Yazar "German, Natalija" seçeneğine göre listele

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    The effect of colloidal solutions of gold nanoparticles on the performance of a glucose oxidase modified carbon electrode
    (SPRINGER WIEN, 2011) German, Natalija; Ramanavicius, Arunas; Voronovic, Jaroslav; Oztekin, Yasemin; Ramanaviciene, Almira
    The aim of this work was to further evaluate the effect of colloidal solutions of gold nanoparticles (Au-NPs) on the performance of a carbon rod electrode modified with glucose oxidase. The amperometric response of the system at +0.3 V vs. Ag/AgCl was studied in the absence and in the presence of Au-NPs (6 nm and 13 nm in diameter) and in presence of N-methylphenazonium methyl sulfate (PMS) at pH 6.0. This study shows that the application of < 0.60 nmol L-1 concentrations of Au-NPs increases the rate of mediated electron transfer, and this effect does not depend on the diameter of Au-NPs. The analytical signal in the presence 0.60 nmol L-1 of Au-NPs (13 nm) and 2 mmol L-1 of PMS linearly depends on the concentration of glucose in the range from 0.1 to 10 mmol L-1, the limit of detection is as low as 0.05 mmol L-1.
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    Visualization of red-ox proteins on the gold surface using enzymatic polypyrrole formation
    (SPRINGER WIEN, 2011) Ramanaviciene, Almira; Kausaite-Minkstimiene, Asta; Oztekin, Yasemin; Carac, Geta; Voronovic, Jaroslav; German, Natalija; Ramanavicius, Arunas
    We describe a new method for the visualization of the activity of red-ox proteins on a gold interface. Glucose oxidase was selected as a model system. Surfaces were modified by adhesion of glucose oxidase on (a) electrochemically cleaned gold; (b) gold films modified with gold nanoparticles, (c) a gold surface modified with self-assembled monolayer, and (d) covalent immobilization of protein on the gold surface modified with a self-assembled monolayer. The simple optical method for the visualization of enzyme on the surfaces is based on the enzymatic formation of polypyrrole. The activity of the enzyme was quantified via enzymatic formation of polypyrrole, which was detected and investigated by quartz microbalance and amperometric techniques. The experimental data suggest that the enzymatic formation of the polymer may serve as a method to indicate the adhesion of active redox enzyme on such surfaces.