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Sol-Gel Synthesis and Characterization of Cerium Substituted Calcium Hydroxyapatite  [cached]
Bogdanoviciene I.,Kareiva A.,Misevicius M.,Bauermeistere L.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2012,
Abstract: In this study, an aqueous sol-gel chemistry route based on phosphoric acid as the phosphorus precursor, calcium acetate monohydrate and cerium (III) nitrate hexahydrate as source of calcium and cerium ions, re-spectively, have been used to prepare cerium-substituted calcium hydroxyapatite (CHAp) powders. The tartaric acid was used as complexing agent in the sol-gel processing. The final products were obtained by calcination of the dry precursor gels for 5 h at 1000 °C. The phase transformations, composition, and structural changes in the polycrystalline samples were studied by infrared spectroscopy (IR), X-ray powder diffraction analysis (XRD), scanning electron microscopy (SEM), UV-visible reflection spectroscopy and luminescence measurements. It was demonstrated, however, that the high substitution of calcium by cerium does not proceed in the CHAp. The reflectance spectra of Ce substituted CHAp show nearly 100% reflection in the wavelength range of 450-800 nm. The luminescent properties of these samples were also investigated.
Comparison of Hydrothermal and Sol-Gel Synthesis of Nano-Particulate Hydroxyapatite by Characterisation at the Bulk and Particle Level  [PDF]
Matthew Bilton, Steven J. Milne, Andrew P. Brown
Open Journal of Inorganic Non-metallic Materials (OJINM) , 2012, DOI: 10.4236/ojinm.2012.21001
Abstract: Hydrothermal and sol-gel synthesis methods have been used to prepare nano-particulate hydroxyapatite (HA) powders for detailed characterisation. Bulk elemental analysis data are compared from X-ray diffraction, X-ray fluorescence and Fourier transform infrared spectroscopy. These show the presence of secondary phases in the sol-gel powders which can be attributed to evaporative loss of precursor phosphite phases during specimen preparation and breakdown of the primary HA phase during calcination. Only the primary HA phase is detected in the hydrothermally prepared powder. In addition, Ca/P ratios of each powder are determined at the particle level using transmission electron microscopy with energy dispersive X-ray spectroscopy (TEM-EDX), having first established a threshold electron fluence below which significant electron-beam-induced alteration of the composition of HA does not occur. The TEM-EDX results show a greater compositional variability of particles from the sol-gel preparation route compared to the hydrothermal route. Overall it is the combination of the analysis techniques that shows the hydrothermal synthesis route produces near- stoichiometric, single phase, hydroxyapatite.
Comparative study of hydroxyapatite coatings obtained by Sol-Gel and electrophoresis on titanium sheets
Peón Avés, Eduardo;Sader, Marcia Soares;Jer?nimo, Fabíola de A. Rodrigues;Sena, Lídia ágata de;Galván Sierra, Juan C.;Soares, Gloria D. de Almeida;
Matéria (Rio de Janeiro) , 2007, DOI: 10.1590/S1517-70762007000100020
Abstract: a comparative study of two coating methods on titanium (ti) substrates, sol-gel and electrophoresis processes, was performed. before coating, two different surface treatments were employed. the hydroxyapatite (ha) powder were characterized by infrared spectroscopy (ftir) and x-ray diffraction (xrd) while coated samples were examined by using scanning electron microscopy (sem) with energy dispersive spectroscopy (eds). both techniques seem to be suitable to coat ti. a previous surface treatment on metallic titanium seems to be fundamental to enhance coat uniformity and adhesion that was estimated by the adhesive tape test. the decrease in calcination temperature did not affect the coating adhesion.
Synthesis and Structural Characterization of Hydroxyapatite-Wollastonite Biocomposites, Produced by an Alternative Sol-Gel Route  [PDF]
Martín A. Encinas-Romero, Jesús Peralta-Haley, Jesús L. Valenzuela-García, Felipe F. Castillón-Barraza
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2013, DOI: 10.4236/jbnb.2013.44041
Abstract:

Hydroxyapatite is a type of calcium phosphate-based material with great interest for biomedical applications, due to the chemical similarity between this material and the mineral part of human bone. However, synthetic hydroxyapatite is essentially brittle; the practice indicates that the use of hydroxyapatite without additives for implant production is not efficient, due to its low strength parameters. In the present work, biocomposites of hydroxyapatite-wollastonite were synthesized by an alternative sol-gel route, using calcium nitrate and ammonium phosphate as precursors of hydroxyapatite, and high purity natural wollastonite was added in ratios of 20, 50 and 80 percent by weight immersed in aqueous medium. Formation of hydroxyapatite occurs at a relatively low temperature of about 350?C, while the wollastonite remains unreacted. After that, these biocomposites were sintered at 1200?C for 5 h to produce dense materials. The characterization techniques demonstrated the presence of hydroxyapatite and wollastonite as unique phases in all products.

Tailoring the Microstructure of Sol–Gel Derived Hydroxyapatite/Zirconia Nanocrystalline Composites
Vasconcelos HC,Barreto MC
Nanoscale Research Letters , 2011,
Abstract: In this study, we tailor the microstructure of hydroxyapatite/zirconia nanocrystalline composites by optimizing processing parameters, namely, introducing an atmosphere of water vapor during sintering in order to control the thermal stability of hydroxyapatite, and a modified sol–gel process that yields to an excellent intergranular distribution of zirconia phase dispersed intergranularly within the hydroxyapatite matrix. In terms of mechanical behavior, SEM images of fissure deflection and the presence of monoclinic ZrO2 content on cracked surface indicate that both toughening mechanisms, stress-induced tetragonal to monoclinic phase transformation and deflection, are active for toughness enhancement.
Sol-Gel-Derived Hydroxyapatite-Carbon Nanotube/Titania Coatings on Titanium Substrates  [PDF]
Xiaoli Ji,Weiwei Lou,Qi Wang,Jianfeng Ma,Haihong Xu,Qing Bai,Chuantong Liu,Jinsong Liu
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13045242
Abstract: In this paper, hydroxyapatite-carbon nanotube/titania (HA-CNT/TiO 2) double layer coatings were successfully developed on titanium (Ti) substrates intended for biomedical applications. A TiO 2 coating was firstly developed by anodization to improve bonding between HA and Ti, and then the layer of HA and CNTs was coated on the surface by the sol-gel process to improve the biocompatibility and mechanical properties of Ti. The surfaces of double layer coatings were uniform and crack-free with a thickness of about 7 μm. The bonding strength of the HA-CNT/TiO 2 coating was higher than that of the pure HA and HA-CNT coatings. Additionally, in vitro cell experiments showed that CNTs promoted the adhesion of preosteoblasts on the HA-CNT/TiO 2 double layer coatings. These unique surfaces combined with the osteoconductive properties of HA exhibited the excellent mechanical properties of CNTs. Therefore, the developed HA-CNT/TiO 2 coatings on Ti substrates might be a promising material for bone replacement.
Stoichiometric hydroxyapatite obtained by precipitation and sol gel processes  [cached]
C. Guzmán Vázquez,C. Pi?a Barba,N. Munguía
Revista mexicana de física , 2005,
Abstract: Se describen tres métodos para obtener hidroxiapatita (HA). La HA es una cerámica muy interesante por sus múltiples aplicaciones médicas. Los primeros dos métodos de precipitación parten de compuestos de calcio y fósforo, mientras que el tercer método es un proceso sol-gel que usa alcóxidos. Los productos fueron caracterizados y comparados entre sí. Las diferencias observadas son importantes para aplicaciones prácticas.
Polyurethane/fluor-hydroxyapatite nanocomposite scaffolds for bone tissue engineering. Part I: morphological, physical, and mechanical characterization
Azadeh Asefnejad, Aliasghar Behnamghader, Mohammad Taghi Khorasani, et al
International Journal of Nanomedicine , 2011, DOI: http://dx.doi.org/10.2147/IJN.S13385
Abstract: lyurethane/fluor-hydroxyapatite nanocomposite scaffolds for bone tissue engineering. Part I: morphological, physical, and mechanical characterization Original Research (6091) Total Article Views Authors: Azadeh Asefnejad, Aliasghar Behnamghader, Mohammad Taghi Khorasani, et al Published Date January 2011 Volume 2011:6 Pages 93 - 100 DOI: http://dx.doi.org/10.2147/IJN.S13385 Azadeh Asefnejad1, Aliasghar Behnamghader2, Mohammad Taghi Khorasani3, Babak Farsadzadeh1 1Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; 2Materials and Energy Research Center, Tehran, Iran; 3Iran Polymer and Petrochemical Institute, Tehran, Iran Abstract: In this study, new nano-fluor-hydroxyapatite (nFHA)/polyurethane composite scaffolds were fabricated for potential use in bone tissue engineering. Polyester urethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and 1,4-butanediol as chain extender. Nano fluor-hydroxyapatite (nFHA) was successfully synthesized by sol-gel method. The solid–liquid phase separation and solvent sublimation methods were used for preparation of the porous composites. Mechanical properties, chemical structure, and morphological characteristics of the samples were investigated by compressive test, Fourier transform infrared, and scanning electron microscopy (SEM) techniques, respectively. The effect of nFHA powder content on porosity and pore morphology was investigated. SEM images demonstrated that the scaffolds were constituted of interconnected and homogeneously distributed pores. The pore size of the scaffolds was in the range 50–250 μm. The result obtained in this research revealed that the porosity and pore average size decreased and compressive modulus increased with nFHA percentage. Considering morphological, physical, and mechanical properties, the scaffold with a higher ratio of nFHA has suitable potential use in tissue regeneration.
Polyurethane/fluor-hydroxyapatite nanocomposite scaffolds for bone tissue engineering. Part I: morphological, physical, and mechanical characterization  [cached]
Azadeh Asefnejad,Aliasghar Behnamghader,Mohammad Taghi Khorasani,et al
International Journal of Nanomedicine , 2011,
Abstract: Azadeh Asefnejad1, Aliasghar Behnamghader2, Mohammad Taghi Khorasani3, Babak Farsadzadeh11Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; 2Materials and Energy Research Center, Tehran, Iran; 3Iran Polymer and Petrochemical Institute, Tehran, IranAbstract: In this study, new nano-fluor-hydroxyapatite (nFHA)/polyurethane composite scaffolds were fabricated for potential use in bone tissue engineering. Polyester urethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and 1,4-butanediol as chain extender. Nano fluor-hydroxyapatite (nFHA) was successfully synthesized by sol-gel method. The solid–liquid phase separation and solvent sublimation methods were used for preparation of the porous composites. Mechanical properties, chemical structure, and morphological characteristics of the samples were investigated by compressive test, Fourier transform infrared, and scanning electron microscopy (SEM) techniques, respectively. The effect of nFHA powder content on porosity and pore morphology was investigated. SEM images demonstrated that the scaffolds were constituted of interconnected and homogeneously distributed pores. The pore size of the scaffolds was in the range 50–250 μm. The result obtained in this research revealed that the porosity and pore average size decreased and compressive modulus increased with nFHA percentage. Considering morphological, physical, and mechanical properties, the scaffold with a higher ratio of nFHA has suitable potential use in tissue regeneration.Keywords: polyester urethane, composite, fluor-hydroxyapatite, scaffold
Characterization and comparison of PZT powder synthesis by solid state and sol gel methods  [cached]
E Pakizeh,GM Khorrami,M Ghasemifard,SM Hosseini
Iranian Journal of Physics Research , 2012,
Abstract: This paper describes the synthesis of Pb(Zr0.95Ti0.05)O3 powder by sol gel and solid state methods. PZT powders were fabricated by solid-state reaction process using metal oxides and in sol gel method salts and organic compounds were employed. The powders were calcined at 700 and 950 oC in sol gel and solid state methods, respectively. The synthesized powders were analyzed by FTIR and XRD. The average crystal grain size of PZT powders determined by X-ray diffraction method using the Scherrer equation, and in sol gel and solid state methods measured 42 and 330 nm, respectively. The optical constants of powders were evaluated and compaed using FTIR transmittance spectroscopy and Kramers-Kronig analysis.
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