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ÜNAL YILDIRIM, SEMRA

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ÜNAL YILDIRIM

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2019 - 201912020 - 20231
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Subject: Biomaterials ×

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Now showing 1 - 2 of 2
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    PublicationOpen 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.
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    3D printing of chitosan/ poly(vinyl alcohol) hydrogel containing synthesized hydroxyapatite scaffolds for hard-tissue engineering
    (ELSEVIER SCI LTD, 2019) KARTAL, İLYAS; Ergul, Necdet Mekki; Unal, Semra; Kartal, Ilyas; Kalkandelen, Cevriye; Ekren, Nazmi; Kilic, Osman; Chi-Chang, Lin; Gunduz, Oguzhan
    In recent years, 3D printed scaffolds becoming a widespread tool, which supports the repair mechanism of natural tissues. In order to support this knowledge, we used 3D printing methods to fabricated Chitosan (CH)/poly(vinyl alcohol)(PVA)-based scaffolds contains with a various ratio of hydroxyapatite (HA) (2.5, 5, 10, and 15 wt%). These composited scaffolds were further characterized for their chemical, morphological, mechanical, and biocompatibility properties. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), swelling test, and compressive strength test were performed to reveal structural, mechanical and chemical characteristics of scaffolds. Among others, 15 wt% HA contained group demonstrated significantly superior and beneficial features in printing quality. Also, the results reveal that scaffolds have similar elastic modulus to natural bone. Bone morphogenetic protein-2 (BMP-2) protein was added to the most successful mechanically produced sample. As a result, it was shown that Chitosan/PVA/HA (15 wt%) with BMP-2 tissue scaffold could form a three-dimensional natural extracellular scaffold suitable for human mesenchymal stem cells. Altogether, these results show that hydroxyapatite added scaffolds produced may be a promising approach for bone tissue engineering applications.