Person: OGAN, AYŞE
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OGAN
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AYŞE
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Publication Metadata only Preparation and drug release properties of lignin-starch biodegradable films(WILEY-V C H VERLAG GMBH, 2012) OGAN, AYŞE; Calgeris, Ilker; Cakmakci, Emrah; Ogan, Ayse; Kahraman, M. Vezir; Kayaman-Apohan, NilhanStarch is one of the most commonly available natural polymers which are obtained from agro-sources. It is renewable and abundant in nature. Unfortunately due to its poor mechanical properties and hygroscopic nature, there are some strong limitations to the development of starch-based products. Usually blends of starch are prepared and plasticized with glycerol to improve some of its properties. In this study, lignin was extracted from hazelnut shells and investigated as a potential additive for starch biofilms. The structural characterization of hazelnut lignin was performed by employing UV spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Lignin was blended with corn starch in different ratios to obtain biofilms. Mechanical and thermal properties of the biofilms were enhanced as the lignin amount was increased in the formulations. Water absorption tests were performed at pH 2.0, 4.0, and 6.0. The percent swelling values of the starch/lignin films increased as pH increased. Also, the biofilm exhibiting the best properties was chosen for the drug release studies. Biofilms showed a fast ciprofloxacin (CPF) release within an hour and then the drug release rate decreased. A pH dependent drug release mechanism was also observed according to KoshnerPeppas model. The drug release increased with a decrease in pH.Publication Metadata only Soybean oil based resin: A new tool for improved immobilization of alpha-amylase(WILEY, 2006) OGAN, AYŞE; Kahraman, MV; Kayaman-Apohan, N; Ogan, A; Gungor, AAcrylated epoxidized soybean resin has been utilized to immobilize the alpha-amylase via UV-curing technique. Among the numerous methods that exist for enzyme immobilization, entrapment and covalent binding are the focus of this study. The properties of immobilized enzyme were investigated and compared with those of the free enzyme. Upon immobilization by the two methods, the catalytic properties of the enzyme were not considerably changed as compared with that of nonimmobilized form; enzyme. The free enzyme lost its activity completely in 20 days, where as storage and repeated usage capability experiments demonstrated higher stability for the immobilized form. Immobilized enzyme prepared by attachment method possesses relatively higher activity compared with the activity of those obtained by entrapment method. (c) 2006 Wiley Periodicals, Inc.Publication Metadata only Preparation, characterization, and drug release properties of poly(2-hydroxyethyl methacrylate) hydrogels having beta-cyclodextrin functionality(JOHN WILEY & SONS INC, 2008) OGAN, AYŞE; Demir, Serap; Kahraman, M. Vezir; Bora, Nil; Apohan, Nilhan Kayaman; Ogan, AyseA new beta-cyclodextrin urethane-methacrylate monomer was synthesized from the reaction of toluene-2,4-diisocyanate, 2-hydroxyethyl methacrylate (HEMA), and beta-cyclodextrin (beta-CD). Based on inclusion character of beta-CD, a series of hydrogels were prepared by irradiating the mixtures of beta-cyclodextrin urethane-methacrylate monomer (beta-CD-UM), poly(ethylene glycol) diacrylate (PEG-DA), HEMA, and the photoinitator. Gel percentages and equilibrium swelling ratios (%) of hydrogels were investigated. It was observed that the equilibrium-swelling ratio increased with increasing beta-CD-UM content in the hydrogel composition. SEM images demonstrated that beta-CD-UM based hydrogel have porous fractured surface. In this study four different drug molecules, salicylic acid, sulfathiazole, rifampicin, and methyl orange as model drug, which are capable of forming inclusion complexes with beta-CD were chosen. For sulfathiazole and rifampicin, the drug loadings are very low (0.04 and 0.008 mmol/g dry gel), whereas methyl orange and salicylic acid drug uptakes are found as 0.15 and 0.18 mmol/g dry gel, respectively. The incorporation of beta-CD-UM comonomer into the gel slightly reduces the methyl orange and salicylic acid releases. However, a significant enhancement was achieved in the case of sulfathiazole delivery. It can be concluded that the inclusion complex formation capability of beta-CD moiety increases the drug release by improving the aqueous solubility of hydrophobic drugs. On the other hand, in the case of hydrophilic drugs, the drug release retards by forming strong drug-beta-CD complex and reducing the drug diffusivity. (C) 2008 Wiley Periodicals, Inc.Publication Metadata only Intrinsic factor and vitamin B12 complex-loaded poly[lactic-co-(glycolic acid)] microspheres: preparation, characterization and drug release(WILEY, 2008) OGAN, AYŞE; Demir, Serap; Ogan, Ayse; Kayaman-Apohan, NilhanBACKGROUND: Vitamin B12 is an essential vitamin required by all mammals. Absorption of vitamin B12 is facilitated by binding of intrinsic factor-vitamin B12 complex to specific receptors in the ileum. In humans a deficiency of this vitamin or a lack of intrinsic factor leads to pernicious anaemia. The major objective of the present study was to prepare intrinsic factor-vitamin B12 complex-loaded poly[lactic-co-(glycolic acid)] (PLGA)-based microparticles and to investigate their release kinetics. RESULTS: PLGA copolymer was synthesized by the ring-opening polymerization method and characterized using gel permeation chromatography, Fourier transform infrared spectroscopy and H-1 NMR. The glass transition temperature measurement showed a single T-g at 40 degrees C. The intrinsic factor-vitamin B12 complex-loaded PLGA microspheres were prepared by a water-in-oil-in-water double emulsion solvent extraction/evaporation technique. An environmental scanning electron microscopy investigation demonstrated that the PLGA particles had a mean particle diameter of 38 gm. Interestingly, different drug release patterns (bi- and triphasic ones) were observed for vitamin B12-loaded and intrinsic factor-vitamin B12 complex-loaded microspheres. In contrast to the rapid release of vitamin B12 by itself, in vitro release tests showed that intrinsic factor and vitamin B12 in the complex were released from PLGA microspheres in a sustained manner over 15 days. CONCLUSION: PLGA microspheres can be an effective carrier for the intrinsic factor-vitamin B12 complex. (C) 2007 Society of Chemical Industry.