Yazar "Saglam, Ozlem" seçeneğine göre listele

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    Biosensing of glucose in flow injection analysis system based on glucose oxidase-quantum dot modified pencil graphite electrode
    (Elsevier Science Bv, 2016) Saglam, Ozlem; Kizilkaya, Bayram; Uysal, Huseyin; Dilgin, Yusuf
    A novel amperometric glucose biosensor was proposed in flow injection analysis (FIA) system using glucose oxidase (GOD) and Quantum dot (ZnS-CdS) modified Pencil Graphite Electrode (PGE). After ZnS-CdS film was electrochemically deposited onto PGE surface, GOD was immobilized on the surface of ZnS-CdS/PGE through crosslinking with chitosan (CT). A pair of well-defined reversible redox peak of GOD was observed at GOD/CT/ZnS-CdS/PGE based on enzyme electrode by direct electron transfer between the protein and electrode. Further, obtained GOD/CT/ZnS-CdS/PGE offers a disposable, low cost, selective and sensitive electrochemical biosensing of glucose in FIA system based on the decrease of the electrocatalytic response of the reduced form of GOD to dissolved oxygen. Under optimum conditions (flow rate, 1.3 mL min(-1); transmission tubing length, 10 cm; injection volume, 100 mu L; and constant applied potential, -500 mV vs. Ag/AgCl), the proposed method displayed a linear response to glucose in the range of 0.01-1.0 mM with detection limit of 3.0 mu M. The results obtained from this study would provide the basis for further development of the biosensing using PGE based FIA systems. (C) 2015 Elsevier B.V. All rights reserved.
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    Differential pulse voltammetric determination of eugenol at a pencil graphite electrode
    (Elsevier Science Bv, 2016) Saglam, Ozlem; Dilgin, Didem Giray; Ertek, Bensu; Dilgin, Yusuf
    In this study, the electrochemical behavior of eugenol, a widely used herbal drug, was investigated at a pencil graphite electrode (PGE). A low-cost, disposable, sensitive and selective electrochemical sensor is proposed for the determination of eugenol by recording its differential pulse voltammograms in Britton-Robinson buffer solution containing 0.1 M KCl with pH of 2.0 at the PGE. The PGE displayed a very good electrochemical behavior with significant enhancement of the peak current compared to a glassy carbon electrode. Under experimental conditions, the PGE had a linear response range from 0.3 mu M to 50.0 mu M eugenol with a detection limit of 0.085 mu M (based on 3S(b)). Relative standard deviations of 2.4 and 4.8% were obtained for five successive determinations of 30.0 and 5.0 mu M eugenol, respectively, which indicate acceptable repeatability. This voltammetric method was successfully applied for the direct determination of eugenol in real samples. The effect of various interfering compounds on the eugenol peak current was also studied. (C) 2015 Elsevier B.V. All rights reserved.
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    Electrochemical behavior and voltammetric determination of some nitro-substituted benzamide compounds
    (Tubitak Scientific & Technological Research Council Turkey, 2018) Saglam, Ozlem; Comert Onder, Ferah; Gungor, Tugba; Ay, Mehmet; Dilgin, Yusuf
    Voltammetric behaviors of six nitro-substituted benzamides, which are potential prodrug candidates for nitroreductase-based cancer therapy, were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The electrochemical behavior of aromatic nitro (ArNO2) compounds by CV indicates that compounds involve various reduction/oxidation steps including the formation of aromatic nitro radical, nitroso, hydroxylamine, and amine groups. Applicability of the voltammetric determination of these prodrug candidates was studied by recording their DPVs, carried out in mixed media (Britton Robinson buffer solution + DMF) at various pH values on a pencil graphite electrode (PGE). Results show that the PGE can offer a disposable, low-cost, and sensitive electrochemical determination method for identifying nitro benzamide compounds. Under the experimental conditions, the PGE had a linear response range from 0.5 to 100 mu M 4-nitro- N-(2-nitrophenyl)benzamide (compound 2). This voltammetric procedure indicates that nitro-substituted benzamide drugs can be successfully determined in pharmaceutical samples.
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    Fabrication of Photoelectrochemical Glucose Biosensor in Flow Injection Analysis System Using ZnS/CdS-Carbon Nanotube Nanocomposite Electrode
    (Wiley-V C H Verlag Gmbh, 2017) Saglam, Ozlem; Dilgin, Yusuf
    In this work, a photoamperometric glucose biosensor based on glucose oxidase (GODx) was developed in flow injection analysis (FIA) system using ZnS-CdS quantum dot (QD) modified multiwalled carbon nanotube/glassy carbon electrode (ZnS-CdS/MWCNT/GCE). Cyclic voltammograms of the proposed electrode (GODx/ZnS-CdS/MWCNT/GCE) showed a pair of well-defined reversible redox peak attributing that direct electron transfer between the protein and electrode. The current of the reduction peak became more cathodic in the presence of O-2 due to the electrocatalytic activity of the electrode towards the reduction of dissolved O-2, but reduction current shifted to a less negative value upon addition of glucose in the solution. The obtained CV currents were affected by the irradiation of the electrode surface. Thus, the photoelectrochemical biosensing of glucose in the FIA system was studied by monitoring of the changes in the electrocatalyzed reduction peak current of dissolved O-2 at the proposed electrode dependent on glucose concentration. The proposed photoelectrochemical FIA method has a linear response to glucose ranging from of 0.01 to 1.0mM with detection limit of 3.0 M under optimized conditions. Photoelectrochemical biosensor was successfully fabricated in FIA system for selective, sensitive and repeatable detection of glucose and has been satisfactorily applied to determination of glucose in real sample.
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    Sensitive Voltammetric Determination of Niclosamide at a disposable pencil graphite electrode
    (Pergamon-Elsevier Science Ltd, 2014) Dede, Eda; Saglam, Ozlem; Dilgin, Yusuf
    Niclosamide (NA), an effective drug against tapeworm infections, was electrochemically studied using a pencil graphite electrode (PGE). A low-cost sensitive and selective procedure was developed for determination of NA by recording differential pulse voltammograms of NA in pH 7.0 Britton-Robinson buffer solution containing 0.1 M KCl and 30% DMF at the PGE. The PGE displayed very good electrochemical behavior with significant enhancement of the peak current compared to a glassy carbon electrode. Moreover, results obtained from the differential pulse voltammograms show that PGE offers a disposable, low cost, selective and sensitive electrochemical sensor for determination of NA. Under experimental conditions, the PGE had a linear response range from 0.05 mu M to 10 mu M NA with a detection limit of 0.015 mu M (based on 3(sb)). A relative standard deviation of 0.57% was obtained for five successive determinations of 5 mu M NA, which indicate acceptable repeatability. This voltammetric method was successfully applied to the direct determination of NA in tablets. No interference from the tablet excipients was encountered. (C) 2014 Elsevier Ltd. All rights reserved.