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    Microwave-assisted synthesis of PtAu@C based bimetallic nanocatalysts for non-enzymatic H2O2 sensor
    (PERGAMON-ELSEVIER SCIENCE LTD, 2015) Sahin, Ozlem Gokdogan
    A simple and effective strategy was developed to construct an amperometric sensor for hydrogen peroxide (H2O2) detection based on microwave-assisted polyol synthesis of PtAu@C nanocatalysts. The structures and characterization of bimetallic catalysts were examined via X-ray diffraction (XRD), X-ray photo electron spectroscopy (XPS), and Transmission electron microscopy (TEM). The catalytic activities of PtAu@C nanocatalysts at different compositions (Pt@C, Pt0.4Au0.68C Pt0.5Au0.5@C, Pt0.7Au0.3@C, Pt0.9Au0.1@C, Au@C) for the electro-oxidation of H2O2 have been investigated by using cyclic voltammetry (CV). It was observed that the electrocatalytic performance was strongly dependent on the PtAu@C nanocatalyst composition. Pt0.5Au0.5@C modified electrode showed the highest sensitivity toward hydrogen peroxide among the catalysts under study. Therefore, further studies performed by chronoamperometry for Pt0.5Au0.5@C optimized ratio catalyst. Electrochemical measurements indicated that the oxidation current of H2O2 is linear between the cohcentrations 7 mu M and 6.5 mM with high sensitivity of 210.3 mu A mM(-1) cm(-2). Pt0.5Au0.5@C modified electrode exhibited good reproducibility, selectivity and stability. Meanwhile, the sensitivity of the H2O2 sensor for real sample was investigated in pasteurized milk and the obtained results were satisfactory. Thus, the prepared non-enzyme sensor has potential application in H2O2 detection. (C) 2015 Elsevier Ltd. All rights reserved.
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    Polyvinylferrocenium based platinum electrodeposited amperometric biosensors for lysine detection
    (ELSEVIER SCIENCE SA, 2013) Sahin, Ozlem Gokdogan; Gulce, Handan; Gulce, Ahmet
    Two amperometric biosensors based on polyvinylferrocenium (PVF+) and platinum deposited PVF+ were constructed for lysine detection. The method for modification of electrodes relied on the electrooxidation of polyvinylferrocene in methylene chloride containing tetrabutylammonium perchlorate (TBAP) at +0.70 V and electrodeposition of platinum particles on the surface of PVF+ClO4- at -0.15 V vs. Ag/AgCl. Lysine oxidase (LyOx) enzyme was immobilized by ion exchange process into modified electrodes. The response of the resulted PVF(+)LyOx(-) and PVF(+)LyOx(-)/Pt biosensors determined by oxidation of enzymatically produced H2O2 at 0.60 V vs. Ag/AgCl. The influence of experimental conditions such as applied potential, pH, temperature on the biosensor responses were examined and analytical performance characteristics of the biosensors were determined. The experimental results of two biosensors compared with each other. The results showed that PVF(+)LyOx(-)/Pt biosensor had a linear range up to 3.0 mM whereas for PVF(+)LyOx(-) biosensor that range was linear up to 1.3 mM. The detection limits of PVF(+)LyOx(-)/Pt and PVF(+)LyOx(-) biosensors were determined to be about 6.5 x 10(-4) and 5.0 x 10(-4) mM, respectively. The response time of sensors was less than 30 s. The anti-interference ability and long-term stability of the biosensors were studied. The proposed biosensors were also used to determine lysine in pharmaceutical samples. (C) 2012 Elsevier B.V. All rights reserved.