Person: OKTAR, FAİK NÜZHET
Loading...
Email Address
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
OKTAR
First Name
FAİK NÜZHET
Name
19 results
Search Results
Now showing 1 - 10 of 19
Publication Metadata only Synthesis and characterization of antibacterial drug loaded beta-tricalcium phosphate powders for bone engineering applications(SPRINGER, 2020) OKTAR, FAİK NÜZHET; Topsakal, Aysenur; Ekren, Nazmi; Kilic, Osman; Oktar, Faik N.; Mahirogullari, Mahir; Ozkan, Ozan; Sasmazel, Hilal Turkoglu; Turk, Mustafa; Bogdan, Iuliana M.; Stan, George E.; Gunduz, OguzhanPowders of beta-tricalcium phosphate [beta-TCP, beta-Ca-3(PO4)(2)] and composite powders of beta-TCP and polyvinyl alcohol (PVA) were synthesized by using wet precipitation methods. First, the conditions for the preparation of single phase beta-TCP have been delineated. In the co-precipitation procedure, calcium nitrate and diammonium hydrogen phosphate were used as calcium and phosphorous precursors, respectively. The pH of the system was varied in the range 7-11 by adding designed amounts of ammonia solution. The filtered cakes were desiccated at 80 degrees C and subsequently calcined at different temperatures in the range between 700-1100 degrees C. Later on, rifampicin form II was used to produce drug-loaded beta-TCP and PVA/beta-TCP powders. All the synthesized materials have been characterized from morphological (by scanning electron microscopy) and structural-chemical (by X-ray diffraction and Fourier transform infrared spectroscopy) point of view. The drug loading capacity of the selected pure beta-TCP powder has been assessed. The biological performance (cytocompatibility in fibroblast cell culture and antibacterial efficacy against Escherichia coli and Staphylococcus aureus) has been tested with promising results. Application perspectives of the designed drug-bioceramic-polymer blends are advanced and discussed. [GRAPHICS] .Publication Metadata only Part 2: biocompatibility evaluation of hydroxyapatite-based clinoptilolite and Al2O3 composites(SPRINGER, 2017) OKTAR, FAİK NÜZHET; Kalkandelen, C.; Suleymanoglu, M.; Kuruca, S. E.; Akan, A.; Oktar, F. N.; Gunduz, O.The biocompatibility of clinoptilolite/alumina/bovine hydroxyapatite (Cp - Al2O3 - BHA) composite, at different ratio obtained by powder pressing process, were investigated studying the behavior of osteosarcoma (SAOS-2) cells. The biocompatibility was examined by means of cytotoxicity and cytocompatibility tests. The structure and morphology of bioceramic composites were studied by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) technique. The results showed that these materials have no toxic effects. The natural composite that fabricated in this study may be a promising approach for bone engineering applications.Publication Metadata only Studies on goat hydroxyapatite/commercial inert glass biocomposites(SPRINGER, 2019) OKTAR, FAİK NÜZHET; Akyurt, N.; Yetmez, M.; Oktar, F. N.In this study, mechanical properties and microstructural analysis of goat-derived hydroxyapatite/commercial inert glass biocomposites are considered in the temperature range between 1000 and 1300 degrees C. The results indicate that the best values of maximum compressive strength and microhardness are achieved in the samples sintered at 1200 degrees C for the glass in the weight of 5 and 10%. Moreover, above 1000 degrees C, decomposition of hydroxyapatite and new phase formations such as whitlockite and silicocarnotite play also a major role in the hardness and strength for goat hydroxyapatite/commercial inert glass biocomposites.Publication Metadata only Hydroxyapatite-TiO2 composites(ELSEVIER SCIENCE BV, 2006) OKTAR, FAİK NÜZHET; Oktar, FNThis article reports the mechanical properties, the microstructure, and the crystallography of composite materials made of hydroxyapatite, obtained from natural bovine bone, and TiO2 (5 and 10 wt.%), which were sintered at different temperatures between 1000 and 1300 degrees C. Higher sintering temperatures resulted in better densification. The samples sintered at 1300 degrees C had the highest microhardness. The best compressive strengths were obtained after sintering at 1300 degrees C for the samples containing 5% TiO2, and at 1200 degrees C for the samples with 10% TiO2. (c) 2005 Elsevier B.V. All rights reserved.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 Metadata only Glioblastoma cell adhesion properties through bacterial cellulose nanocrystals in polycaprolactone/gelatin electrospun nanofibers(ELSEVIER SCI LTD, 2020) YILMAZ, BETÜL; Unal, Semra; Arslan, Sema; Yilmaz, Betul Karademir; Kazan, Dilek; Oktar, Faik Nuzhet; Gunduz, OguzhanGlioblastoma (GBM), the most common and extremely lethal type of brain tumor, is resistant to treatment and shows high recurrence rates. In the last decades, it is indicated that standard two-dimensional (2D) cell culture is inadequate to improve new therapeutic strategies and drug development. Hence, well-mimicked three-dimensional (3D) tumor platforms are needed to bridge the gap between in vitro and in vivo cancer models. In this study, bacterial cellulose nano-crystal (BCNC) containing polycaprolactone (PCL) /gelatin (Gel) nanofibrous composite scaffolds were successfully fabricated by electrospinning for mimicking the extracellular matrix of GBM tumor. The fiber diameters in the nanofibrous matrix were increased with an increased concentration of BCNC. Moreover, fiber morphology changed from the smooth formation to the beaded formation by increasing the concentration of the BCNC suspension. In-vitro biocompatibilities of nanofibrous scaffolds were tested with U251 MG glioblastoma cells and improved cell adhesion and proliferation was compared with PCL/Gel. PCL/Gel/BCNC were found suitable for enhancing axon growth and elongation supporting communication between tumor cells and the microenvironment, triggering the process of tumor recurrence. Based on these results, PCL/Gel/BCNC composite scaffolds are a good candidate for biomimetic GBM tumor platform.Publication Open Access A New Method for Fabrication of Nanohydroxyapatite and TCP from the Sea Snail Cerithium vulgatum(HINDAWI LTD, 2014) OKTAR, FAİK NÜZHET; Gunduz, O.; Sahin, Y. M.; Agathopoulos, S.; Ben-Nissan, B.; Oktar, F. N.Biphasic bioceramic nanopowders of hydroxyapatite (HA) and beta-tricalcium phosphate (TCP) were prepared from shells of the sea snail Cerithium vulgatum (Bruguiere, 1792) using a novel chemical method. Calcination of the powders produced was carried out at varying temperatures, specifically at 400 degrees C and 800 degrees C, in air for 4 hours. When compared to the conventional hydrothermal transformation method, this chemical method is very simple, economic, due to the fact that it needs inexpensive and safe equipment, because the transformation of the aragonite and calcite of the shells into the calcium phosphate phases takes place at 80 degrees C under the atmospheric pressure. The powders produced were determined using infrared spectroscopy (FT-IR), X-ray diffraction, and scanning electron microscopy (SEM). The features of the powders produced along with the fact of their biological origin qualify these powders for further consideration and experimentation to fabricate nanoceramic biomaterials.Publication Open Access Polycaprolactone/Gelatin/Hyaluronic Acid Electrospun Scaffolds to Mimic Glioblastoma Extracellular Matrix(MDPI, 2020-06-11) YILMAZ, BETÜL; Unal, Semra; Arslan, Sema; Yilmaz, Betul Karademir; Oktar, Faik Nuzhet; Ficai, Denisa; Ficai, Anton; Gunduz, OguzhanGlioblastoma (GBM), one of the most malignant types of human brain tumor, is resistant to conventional treatments and is associated with poor survival. Since the 3D extracellular matrix (ECM) of GBM microenvironment plays a significant role on the tumor behavior, the engineering of the ECM will help us to get more information on the tumor behavior and to define novel therapeutic strategies. In this study, polycaprolactone (PCL)/gelatin(Gel)/hyaluronic acid(HA) composite scaffolds with aligned and randomly oriented nanofibers were successfully fabricated by electrospinning for mimicking the extracellular matrix of GBM tumor. We investigated the effect of nanotopography and components of fibers on the mechanical, morphological, and hydrophilic properties of electrospun nanofiber as well as their biocompatibility properties. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) have been used to investigate possible interactions between components. The mean fiber diameter in the nanofiber matrix was increased with the presence of HA at low collector rotation speed. Moreover, the rotational velocity of the collector affected the fiber diameters as well as their homogenous distribution. Water contact angle measurements confirmed that hyaluronic acid-incorporated aligned nanofibers were more hydrophilic than that of random nanofibers. In addition, PCL/Gel/HA nanofibrous scaffold (7.9 MPa) exhibited a significant decrease in tensile strength compared to PCL/Gel nanofibrous mat (19.2 MPa). In-vitro biocompatibilities of nanofiber scaffolds were tested with glioblastoma cells (U251), and the PCL/Gel/HA scaffolds with random nanofiber showed improved cell adhesion and proliferation. On the other hand, PCL/Gel/HA scaffolds with aligned nanofiber were found suitable for enhancing axon growth and elongation supporting intracellular communication. Based on these results, PCL/Gel/HA composite scaffolds are excellent candidates as a biomimetic matrix for GBM and the study of the tumor.