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1
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Sonochemical Synthesis of Hydroxyapatite Nanoparticles with Different Precursor Reagents

100%
Hazar Yoruç A., İpek Y.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
230-232
EN
Different precursor chemicals (3Ca(OH)_2, Ca(NO_3)_2 and CaO as Ca^{2+} sources, H_3PO_4 and (NH_4)_2HPO_4 as PO_4^{3-} sources were used to synthesis of nanosized hydroxyapatite powder with ultrasonic precipitation method. The effect of different chemical precursors was investigated. Sample characterization was achieved by powder X-ray diffraction, the Fourier transformed infrared transmission spectroscopy, zeta sizer, scanning electron microscopy, density and surface area measurements.
2
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Effect of Precipitation Method on Properties of Hydroxyapatite Powders

81%
Hazar Yoruç A., Karakaş A., Ayas E., Koyun A.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
371-373
EN
The aim of this study was the compare the properties of hydroxyapatite as a function of two different methods (chemical and biomimetic precipitation). Powder products were called as chemical hydroxyapatite for chemical method and biomimetic hydroxyapatite for biomimetic method. Precipitated powders with both methods were characterized by Fourier transform infrared, X-ray diffraction, X-ray fluorescence and measurements of hardness and density. Chemical analysis results showed that dried-biomimetic hydroxyapatite sample consists of hydroxyapatite [Ca_{10}PO_4)_6(OH)_2] as main phase and beta-tricalcium phosphate (β-TCP) as secondary phase and dried-chemical hydroxyapatite sample also includes pure hydroxyapatite phase. Chemical hydroxyapatite and biomimetic hydroxyapatite powders were sintered using by spark plasma sintering method. Vickers hardness values of sintered disk samples were measured. Furthermore chemical structure of the final products was analyzed. Also density values of chemical hydroxyapatite and biomimetic hydroxyapatite disks were measured. Finally it is concluded that different precipitation methods affect hydroxyapatite properties and this can be an advantage for biomedical applications.
3
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Comparison of Properties of Hydroxyapatite Powders Synthesized by Chemical and Biomimetic Techniques

81%
Hazar Yoruç A., Karakaş A., Koyun A., Yildiz T.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
233-235
EN
Hydroxyapatite [HA; Ca_{10}(PO_4)_6(OH)_2] which composes inorganic phase of bones and teeth is one of the biomedical materials for artificial bone, reconstruction of broken or disordered bones, coating of metallic biomedical materials and dental surgery with its great biocompatibility. In this study, HA powders were synthesized from aqueous suspensions containing H_3PO_4 and Ca(OH)_2 with 1.67 Ca/P ratios (chemical HA, CHA) and second process is carried out in simulated body fluids consisting of (NH_4)_2HPO_4 and Ca(NO_3)_2 ·4H_2O as biomimetic hydroxyapatite (BHA). Moreover, properties of bovine HA (BoHA) and commercial HA (CoHA) were compared with properties of synthesized HA powders. Chemical structures of synthesized powders have been examined by the Fourier transform infrared technique and X-ray diffraction. The results showed that BHA powders have a pure HA content and no secondary phase, CHA also has monetite phase as secondary phase with HA in its structure. Particle size analysis was carried out with laser particle sizer and zeta-sizer, surface area of powders has been analyzed by the Brunauer-Emmett-Teller technique. Powder morphology is determined using scanning electron microscopy. As a result two different synthesis methods affected properties of HA powders.
4
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Effect of Different Calcium Precursors on Biomimetic Hydroxyapatite Powder Properties

81%
Karakaş A., Hazar Yoruç A., Ceylan Erdoğan D., Doğan M.
Acta Physica Polonica A
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2012
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vol. 121
|
issue 1
236-239
EN
Hydroxyapatite is the main component of human hard tissues such as bones and teeth. Because it has a great biocompatibility with human organism, it is used as biomaterial with the purpose of form and repair hard tissues. Hydroxyapatite is formulated as Ca_{10}(PO_4)_6(OH)_2 and shows high stability under physiological conditions. In this study, biomimetic hydroxyapatite powder has been synthesized using by synthetic body fluids which has the same composition as human blood plasma. Moreover, the effect of different precursors on properties of synthesized powders has been investigated. For that purpose calcium nitrate tetrahydrate [Ca(NO_3)_2 ·4H_2O], calcium chloride [CaCl_2], calcium hydroxide [Ca(OH)_2] and diammonium hydrogen phosphate [(NH_4)_2HPO_4] were used as precursors. Mainly literature focused on the synthesis of hydroxyapatite powders was carried out using chemical method. However, in this study, the synthesis of hydroxyapatite powder is carried out using biomimetic method. Chemical structures of synthesized powders have been investigated by the Fourier transform infrared and X-ray diffraction methods. Results showed that synthesized powders have a pure hydroxyapatite structure. Surface area of the synthesized powders was measured by the Brunauer-Emmett-Teller method. Morphological structures have been characterized by using scanning electron microscopy. Furthermore, particle size of powders was calculated using the Brunauer-Emmett-Teller method. It was clearly seen that morphological properties of biomimetic hydroxyapatite have affected the use of different calcium precursors.
5
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Effect of Different Phosphorus Precursors on Biomimetic Hydroxyapatite Powder Properties

71%
Karakaş A., Hazar Yoruç A., Gökçe H., Karabulut A., Ceylan Erdoğan D.
Acta Physica Polonica A
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2013
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vol. 123
|
issue 2
418-420
EN
Hydroxyapatite is the main component of natural hard tissues, such as teeth and bone. It has been studied extensively as a candidate biomaterial for its use in prosthetic applications. Hydroxyapatite was formulated as Ca_{10}(PO_4)_6(OH)_2 and it has a high stability under physiological conditions. Also hydroxyapatite can be synthesized using different calcium and phosphorus precursors. In this study, biomimetic hydroxyapatite powder has been synthesized simulating physiological conditions. Synthetic body fluids which have the same composition as human blood plasma instead of pure water were used as precipitation media to obtain biological conditions. Recent research involved the effect of different Ca-precursors however aim of this study is to determine the effect of phosphorus resources. In this study, the synthesis of hydroxyapatite powder is carried out by using biomimetic method in synthetic body fluids. Calcium acetate [Ca(CH_3COO)_2, CA] and diammonium hydrogen phosphate [(NH_4)_2HPO_4, DAHP], ammonium dihydrogen phosphate [NH_4H_2PO_4, ADHP], dipotassium hydrogen phosphate [K_2HPO_4, DPHP] and orthophosphoric acid [H_3PO_4, OPA] were used as Ca- and P-precursors. Chemical structures of synthesized powders have been examined by Fourier transform infrared and X-ray diffraction. Results showed that synthesized powders have a pure hydroxyapatite structure. However, ADHP precursors have an unfavorable effect on sintered hydroxyapatite powders. Using ADHP phase transition was caused in pure hydroxyapatite structure and apatite and whitlockite were observed as secondary phases. Their particle size, surface area determination and morphological structures have been characterized by Zeta-Sizer, biomimetic hydroxyapatite the Brunauer-Emmett-Teller analysis and scanning electron microscopy images, respectively. As a result different starting materials have affected the structure, particle size and morphological properties of biomimetic hydroxyapatite.
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