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    Carbon Nanotubes Modified Graphite Electrodes for Monitoring of Biointeraction Between 6-Thioguanine and DNA
    (Wiley-V C H Verlag Gmbh, 2017) Unal, Didem Nur; Eksin, Ece; Erdem, Arzum
    In this present study, single-walled carbon nanotubes (SWCNT) modified disposable pencil graphite electrodes (SWCNT-PGEs) were developed for the electrochemical monitoring of anticancer drug, and its interaction with double stranded DNA (dsDNA). Under this aim, SWCNT-PGEs were applied for the first time in the literature to analyse of 6-Thioguanine (6-TG), and also to investigate its interaction with DNA by voltammetric and impedimetric methods. The surface morphologies of PGE and SWCNT-PGE were explored using scanning electron microscopy (SEM) and electrochemical characterization of unmodified/modified electrodes was performed by cyclic voltammetry (CV). Experimental parameters; such as, the concentration of 6-TG and its interaction time with dsDNA were optimized by using differential pulse voltammetry (DPV). Additionally, the interaction of 6-TG with dsDNA was studied in case of different interaction times by electrochemical impedance spectroscopy (EIS) in contrast to voltammetric results. The detection limit of 6-TG was found to be 0.25 mu M by SWCNT-PGE.
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    Electrochemical Determination of 6-Thioguanine and Its Interaction with DNA Oligonucleotides Using Disposable Graphite Pencil Electrodes
    (Taylor & Francis Inc, 2018) Unal, Didem Nur; Eksin, Ece; Erdem, Arzum
    Disposable graphite pencil electrodes were used in this study for the electrochemical determination of 6-thioguanine using its interaction with a single-stranded Oligo (A)(25) composed of 25 adenine (A) bases or double-stranded Oligo (A)(25)-Oligo (T) 25, a hybrid form of Oligo (A)(25) and Oligo (T)(25) composed of 25 thymine (T) bases. The surface interaction was evaluated by monitoring the changes of the oxidation signals of 6-thioguanine and adenine. The electrochemical measurements were performed using differential pulse voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy. The experimental conditions, including the concentration of 6-thioguanine and its period of interaction with single-stranded Oligo (A)(25) or double-stranded Oligo (A)(25)-Oligo (T)(25), were optimized by observing the changes in the 6-thioguanine and adenine oxidation currents by differential pulse voltammetry. The detection limit was determined to be 0.24 mu M across the useful linear concentration range from 1 to 4 mu M 6-thioguanine. The reported single-use graphite sensor provides a cost-effective, rapid, and sensitive detection approach for the electrochemical characterization of the interaction between DNA and 6-thioguanine.
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    Electrochemical Monitoring of Interaction of Temozolamide with DNA by Graphene Oxide Modified Single-Use Electrodes
    (Electrochemical Soc Inc, 2022) Eksin, Ece; Isin, Deniz; Unal, Didem Nur; Erdem, Arzum
    Graphene oxide (GO) modified single-use pencil graphite electrodes (PGEs) were used for electrochemical monitoring of surface confined interaction between Temozolamide (TMZ) and calf thymus double stranded DNA (ctdsDNA). First, the PGE surface was activated by EDC/NHS (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide) as covalent agents (CA). Then, modification of GO was done onto the surface of chemically activated PGE surface to obtain CA-GO-PGEs. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy studies were used to establish the interfacial electron transfer of the electrodes. The optimization of experimental conditions was carried out via CV technique followed by electrochemical examination of the interaction of TMZ with ctdsDNA. (c) 2022 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.