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    A novel impedimetric biosensor based on graphene oxide/gold nanoplatform for detection of DNA arrays
    (Elsevier Science Sa, 2013) Gupta, Vinod Kumar; Yola, Mehmet Lutfi; Qureshi, Munewar Saeed; Solak, Ali Osman; Atar, Necip; Ustundag, Zafer
    A highly sensitive method for detection of DNA hybridization was developed. This method was based on the modification of glassy carbon electrode with gold nanoparticles (AuNPs) involving p-aminothiophenol (ATP) functionalized graphene oxide (GO). This GO was used as a platform for impedimetric genosensing using 5'-TA GGG CCA CTT GGA CCT-(CH2)(3)-SH-3' single-stranded probe (ss-DNA), 5'-AGG TCC AAG TGG CCC TA-3'(target DNA), 5'-SH-C-6-TAG GGC CA-3'(non-complementary-1) and 5'-SH-C-6-TGC CCG TTA CG 3-' (non-complementary-2) oligonucleotide sequences. The film exhibited excellent properties for immobilizing DNA probes and sensing DNA hybridization. The DNA immobilization and hybridization on the film were studied by cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), and found that the charge transfer resistance (R-ct) of the electrode increased with the concentration of the target DNA hybridized with the ss-DNA. The linear detectionrange was from 1.0 x 10(-13) M to 1.0 x 10(-7) M and the detection limit was 1.10 x 10(-14) M (n = 6). Compared with the other electrochemical DNA biosensors, the proposed biosensor showed its own performance of simplicity, good stability, and high sensitivity. (C) 2013 Elsevier B. V. All rights reserved.
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    Electrochemically grafted etodolac film on glassy carbon for Pb(II) determination
    (Elsevier Science Sa, 2012) Yola, Mehmet Lutfi; Atar, Necip; Qureshi, Munewar Saeed; Ustundag, Zafer; Solak, Ali Osman
    This study reports the electrochemical modification of glassy carbon (GC) surface with etodolac (ETO), the characterization of this ETO modified glassy carbon (ETO/GC) electrode and its electroanalytical application for the determination of Pb(II) ions. Binding type of the etodolac with the glassy carbon surface was investigated and found that it was through the etheric linkage revealed from the reflection-absorption infrared spectroscopy (RAIRS). The ETO/GC electrode was characterized by cyclic voltammetry (CV), reflection-adsorption IR spectroscopy, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The ETO/GC electrode was found to be suitable for selective determination of Pb(II) by adsorptive stripping voltammetry in the solutions of the mixture of heavy metal ions, such as Cu(II) and Cd(II) and showed high stability and reproducibility. The stability and the potential range of the ETO/GC electrode were also studied. The developed method was validated according to the ICH guideline and found to be linear, sensitive, selective, precise and accurate. The linearity range of Pb(II) was 5.0 x 10(-10) to 1.0 x 10(-8) M with the detection limit (S/N = 3) of 1.67 x 10(-10) M. The validated method was applied successfully for the determination of Pb(II) in real samples. (c) 2012 Elsevier B.V. All rights reserved.