Yazar "Toppare, Levent" seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Calixarene assembly with enhanced photocurrents using P(SNS-NH2)/CdS nanoparticle structure modified Au electrode systems(ROYAL SOC CHEMISTRY, 2015) Sayın, Serkan; Azak, Hacer; Yıldız, Hüseyin Bekir; Çamurlu, Pınar; Akkuş, Gülderen Uysal; Toppare, Levent; Ersöz, MustafaTwo novel calix[n] arene-adorned gold electrodes producing high photocurrent intensities were successfully constructed by embedding gold electrode surfaces with both P(4-(2,5-di(thiophen-2-yl)-1H- pyrrol-1-yl)benzenamine) conducting polymer and 4-mercaptoboronic acid-functionalized semiconductor CdS nanoparticles to facilitate the binding of calix[n]arene sulfonic acids with nanoparticles. This structure enabled an electron transfer cascade that both induced effective charge separation and efficiently generated photocurrent. The prepared electrodes were used to generate photocurrent by relying on the host-guest interactions of guests Br-3(-) and I-3(-), which if positioned well in the system was able to fill electron-hole pairs of CdS nanoparticles. As a result, host calixarene derivatives crucially held Br-3(-) and I-3(-) ions at a substantial distance from CdS nanoparticles. Furthermore, the effects of various calixarenes on the photocurrent obtained indicate that the generation of photocurrent intensities by the system depends on the cavity sizes of calixarene derivatives, which provide an essential center for Br-3(-) and I-3(-) ions.Öğe Immobilization of tyrosinase and alcohol oxidase in conducting copolymers of thiophene functionalized poly(vinyl alcohol) with pyrrole(ELSEVIER SCIENCE BV, 2007) Yildiz, Huseyin Bekir; Sahmetlioglu, Ertugrul; Boyukbayram, Ayse Elif; Toppare, Levent; Yagci, YusufImmobilization of tyrosinase and alcohol oxidase is achieved in the copolymer of pyrrole with vinyl alcohol with thiophene side groups (PVATh-co-PPy) which is a newly synthesized conducting polymer. PVATh-co-PPy/alcohol oxidase and PVATh-co-PPy/tyrosinase electrodes are constructed by the entrapment of enzyme in conducting copolymer matrix during electrochemical copolymerization. For tyrosinase and alcohol oxidase enzymes, catechol and ethanol are used as the substrates, respectively. Kinetic parameters: maximum reaction rates (V-max) and Michaelis-Menten constants (K-m) are obtained. V-max and K-m are found as 2.75 mu mol/(min electrode) and 18 mM, respectively, for PVATh-coPPy/alcohol oxidase electrode and as 0.0091 mu mol/(min electrode) and 40 mM, respectively, for PVATh-co-PPy/tyrosinase electrode. Maximum temperature and pH values are investigated and found that both electrodes have a wide working range with respect to both temperature and pH. Operational and storage stabilities show that although they have limited storage stabilities, the enzyme electrodes are useful with respect to operational stabilities. (c) 2007 Elsevier B.V. All rights reserved.Öğe Phenol biosensor based on electrochemically controlled integration of tyrosinase in a redox polymer(SPRINGER WIEN, 2007) Yildiz, Huseyin Bekir; Castillo, Jaime; Guschin, Dmitrii A.; Toppare, Levent; Schuhmann, WolfgangAn amperometric biosensor for the detection of phenolic compounds was developed based on the immobilization of tyrosinase within an Os-complex functionalized electrodeposition polymer. Integration of tyrosinase within the redox polymer assures efficient catechol recycling between the enzyme and the polymer bound redox sites. The non-manual immobilization procedure improves the reproducibility of fabrication process, greatly reduces the desorption of the enzyme from the immobilization layer, and, most importantly prevents fast inactivation of the enzyme by its substrate due to fast redox cycling. A two-layer sensor architecture was developed involving ascorbic acid oxidase entrapped within an electrodeposition polymer in a second layer on top of the redox polymer/tyrosinase layer. Using this sensor architecture it was possible to eliminate the current interference arising from direct ascorbate oxidation up to a concentration of 630 mu M ascorbic acid. The effects of the polymer thickness, the enzyme/polymer ratio, and the applied potential were evaluated with respect to optimal sensor properties. The sensitivity of the optimized sensors for catechol was 6.1 nA mu M-1 with a detection limit of 10 nM, and for phenol 0.15 nA mu M-1 with a detection limit of 100 nM.Öğe Photoelectrochemical Biosensing Approach for Alcohol Determination by "Wiring" of Alcohol Oxidase Photonically with P(SNS-NH2)/AOx/CNT/[Ru(bpy)(3)](2+) Modified Electrodes(TAYLOR & FRANCIS INC, 2014) Yildiz, H. B.; Kamaci, Musa; Karaman, Mustafa; Toppare, Levent; Sayin, SerkanA photoelectrochemical alcohol biosensor was designed through photonic wiring of alcohol oxidase (AOx) onto conducting polymer of 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine (SNS-NH2) and carbon nanotubes (CNTs) modified gold slides. The photoelectrochemical biosensors utilize a photonically wired electrode that oxidizes primary alcohols to aldehydes. Three different alcohols namely methanol, ethanol, and n-propanol were used as the substrates. In the presence of different concentrations of primary alcohol, the photocurrents were obtained by irradiating of the photoelectrochemical cell containing P(SNS-NH2)/AOx/CNT/[Ru(bpy)(3)](2+) electrode as the anode under air. The bipyridine complex [Ru(bpy)(3)](2+) was used to activate photoinduced electron-transfer reaction and it acted as a redox mediator to activate the bioelectrocatalytic functions of AOx. Therefore, it was shown the photonic electron-transfer wiring of AOx with the electrode. Sensitivity experiments, optimum pH value, operational stabilization and shelf life of the photoelectrochemical biosensor were investigated. Finally, the photoelectrochemical biosensors were used for alcohol detection in real samples.Öğe A photoelectrochemical device for water splitting using oligoaniline-crosslinked [Ru(bpy)(2)(bpyCONHArNH(2))](+2) dye/IrO2 nanoparticle array on TiO2 photonic crystal modified electrode(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Yildiz, Huseyin Bekir; Carbas, Buket Bezgin; Sonmezoglu, Savas; Karaman, Mustafa; Toppare, LeventThis article describes the construction of photoelectrochemical cell system splitting water into hydrogen and oxygen using UV-vis light under constant applied voltage. Oligoaniline-crosslinked 2-(4-aminobenzyl)malonic acid functionalized IrO2 center dot nH(2)O nanoparticles and visible light absorbing dye, [Ru(bpy)(2)(bpyCONHArNH(2))(+2)] arrays on titanium dioxide (TiO2) photonic crystals modified electrodes were used as photoanode, and nanostructures based on bonding of Pt nanoparticles by using electropolymerization on poly 4-(2,5-di(thiophene-2-il)-1H-pyrrol-1-il)benzenamine P(SNS-NH2) conducting polymer modified gold electrode acted as cathode. Each component in anode and cathode of the system was characterized successfully using the methods related. Some optimization studies such as the molar concentration ratio of [Ru(bpy)(2)(bpyCONHArNH(2))(+2)] dye to IrO2 center dot nH(2)O nanoparticles, the optimum cycle number of each components and thickness of TiO2 film were performed in order to investigate the system performance. Furthermore, the photocurrent generation capacity of the photoanode against oxygen resulting and UV stability experiments of photoanode were also investigated. After obtained all necessary informations and improvements of the system, the cell was constructed, and corresponding hydrogen gas evolution from water splitting was calculated as 1.25 x 10(-8) mol/cm(2) by using a gas chromatography (GC). The cell generated a photocurrent with a quantum yield of 3.5%. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
