Yazar "Saglam, Muhammed Esad" seçeneğine göre listele

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    Green synthesis of reduced graphene oxide/nanopolypyrrole composite: characterization and H2O2 determination in urine
    (Royal Soc Chemistry, 2014) Zor, Erhan; Saglam, Muhammed Esad; Akin, Ilker; Saf, Ahmet Ozgur; Bingol, Haluk; Ersoz, Mustafa
    Here we report on a novel, simple and eco-friendly approach for the fabrication of a reduced Graphene Oxide/nanopolypyrrole (rGO/nPPy) composite material and its electrochemical performance for detection of hydrogen peroxide on a glassy carbon electrode. The characterization of the as-prepared rGO/nPPy composite was investigated by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet-visible spectroscopy, scanning electron microscopy, contact angle measurement, cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry, differential pulse voltammetry and chronoamperometry techniques were used to investigate and optimize the performance of the developed electrochemical biosensor. The proposed biosensor showed excellent analytical response towards the quantification of H2O2 at pH 7.40. Under the optimized conditions, the biosensor shows a linear response range from 1.0 x 10(-7) to 4.0 x 10(-6) M concentrations of H2O2. The limit of detection was determined to be 34 nM. Reproducibility, sensitivity, stability and anti-interference capability of the fabricated biosensor for the detection of H2O2 were examined. The biological relevance of the developed electrochemical biosensor was further studied by the determination of H2O2 in urine samples. The real sample analysis of H2O2 was achieved before and after drinking coffee in urine samples. The successful and sensitive determination of H2O2 urine samples indicates that the proposed electrochemical biosensor can be applied to the quantification analysis of H2O2 in real samples.
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    Photoluminescent nanopaper-based microcuvette for iodide detection in seawater
    (Elsevier Science Sa, 2018) Zor, Erhan; Alpaydin, Sabri; Arici, Aylin; Saglam, Muhammed Esad; Bingol, Haluk
    Nanopaper defined as a sheet made of cellulose nanofibers has recently attracted a growing interest in paper-based flexible and transparent sustainable transistors, electronics, devices and sensors. Use of bacterial cellulose nanopaper, particularly in optical sensing platforms, is becoming increasingly popular owing to its numerous desirable properties. Herein, we propose a carbon quantum dots embedded paper-based sensor for selective iodide sensing. To this aim, the nanopaper was obtained by an environment-friendly approach using bacterial cellulose made of nanofibers (the diameter of nanofibers was observed as 40 +/- 10 nm), which were produced by A. xylinum. Then, nitrogen-doped carbon quantum dots were embedded into nanopaper to gain photoluminescence properties. The obtained photoluminescent nanopaper was cut into circular pieces for easily handling, or rectangular pieces for use in a disposable wax-printed paper-based microcuvette which could be inserted in a common spectrofluorometer. Finally, the nanopaper pieces were used for anion sensing and we obtained a selective detection of iodide in seawater (as a model real sample media). Limit of detection (LOD) and limit of quantification (LOQ) values were respectively calculated as 48 and 144 mu M (6.1 and 18.3 ppm) for microcuvette application in seawater. (C) 2017 Elsevier B.V. All rights reserved.
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    A reduced graphene oxide/?-cyclodextrin hybrid for the detection of methionine: electrochemical, fluorometric and computational studies
    (Royal Soc Chemistry, 2014) Zor, Erhan; Saglam, Muhammed Esad; Alpaydin, Sabri; Bingol, Haluk
    We report on fluorometric and voltammetric detection of L-methionine (Met) based on host-guest interactions between Met and reduced graphene oxide/alpha-cyclodextrin (rGO/alpha-CD) hybrid materials. For voltammetric measurements, rGO/alpha-CD was used as an electrode modification material and successful detection of Met was achieved. Also, rGO/alpha-CD was used as a fluorescence quencher (turn off) for luminol which was employed as a fluorescent probe. The addition of Met into the same solution gave rise to fluorescence enhancement (turn on) after the host-guest recognition between Met and rGO/alpha-CD which caused the release of luminol. Interactions of luminol and Met with rGO/alpha-CD were modeled by molecular docking using AutoDock Vina and the interaction energies were predicted to be -4.3 and -4.4 kcal mol(-1), respectively. The proposed biosensor is considered to be a promising model for the detection of Met.