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Öğe Analysing the impact of Dy dopants on Zn-based hydroxyapatites: modelling and characterization perspectives(Indian Acad Sciences, 2024) Buyuk, Oznur; Bulut, Niyazi; Temuz, M. mursit; Orek, Cahit; Ates, Tankut; Kaygili, Omer; Oezcan, ImrenThis study is aimed to investigate the effects of introducing dysprosium (Dy) into Zn-based hydroxyapatite (HAp) at various concentrations (0.45, 0.90, 1.35 and 1.80%). The structural and optical properties of pure and doped HAp were thoroughly examined through theoretical and empirical analyses, including X-ray diffraction, Raman spectroscopy and Fourier transform infrared (FTIR) studies. The results confirmed the successful incorporation of Dy into the HAp lattice without significantly affecting its thermal stability or stoichiometry. The introduction of Dy into Zn-based HAp led to notable alterations in several material parameters. The lattice parameters, crystallinity, lattice stress, strain and anisotropic energy density varied with different Dy concentrations. In comparison with undoped HAp, all Dy-doped Zn-based HAps exhibited reduced crystallite size values, indicating a change in the microstructure. Furthermore, the material density increased from 3.159 to 3.228 g cm-3 with Dy doping. The band gap (BG), an important parameter for optical applications, is consistently decreased from 4.6 to 3.9 eV as the Dy concentration increased. This decrease in BG suggests the potential for improved photocatalytic or optoelectronic properties in Dy-doped Zn-based HAp. Additionally, the linear absorption coefficient (LAC) increased, indicating enhanced light absorption. Overall, this study provides a comprehensive understanding of structural and optical modifications induced by Dy doping in Zn-based HAp. These findings contribute to the potential application of Dy-doped Zn-based HAp in various fields, including biomedicine, photocatalysis and optoelectronics.Öğe Ce/Sm co-doped hydroxyapatites: synthesis, characterization, and band structure calculation(Springer, 2021) Kaygili, Omer; Vural, Gulay; Keser, Serhat; Yahia, I. S.; Bulut, Niyazi; Ates, Tankut; Koytepe, SuleymanIn this paper, Ce/Sm co-doped hydroxyapatites (HAps) were synthesized by a wet chemical route. The amount of Ce was kept at constant at the value of at.% 0.4, and the second dopant of Sm was used at different amounts of at.% 0, 0.6, 1.2, and 1.8, respectively. The effects of these co-dopants on the crystal structure, morphology, and thermal properties of HAp were determined experimentally using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA), and thermogravimetric analysis (TGA). Furthermore, the band structure of the prepared samples was modeled theoretically using the quantum calculations of the density of states and band structure. A gradual increase from 26.56 to 36.23 nm in the crystallite size was observed. Although the amounts of the co-dopants of Ce and Sm did not affect the thermal stability and microstructure of HAp, its crystal structure-related parameters were affected by the amount of these co-additives. The partial substitution of both co-dopants was detected. The 0.4Ce-1.2Sm-HAp sample may be considered as the best crystal structure with a steady-state. It was seen that the band structure and density of states were also affected by these co-dopants. The bandgap value decreased gradually from 4.6078 to 4.0477 eV due to these dopants.Öğe Chemical composition, antimicrobial activities, and molecular docking studies of Turkish propolis ethanol extract(Czech Academy Agricultural Sciences, 2023) Ozbey, Gokben; Muz, Mustafa Necati; Tanriverdi, Elif Seren; Erkan, Sultan; Bulut, Niyazi; Otlu, Baris; Zigo, FrantisekThe purpose of the present study was to investigate the antimicrobial effect of propolis ethanol extract col-lected from the Tarsus district of Mersin province, Kilis province, Yayladagi district of Hatay province in southern Turkiye and Sarkoy district of Tekirdag province of northwestern Turkiye against Escherichia coli (ATCC 25922), Helicobacter pylori (ATCC 43504), Pseudomonas aeruginosa (ATCC 27853), and Staphylococcus aureus (ATCC 29213). Their chemical constituents were detected via liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). They were used in a molecular docking approach to search the interactions between the propolis compounds. A total of 24 phenolic compounds were detected in all samples. 3-4 dimethoxycinnamic acid, caffeic acid and genistein were indicated to be the predominant phenolic compounds in propolis extracts by LC-MS/MS, while rutin was found in the lowest concentra-tion. Phenolic compounds were detected in a high concentration of the propolis samples collected from the Tarsus dis-trict of Mersin province. The broth microdilution method determined minimum inhibition concentration (MIC) values. MIC values ranged from 0.02 to 14 mg center dot mL-1. E. coli and S. aureus examined were as susceptible to the propolis extracts ex-cept for Mersin and Tekirdag propolis samples. The propolis sample collected from the Tarsus district of Mersin province presented the highest antibacterial activity on P aeruginosa with MIC values of 1 mg center dot mL-1. Active substances in propolis were docked to the relevant target proteins (5LMM, 4NX9, 5YHG, and 5FXT) representing E. coli (ATCC 25922), H. py-lori (ATCC 43504), P aeruginosa (ATCC 27853), and S. aureus (ATCC 29213), and with the help of molecular simulation. With this study, we indicated that the ethanol extract of propolis had a stronger antibacterial activity on S. aureus isolates than that of E. coli, H. pylori, and P aeruginosa. Although each component of propolis contributed to the antibacterial activity, the contribution of the vitexin component to the antibacterial activity was found to be quite significant.Öğe Co Katkılı SnO2 Numunelerinin Sentez ve Karakterizasyonu(2020) Ateş, Tankut; Kaygılı, Ömer; Bulut, Niyazi; Okur, Havva Esma; Keser, Serhat; Yahıa, I.S.; Köytepe, SüleymanYüksek kristalleşmeye sahip katkısız ve Co katkılı SnO2 numuneleri başarılı bir biçimde hazırlandı. Coiçeriğinin SnO2’nin termal ve morfolojik özellikleri üzerine etkileri araştırıldı. Co ilavesiyle Kristalbüyüklüğünde ve birim hücre parametrelerinde değişimler tespit edildi. Co ilavesiyle faz bileşimi değişmedi.Hem X-ışını kırınımı hem de Fourier dönüşümlü kızılötesi sonuçları her bir numune için SnO2 fazınınoluşumunu doğruladı. Üretilen numunelerin oda sıcaklığından 900 °C’ye kadar termal kararlılığı gözlendi.Morfoloji Co içeriğinden etkilendi ve enerji dağılımlı X-ışını sonuçları SnO2 yapısı içerisine Co’ın nüfuz ettiğinidoğruladı.Öğe The effects of gamma irradiation on dielectric properties of Ag/Gd co-doped hydroxyapatites(Springer, 2019) Kaygili, Omer; Keser, Serhat; Selcuk, A. Birkan; Bulut, Niyazi; Koytepe, Suleyman; Yahia, I. S.; Ates, Tankut1.0 at% Ag-containing hydroxyapatites (HAps) doped with the different amounts of Gd (e.g., 0, 0.8, 1.6 and 2.4 at%) were synthesized by a wet chemical method and their dielectric properties were investigated before and after gamma irradiation. The changes in the relative permittivity and alternating current (AC) conductivity values of the as-synthesized samples before and after irradiation were investigated using dielectric measurements. It was found that both Gd content and gamma irradiation dose significantly affect the dielectric properties and AC conductivity. It was concluded that especially due to the thermal stabilities and suitable dielectric properties, the as-synthesized Gd-doped Ag containing HAps could be used for bone healing applications.Öğe The effects of Mn and/or Ni dopants on the in vitro/in vivo performance, structural and magnetic properties of ?-tricalcium phosphate bioceramics(Elsevier Sci Ltd, 2019) Ates, Tankut; Dorozhkin, Sergey, V; Kaygili, Omer; Kom, Mustafa; Ercan, Ismail; Bulut, Niyazi; Firdolas, FatihThe present study describes the effects of dopants of Mn and/or Ni on the structural, magnetic and in vivo/in vitro performances of beta-tricalcium phosphate (beta-TCP) bioceramics synthesized by a sol-gel method. Both types of dopants caused significant effects on the structure-related parameters of beta-TCP, including the crystallite dimensions and lattice parameters. The magnetic properties of as-prepared samples were found to be affected by the type and amount of the dopant(s). The in vitro antimicrobial activities of doped beta-TCPs against American Type Culture Collection (ATCC) reference bacterial and fungal strains were evaluated. Among them, only 1.35Ni-TCP displayed an effective antimicrobial activity against Gram-positive bacteria (50 mu g/mL Minimum Inhibitory Concentration (MIC) range), while other types of doped beta-TCPs did not possess with such effect. The in vivo tests showed that each formulation could be a good nominate for bone healing and bone treatment.Öğe The effects of Ni-addition on the crystal structure, thermal properties and morphology of Mg-based hydroxyapatites synthesized by a wet chemical method(Elsevier Sci Ltd, 2018) Ince, Turan; Kaygili, Omer; Tatar, Cengiz; Bulut, Niyazi; Koytepe, Suleyman; Ates, TankutFour Mg-based hydroxyapatites (HAps) doped with Ni at various amounts of 0, 0.6, 1.2 and 1.8 at% were prepared at the temperature of 870 degrees C by a wet chemical synthesis. The crystallite size, lattice parameters and crystallinity percent dramatically decreased with adding of Ni. The amount of HAp phase for all the Ni-containing samples is smaller than that of the Ni-free MgHAp. Furthermore, the lattice strain, stress and anisotropic energy density values were affected by the amount of Ni. The differential thermal analysis (DTA) measurements taken in the temperature range from 25 to 1000 degrees C showed that all the samples are thermally stable. No significant change in the morphology was observed. It was observed that the gradual introduction of Ni caused the Ca-deficiency.Öğe Effects of strontium - erbium co-doping on the structural properties of hydroxyapatite: An Experimental and theoretical study(Elsevier Sci Ltd, 2020) Mahmood, Bahroz Kareem; Kaygili, Omer; Bulut, Niyazi; Dorozhkin, Sergey, V; Ates, Tankut; Koytepe, Suleyman; Gurses, CanbolatFive different samples of Sr-based Er-doped hydroxyapatites (HAps) in the dissimilar quantities like 0, 0.35, 0.70, 1.05 and 1.40 at% were produced via a wet chemical process. The prepared samples were investigated experimentally by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis (DTA), and in vitro biocompatibility tests. In addition, the density of states (DOS) and band structures were investigated theoretically. It was found that the presence of Er as a dopant affected the lattice parameters, while the EDX measurements confirmed that the presence of Er at various concentrations caused a Ca-deficiency because the addition of Er decreased the Calcium/Phosphorus molar ratio from 1.67 to 1.61. For all samples, the single-phase distribution of HAp was observed. The crystallinity percentage of the samples was found to be 89% or more according to two different methods. The calculations with respect to Scherrer and Williamson-Hall methods showed that the crystallite sizes of the samples were found to be in the ranges of 29-34 nm and 25-42 nm, respectively. DTA investigations revealed that all samples exhibited thermal stability in the temperature range of 25 degrees C - 1000 degrees C. No remarkable morphological alterations were observed. Furthermore, the theoretical studies confirmed that the band structures narrowed with an increase in Er concentration.Öğe The effects of urea content on the structural, thermal and morphological properties of MgO nanopowders(Elsevier Sci Ltd, 2018) Ercan, Ismail; Kaygili, Omer; Ates, Tankut; Gunduz, Bayram; Bulut, Niyazi; Koytepe, Suleyman; Ozcan, ImrenIn the present study, we have looked into the effects of the amount of the combustion fuel of urea on the morphological, thermal and morphological properties of MgO structure. To this goal, three Magnesium Oxide (MgO) samples were synthesized by the combustion method and the as-mentioned properties were characterized by the experimental analysis techniques of X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). The functional groups in the samples were also determined using Fourier Transform Infrared (FTIR) spectrometry. The crystallinity percent values for each sample were found to be about in the range of 94-96%. The crystallite sizes of the samples were computed to be in the ranges of 26-37 nm and 23-32 nm for Scherrer and Williamson-Hall methods, respectively. The increasing quantity of urea caused a gradual growth in the lattice parameter of Magnesium Oxide structure. The thermal properties and morphology were affected by the urea content.Öğe Effects of Yttrium Doping on Erbium-Based Hydroxyapatites: Theoretical and Experimental Study(Mdpi, 2022) Ahmed, Lana Omar; Bulut, Niyazi; Kebiroglu, Hanifi; Alkhedher, Mohammad; Ates, Tankut; Koytepe, Suleyman; Ates, BurhanThis is the first investigation of yttrium (Y) and erbium (Er) co-doped hydroxyapatite (HAp) structures, conducted using theoretical and experimental procedures. By using a wet chemical method, the materials were synthesized by varying the concentration of Y amounts of 0.13, 0.26, 0.39, 0.52, 0.65, and 0.78 at.% every virtual 10 atoms of calcium, whereas Er was kept fixed at 0.39 at.%. Spectroscopic, thermal, and in vitro biocompatibility testing were performed on the generated samples. Theoretical calculations were carried out to compute the energy bandgap, density of states, and linear absorption coefficient. The effects of Y concentration on thermal, morphological, and structural parameters were investigated in detail. Raman and Infrared (FTIR) spectroscopies confirmed the formation of the HAp structure in the samples. Theoretical investigations indicated that the increasing amount of Y increased the density from 3.1724 g cm(-3) to 3.1824 g cm(-3) and decreased the bandgap energy from 4.196 eV to 4.156 eV, except for the sample containing 0.39 at. % of the dopant, which exhibited a decrease in the bandgap. The values of linear absorption appeared reduced with an increase in photon energy. The samples exhibited cell viability higher than 110%, which revealed excellent biocompatibility for biological applications of the prepared samples.Öğe The effects of Zn and Yb co-dopants on the electronic, radiation shielding, structural, thermal and spectroscopic properties of hydroxyapatite(Elsevier, 2024) Ayhan, Yasemin Merve; Ates, Tankut; Seckin, Turgay; Ozcan, Imren; Bulut, Niyazi; Kurucay, Ali; Kaygili, OmerThis work presents a comprehensive investigation of the electronic properties of hydroxyapatite (HA) doped with zinc (Zn) and ytterbium (Yb). Four different compositions, namely 0.33Zn-0.33Yb-HA, 0.33Zn-0.66Yb-HA, 0.66Zn-0.33Yb-HA, and 0.66Zn-0.66Yb-HA, were studied using Density of States (DOS) and band structure calculations. The computed band gap values for each composition were determined to be 4.3097 eV, 4.1324 eV, 4.2527 eV, and 4.2088 eV, respectively. The observed decrease in the band gap energy from 0.33Zn-0.33Yb-HA to 0.66Zn-0.66Yb-HA signifies a significant impact of the dopant composition on the electronic properties of the material. Furthermore, the inclusion of ytterbium in the HA matrix resulted in the formation of a distinct band and peak in the density of states. This indicates the emergence of specific energy levels associated with Yb, suggesting a distinct influence on the electronic structure of the material. These findings provide valuable insights into the tunability of the electronic properties of HA through controlled doping with Zn and Yb. Such knowledge is crucial for tailoring materials with desired electronic characteristics, thus holding promise for various applications in electronic devices and biocompatible coatings. The as-modeled structures were synthesized via a wet chemical route. Fourier transform infrared (FTIR), Raman, and X-ray diffraction (XRD) analyses verified the formation of the HA structure for each sample. Differential thermal analysis (DTA) results showed that all the as-prepared samples were thermally stable. The negligible mass losses were detected for all the samples in the thermogravimetric analysis (TGA) measurements. The addition of both co-dopants affected crystal structure related parameters and decreased the crystallinity and cell viability.Öğe The effects of Zn/Fe co-dopants on the structural, thermal, magnetic, and in vitro biocompatibility properties of calcium pyrophosphate ceramics(Elsevier, 2022) Kebiroglu, Hanifi; Ates, Tankut; Bulut, Niyazi; Ercan, Ismail; Ercan, Filiz; Acari, Idil Karaca; Koytepe, SuleymanIn the present work, calcium pyrophosphate (CPP) samples co-doped with Zn and Fe were prepared by using a wet chemical method, and their thermal, magnetic, structural, morphologic, and in vitro biocompatibility properties were investigated for the first time. X-ray diffraction (XRD) results showed that a continuous decreasing trend in two lattice parameters, unit cell volume, and average crystallite size was observed with the increasing Zn content. Zn content affected the magnetic and thermal behaviors, cell viability property of the CPP, as well as morphology. The sample containing 0.22 at.% Zn and 0.22 at.% Fe showed the best biocompatibility among all the samples, and the higher amount of Zn caused the lower cell viability. The bandgap of the CPP decreased with adding of Zn, while the linear absorption coefficient value increased.Öğe Experimental and theoretical characterization of Bi-based hydroxyapatites doped with Ce(Elsevier Sci Ltd, 2022) Kareem, Rebaz Obaid; Kaygili, Omer; Ates, Tankut; Bulut, Niyazi; Koytepe, Suleyman; Kurucay, Ali; Ercan, FilizThis study deals with the theoretical and experimental characterizations of Bi-based hydroxyapatites (HAps) codoped with Ce. Five samples of Bi-based HAp (at a constant amount of 0.125 at.%) with additions of the Ce in various amounts (0, 0.125, 0.25, 0.375, and 0.500 at. %) were synthesized by using the wet chemical method. The prepared samples were investigated experimentally by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). All the samples were also modeled by using a density functional theory (DFT), and theoretical results were obtained. Both experimental and theoretical results showed that the lattice parameters and unit cell volume were significantly affected by Ce content. Calculated bandgap energy results of the samples gradually reduced from 4.6308 eV to 4.5299 eV. The bandgap decreased with increasing Ce content, and the densities of states (DOS) values were also affected by the amount of Ce. It was found that the sample doped with 0.500 at. % Ce showed the best biocompatibility among all the as-synthesized samples. The linear absorption coefficient increased with increasing amounts of Ce in all samples, while this parameter decreased with increasing photon energy. The density increases with the increasing Ce content ranging from 3.1615 g cm-3 to 3.1772 g cm- 3. Both crystallite size and crystallinity decreased gradually with the increasing amount of Ce. FTIR and Raman spectra confirm the formation of the HAp structure for all the samples.Öğe Experimental and theoretical characterization of Dy-doped hydroxyapatites(Springer, 2023) Isen, Fatih; Kaygili, Omer; Bulut, Niyazi; Ates, Tankut; Osmanlioglu, Fatih; Keser, Serhat; Tatar, BeyhanThe effects of adding Dy to the hydroxyapatite (HAp) structure were investigated experimentally and theoretically. The as-obtained experimental results with an increasing amount of Dy are as follows. X-ray diffraction, Raman, and Fourier transform infrared measurements verified the HAp structure for each specimen. The crystallinity, lattice parameters, lattice stress, strain, and anisotropic energy density were affected. Thermal stability and stoichiometry were not affected. It was observed that all the Dy-doped HAps have smaller crystallite size values compared to the un-doped HAp. The cell viability obtained from mouse fibroblast cell (L929) was higher than 82%, indicating all the samples were biocompatible. The theoretical findings, obtained from the density functional theory (DFT) calculations, exhibited a continuous decrease in the bandgap from 4.7109 to 3.7982 eV, an increase in the density from 3,155 to 3,189 kg m(-3), and an increase in the linear absorption coefficient.Öğe The experimental and theoretical investigation of Sm/Mg co-doped hydroxyapatites(Elsevier, 2022) Hssain, Ala Hamd; Bulut, Niyazi; Ates, Tankut; Koytepe, Suleyman; Kurucay, Ali; Kebiroglu, Hanifi; Kaygili, OmerThis study presents an extensive experimental and theoretical analysis of Mg -doped hydroxyapatite (HAp) samples with additional Sm doping at varying amounts. A wet chemical method was used to synthesize Mg-containing HAps at a constant amount of 0.133 at. %, and in addition the second dopant of Sm was utilized at varying amounts of 0.133, 0.266, 0.399, 0.532, and 0.665 at. %. All of these samples were investigated experimentally and theoretically by using the X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), in-vitro cell viability tests, and density functional theory (DFT) calculations. The bandgap energy was found to have reduced from 4.6115 eV to 4.3870 eV. The linear attenuation (or absorption) coefficient increased as the amount of Sm in the sample increased, and this parameter decreased as the photon energy increased for all samples. Both the lattice parameter and the theoretical density increased, whereas the unit cell volume and the lattice parameters declined. The XRD and FTIR results revealed that the HAp phase (over 98 percent for all samples) was a major phase formed, while the beta -TCP phase (beta-tricalcium phosphate) was a minor phase. The beta-TCP phase increased from 0.91 to 1.57 percent with an increasing amount of Sm. The volume of the unit cell trended in the same direction as predicted by the obtained results theoretically. Increased anisotropic energy density and a decrease in crystallinity have been observed. All samples were found to be thermally stable. Due to the presence of Sm content, cell viability was observed to be affected.Öğe Experimental characterization and theoretical investigation of Ce/Yb co-doped hydroxyapatites(Elsevier Science Sa, 2022) Acar, Serdar; Kaygili, Omer; Ates, Tankut; Dorozhkin, Sergey, V; Bulut, Niyazi; Ates, Burhan; Koytepe, SuleymanIn the present study, the effects of variable amounts of Yb addition on the structural, thermal, and in vitro biocompatibility properties of Ce-doped hydroxyapatite (HAp) samples synthesized via the wet chemical method were investigated. Besides, the prepared formulations were also modeled for making the theoretical investigations. The single-phase compositions were detected for all samples, and no formation of additional phases was observed. Doping with Yb was observed to produce some variations in the lattice parameters, unit cell volume, lattice strain, and lattice stress. While a decreasing trend in the crystallite size and crystallization percent with increasing Yb content was found, a gradual increase in the anisotropic energy density was observed. All samples were found to be thermally stable from room temperature to 1000 degrees C with negligible mass losses during heating. No significant morphological changes were caused by the addition of Yb. For all samples, the numerical values of (Ca + Ce + Yb)/P molar ratio were found to be close to that for stoichiometric HAp (1.67). It was observed that the increased Yb additive caused a decrease in cell viability values. A continuous decrease in the bandgap energy with the increasing amounts of Yb added to the Ce-based HAp structure was observed from the theoretical investigations. A sharp decrease in the cell viability of the Ce-based HAp was observed with the addition of Yb.Öğe Experimental characterization and theoretical investigation of Zn/Sm co-doped hydroxyapatites(Elsevier, 2022) Hssain, Ala Hamd; Bulut, Niyazi; Ates, Tankut; Koytepe, Suleyman; Kurucay, Ali; Kebiroglu, Hanifi; Kaygili, OmerIn this study, the wet chemical method was used to synthesize Zn-doped hydroxyapatite (HAp) samples, and the effects of varying the amount of Sm addition on structural, thermal, and biocompatibility in vitro properties were studied. In addition, a density functional theory was used for modeling the as-synthesized samples to obtain the theoretical calculation results. XRD results confirmed the formation of biphasic compositions for all samples, and FTIR data supported the formation of the functional groups of hydroxyl and phosphate. More than 98% of samples showed the formation of the HAp phase. The addition of Sm resulted in an increase in the secondary phase of the beta-TCP from 0.60 % to 1.49 %. The lattice parameters (aandc), unit cell volume (V), lattice strain (epsilon), and lattice stress (sigma) varied when Sm was added as a dopant. The crystallite size and crystallinity decreased as the Sm content increased, however, the anisotropic energy density gradually increased. Thermal analysis results confirmed that all samples seemed to be thermally stable. The addition of Sm did not result in any notable morphological modifications. Cell viability values of the Zn-based HAp sharply decreased as a result of an increase in the Sm additive. Theoretical studies show that when the amount of Sm in the Zn-based HAp structure increases, the bandgap energy decreases from 4.68 to 4.40eV. An increasing density and decreasing unit cell volume have been observed, as confirmed by the theoretical results. In addition, there was a decrease in crystallinity as well as an increase in anisotropic energy density.Öğe Exploring the electronic band structure, spectroscopic signatures, and structural properties of Er3+-based hydroxyapatites co-doped with Ce3+ions(Elsevier, 2023) Ahmed, Lana Omar; Bulut, Niyazi; Banares, Luis; Kaygili, Omer; Kebiroglu, Hanifi; Ates, Tankut; Koytepe, SuleymanIn this work, we have investigated Ce3+ and Er3+ co-doped hydroxyapatite (HAp) structures both theoretically and experimentally for the first time. The Ce3+ content was incrementally varied in steps of 0.13 at. %, ranging from 0.13 at. % to 0.78 at. %. Meanwhile, the Er3+ content remained constant at 0.39 at. % for all samples. We employed X-ray diffraction, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry, and in vitro biocompatibility tests to examine the prepared samples. Our findings demonstrate that the thermal behavior, morphology, and other crystal structure-related parameters are significantly influenced by the con-centration of Ce3+. The formation of HAp structures was confirmed through FTIR and Raman spectroscopic analyses. Furthermore, we conducted theoretical calculations to determine the linear absorption coefficient, density of states, and bandgap. These calculations revealed that the addition of Ce3+ atoms at varying concen-trations resulted in an increase in density from 3.174 to 3.195 g cm-3, while the bandgap gradually decreased from 4.16 to 4.10 eV, except for the 0.26Ce-0.39Er-HAp and 0.52Ce-0.39Er-HAp compositions, where the energy bandgap exhibited an increase.Öğe Fe ve Ti katkılı Çift Fazlı Kalsiyum Fosfatların Sentez ve Karakterizasyonu(2021) Ateş, Tankut; İnce, Turan; Kaygılı, Ömer; Keser, Serhat; Köytepe, Süleyman; Acar, Serdar; Bulut, NiyaziBu çalışmada, Ti katkısının Fe esaslı çift fazlı kalsiyum fosfat malzemelerinin yapısal, morfolojik ve termal özellikleri üzerine etkileri araştırılmıştır. X-ışını kırınımı (XRD) analizi, üretilen numunelerin hem hidroksiapatit (HAp) hem de beta trikalsiyum fosfat (?-TCP) fazlarına sahip olduğunu doğrulamaktadır. Ayrıca, Ti katkısındaki artışla ?-TCP fazının miktarının arttığı görülmektedir. Fourier dönüşümlü kızılötesi (FTIR)spektroskopisi sonuçları, numunelerdeki karakteristik fonksiyonel grupların varlığını doğrulamaktadır. Ti miktarı morfolojiyi etkilemektedir. Numunelerin ısıl davranışları birbirine benzerdir ve oda sıcaklığından 1000 °C’ye kadar tüm numuneler termal olarak kararlıdırlar. Bu sıcaklık aralığında numunelerdeki kütle kayıpları % 1,63’e eşit veya altındadır.Öğe Investigation of structural, spectroscopic, dielectric, magnetic, and in vitro biocompatibility properties of Sr/Ni co-doped hydroxyapatites(Elsevier Sci Ltd, 2022) Ercan, Filiz; Kayed, Tarek S.; Kaygili, Omer; Bulut, Niyazi; Almohazey, Dana; Ates, Tankut; Al-Ahmari, Fatimah SaadIn this study, the changes caused by Ni and Sr additives on the structural, thermal, dielectric, and magnetic properties of hydroxyapatite (HAp) samples were examined and reported for the first time in detail. Some effects of the Sr/Ni site disorder on the crystallographic, dielectric, and magnetic properties in Sr/Ni-HAp have been examined, as well as their cytotoxicity effects. The addition of Ni affected the morphology of nanoparticles with a low agglomeration increase. Our results showed that the dielectric constant (epsilon') and dielectric loss (epsilon '') have greater values at low frequencies than at higher frequencies for all the samples. It can be concluded that Ni and Sr additions to the HAp structure contribute to the development of thermal, magnetic, and dielectric properties required to mimic natural HAp in the study conducted with the idea of creating a medical application area for bone healing and regeneration. The cytotoxicity test of the produced nanoparticles and the evaluation of the results were also performed using human foreskin fibroblasts (HFF). The viability of cells after treatment for 48 h ranged between 50 and 75%. While 0.37Ni-0.37Sr-HAp and 1.11Ni-0.37Sr-HAp were similar to 0.37Sr-HAp, 0.74Ni-0.37Sr-HAp had the highest cellular viability. At 0.1 mg/mL, 0.74Ni-0.37Sr-HAp had a viability of 79.97% compared to the untreated control cells. Our Sr/Ni-HAp nanoparticles have promising medical applications in bone healing and regeneration.
