Person: ÜNAL YILDIRIM, SEMRA
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ÜNAL YILDIRIM
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Publication Open Access The effect of polycaprolactone/graphene oxide electrospun scaffolds on the neurogenic behavior of adipose stem cells(2022-02-01) PINAR, ERTUĞRUL; ÜNAL YILDIRIM, SEMRA; GÜNDÜZ, OĞUZHAN; HARMAN, FERHAT; Pınar E., Şahin A., Ünal Yıldırım S., Gündüz O., Harman F., Kaptanoğlu E.Stem cell destiny can be controlled with scaffold biomaterials in tissue engineering and regenerative medicine. This study aimed to investigate the neuronal differentiation potential of human adipose tissue-derived mesen- chymal stem cells in graphene nanofiber matrix in vitro. Stem cell isolation was performed from adipose tissue taken from human by mechanical and enzymatic methods. The differentiation potential was examined after incubation of adipose stem cells in normal medium and neural differentiation medium, on graphene oxide (GO) and polycaprolactone (PCL) composite scaffolds produced by electrospinning technique. In vitro studies indi- cated that the presence of GO in PCL scaffold increases an effect on cell attachment, proliferation, infiltration into the scaffold, and neuronal differentiation. Also, unlike subcutaneous tissue, it has been shown immunohis- tochemically that mesenchymal stem cells derived from epidural adipose tissue tend to differentiate into oligodendrocytes.Publication Metadata only Combination of proteasome inhibitors with temozolomide to increase the anti-tumor effect in 3D culture model of glioblastoma(ELSEVIER SCIENCE INC, 2018) YILMAZ GÖLER, AYŞE MİNE; Unal, Semra; Gokce, Tilbe; Arslan, Sema; Yilmaz, Ayse Mine; Gunduz, Oguzhan; Karademir, BetulPublication Metadata only Metabolic Biomarkers and Neurodegeneration: A Pathway Enrichment Analysis of Alzheimer's Disease, Parkinson's Disease, and Amyotrophic Lateral Sclerosis(MARY ANN LIEBERT, INC, 2016) KAZAN, DİLEK; Kori, Medi; Aydin, Busra; Unal, Semra; Arga, Kazim Yalcin; Kazan, DilekNeurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) lack robust diagnostics and prognostic biomarkers. Metabolomics is a postgenomics field that offers fresh insights for biomarkers of common complex as well as rare diseases. Using data on metabolite-disease associations published in the previous decade (2006-2016) in PubMed, ScienceDirect, Scopus, and Web of Science, we identified 101 metabolites as putative biomarkers for these three neurodegenerative diseases. Notably, uric acid, choline, creatine, L-glutamine, alanine, creatinine, and N-acetyl-L-aspartate were the shared metabolite signatures among the three diseases. The disease-metabolite-pathway associations pointed out the importance of membrane transport (through ATP binding cassette transporters), particularly of arginine and proline amino acids in all three neurodegenerative diseases. When disease-specific and common metabolic pathways were queried by using the pathway enrichment analyses, we found that alanine, aspartate, glutamate, and purine metabolism might act as alternative pathways to overcome inadequate glucose supply and energy crisis in neurodegeneration. These observations underscore the importance of metabolite-based biomarker research in deciphering the elusive pathophysiology of neurodegenerative diseases. Future research investments in metabolomics of complex diseases might provide new insights on AD, PD, and ALS that continue to place a significant burden on global health.Publication Open Access Synthesis and characterization of interpenetrating network (IPN) based levan-polyacrylamide hydrogels and their application in conservation of cultural heritage(2023-11-01) ÜNAL YILDIRIM, SEMRA; OKTAR, FAİK NÜZHET; GENÇ, SEVAL; TOKSOY ÖNER, EBRU; Özen Sağlam R., Ünal Yıldırım S., Oktar F. N., Genç S., Erdem G., Toksoy Öner E.In this study, an IPN based enzymatic levan-polyacrylamide hydrogel (EL-PA) was developed and characterized for its structural, morphological, rheological properties and swelling kinetics to underline hydrogel properties and its potential use in paper conservation. The addition of levan also led to changes in the viscoelastic behavior of the hydrogels, with the complex viscosity of EL-PA samples showing pronounced dependence on shear rate. The swelling and the overall surface area of the hydrogels were increased with the addition of levan into the polymer network. Source associated structural differences were found to be negligible such that both microbially produced linear and enzymatically produced branched forms of levan performed equally well. Solvent loaded hydrogels were then applied on an artifact, a 19th century book of Namık Kemal, and investigated using FTIR, SEM, XRD and colorimetric analysis. Old adhesive layers were successfully removed, and hydrogels showed good compatibility and ease of application. This study has shown that levan has improved hydrogel properties and levan based systems bear high potential in conservation science.Publication Metadata only Tissue engineering applications of bacterial cellulose based nanofibers(Springer, 2020-01-01) ÜNAL YILDIRIM, SEMRA; GÜNDÜZ, OĞUZHAN; UZUN, MUHAMMET; ÜNAL S., GÜNDÜZ O., UZUN M.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 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 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.