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Kaygili O.,Firat University | Keser S.,Firat University | Dorozhkin S.V.,Kudrinskaja Square 1 155 | Yakuphanoglu F.,Firat University | And 5 more authors.
Journal of Inorganic and Organometallic Polymers and Materials | Year: 2014

Ag- and Ba-doped hydroxyapatite (HAp) samples were synthesized by sol–gel method. The crystallite sizes for all the samples were found to vary from 26 to 39 nm. Neither Ag nor Ba did result in dramatic changes in the morphology of all the samples, and the Ca/P molar ratio was varied. The dielectric parameters of the samples were changed with the dopant content. The maximum and minimum values of the dielectric constant were observed for 2.0 %Ba-HAp and 0.5 %Ba-HAp samples. The alternating current conductivity indicates that all the samples exhibit the insulator behavior. The results of the biological tests revealed that Ag-containing samples have an antimicrobial activity, while no antimicrobial activity was detected for both HAp and Ba-doped HAp samples. © 2014, Springer Science+Business Media New York. Source


Kaygili O.,Firat University | Dorozhkin S.V.,Kudrinskaja Square 1 155 | Keser S.,Firat University | Yakuphanoglu F.,Firat University
Medziagotyra | Year: 2015

Pure hydroxyapatite and cobalt-containing calcium orthophosphate ceramics were synthesized by the sol-gel method and their properties were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, dielectric impedance spectroscopy and scanning electron microscopy techniques. The average crystallite size of the samples was found to be 30 nm– 56 nm. The crystallinity decreased gradually with the addition of Co. The resistance values were found to be ~1012 Ω. Dielectric permittivity and alternating current conductivity of all the samples showed substantial changes in the presence of cobalt. The morphology and particle size distribution of all the samples were changed with increasing amount of Co. In addition, the high content of Co ions was found to both destroy the apatitic structure of the hydroxyapatite and cause the calcium deficiency. The results indicated that, in presence of high amounts of Co, Ca9.5Co(PO4)7 ceramics could be prepared. © 2015, Kauno Technologijos Universitetas. All rights reserved. Source


Swain S.K.,National Institute of Technology Rourkela | Dorozhkin S.V.,Kudrinskaja Square 1 155 | Sarkar D.,National Institute of Technology Rourkela
Materials Science and Engineering C | Year: 2012

Spherical, rod and fibroid hydroxyapatite [HAp, Ca 10(PO 4) 6(OH) 2] nanoparticles were prepared and dispersed in aqueous media. Temperature and solution pH were the key factors to synthesis of different morphology and crystallinity. Processing conditions were selected from ternary diagram of pH, temperature and Ca:P ratio. High hydroxyl ion concentration (12.25 ≥ pH ≥ 10.5) and low temperature (298 K) favored isotropic non-confined spherical particles, intermediate concentration (9.5 ≥ pH ≥ 7.75) and low temperature (303 K) initiated the anisotropic growth of rod shaped particles but low concentration (7 ≥ pH ≥ 5.25) and high temperature (353 K) accelerated one-dimensional fibroid morphology. The dispersed HAp-citrate complex exhibited a constant zeta potential and size distribution for six months. © 2012 Elsevier B.V. All rights reserved. Source


Kaygili O.,Firat University | Dorozhkin S.V.,Kudrinskaja Square 1 155 | Ates T.,Firat University | Al-Ghamdi A.A.,King Abdulaziz University | And 2 more authors.
Ceramics International | Year: 2014

Iron-doped hydroxyapatite (HAp) samples with variable amounts of Fe were synthesized and their properties were investigated. Namely, the structure and composition of the prepared samples were analyzed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. In addition, the dielectric and alternating current conductivity properties were investigated at room temperature. The samples were found to consist of a high crystalline HAp with a minor admixture of β-tricalcium phosphate (β-TCP). With increasing amount of Fe, the crystallite sizes of the samples were found to gradually decrease from 32.54 nm to 27.91 nm with simultaneous changes in the crystallinity degree, lattice parameters, unit cell volume and the phase composition. The fine-grained microstructure was observed and EDX analysis confirmed Fe-substitution in the apatitic structure because the Ca/P molar ratios were gradually decreased from 1.68 to 1.35 by addition of Fe. The alternating current conductivity confirmed that Fe doped HAp samples exhibited the insulator behavior. The relative permittivity of the HAp was increased with the addition of Fe. The samples exhibited a non-Debye relaxation mechanism. © 2014 Elsevier Ltd and Techna Group S.r.l. Source


Dorozhkin S.V.,Kudrinskaja Square 1 155
Acta Biomaterialia | Year: 2012

Biphasic, triphasic and multiphasic (polyphasic) calcium orthophosphates have been sought as biomaterials for reconstruction of bone defects in maxillofacial, dental and orthopedic applications. In general, this concept is determined by advantageous balances of more stable (frequently hydroxyapatite) and more resorbable (typically tricalcium orthophosphates) phases of calcium orthophosphates, while the optimum ratios depend on the particular applications. Therefore, all currently known biphasic, triphasic and multiphasic formulations of calcium orthophosphate bioceramics are sparingly soluble in water and, thus, after being implanted they are gradually resorbed inside the body, releasing calcium and orthophosphate ions into the biological medium and, hence, seeding new bone formation. The available formulations have already demonstrated proven biocompatibility, osteoconductivity, safety and predictability in vitro, in vivo, as well as in clinical models. More recently, in vitro and in vivo studies have shown that some of them might possess osteoinductive properties. Hence, in the field of tissue engineering biphasic, triphasic and multiphasic calcium orthophosphates represent promising biomaterials to construct various scaffolds capable of carrying and/or modulating the behavior of cells. Furthermore, such scaffolds are also suitable for drug delivery applications. This review summarizes the available information on biphasic, triphasic and multiphasic calcium orthophosphates, including their biomedical applications. New formulations are also proposed. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source

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