Researcher: Gidon, Doğan
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Gidon, Doğan
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Publication Metadata only Photocrosslinking of styrene-butadiene-styrene (SBS) networks formed by thiol-ene reactions and their influence on cell survival(IOP Publishing Ltd, 2015) Department of Chemical and Biological Engineering; N/A; Department of Chemical and Biological Engineering; Gidon, Doğan; Aydın, Derya; Kızılel, Seda; Researcher; Researcher; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; N/A; College of Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; N/A; 28376Styrene-butadiene-styrene (SBS) triblock copolymer has been conventionally used as synthetic rubber. However, the potential of SBS for biomedical applications has only been considered in limited earlier reports. Here, we demonstrate an effective approach to designing a photocrosslinked SBS network. Rheological analysis has been conducted for the investigation of the storage modulus of the resultant network. Crosslinked SBS networks were synthesized and characterized through optical and electron microscope imaging. The crosslink density of the network, calculated from swelling experiments, was 643 mol m(-3), where higher swelling in a hydrophobic medium was observed compared to the swelling measured in water. Cell survival analysis with HeLa cells and NIH/3T3 fibroblasts revealed that these networks are non-toxic, and that they could be considered for a variety of biomedical applications.Publication Metadata only Visible-light-induced synthesis of pH-responsive composite hydrogels for controlled delivery of the anticonvulsant drug pregabalin(Elsevier Sci Ltd, 2015) N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Çevik, Özlem; Gidon, Doğan; Kızılel, Seda; N/A; Undergraduate; Faculty Member; Department of Chemical and Biological Engineering; N/A; College of Engineering; College of Engineering; N/A; N/A; 28376We report here a novel method for the synthesis of a pH-responsive composite using visible light. Formation of the pH-responsive layer is based on poly(methacrylic acid-g-ethylene glycol) as the macromer, eosin Y as the photoinitiator and triethanolamine as the co-initiator. The hydrogel was functionalized with hydrophobic domains through incorporation of crosslinked styrene-butadiene-styrene (SBS) copolymer into the pH-responsive prepolymer. Swelling ratios were decreased with the addition of SBS, and resulted in high hydrogel crosslink density. The composite allowed for controlled release of an anticonvulsant model drug, pregabalin, under neutral pH condition and the release was analyzed to describe the mode of transport through the network. In vitro human fibroblast survival assay and in vivo rabbit implantation experiments demonstrated that this hybrid network is not toxic and has desirable biocompatibility properties. This is the first report about the synthesis of a pH-responsive network incorporating crosslinked SBS synthesized under visible light. The approach for multifunctional membranes could allow the incorporation of molecules with specific functionalities so that sequential molecule delivery in response to specific stimuli could be achieved. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.Publication Metadata only Detection of interaction constants between biological clock proteins by Surface Plasmon Resonance(AIChE, 2012) Çakır, Bilal; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; N/A; Department of Chemical and Biological Engineering; Kızılel, Seda; Kavaklı, İbrahim Halil; Gidon, Doğan; Asımgil, Hande; Kızılel, Rıza; Kepsütlü, Burcu; Demirer, Gözde Sultan; Faculty Member; Faculty Member; Undergraduated Student; PhD Student; Researcher; Master Student; Undergraduated Student; Department of Chemical and Biological Engineering; College of Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; 28376; 40319; N/A; N/A; 114475; N/A; N/AOrganisms adopt their behaviors and physiology to the appropriate time of the day to anticipate daily environmental changes and the circadian clock regulates their daily rhythms. In mammals, the clock is present in essentially every cell. A heterodimer of CLOCK and BMAL1 proteins binds to the E-box in Per and Cry promoters and activates their transcription. In this work, we have purified core clock proteins and characterized the affinity of previously identified clock-relevant transcription factors. We have investigated the mechanism of the clock complex and the interactions of clock proteins with and without DNA using Surface Plasmon Resonance (SPR). Kinetic parameters determined from real time data bring a solid insight into the interactions of the clock proteins with their cognate promoter.