Person: OKTAR, FAİK NÜZHET
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OKTAR
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FAİK NÜZHET
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Publication Open Access Marine-derived bioceramics for orthopedic, reconstructive and dental surgery applications(2022-11-01) OKTAR, FAİK NÜZHET; ÜNAL YILDIRIM, SEMRA; GÜNDÜZ, OĞUZHAN; EKREN, NAZMİ; ALTAN, ERAY; OKTAR F. N. , Unal S., GÜNDÜZ O., Ben Nissan B., Macha I. J. , Akyol S., Duta L., EKREN N., ALTAN E., YETMEZ M.Bioceramics are a fast-growing materials group, which are widely used in orthopedics, maxillofacial, dental, and reconstructive surgeries. They are produced using raw materials either from synthetic or natural sources. As naturally originated resources, the bones of sheep and cows are used after converting to calcium phosphates. Human-originated sources in the past were obtained from human cadaver bones, however now-a-days this has been discontinued. On the other hand, the \"golden standard\" in the reconstruction surgery has been using patients own bones, -i.e., autogenous bones, which heal better than other alternatives. Besides natural products, synthetic materials are produced from a range of inorganic raw and natural materials based on marine sources, such as corals, and other marine-derived materials (i.e., seashells, nacre). These are used to produce bioceramics and hence implants, devices, and bone grafts. Although during the last four decades a number of excellent books and book chapters have been published, no comprehensive review has been yet reported to cover the available marine materials and to indicate the related work and corresponding references to allow for both medical and ceramic scientists to access directly and open new avenues for further research on marine structures and their applications in orthopedic, maxillofacial, and reconstructive surgery areas. Hence, this review covers the general marine structures, their locations and availability in different countries and, current research on production methods of these unique structures that are difficult to fabricate synthetically. The authors are confident that this comprehensive review will be an excellent source not only for the ceramists, but also for the medical scientists.Publication Metadata only Preparation and evaluation of cerium oxide-bovine hydroxyapatite composites for biomedical engineering applications(ELSEVIER SCIENCE BV, 2014) OKTAR, FAİK NÜZHET; Gunduz, O.; Gode, C.; Ahmad, Z.; Gokce, H.; Yetmez, M.; Kalkandelen, C.; Sahin, Y. M.; Oktar, F. N.The fabrication and characterization of bovine hydroxyapatite (BHA) and cerium oxide (CeO2) composites are presented. CeO2 (at varying concentrations 1, 5 and 10 wt%) were added to calcinated BHA powder. The resulting mixtures were shaped into green cylindrical samples by powder pressing (350 MPa) followed by sintering in air (1000-1300 degrees C for 4 h). Density, Vickers microhardness (HV), compression strength, scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies were performed on the products. The sintering behavior, microstructural characteristics and mechanical properties were evaluated. Differences in the sintering temperature (for 1 wt% CeO2 composites) between 1200 and 1300 degrees C, show a 3.3% increase in the microhardness (564 and 582.75 HV, respectively). Composites prepared at 1300 degrees C demonstrate the greatest compression strength with comparable results for 5 and 10 wt% CeO2 content (106 and 107 MPa) which are significantly better than those for 1 wt% and those that do not include any CeO2 (90 and below 60 MPa, respectively). The results obtained suggest optimal parameters to be used in preparation of BHA and CeO2 composites, while also highlighting the potential of such materials in several biomedical engineering applications. (C) 2014 Elsevier Ltd. All rights reserved.Publication Open Access Fabrication of naturel pumice/hydroxyapatite composite for biomedical engineering(BMC, 2016-12) OKTAR, FAİK NÜZHET; Komur, Baran; Lohse, Tim; Can, Hatice Merve; Khalilova, Gulnar; Gecimli, Zeynep Nur; Aydogdu, Mehmet Onur; Kalkandelen, Cevriye; Stan, George E.; Sahin, Yesim Muge; Sengil, Ahmed Zeki; Suleymanoglu, Mediha; Kuruca, Serap Erdem; Oktar, Faik Nuzhet; Salman, Serdar; Ekren, Nazmi; Ficai, Anton; Gunduz, OguzhanBackground: We evaluated the Bovine hydroxyapatite (BHA) structure. BHA powder was admixed with 5 and 10 wt% natural pumice (NP). Compression strength, Vickers micro hardness, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction studies were performed on the final NP-BHA composite products. The cells proliferation was investigated by MTT assay and SEM. Furthermore, the antimicrobial activity of NP-BHA samples was interrogated. Results: Variances in the sintering temperature (for 5 wt% NP composites) between 1000 and 1300 degrees C, reveal about 700 % increase in the microhardness (similar to 100 and 775 HV, respectively). Composites prepared at 1300 degrees C demonstrate the greatest compression strength with comparable result for 5 wt% NP content (87 MPa), which are significantly better than those for 10 wt% and those that do not include any NP (below 60 MPa, respectively). Conclusion: The results suggested the optimal parameters for the preparation of NP-BHA composites with increased mechanical properties and biocompatibility. Changes in micro-hardness and compression strength can be tailored by the tuning the NP concentration and sintering temperature. NP-BHA composites have demonstrated a remarkable potential for biomedical engineering applications such as bone graft and implant.Publication Open Access Effects of temperature and pH on the synthesis of nanohydroxyapatite powders by chemical precipitation(2023-01-01) ALTAN, ERAY; OKTAR, FAİK NÜZHET; GÜNDÜZ, OĞUZHAN; Mahmutoglu G., Topsakal A., ALTAN E., KUŞKONMAZ N., DAĞLILAR S., OKTAR F. N., Erdemir G., Kuruca S. E., AKYOL S., GÜNDÜZ O., et al.Bone tissue engineering is based on a comprehensive understanding of bone structure, bone mechanics, and biology. In order to create nanostructured hydroxyapatite powders with customized properties, many synthesis strategies such as wet chemical precipitation, sol-gel, hydrothermal, and biomimetic approaches have been intensively researched through the years. Calcium phosphate (CaP)-based ceramic nanoparticles, including hydroxyapatite (HAp), were synthesized by the chemical precipitation technique at pH ranges of 7 to 11 and different calcination temperatures of 600 to 1100 °C. The synthesized powders were characterized by several techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), energy dispersive X-ray analysis (EDX), and in vitro cell culture assays. The particle size analysis and zeta potential of these powders were also carried out using the dynamic light scattering (DLS) and laser Doppler electrophoresis methods. The results showed that the pH levels of 9 to 11 range and calcination temperatures of 600 to 800 °C were adequate for appropriate nanohydroxyapatite powder production using this method. The particle size of the nanohydroxyapatite was approximately 55 nm, although they were agglomerated after calcination. The biocompatibility tests demonstrated that these nanohydroxyapatite (nHAp) powders produced have appropriate cytocompatibility and can be used for bone graft production and other biomedical applications.