Yazar "Gungor, Zeynep" seçeneğine göre listele

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    A New Approach to Synthesis of Highly Dispersed Gold Nanoparticles via Glucose Oxidase-Immobilized Hydrogel and Usage in The Reduction of 4-Nitrophenol
    (Wiley-V C H Verlag Gmbh, 2020) Ozay, Hava; Tarimeri, Nur; Gungor, Zeynep; Demirbakan, Burcak; Ozcan, Burcu; Sezgintürk, Mustafa Kemal; Özay, Özgür
    In this study, for the first time in the literature, synthesis of Au(0) nanoparticles supported by a crosslinked gel structure was performed via enzyme-mediated reduction of Au(III) ions without using any chemical reductant. In our newly-developed method, glucose oxidase enzymes immobilized in the crosslinked gelatine structure ensured simultaneous reduction of the Au(III) ions diffused within the gel to Au(0). The Au@Gel obtained was structurally characterised with TEM (Transmission electron microscopy), EDX (Energy dispersive X-ray analysis) elemental mapping, XPS (X-Ray photoelectron spectroscopy) and XRD (X-Ray Diffraction) analyses. The catalytic activity of Au(0) particles with nearly 8 nm size in the Au@Gel was investigated for the reduction of 4-nitrophenol (4-NP) as a model compound in the presence of NaBH(4)as reducing agent. The activation parameters for the reduction reaction of 4-nitrophenol in the presence of Au@Gel catalyst were determined as E-a= 30.16 kJmol(-), Delta H= 27.52 kJmol(-)and Delta S= -197.45 Jmol(-)K(-). The Au@Gel catalyst system, with good catalytic activity, simultaneously has nearly perfect reusability.
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    Dual use of colorimetric sensor and selective copper removal from aqueous media with novel p(HEMA-co-TACYC) hydrogels: Cyclen derivative as both monomer and crosslinker
    (Elsevier, 2020) Ozay, Hava; Gungor, Zeynep; Yilmaz, Betul; Ilgin, Pinar; Özay, Özgür
    Within the scope of this study, p(2-hydroxyethyl methacrylate-co-tetraacrylic cyclen) (p(HEMA-co-TACYC)) hydrogels were synthesized for the first time in the literature using a tetraacrylic cyclen (TACYC) as both functional monomer and crosslinker. The hydrogels designed especially for Cu2+ ions showed colorimetric sensor behavior selective for Cu2+ ions in all aqueous media (deionized, tap, river and sea water) and in metal ion mixtures. The p(HEMA-co-TACYC) hydrogels forming a stable complex with Cu2+ ions simultaneously showed properties of being a good adsorbent material. The hydrogels have reuse capacity as both sensor and adsorbent material. Changing the amount of TACYC in the hydrogel structure changes the maximum adsorption capacity for Cu2+ ions. The Langmuir and Freundlich adsorption constants for Cu2+ ion adsorption of the hydrogels, acting as selective adsorbent in all aqueous media and metal ion mixtures, were determined.
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    Synthesis of new type temperature and pH sensitive hydrogels using drug-based p-(methacryloyloxy)acetanilide monomer and their usage as controlled drug carrier material
    (Taylor & Francis Inc, 2022) Gungor, Zeynep; Ozay, Hava
    In our study, as a functional monomer, p-(methacryloyloxy)acetanilide (MOAA) was synthesized and utility in hydrogel systems with various commercial monomers after the structural characterization was analyzed. In terms of temperature sensitivity and suitability for use in biological applications, N-isopropyl acrylamide (NIPAm) monomer and pH-sensitive acrylic acid (AAc) monomer were chosen among the commercial monomers. To the best of our knowledge, p(N-isopropyl acrylamide-co-p-(p-methacryloyloxy)acetanilide) (GEL 5) and p(N-isopropyl acrylamide-co-acrylic acid-co-p-(p-methacryloyloxy)acetanilide) (GEL 8) were synthesized in the form of a film with the free radical polymerization technique for first time in the literature. The structural characterizations and surface morphologies of the hydrogels p(NIPAm) (GEL 1), p(NIPAm-co-MOAA) (GEL 5), and p(NIPAm-co-AAc-co-MOAA) (GEL 8) were investigated by using the techniques of FTIR spectroscopy and scanning electron microscope (SEM). Moreover, the thermal resistance of all three hydrogels was brightened by the thermal gravimetric analysis (TGA). Swelling behaviors in different environments of the MOAA-based hydrogels, prepared as pH and temperature-sensitive, were examined, and biomedical applications are occurred by the investigation of the usability as a controlled drug delivery material. For this purpose, sodium diclofenac (NaDc) drug, used in pain and inflammation treatment, was chosen. In vitro release of NaDc from the drug-loaded hydrogel was examined in pH 5.5 (PBS) and pH 7.4 (PBS) media. Korsmeyer-Peppas model was used in defining the drug release mechanism.
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    Öğe
    The preparation of various shapes and porosities of hydroxyethyl starch/p(HEMA-co-NVP) IPN hydrogels as programmable carrier for drug delivery
    (Taylor & Francis Inc, 2020) Özay, Özgür; Ilgin, Pinar; Ozay, Hava; Gungor, Zeynep; Yilmaz, Betul; Kivanc, Mehmet Riza
    This study used biocompatible and biodegradable hydroxyethyl starch (HES), 2-hydroxyethyl methacrylate (HEMA) and N-vinyle-2-pyrrolidone (NVP) monomers for hydrogel synthesis with the aim of use as a drug carrier system. As a result of the synthesis reactions using the redox polymerization technique, hydrogels were produced in both film and cylindrical form. The morphological characterization and structural characterization of hydrogels were performed using scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. In addition, swelling characterizations of hydrogels to be used for drug release in various media were examined. The release properties of sodium diclofenac (NaDc) and trimethoprim (TMP) loaded into hydrogels produced in order to use as drug carrier material for controlled drug release were examined in media with pH = 1.2 and 7. It was determined that the hydrogels performed controlled release according to the type of drug and the pH values of the medium. Drug release mechanisms deviated from Fickian mode according to determined drug release rate constants, diffusion exponent (n) and regression values at different pH values. In addition, antibacterial properties of drug-loaded hydrogels against B. subtilus, S. aureus and E. coli were investigated.
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    Ultra-fast pH determination with a new colorimetric pH-sensing hydrogel for biomedical and environmental applications
    (Elsevier, 2022) Gungor, Zeynep; Ozay, Hava
    In this study that demonstrates many firsts in the literature, the acrylate derivative (BTBm) of bromothymol blue, retaining its indicator feature, was synthesized as a monomer via using an organic indicator bromothymol blue (BTB). After the structural characterization of BTBm synthesized by ourselves for the first time, copolymeric hydrogel systems were formed with three different commercial monomers in cationic (3-Acrylamidopropyl-tri-methylammonium chloride / APTMACl), anionic (3-Sulfopropyl acrylate potassium salt / SPA) and neutral (acrylamide / AA) structures. Structural characterization of BTBm-based hydrogels, which was successfully synthesized by using a 0.5% methylene bisacrylamide (MBA) crosslinker, was elucidated by FT-IR spectroscopy. The morphological structures and elemental compositions of the hydrogels were examined by SEM and EDX elemental mapping analyses. The color changes of BTBm-based hydrogels, which are intended to be used as colorimetric pH sensors, were examined in different pH environments both with naked-eye and by using a UV-Vis spectrophotometer. It has been observed that APTMACl-BTBm hydrogel can be a more beneficial colorimetric pH sensor material than other BTBm-based hydrogels in terms of its ability to respond to pH changes in a wide color range, short response time, and mechanical strength performance.
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    Öğe
    Use of cationic p[2-(acryloyloxy)ethyl] trimethylammonium chloride in hydrogel synthesis and adsorption of methyl orange with jeffamine based crosslinker
    (Taylor & Francis Inc, 2023) Gungor, Zeynep; Ozay, Hava
    In this study, a noncommercial polyetheric-structured jeffamine-based crosslinker was used by being synthesized in the synthesis of a hydrogel of a cationic-structured p[2-(acryloyloxy)ethyl] trimethylammonium chloride p(AETAC). The hydrogels containing crosslinkers with five various percentages (0.1, 0.25, 0.75, 1) were synthesized and were aimed to be used as an adsorption material. For the applications, a 1% crosslinked hydrogel (GEL 5) was utilized for the adsorption of a mono-azo chemically structured anionic characterized methyl orange (C14H14N3NaO3S) (MO) colorant. The structure of the jeffamine-based crosslinker was inspired by FT-IR, H-1-NMR, C-13-NMR, and LC-MS analysis, while the hydrogel structure characterization was elucidated by FT-IR spectroscopy. The morphological structure of the hydrogel was examined using scanning electron microscopy (SEM), SEM-EDX, and elemental mapping methods. Concurrently, the mechanical resistance of GEL 5 was tested, and its swelling behavior was examined in different media and pH values. GEL 5, considered decent adsorbent material owing to its structural qualifications, was used in the toxic MO dye adsorption process. In adsorption studies, the maximum qe value of the GEL 5 hydrogel was 547.34 +/- 40.00 mg/g in 1000 mg/L MO dye solution. Furthermore, desorption studies have shown that it has reusability, which is a crucial factor in adsorbent selection.