Person: MUTLU, ÖZAL
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MUTLU
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ÖZAL
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Publication Open Access Experimentation and analysis of powder injection molded Ti10Nb10Zr alloy: a promising candidate for electrochemical and biomedical application(ELSEVIER, 2019-11) GÜLSOY, HAMİT ÖZKAN; Yemisci, Isil; Mutlu, Ozal; Gulsoy, Nagihan; Kunal, Kate; Atre, Sundar; Gulsoy, H. OzkanThis paper describes the microstructural, mechanical and corrosion properties of injection molded Ti10Nb10Zr alloys. T10Nb10Zr powder was injection molded with wax-based binder. The critical powder loading for injection molding was 55 vol% for feedstock. Binder debinding was performed in solvent and thermal method. After debinding the samples were sintered at different temperatures and times in vacuum atmosphere (10-5 mbar) to obtain fully dense parts. Metallographic studies were conducted to determine the extent of densification and the corresponding microstructural changes. The electrochemical property and biocompatibility of the sintered samples were performed electrochemically, by selfbody -fluid immersion tests and cell culture experiments. The results show that Ti10Nb10Zr alloys could be sintered to a maximum 99% of theoretical density. Maximum ultimate tensile strength, elongation and hardness obtained were 748 MPa, 14.3 and 114 HRB respectively at 1500 degrees C for 3 h. Additionally, the sintered i10Nb10Zr alloys exhibited high mechanical and corrosion properties in a physiological environment. (C) 2019 The Author. Published by Elsevier B.V.Publication Metadata only Effect of Zr, Nb and Ti addition on injection molded 316L stainless steel for bio-applications: Mechanical, electrochemical and biocompatibility properties(ELSEVIER SCIENCE BV, 2015) GÜLSOY, HAMİT ÖZKAN; Gulsoy, H. Ozkan; Pazarlioglu, Serdar; Gulsoy, Nagihan; Gundede, Busra; Mutlu, OzalThe research investigated the effect of Zr, Nb and Ti additions on mechanical, electrochemical properties and biocompatibility of injection molded 316L stainless steel. Addition of elemental powder is promoted to get high performance of sintered 316L stainless steels. The amount of additive powder plays a role in determining the sintered microstructure and all properties. In this study, 316L stainless steel powders used with the elemental Zr, Nb and Ti powders. A feedstock containing 62.5 wt% powders loading was molded at different injection molded temperature. The binders were completely removed from molded components by solvent and thermal debinding at different temperatures. The debinded samples were sintered at 1350 degrees C for 60 min. Mechanical, electrochemical property and biocompatibility of the sintered samples were performed mechanical, electrochemical, SBF immersion tests and cell culture experiments. Results of study showed that sintered 316L and 316L with additives samples exhibited high corrosion properties and biocompatibility in a physiological environment. (C) 2015 Elsevier Ltd. All rights reserved.Publication Metadata only Novel hydroxyapatite/graphene oxide/collagen bioactive composite coating on Ti16Nb alloys by electrodeposition(ELSEVIER SCIENCE BV, 2019) GÜLSOY, HAMİT ÖZKAN; Yilmaz, Eren; Cakiroglu, Bekir; Gokce, Azim; Findik, Fehim; Gulsoy, H. Ozkan; Gulsoy, Nagihan; Mutlu, Ozal; Ozacar, MahmutA novel implant coating material containing graphene oxide (GO) and collagen (COL), and hydroxyapatite (HA) was fabricated with the aid of tannic acid by electrodeposition. The surface of Ti16Nb alloy was subjected to anodic oxidation, and then HA-GO coating was applied to Ti16Nb surface by cathodic method. Then, COL was deposited on the surface of the HA-GO coating by the biomimetic method. HA, HA-GO, HA-GO-COL coatings on the surface of the Ti16Nb alloy have increased the corrosion resistance by the formation of a barrier layer on the surface. For HA-GO-COL coating, the highest corrosion resistance is obtained due to the compactness and homogeneity of the coating structure. The contact angle of the bare Ti16Nb is approximately 65 degrees, while the contact angle of the coated samples is close to 0 degrees. Herein, the increased surface wettability is important for cell adhesion. The surface roughness of the uncoated Ti16Nb alloy was between 1 and 3 mu m, while the surface roughness of the coated surfaces was measured between 20 and 110 mu m. The contact between the bone and the implant has been improved. Graphene oxide-containing coatings have improved the antibacterial properties compared to the GO-free coating using S. aureus. The hardness and elastic modulus of the coatings were measured by the nanoindentation test, and the addition of GO and collagen to the HA coating resulted in an increase in strength. The addition of GO to the HA coating reduced the viability of 3 T3 fibroblast cells, whereas the addition of collagen to HA-GO coat increased the cell adhesion and viability.Publication Open Access Toxicity of cadmium based and cadmium free quantum dots in primary cultured zebrafish hepatocytes(2020-07-01) BİLGİSEVEN, IRMAK; MUTLU, ÖZAL; GÜLSOY, NAGİHAN; Kaluç N., Bilgiseven I., Mutlu Ö., Gülsoy N.Quantum Dots (QDs) are one of the most im-portant nanomaterials in nanotechnology owing to their unique physicochemical properties. A conven-tional QD contains Cd2+ in its core and in order to reduce its toxicity Cd-core/ZnS-shell and Cd-free QDs were produced. However, ZnS shell was not found as protective as predicted. Also, still not much is known about the toxicity of Cd-free QD. In this paper, we evaluated and compared the cytotoxicity and genotoxicity of three types of QDs (Cd-based core, Cd-based core/shell, and Cd-free QDs) in pri-mary cultured zebrafish hepatocytes. We show that Cd-based QDs significantly decreased cell viability whereas Cd-Free QDs caused a significant increase in cell viability in 24h. Moreover, ZnS shell reduced Cd2+ ion release into the cell but did not effectively prevent the cell from cytotoxic or genotoxic effects of the QD. Although the effects of Cd-based and Cd-Free QDs on cell viability were different, they both induced reactive oxygen species (ROS) production, DNA strand breaks and Rad51 downregulation in primary cultured zebrafish hepatocytes, revealing that they induce oxidative stress in these cells. To the best of our knowledge, this is the first report on the comparative toxicity evaluation of Cd-based with core and core/shell type, Cd-free QDs and CdCl2 by assessing ROS production, DNA damage and Rad51 expression.Publication Metadata only Preparation and antimicrobial properties of LL-37 peptide immobilized lignin/caprolactone polymer film(WILEY, 2020) OGAN, AYŞE; Ogan, Ayse; Yuce-Dursun, Basak; Abdullah, Deka; Beyler-Cigil, Asli; Kahraman, Memet Vezir; Caglayan, Pinar; Birbir, Meral; Mutlu, Ozal; Gulsoy, NagihanThe use of biopolymers has gained priority in tissue engineering and biotechnology, both as dressing material and for enhancing treatment efficiency. There is a demand for new biopolymers designed with protease inhibitors and antimicrobials. LL-37 is an important antimicrobial peptide in human skin and exhibits a broad spectrum of antimicrobial activity against bacteria, fungi, and viral pathogens. Using lignin which is an abundant carbohydrate polymer in nature and a polyacrylic acid, we prepared a lignin/caprolactone biodegradable film by plastifying caprolactone and polyacyrlic acid. Lignin/caprolactone biodegradable film was activated with CDI and then immobilized LL-37 peptide. The structure was elucidated in terms of its functional groups by attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), and the morphology of the lignin/caprolactone biodegradable film was characterized by scanning electron microscopy (SEM) before and after the immobilization process. The amount of LL-37 immobilized was determined by ELISA method. It was found that 97% of LL-37 peptide was successfully immobilized onto the lignin/caprolactone biodegradable film. Antimicrobial activity was determined in the lignin/caprolactone biodegradable film samples by quantitative antimicrobial activity method. According to the results, LL-37 immobilized lignin/caprolactone biodegradable film samples were effective on test organisms; Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. In bio-compatibility assays, the ability to support tissue cell integration was detected by using 3 T3 mouse fibroblasts. Samples were examined under transverse microscope, non-immobilized sample showed a huge cellular death, whereas LL-37 immobilized lignin/caprolactone biodegradable film had identical cellular growth with the control group. This dual functional lignin/caprolactone biodegradable film with enhanced antibacterial properties and increased tissue cell compatibility may be used to design new materials for various types of biological applications.