Person: EKREN, NAZMİ
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EKREN
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NAZMİ
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Publication Metadata only Preparation and characterization of electrospun polylactic acid/sodium alginate/orange oyster shell composite nanofiber for biomedical application(SPRINGER, 2020) BİLĞİÇ ALKAYA, DİLEK; Cesur, Sumeyye; Oktar, Faik Nuzhet; Ekren, Nazmi; Kilic, Osman; Alkaya, Dilek Bilgic; Seyhan, Serap Ayaz; Ege, Zeynep Ruya; Lin, Chi-Chang; Erdem, Serap; Erdemir, Gokce; Gunduz, OguzhanBone tissue engineering has begun to draw attention in recent years. The interactive combination of biomaterials and cells is part of bone tissue engineering. Sodium alginate (SA) is a biologically compatible, degradable, non-toxic natural polymer accepted by the human body and is widely used in the field of tissue engineering. Polylactic acid (PLA) is another type of biodegradable thermoplastic polyester derived from renewable sources which are used in bone tissue engineering and biomedical owing to its biocompatibility and biodegradability. Hydroxyapatite (HA) and tricalcium phosphate (TCP) derived from natural sources such as marine species and bovine bone are biocompatible and non-toxic biomaterials which are used to reconstruct many parts of the skeleton. In this study, PLA, SA with different compositions, and nanofibers obtained by adding orange spiny oyster shell powders (Spondylus barbatus) to them by using electrospining technique. Cell culture study, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and physical analysis such as density, electrical conductivity, surface tension, viscosity measurement, and tensile strength measurement tests were carried out after the production process. Produced nanofibers showed smooth and beadless surface. The average diameters and distributions decreased with the addition of optimum PLA and TCP amount. The tensile strength of nanofibers was enhanced with the additional SA and TCP. The produced nanofibers are compatible with human bone tissue, which are not cytotoxic, and in addition, a high cell efficiency of SaOS-2 cells on the nanofibers was observed with SEM images.Publication Metadata only Fabrication and characterization of pla/sa/ha composite nanofiber by electrospinning for bone tissue engineering applications(2018-07-18) CESUR, SÜMEYYE; EKREN, NAZMİ; KILIÇ, OSMAN; OKTAR, FAİK NÜZHET; BİLĞİÇ ALKAYA, DİLEK; AYAZ SEYHAN, SERAP; GÜNDÜZ, OĞUZHAN; Cesur S., Ekren N., Kılıç O., Oktar F. N., Bilğiç Alkaya D., Ayaz Seyhan S., Ege Z. R., Gündüz O.Publication Open Access Bioinspired scaffold induced regeneration of neural tissue(PERGAMON-ELSEVIER SCIENCE LTD, 2019-05) EKREN, NAZMİ; Altun, Esra; Aydogdu, Mehmet O.; Togay, Sine O.; Sengil, Ahmet Z.; Ekren, Nazmi; Haskoylu, Merve E.; Oner, Ebru T.; Altuncu, Nese A.; Ozturk, Gurkan; Crabbe-Mann, Maryam; Ahmed, Jubair; Gunduz, Oguzhan; Edirisinghe, MohanIn the last decade, nerve tissue engineering has attracted much attention due to the incapability of self-regeneration. Nerve tissue regeneration is mainly based on scaffold induced nanofibrous structures using both bio and synthetic polymers. The produced nanofibrous scaffolds have to be similar to the natural extracellular matrix and should provide an appropriate environment for cells to attach onto. Nanofibrous scaffolds can support or regenerate cells of tissue. Electrospinning is an ideal method for producing the nanofibrous scaffolds. In this study, Bacterial cellulose (BC)/Poly (epsilon-caprolactone) (PCL) blend nanofibrous scaffolds were successfully prepared by electrospinning for nerve tissue induced repair. The produced nanofibrous scaffolds contain well defined interconnected nanofiber networks with hollow micro/nanobeads. Firstly, in-vitro biocompatibilities of nanofibrous scaffolds were tested with L2929 murine fibroblasts and improved cell adhesion and proliferation was observed with polymer blends compared with PCL only. The primary cell culture was performed with dorsal root ganglia (DRG) cells on nanofibrous samples and the samples were found suitable for enhancing neural growth and neurite outgrowth. Based on these results, the BC/PCL (50:50 wt.%) nanofibrous scaffolds exhibited nerve-like branching and are excellent candidate for potential biomimetic applications in nerve tissue engineering regeneration.Publication Open Access A drug-eluting nanofibrous hyaluronic acid-keratin mat for diabetic wound dressing(2022-01-01) EKREN, NAZMİ; GÜNDÜZ, OĞUZHAN; Su S., Bedir T., KALKANDELEN C., Sasmazel H. T. , Basar A. O. , Chen J., EKREN N., GÜNDÜZ O.© 2022, Qatar University and Springer Nature Switzerland AG.Diabetes mellitus is a chronic metabolic disease associated with long-term multisystem complications, among which are non-healing diabetic foot ulcers (DFUs). Electrospinning is a sophisticated technique for the preparation of polymeric nanofibers impregnated with drugs for wound healing, burns, and diabetic ulcers. This study describes the fabrication and characterization of a novel drug-eluting dressing made of core–shell structured hyaluronic acid (HA)–keratin (KR)-polyethylene oxide (PEO) and polycaprolactone (PCL) nanofibers to treat diabetic wounds. The core–shell nanofibers produced by the emulsion electrospinning technique provide loading of metformin hydrochloride (MH), HA, and KR in the core of nanofibers, which in return improves the sustained long term release of the drug and prolongs the bioactivity. Morphological and chemical properties of the fibers were examined by SEM, FTIR, and XRD studies. It was observed that the fibers which contain HA and KR showed thin fiber structure, greater swelling capacity, fast degradation and increased cumulative drug release amount than neat emulsion fibers due to the hydrophilic nature of HA and KR. MH showed a sustained release from all fiber samples over 20 days and followed the first-order and Higuchi model kinetics and Fickian diffusion mechanism according to kinetic analysis results. In vitro cell culture studies showed that the developed mats exhibited enhanced biocompatibility performance with HA and KR incorporation. The results show that HA and KR-based emulsion electrospun fiber mats are potentially useful new nanofiber-based biomaterials in their use as drug carriers to treat diabetic wounds.Publication Metadata only Cell studies on Electrohydrodynamic (EHD)-3D-bioprinted Bacterial Cellulose\Polycaprolactone scaffolds for tissue engineering(ELSEVIER SCIENCE BV, 2019) EKREN, NAZMİ; Altun, Esra; Ekren, Nazmi; Kuruca, Serap Erdem; Gunduz, OguzhanThe application of three-dimensional (3D) printed scaffolds for tissue engineering have gained significant attention in recent years. The biological activity of scaffolds used in tissue engineering applications depends on fabricating high-resolution patterns with fiber orientation and scale. In this study, Bacterial Cellulose (BC) and Polycaprolactone (PCL) composite scaffolds with the line spacing of 100 mu m are produced using Electrohydrodynamic (EHD)-3D-bioprinting technique. The composite scaffolds exhibit enhanced biocompatibility with facilitated cell attachment and proliferation in vitro. The results of this work have demonstrated that EHD-3D-bioprinting method shows great potential for the preparation of BC/PCL composite scaffold and patterns for tissue engineering with enhanced bioactivity. (C) 2018 Published by Elsevier B.V.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 Production and Characterization of Antimicrobial Electrospun Nanofibers Containing Polyurethane, Zirconium Oxide and Zeolite(SPRINGER, 2018) OKTAR, FAİK NÜZHET; Aydogdu, Mehmet Onur; Oprea, Alexandra Elena; Trusca, Roxana; Surdu, Adrian Vasile; Ficai, Anton; Holban, Alina Maria; Iordache, Florin; Paduraru, Andrei Viorel; Filip, Diana Georgiana; Altun, Esra; Ekren, Nazmi; Oktar, Faik Nuzhet; Gunduz, OguzhanIn this study, electrospinning technique has been utilized to prepare composite nanofiber mats of polyurethane (PU)/zirconium dioxide (ZrO2) and PU/zeolite, consisted by antimicrobial properties. Tensile strength measurement test was performed for the mechanical analysis of the nanofibers. Scanning electron microscopy (SEM) were performed for displaying the morphological features of the fiber structure. XRD tests were performed for revealing the chemical structure. Antimicrobial tests were also performed to display antimicrobial effects of the produced materials. In vitro test was also performed to determine cytotoxicity and biocompatibility. The present PU/ZrO2 and PU/zeolite composite nanofibers resulted with improved mechanical properties and good antimicrobial properties against either their pure forms or other studies. Cell proliferation and viability also increased significantly with increase in zeolite and ZrO2 ratio. It is concluded that this composition provides a novel alternative as an antimicrobial material which can be suitable as a wound dressing or a coating material for various healthcare engineering applications.Publication Open Access Levodopa-Loaded 3D-Printed Poly (Lactic) Acid/Chitosan Neural Tissue Scaffold as a Promising Drug Delivery System for the Treatment of Parkinson's Disease(MDPI, 2021-11-13) ŞAHİN, ALİ; Saylam, Ezgi; Akkaya, Yigit; Ilhan, Elif; Cesur, Sumeyye; Guler, Ece; Sahin, Ali; Cam, Muhammmet Emin; Ekren, Nazmi; Oktar, Faik Nuzhet; Gunduz, Oguzhan; Ficai, Denisa; Ficai, AntonParkinson's disease, the second most common neurodegenerative disease in the world, develops due to decreased dopamine levels in the basal ganglia. Levodopa, a dopamine precursor used in the treatment of Parkinson's disease, can be used as a drug delivery system. This study presents an approach to the use of 3D-printed levodopa-loaded neural tissue scaffolds produced with polylactic acid (PLA) and chitosan (CS) for the treatment of Parkinson's disease. Surface morphology and pore sizes were examined by scanning electron microscopy (SEM). Average pore sizes of 100-200 mu m were found to be ideal for tissue engineering scaffolds, allowing cell penetration but not drastically altering the mechanical properties. It was observed that the swelling and weight loss behaviors of the scaffolds increased after the addition of CS to the PLA. Levodopa was released from the 3D-printed scaffolds in a controlled manner for 14 days, according to a Fickian diffusion mechanism. Mesenchymal stem cells (hAD-MSCs) derived from human adipose tissue were used in MTT analysis, fluorescence microscopy and SEM studies and confirmed adequate biocompatibility. Overall, the obtained results show that PLA/CS 3D-printed scaffolds have an alternative use for the levodopa delivery system for Parkinson's disease in neural tissue engineering applications.Publication Metadata only Patch-Based Technology for Corneal Microbial Keratitis(Springer, 2020) AKSU, MEHMET BURAK; Ulag S., Ilhan E., Aksu B., Sengor M., Ekren N., Kilic O., Gunduz O.Corneal opacities, which happened mainly due to microbial keratitis, are the fourth cause of blindness worldwide. Antimicrobial therapy is an alternative solution for microbial keratitis caused by Staphylococcus aureus and Pseudomonas Aeruginosa. The aim of this study, to develop patches for the treatment of corneal keratitis which caused significant corneal blindness by using electrospinning method. Polyvinyl-alcohol (PVA) patches with Gelatine (GEL) studied in various ratios. Different amounts of gelatine added to PVA to resemble the collagen fibril structure of the cornea. To enable the patches to the antimicrobial effect against the bacterias, the special plant extract was used. The produced corneal patches were examined separately for chemical, morphological, and antimicrobial properties. Scanning electron microscope (SEM), Fourier-transform infrared (FT-IR) spectroscopy were performed to observe the surface morphology and chemical structure of the patches, respectively. © Springer Nature Switzerland AG 2020.Publication Metadata only Effect of yttria-doping on mechanical properties of bovine hydroxyapatite (BHA)(SAGE PUBLICATIONS LTD, 2008) OKTAR, FAİK NÜZHET; Gunduz, O.; Daglilar, S.; Salman, S.; Ekren, N.; Agathopoulos, S.; Oktar, F. N.Sintered bodies of hydroxyapatite, derived from calcinated bovine bone (BHA) and doped with 0.5 and 1wt% Y2O3, were prepared. Measurements of density, compression strength, and microhardness, along with scanning electron microscopy (SEM) and X-ray diffraction (XRD) were carried out. The experimental results showed that BHA doping with yttria favors formation of glassy phase, which advances sintering and results in a dense and reinforced BHA matrix. The best mechanical properties were achieved after sintering at 1200 degrees C for compressive strength (82 MPa) and 1300 degrees C for microhardness (672 HV). These results are better than pure BHA or composites of hydroxyapatite with Y2O3-stablized zirconia, qualifying yttria (as dopant of BHA) for further in vitro and in vivo experimentation.