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Dive into the research topics where Yasemin Oztekin is active.

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Featured researches published by Yasemin Oztekin.


Talanta | 2011

Square wave voltammetry based on determination of copper (II) ions by polyluteolin- and polykaempferol-modified electrodes

Yasemin Oztekin; Zafer Yazicigil; Almira Ramanaviciene; Arunas Ramanavicius

Applicability of square wave voltammetry for the determination of Cu(II) ions by PolyLut/GC and PolyKae/GC electrodes was evaluated in this study. For this luteolin and kaempferol were electrochemically polymerized on glassy carbon (GC) electrode surface in order to get polyluteolin and polykaempferol-modified glassy carbon electrodes (PolyLut/GC and PolyKae/GC, correspondingly). The formation of polyphenol layer on the GC electrode surface was evidenced by atomic force microscopy. Square wave voltammetry was found to be more sensitive in comparison with differential pulse voltammetry. It was determined that PolyLut/GC and PolyKae/GC electrodes offered great sensitivity towards Cu(II) ions with very low limit of detection, good reproducibility, sufficient stability and excellent selectivity of analytical signal.


Biosensors and Bioelectronics | 2010

1,10-Phenanthroline derivatives as mediators for glucose oxidase.

Yasemin Oztekin; Vida Krikstolaityte; Almira Ramanaviciene; Zafer Yazicigil; Arunas Ramanavicius

This study is focused on possible application of some 1,10-phenanthroline derivatives (PDs) in the development of biosensors and biofuel cells. Differently from some other studies, the PDs that were not involved into structures of metal complexes were investigated. Five PDs [1,10-phenanthroline monohydrate (PMH); 5-nitro-1,10-phenanthroline (5NP); 5-amino-1,10-phenanthroline (5AP), 5-amino,6-nitro-1,10-phenanthroline (5A6NP) and 5,6-diamino-1,10-phenanthroline (56DAP)] were selected for this study. Bioelectrochemical responses of PDs and glucose oxidase (GOX)-modified graphite rod electrodes (GREs) were studied amperometrically and potentiometrically. The best redox mediators for GOX were found on PDs containing amino groups: 5AP and 56DAP. Amperometrical measurements have shown that 5NP derivative was also acting as a redox mediator but activity of 5NP was approximately four times lower than 5AP and three times lower than 56DAP. This study clearly illustrates that some PDs can be applied as redox mediators for oxidases and are suitable for the development of reagent-less biosensors and biofuel cells. Since amino groups can be very easily involved in the formation of chemical bounds, the amino-PDs are interesting compounds for the development of nanobiotechnological tools by bottom-up technique.


Talanta | 2014

Development of poly(3-aminophenylboronic acid) modified graphite rod electrode suitable for fluoride determination

Hakan Çiftçi; Yasemin Oztekin; Ugur Tamer; Almira Ramanavicine; Arunas Ramanavicius

Poly(3-aminophenylboronic acid), (PAPBA) film was formed on the graphite rod surface by potential cycling. The PAPBA-modified graphite rod (PAPBA/GR) electrode prepared in this way was used for potentiometric fluoride determination. The linear calibration range was from 5×10(-4) to 5×10(-2)M with the slope of the linear part of the calibration curve of 42.5mV/logC. No interference effect of the most common ions such as sodium, potassium, chloride, nitrate, iodide, calcium, zinc, aluminum, sulfate and sorbitol was observed during electrochemical determination of fluoride. On the other hand, the PAPBA/GR electrode showed not only good sensitivity and selectivity, but also relatively rapid response to changes of analyte concentrations in the range of 20s. The sensor was successfully applied for fluoride determination in real sample - toothpaste.


Journal of Hazardous Materials | 2008

The electrochemical investigation of salts partition with ion exchange membranes.

Nejla Ata; Zafer Yazicigil; Yasemin Oztekin

The regenaration of acid and base from the solutions containing metallic salts was achieved by salt splitting method (SSM) using not only anion-exchange membranes (AEM) but also cation-exchange membrane (CEM). In these experiments, while the ion exchange membrane was anion-exchange membrane, acid solutions were used as an anolyte and different salts of potassium were used as a catholyte. In addition to these experiments, while the ion exchange membrane was cation-exchange membrane, base solutions were used as a catholyte and different salts of potassium were used as an anolyte. The effects of current density, initial concentrations of anolyte and catholyte solutions, the type of salt solution and the type of the ion-exchange membranes on the recovery ratio of bases and acids were investigated. The results of the experiments were investigated with the Statistical Package for Social Sciences (SPSS) program. The obtained results show that this technique can be used not only for recovering the acid and base wastes of industry but also for removing the impurities in order to obtain pure acids and bases in laboratory conditions.


Colloids and Surfaces B: Biointerfaces | 2014

Electrochemical biosensor based on glucose oxidase encapsulated within enzymatically synthesized poly(1,10-phenanthroline-5,6-dione).

Hakan Çiftçi; Yasemin Oztekin; Ugur Tamer; Almira Ramanaviciene; Arunas Ramanavicius

This study is focused on the investigation of electrocatalytic effect of glucose oxidase (GOx) immobilized on the graphite rod (GR) electrode. The enzyme modified electrode was prepared by encapsulation of immobilized GOx within enzymatically formed poly(1,10-phenanthroline-5,6-dione) (pPD) film. The electrochemical responses of such enzymatic electrode (pPD/GOx/GR) vs. different glucose concentrations were examined chronoamperometrically in acetate-phosphate buffer solution (A-PBS), pH 6.0, under aerobic or anaerobic conditions. Amperometric signals of the pPD/GOx/GR electrode exhibited well-defined hyperbolic dependence upon glucose concentration. Amperometric signals at 100mM of glucose were 41.17 and 32.27 μA under aerobic and anaerobic conditions, respectively. Amperometric signals of the pPD/GOx/GR electrode decreased by 6% within seven days. The pPD/GOx/GR electrode showed excellent selectivity in the presence of dopamine and uric acid. Furthermore it had a good reproducibility and repeatability with standard deviation of 9.4% and 8.0%, respectively.


Desalination and Water Treatment | 2012

Electrochemical determination of copper(II) using modified glassy carbon electrodes

Esra Bilici; Zafer Yazicigil; Mutahire Tok; Yasemin Oztekin

Abstract Electrochemical modification of glassy carbon (GC) electrode surface via electrochemical oxidation of 1-aminoindan in acetonitrile including 100.0 mM of tetrabutylammonium tetrafluoroborate and applicability of electrode modified in this way for electrochemical determination of copper(II) (Cu(II)) were reported in this study. Electrochemical surface modification was performed by cyclic voltammetry in the potential range between +0.9 and +1.5 V vs. Ag/Ag+ (10.0 mM of AgNO3) at the scan rate of 100 mV/s by 30 potential cycles. The modified electrode surface was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and contact angle measurement. The characterization results were compared with the characterization results of bare GC electrode. The results of the amperometric measurements of the modified GC electrode towards Cu(II) ions were investigated. It was determined that the modified electrode surface had electrochemical responses towards Cu(II) ions with high sensitivity,...


RSC Advances | 2018

Strategies to synthesize various nanostructures of silver and their applications – a review

Umme Thahira Khatoon; G.V.S. Nageswara Rao; Krishna Mohan Mantravadi; Yasemin Oztekin

Due to their various beneficial application-based properties, such as behavior, structure, and size, the synthesis of silver nanoparticles (Ag-NPs) with different structures has become an interesting yet common task for researchers to produce nanostructures for applications in various fields. This is because silver nanoparticles have interesting and unique properties, such as optical and catalytic, resulting from their different structures and sizes. These properties extend the use of nanostructures in various fields of research, especially in medicine, pharmacy, electronics, etc. Also, variations in their parameters affect the structures and sizes of Ag-NPs. This review provides an overview/brief presentation of various methodologies used to synthesize different application-based silver nanoparticles and lists areas where these nanoparticles are suitable for use according to their specific structures and sizes.


Journal of Analytical Chemistry | 2016

Evaluation of 1,10-phenanthroline-5,6-dione as redox mediator for glucose oxidase

Erhan Zor; Yasemin Oztekin; Almira Ramanaviciene; Zilvinas Anusevicius; Jaroslav Voronovic; Haluk Bingol; Dana Barauskas-Memenas; Linas Labanauskas; Arunas Ramanavicius

A low-cost and simply fabricated amperometric glucose biosensor based on glucose oxidase (GOx) and 1,10-phenanthroline-5,6-dione (PD) modified graphite rod electrode was developed. The electrode exhibited good electrocatalytic activity with a well-defined hyperbolic dependence of amperometric signal upon glucose concentration in the presence and in the absence of oxygen. The electrode showed a good reproducibility and repeatability with relative standard deviation of less than 3 and 5%, respectively. The interaction of GOx with PD mediator was confirmed by means of UV?Vis absorbance spectroscopy.


Biosensors and Bioelectronics | 2011

Direct electron transfer from glucose oxidase immobilized on polyphenanthroline-modified glassy carbon electrode

Yasemin Oztekin; Almira Ramanaviciene; Zafer Yazicigil; Ali Osman Solak; Arunas Ramanavicius


Desalination | 2006

Boron removal by electrodialysis with anion-exchange membranes

Zafer Yazicigil; Yasemin Oztekin

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