study, the sol–gel method was used to add MgO and SrBr2 to biografts containing Ca(NO3)2·4H2O, SiO2, P2O5, H3BO3 and AgNO3. In addition, urea (15–35% by weight) was added to these biografts...

3 citations

References
More filters
Book
18 Jun 2004
TL;DR: This new edition of this highly successful manual is not only a revised text but has been extended to meet the interpretive needs of Raman users as well as those working in the IR region, creating a uniquely practical, comprehensive and detailed source for spectral interpretation.
Abstract: The third edition of this highly successful manual is not only a revised text but has been extended to meet the interpretive needs of Raman users as well as those working in the IR region. The result is a uniquely practical, comprehensive and detailed source for spectral interpretation. Combining in one volume, the correlation charts and tables for spectral interpretation for these two complementary techniques, this book will be of great benefit to those using or considering either technique.In addition to the new Raman coverage the new edition offers:* new section on macromolecules including synthetic polymers and biomolecules;* expansion of the section on NIR (near infrared region) to reflect recent growth in this area;* extended chapter on inorganic compounds including minerals and glasses;* redrawn and updated charts plus a number of new charts covering data new to this edition.This new edition will be invaluable in every industrial, university, government and hospital laboratory where infrared (FT-IR) and Raman spectral data need to be analysed.

6,428 citations

Book
01 Jan 1994
TL;DR: In this paper, the authors describe the structure of carbonate apatites and the properties of apatite powders, including their properties in terms of their nucleation and crystal growth.
Abstract: 1. General Chemistry of the Calcium Orthophosphates. Introduction. Monocalcium phosphates (monohydrate and anhydrous). Octacalcium phosphate. Dicalcium phosphate dehydrate, brushite. Dicalcium phosphate anhydrous, monetite. Anhydrous tricalcium phosphates and whitlockite. Tetracalcium phosphate. Amorphous calcium phosphates. 2. Fluorapatite and chlorapatite. Introduction. Structures. Substitutions in apatites. Preparation of powders. Growth of single crystals. Infrared and Raman spectra. Other physical and chemical studies. 3. Hydroxapatite and Nonstoichiometric Apatites. Introduction. Structure of hydroxyapatite. Preparation of stoichiometric hydroxyapatite powders. Preparation of other apatites with hydroxyl ions. Growth of hydroxyapatite single crystals. Special analytical methods. Structure of calcium-deficient hydroxyapatites. Kinetics of nucleation and crystal growth. Solubility and interfacial phenomena. Reactions in solution. Infrared and Raman spectroscopy. NMR spectroscopy. Other physical and chemical studies. 4. Mineral, synthetic and biological carbonate apatites. Introduction. Francolite and dahllite. A-type carbonate apatite, Caio(PO4)6CO3. Synthetic high temperature B-type carbonate apatites. Carbonate apatites from aqueous systems. Biological apatites. Electron spin resonance of X-irradiated carbonate apatites. Summary. Appendix. Calculated X-ray diffraction patterns of the calcium orthophosphates. References. Index.

2,352 citations


"Accurate characterization of pure s..." refers background or methods in this paper

  • ...0 powders mainly present bands characteristic of 432 hydroxyapatite with the ν1 (962 cm ), ν2 (473 cm ), ν3 (1021 and 1085 cm ) and ν4 (562 and 433 600 cm) modes of PO4 , as well as the stretching ( νS: 3572 cm ) and librational ( νL: 629 cm 434 (1)) modes of hydroxide groups [81, 92, 94]....

    [...]

  • ...and ν4), and the stretching ( νS) and librational ( νL) modes of the hydroxide groups [81, 92-94]....

    [...]

  • ...The former was chosen 182 according to phosphate and silicate speciation curv es, in order to have HPO 4 2- [81] and 183 H3SiO4 - ions [82] in solution as the main phosphate and si licate species, respectively....

    [...]

Journal ArticleDOI
16 Jan 1970-Science
TL;DR: Silicon, a relatively unknown trace element in nutritional research, has been uniquely localized in active calcification sites in young bone and is suggested to be associated with calcium in an early stage of calcification.
Abstract: Silicon, a relatively unknown trace element in nutritional research, has been uniquely localized in active calcification sites in young bone. Silicon increases directly with calcium at relatively low calcium concentrations and falls below the detection limit at compositions approaching hydroxyapatite. It is suggested that silicon is associated with calcium in an early stage of calcification.

867 citations


"Accurate characterization of pure s..." refers background in this paper

  • ...Two other SAED patterns were 324 obtained for the [1-10] zone axis....

    [...]

  • ...established that silicon plays an important role in the early stage of cartilage and bone growth 52 [1-4]....

    [...]

Journal ArticleDOI
01 Feb 2003-Bone
TL;DR: In conclusion, orthosilicic acid at physiological concentrations stimulates collagen type 1 synthesis in human osteoblast-like cells and enhances osteoblastic differentiation.

773 citations


"Accurate characterization of pure s..." refers background in this paper

  • ...Two other SAED patterns were 324 obtained for the [1-10] zone axis....

    [...]

  • ...collagen by human osteoblast cells (MG-63 cell line ) vitro [7]....

    [...]

Journal ArticleDOI
TL;DR: The subject of hydrogen bonding plays a significant role in determining the structure of crystals and hence the subject is of much interest to physicists, chemists and molecular biologists as discussed by the authors, and as there is now considerable agreement in recognizing hydrogen bonding experimentally, it is also timely.
Abstract: W. C. Hamilton and J. A. Ibers New York: W. A. Benjamin Inc. 1968 Pp. xv+ 284. Price $13.95. Hydrogen bonding plays a significant role in determining the structure of crystals and hence the subject is of much interest to physicists, chemists and molecular biologists. This book should serve their needs for a concise text admirably, and as there is now considerable agreement in recognizing the occurrence of hydrogen bonding experimentally, it is also timely.

752 citations

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