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    Fabrication of Cu?CeO2 Coated Multiwall Carbon Nanotube Composite Electrode for Simultaneous Determination of Guanine and Adenine
    (Wiley-VCH Verlag, 2018) Aktürk M.; Karabiberoğlu Ş.U.; Dursun Z.
    A copper nano particles and cerium (IV) oxide modified carbon nanotube based composite on glassy carbon electrode (Cu?CeO2/MWCNT/GCE) was fabricated for simultaneous determination of guanine and adenine. The surface morphology, chemistry and conductance of the prepared electrodes were characterized by scanning electron microscopy (SEM), energy dispersion X-ray (EDX), X-Ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The Cu?CeO2/MWCNT/GCE improved electrochemical behaviour of guanine and adenine compared to other electrodes. The modified electrode was also used for individual and simultaneous determination of guanine and adenine. Under optimized conditions, the calibration curves were obtained linearly in the range of 0.20 to 6.00 ?M for the guanine and 0.10 to 8.0 ?M for the adenine by differential pulse voltammetry. The limits of detection of guanine and adenine were calculated as 0.128 and 0.062 ?M, respectively. Interferences studies were also performed in the presence of inorganic and organic compounds. Moreover, the determination of guanine and adenine contents were carried out in a calf thymus DNA sample by the developed method with satisfactory results. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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    An over-oxidized poly(Rutin) modified electrode for selective and sensitive determination of catechol and hydroquinone
    (Elsevier B.V., 2019) Karabiberoğlu Ş.U.; Koçak Ç.C.; Dursun Z.
    Herein, a new facile and sensitive method was developed that enables the individual and simultaneous determination of catechol (CC) and hydroquinone (HQ) using an over-oxidized and electrochemically polymerised rutin film glassy carbon electrode. The proposed electrode exhibits a large peak potential difference between CC and HQ, resulting in well-separated peaks—an important factor for selective determination. CC and HQ were individually and simultaneously determined via differential pulse voltammetry in a pH -7.2 phosphate buffer solution. The individually calculated detection limits for CC and HQ were 8.8 and 5.2 nM, respectively. In simultaneous determination, the limits of detection were calculated to be 31 and 53 nM for CC and HQ, respectively. Moreover, real sample analyses were successfully conducted using tap and waste water. © 2019
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    Polymer Film Supported Bimetallic Au–Ag Catalysts for Electrocatalytic Oxidation of Ammonia Borane in Alkaline Media
    (SpringerOpen, 2016) Karabiberoğlu Ş.U.; Koçak Ç.C.; Koçak S.; Dursun Z.
    Abstract: Ammonia borane is widely used in most areas including fuel cell applications. The present paper describes electrochemical behavior of ammonia borane in alkaline media on the poly(p-aminophenol) film modified with Au and Ag bimetallic nanoparticles. The glassy carbon electrode was firstly covered with polymeric film electrochemically and then, Au, Ag, and Au–Ag nanoparticles were deposited on the polymeric film, respectively. The surface morphology and chemical composition of these electrodes were examined by scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. It was found that alloyed Au–Ag bimetallic nanoparticles are formed. Electrochemical measurements indicate that the developed electrode modified by Au–Ag bimetallic nanoparticles exhibit the highest electrocatalytic activity for ammonia borane oxidation in alkaline media. The rotating disk electrode voltammetry demonstrates that the developed electrode can catalyze almost six-electron oxidation pathway of ammonia borane. Our results may be attractive for anode materials of ammonia borane fuel cells under alkaline conditions. Graphical Abstract: [Figure not available: see fulltext.] © 2016, The Author(s).