Person: OKTAR, FAİK NÜZHET
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OKTAR
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FAİK NÜZHET
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Publication Metadata only Design and characterization of polycaprolactone-gelatin-graphene oxide scaffolds for drug influence on glioblastoma cells(PERGAMON-ELSEVIER SCIENCE LTD, 2019) ATASOY, BESTE MELEK; Unal, Semra; Arslan, Sema; Gokce, Tilbe; Atasoy, Beste Melek; Karademir, Betul; Oktar, Faik Nuzhet; Gunduz, OguzhanThree-dimensional (3D) scaffolds that mimic in vivo tumor microenvironments can be used to study tumor response to anticancer treatments, since most preclinical combination treatment strategy for anti-glioma were evaluated with traditional 2D cell culture. In this research, the nanofiber scaffolds of polycaprolactone (PCL) containing gelatin (Gel) nano/microparticles coated with different concentrations of graphene oxide (GO) and were successfully produced by combining electrospinning and electrospraying techniques. Scanning electron microscope (SEM), Fourier-transform infrared (FT-IR) spectroscopy and mechanical testing were used to characterize the structure and properties of the composites. The results show that gelatin and graphene particles can be well dispersed in the polycaprolactone nanofiber matrix by using the combination technique of electrospinning and electrospraying. The presence of 1 wt% graphene oxide increased mechanical strength of PCL/Gel scaffold and was found to be well consistent with the drug treatments (temozolomide and bortezomib) and radiotherapy by not showing additional toxicity.Publication Metadata only Effects of Polymethylsilsesquioxane concentration on morphology shape of electrosprayed particles(ELSEVIER SCIENCE BV, 2018) OKTAR, FAİK NÜZHET; Unal, Semra; Oktar, Faik Nuzhet; Gunduz, OguzhanThe investigation of unique sizes and shapes as they relate to various properties has become a great study for large field applications. Polymethylsilsesquioxane (PMSQ) particles are produced by electrospraying. Morphology of the electrosprayed particles develops from the needle-like to star-like particles by controlling the concentration of the polymer solution. Therefore, electrospraying process instead of conventional methods has opened up an alternative for the fabrication of particles by controlling with three main parameters (applied voltage, flow rate and concentration of the polymer) that are used to manipulate their morphologies during preparation. (C) 2018 Elsevier B.V. All rights reserved.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 Metadata only Production and characterization of calcium phosphates from marine structures: The fundamentals basics(Springer, 2019-01-01) ÜNAL YILDIRIM, SEMRA; GÜNDÜZ, OĞUZHAN; OKTAR, FAİK NÜZHET; ÜNAL S., GÜNDÜZ O., AKYOL S., Ben Nissan B., OKTAR F. N.Publication Metadata only Synthesis, characterization, and biological properties of composites of hydroxyapatite and hexagonal boron nitride(WILEY, 2018) OKTAR, FAİK NÜZHET; Unal, Semra; Ekren, Nazmi; Sengil, Ahmet Z.; Oktar, Faik N.; Irmak, Ster; Oral, Ozlem; Sahin, Yesim M.; Kilic, Osman; Agathopoulos, Simeon; Gunduz, OguzhanHydroxyapatite (HA), obtained from bovine bones, was successfully reinforced with hexagonal boron nitrite (h-BN). h-BN/HA composites, with BN content up to 1.5 wt %, were sintered at various temperatures between 1000 and 1300 degrees C, in air. Well-sintered samples were obtained after sintering at 1200 and 1300 degrees C. The presence of h-BN contributed to dense, fine, and well-crystallized microstructure. The results of X-ray diffraction analysis and FT-IR spectroscopy showed that the produced composites comprised biphasic beta-TCP/HCA (HCA: carbonate partially substituted HA). High values of mechanical properties were achieved, namely compression strength 155 MPa for the sample 0.5% h-BN/HA and Vickers microhardness of 716 HV for the samples 1.5% h-BN/HA, both sintered at 1300 degrees C. U2OS human bone osteosarcoma proliferation and cell viability showed no adverse effect in the presence of h-BN/HA, suggesting the potential use of the produced materials as safe biomaterials in bone tissue engineering. (C) 2017 Wiley Periodicals, Inc.Publication Metadata only Production and characterization of bacterial cellulose scaffold and its modification with hyaluronic acid and gelatin for glioblastoma cell culture(SPRINGER, 2021) YILMAZ, BETÜL; Unal, Semra; Arslan, Sema; Yilmaz, Betul Karademir; Oktar, Faik Nuzhet; Sengil, Ahmet Zeki; Gunduz, OguzhanThree-dimensional (3D) in vitro cell culture models have recently gained increasing interest in predicting the response of anticancer drugs. In this study first, we tried to obtain a novel hyaluronic acid (HA)/gelatin (Gel) modified bacterial cellulose (BC) composite scaffolds by in situ fermentation method. Morphological and chemical structures, wettability, and thermal stability of scaffolds were evaluated. In particular, the human glioblastoma (GBM) cancer cell line (U251) was seeded into BC/HA/Gel scaffolds to evaluate their potential as in vitro 3D cancer cell culture. MTT proliferation assay, scanning electron microscopy, and confocal microscopy were utilised to determine cell proliferation, morphology and adhesion. The results suggest that our hyaluronic acid and gelatin modified bacterial cellulose scaffold is promising to be used as in vitro 3D culture of GBM cells and may be used to predict treatment response or reactions of new therapeutics.