Yazar "Kozgus, Ozge" seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Determination of calcium in milk and water samples by using catalase enzyme electrode(Elsevier Sci Ltd, 2009) Akyilmaz, Erol; Kozgus, OzgeA biosensor based on catalase enzyme was developed for the investigation of the effect of calcium ions on the activity of the enzyme. Calcium plays an activator role for the catalase enzyme that catalyses the degradation of hydrogen peroxide to 02 and H(2)O. Determination method of the effect of calcium ion on the activity of the enzyme was based on the assay of the differences on the responses of the biosensor in the absence and the presence of calcium in the reaction medium. The biosensor had a linear relation to calcium concentrations and good measurement correlation between 1 and 10 mM with 1 min response time. Tris-HCl buffer (pH 7.0; 50 mM) and 37 degrees C were obtained as the optimum working conditions. In the application studies, the biosensor was used determination of calcium level of real samples such as milk, spring and mineral water. (c) 2008 Elsevier Ltd. All rights reserved.Öğe Determination of calcium in milk and water samples by using catalase enzyme electrode(Elsevier Sci Ltd, 2009) Akyilmaz, Erol; Kozgus, OzgeA biosensor based on catalase enzyme was developed for the investigation of the effect of calcium ions on the activity of the enzyme. Calcium plays an activator role for the catalase enzyme that catalyses the degradation of hydrogen peroxide to 02 and H(2)O. Determination method of the effect of calcium ion on the activity of the enzyme was based on the assay of the differences on the responses of the biosensor in the absence and the presence of calcium in the reaction medium. The biosensor had a linear relation to calcium concentrations and good measurement correlation between 1 and 10 mM with 1 min response time. Tris-HCl buffer (pH 7.0; 50 mM) and 37 degrees C were obtained as the optimum working conditions. In the application studies, the biosensor was used determination of calcium level of real samples such as milk, spring and mineral water. (c) 2008 Elsevier Ltd. All rights reserved.Öğe Gold nanoparticle probes: Design and in vitro applications in cancer cell culture(Elsevier Science Bv, 2012) Unak, Gulcan; Ozkaya, Feriha; Medine, E. Ilker; Kozgus, Ozge; Sakarya, Serhan; Bekis, Recep; Unak, Perihan; Timur, SunaA new architecture has been designed by the conjugation of [(18)F]2-fluoro-2-deoxy-D-glucose ((18)F-FDG), gold nanoparticles (AuNPs), and anti-metadherin (Anti-MTDH) antibody which is specific to the metadherin (MTDH) over-expressed on the surface of breast cancer cells. Mannose triflate molecule is used as a precursor for synthesis of (18)F-FDG by nucleophilic fluorination. For the conjugation of (18)F-FDG and AuNPs, cysteamine was first bound to mannose triflate (Man-CA) before synthesizing of (18)F-FDG which has cysteamine sides ((18)FDG-CA). Then, (18)FDG-CA was reacted with HAuCl(4) to obtain AuNPs and with NaBH(4) for reduction of AuNPs. At the end of this procedure. AuNPs were conjugated to (18)F-FDG via disulphide bonds ((18)FDG-AuNP). For the conjugation of Anti-MTDH, 1,1'-carbonyl diimidazol (CDI) was bound to the (18)FDG-AuNP, and Anti-MTDH was conjugated via CDI ((18)FDG-AuNP-Anti-MTDH). This procedure was also performed by using Na(19)F to obtain non-radioactive conjugates ((19)FDG-AuNP-Anti-MTDH). Scanning electron microscopy (SEM) images demonstrated that synthesized particles were in nano sizes. (18)FDG-AuNP-Anti-MTDH conjugate was characterized and used as a model probe containing both radioactive and optical labels together as well as the biological target. The (18)FDG-AuNP-Anti-MTDH conjugate was applied to MCF7 breast cancer cell line and apoptotic cell ratio was found to be increasing from 2% to 20% following the treatment. Hence, these results have promised an important application potential of this conjugate in cancer research. (C) 2011 Elsevier B.V. All rights reserved.Öğe A mediated polyphenol oxidase biosensor immobilized by electropolymerization of 1,2-diamino benzene(Elsevier Science Sa, 2010) Akyilmaz, Erol; Kozgus, Ozge; Turkmen, Hayati; Cetinkaya, BekirA biosensor based on a partially purified polyphenol oxidase (PPO) enzyme was developed by using electropolymerization of [(2,2'-bipyridine)(chloro)(p-cymene)rutenium(II)]chloride] mediator complex and 1,2-diamino benzene (DAB) on a screen printing Pt electrode (1 mm diameter). The electropolymerization was carried out at +0.7 V for 45 min in phosphate buffer (50 mM, pH 7.0) which contained 14.0 U/10 mL polyphenole oxidase, 200 mM DAB and 2.5 mM Ru-mediator complex solutions. Measurement is based on the detection of the oxidation current of the Ru-mediator complex that related to the enzymatic reaction catalyzed by PPO at +0.65 V. The phosphate buffer (50 mM, pH 7.0 containing 0.1 M KCl) and 30 degrees C were established as being the optimum working conditions. Under the optimum experimental conditions a linear calibration curve was obtained between 5 and 100 mu M catechol concentration. The detection limit of the biosensor is 2.385 mu M. In the characterization studies of the biosensor some parameters such as effect of Ru-mediator types on the biosensor response, substrate specificity, reproducibility and storage stability were studied. From the experiments, the average value (x), standard deviation (SD) and coefficient of variation (CV%) were found to be 48.75 mu M, 1.56 mu M, and 3.2% respectively for 50 mu M catechol standard. (C) 2009 Elsevier B.V. All rights reserved.Öğe The synthesis and targeting of PPP-type copolymers to breast cancer cells: Multifunctional platforms for imaging and diagnosis(Royal Soc Chemistry, 2012) Colak, Demet Goen; Cianga, Ioan; Demirkol, Dilek Odaci; Kozgus, Ozge; Medine, E. Ilker; Sakarya, Serhan; Unak, Perihan; Timur, Suna; Yagci, YusufHerein, we demonstrate the synthesis and application of water-soluble, biomolecule conjugated PPP copolymers bearing poly(ethylene glycol) (PEG) side chains as fluorescent probes for the in vitro imaging of cancer cells. The targeting of fluorescent polymers to breast cancer cells allows effective visualization and discrimination of MCF7 cells from human mammary epithelial cells. Furthermore, these materials are also suitable for efficient radiolabeling via I-125 which enables dual-modality holding the possibility of both radioactive and fluorescence imaging in cancer diagnosis applications.