Yazar "Uygun, Zihni Onur" seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • [ X ]
    Öğe
    A novel impedimetric sensor based on molecularly imprinted polypyrrole modified pencil graphite electrode for trace level determination of chlorpyrifos
    (Elsevier Science Sa, 2013) Uygun, Zihni Onur; Dilgin, Yusuf
    A chlorpyrifos (CPF) templated molecularly imprinted film was electrochemically synthesized on a pencil graphite electrode (PGE) by electropolymerization of pyrrole (Py) in the presence of CPF. The fabricated modified electrode was used as a novel impedimetric sensor for the determination of an important organophosphorus pesticide, CPF. The binding performance of CPF toward the polypyrrole (PPy) film was examined using electrochemical impedance spectroscopy (EIS). The surface morphology of the imprinted film was characterized by scanning electron microscopy (SEM). Results obtained from the impedance measurements show that imprinted PPy modified PGE offers a disposable, low cost, selective and sensitive electrochemical sensor for the determination of CPF. Under experimental conditions, the proposed impedimetric sensor has a linear response range from 20 to 300 mu g L-1 CPF with a detection limit of 4.5 mu g L-1 (based on 3(sb)). Furthermore, the fabricated sensor was successfully applied to determine CPF in CPF-added artificial samples. (C) 2013 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    A novel, ultra sensible biosensor built by layer-by-layer covalent attachment of a receptor for diagnosis of tumor growth
    (Elsevier, 2011) Uygun, Zihni Onur; Sezgintürk, Mustafa Kemal
    In the presented research, a novel, ultra sensitive biosensor for the impedimetric detection of vascular endothelial growth factor (VEGF) is introduced. The human vascular endothelial growth factor receptor 1 (VEGF-R1, Flt-1) was used as a biorecognition element for the first time. The immobilization of VEGF-R1 on glassy carbon electrodes was carried out using layer-by-layer covalent attachment of VEGF-R1. The electrochemical properties of the layers constructed on the electrodes were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The differences in electron transfer resistance (R-er) between the working solution and the biosensor surface, recorded by the redox probe K-3[Fe(CN)(6)]/K-4[Fe(CN)(6)], confirmed the binding of VEGF to VEGF-R1. The new biosensor allowed a detection limit of 100 fg mL(-1) with a linear range of 100-600 fg mL(-1) to be obtained. The biosensor also exhibited good repeatability (with a correlation coefficient of 1.95%), and reproducibility. (C) 2011 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    An impedimetric vascular endothelial growth factor biosensor-based PAMAM/cysteamine-modified gold electrode for monitoring of tumor growth
    (Academic Press Inc Elsevier Science, 2012) Sezgintürk, Mustafa Kemal; Uygun, Zihni Onur
    In the present work, we have developed a new biosensor based on fourth-generation (G4) PAMAM dendrimers for the analysis of vascular endothelial growth factor (VEGF). First, the PAMAM dendrimers were covalently attached to a cysteamine-modified Au electrode by glutaraldehyde. With the help of the amino groups located on its surface, vascular endothelial growth factor receptor-1 (VEGF-R1) was immobilized via glutaraldehyde cross-linking. VEGF-R1 loading was investigated to identify the optimal VEGF-R1 immobilization conditions for the best sensitivity of the new biosensor. In addition, Kramers-Kronig transforms were also analyzed for immobilization and measurement processes. The biosensor had a linear range of 5 to 125 pg/mL VEGF. The fabricated biosensor had good repeatability and reproducibility. Finally, the results for artificial serum samples measured by the present biosensor showed a good recovery for VEGF detection. (C) 2012 Elsevier Inc. All rights reserved.
  • [ X ]
    Öğe
    Biosensors for Cancer Biomarkers
    (Intech Europe, 2011) Uygun, Zihni Onur; Sezgintürk, Mustafa Kemal
    [Anstract Not Available]
  • [ X ]
    Öğe
    Impedimetric Biosensors for Label-Free and Enzymless Detection
    (Intech Europe, 2013) ErtugruL, Hilmiye Deniz; Uygun, Zihni Onur
    [Anstract Not Available]
  • [ X ]
    Öğe
    Organofosfat türü pestisitlerin tayinine yönelik elektrokimyasal impedans temelli sensör geliştirilmesi
    (Çanakkale Onsekiz Mart Üniversitesi, 2012) Uygun, Zihni Onur; Dilgin, Yusuf
    Bu çalışmada CPF ile moleküler baskılanmış film, kalem grafit elektrot yüzeyine döngüsel voltammetri ile CPF ve Pirol varlığında elektropolimerize edilerek hazırlanmıştır. Geliştirilen yeni impedimetrik modifiye elektrot, önemli bir pestisit türü olan CPF tayininde kullanılmıştır. CPF'un Polipirol(PPy) film üzerine bağlanma performansı elektrokimyasal impedans spektroskopisi ile izlenmiştir. Modifiye edilen elektrotun yüzeyi taramalı elektron mikroskobu ile incelenmiştir. Elde edilen impedans sonuçlarına göre, baskılanmış PPy modifiyeli kalem grafit elektrot yenilenebilirliği yüksek, tek kullanımlılık, düşük maliyetli, seçici ve duyarlı bir şekilde CPF tayinine olanak sağlamıştır. Deney koşullarında, geliştirilen impidimetrik sensör 20-300 µg L-1 CPF aralığında doğrusal değiştiği saptanmıştır. Sensörün belirtme alt sınırı ise 5,8 µg L-1 olarak bulunmuştur. Bununla birlikte geliştirilen sensör yapay örneklerde CPF tayinine başarılı bir şekilde uygulanmıştır.