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 A review of anti-reflection and self-cleaning coatings on photovoltaic panels(PERGAMON-ELSEVIER SCIENCE LTD, 2020) EKREN, NAZMİ; Sarkin, Ali Samet; Ekren, Nazmi; Saglam, SafakThe production of electrical energy from solar energy through the photovoltaic method has become increasingly widespread throughout the world in the last 20 years. The photovoltaic energy system generates electricity depending on the amount of sunlight reaching the solar cell, and the amount of sunlight that reaches the solar cells in a solar panel decreases due to factors such as soil and organic dirt. At the same time, sunlight is refracted and reflected due to the reflective effect of the cover glass surface, even if the surface of the photovoltaic panel is clean. The remaining solar rays are broken and reach the solar cell. Decreasing sunlight also causes a decrease in electrical power output. Thus, to overcome these problems, photovoltaic solar cells and cover glass are coated with anti-reflective and self-cleaning coatings. As observed in this study, SiO2, MgF2, TiO2, Si3N4, and ZrO2 materials are widely used in anti-reflection coatings. Common methods used are sol-gel + spin-coating or + dipcoating, sputtering, DC or RF magnetron, and electrospun methods. Regarding self-cleaning applications, fabricating superhydrophobic surfaces stands out among other methods. In self-cleaning applications, Al2O3, TiO2, and Si3N4 are the most suitable materials; the double- and triple-layer coatings yield successful results in terms of surface adhesion and durability. In multi-layer anti-reflection coatings, the reflectance was reduced in studies in which materials with low and high reflection indexes were applied and light transmittance was increased.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 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 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 Investigation of light transmittance of coatings containing sio2 and tio2 nano-particle made by electrospinning technique(2022-04-07) EKREN, NAZMİ; SAĞLAM, ŞAFAK; SARKIN A. S., EKREN N., SAĞLAM Ş.The electrospinning technique is a coating method with controllable parameters. This study aims to make a coating that increases light transmission, reduces reflection, and has self-cleaning properties on laboratory slide glasses by the electrospinning method. Studies in the literature were investigated that had been used SiO2, TiO2, polymers for it. PLA and PMMA were used as polymers, SiO2 and TiO2 were used as nanoparticles, and Chloroform was used as the solvent. Solutions were prepared at different mixtures and ratios. The solutions were applied with different electrospinning parameters. The coatings were examined in terms of surface adhesion and surface distribution, and some were found to be successful. The light transmittance was the highest with 66.2% in solution-6 containing 1.6 g PLA and 0.05 g SiO2. In coatings containing SiO2 and TiO2, the light transmittance of solution-7 with 1.6 g PLA, 0.025 g SiO2, and 0.025 g TiO2 was 64.8%, and solution-10 with 2 g PLA and 0.05 g SiO2, and 0.05 g TiO2 had 64.4% light transmission.Publication Metadata only Design and fabrication of electrospun polycaprolactone/chitosan scaffolds for ligament regeneration(PERGAMON-ELSEVIER SCIENCE LTD, 2021) İNAN, AHMET TALAT; Saatcioglu, Elif; Ulag, Songul; Sahin, Ali; Yilmaz, Betul Karademir; Ekren, Nazmi; Inan, Ahmet Talat; Palaci, Yuksel; Ustundag, Cem Bulent; Gunduz, OguzhanTendon and ligament impairments are among the most familiar injuries of the knee with acute or chronic pain conditions. The defects of anterior cruciate ligament (ACL) stay a known clinical problem. In the present study, the electrospinning method was used to fabricate 10wt.%PCL/(1, 3, 5)wt.%Chitosan (CS) appropriate and biocompatible scaffolds with a similar connective ligament geometry and structure. 10wt.%PCL/3wt.%CS demonstrated higher tensile strength value (0.58854 MPa) than other scaffolds in the tensile test. Moreover, 10wt.%PCL/3wt.%CS scaffolds had high mesenchymal stem cells (MSCs) viability value for all incubation periods. Swelling and degradation behaviours of the ligament-like scaffolds were examined in vitro for 15 days. Results reported that the highest swelling ratio was observed with CS addition for 10wt.%PCL/5wt.%CS scaffolds which value nearly reached to the 270% ratio. Scanning electron microscope proved the geometry of the scaffolds, which were suitable for ligament-like tissue. Attachment of MSCs on the scaffolds proved the network-like structure of the cells on the scaffolds.Publication Open Access A Hydrophobic antireflective and antidust coating with $\text{SiO}_2$ and $\text{TiO}_2$ nanoparticles using a new 3-D printing method for photovoltaic panels(2022-07-01) EKREN, NAZMİ; SAĞLAM, ŞAFAK; Ekren N., Sarkin A. S., Sağlam Ş.The main outdoor factors that reduce the efficiency of the photovoltaic (PV) panel are the reflection and refraction of light, dirt, dust, and organic waste accumulating on the panel surface. In this article, an antireflection, self-cleaning coating was applied on the PV panel cover glass with a new method. With the coating, the surface has been given a hydrophobic feature. As a coating method, a 3-D printer has not been seen in the literature and used as a new method. The electrospinning method has also been tried as an alternative method. Solutions in different combinations were developed using polylactic acid or polymethylmethacrylate polymer, chloroform ($\text{CHCl}_3$) as a solvent, and silicon dioxide ($\text{SiO}_2$) and titanium dioxide ($\text{TiO}_2$) nanoparticles as primary materials in a modified 3-D printer for bioprinting. Five PV panels were obtained by applying different 3-D parameters from three solutions, which have the best results. Coating thicknesses are in the range of 3.12-8.47 mu m. Coated and uncoated PV panels were tested in outdoor conditions for ten-day periods. The power outputs of the PV panels were measured, and their ten-day average efficiency was presented. According to the results, the highest efficiency increase is 8.7%. The highest light transmittance is 88.2% at 550 nm. In addition, hydrophobic properties were observed on all surfaces and the water contact angle was measured as 96.18 degrees.Publication Metadata only Recent developments and characterization techniques in 3D printing of corneal stroma tissue(WILEY, 2021) ŞENGÖR, MUSTAFA; Ulag, Songul; Uysal, Ebru; Bedir, Tuba; Sengor, Mustafa; Ekren, Nazmi; Ustundag, Cem Bulent; Midha, Swati; Kalaskar, Deepak M.; Gunduz, OguzhanCorneal stroma has a significant function in normal visual function. The corneal stroma is vulnerable because of being the thickest part of the cornea, as it can be affected easily by infections or injuries. Any problems on corneal stroma can result in blindness. Donor shortage for corneal transplantation is one of the main issues in corneal transplantation. To address this issue, the corneal tissue engineering focuses on replacing injured tissues and repairing normal functions. Currently, there are no available, engineered corneal tissues for widely accepted routine clinical treatment, but new emerging 3D printing applications are being recognized as a promising option. Recent in vitro researches revealed that the biocompatibility and regeneration possessions of 3D-printed hydrogels outperformed conventional tissue engineering approaches. The goal of this review is to highlight the current developments in the characterization of 3D cell-free and bioprinted hydrogels.
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