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    Anticancer, antimicrobial, spectral, voltammetric and DFT studies with Cu(II) complexes of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its N(4)-substituted derivatives
    (Elsevier Science Sa, 2017) Turkkan, Ercan; Sayin, Ulku; Erbilen, Nesibe; Pehlivanoglu, Suray; Erdogan, Gokce; Tasdemir, Halil Ugur; Saf, Ahmet Ozgur
    New copper complexes of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its N(4)-substituted derivatives were synthesized and characterized by theoretical DFT studies and experimental UV-Vis, FT-IR, EPR spectral analysis, cyclic voltammetry, magnetic susceptibility and conductivity measurements. The DFT calculation results have been used to predict and interpret the experimental results. The geometric parameter G within the range of 7.61-7.86 for all complexes confirms the mononuclear nature of the complexes. The EPR, UV-Vis, DFT studies and obtained bonding parameters show that all the complexes have square planar geometry and their M-L bonds have strong ionic and some in-plane a-bond character. In addition, the experimental and DFT studies showed that HOMO and LUMO energy levels of the complexes may present good electron transporting properties. Also, the investigated Cu(II) complexes were tested for biological activity, proving both in vitro antibacterial and anticancer activity. The complexes exhibited antibacterial activity against Gram positive bacteria S. aureus while exhibiting no activities against gram negative bacteria E. toll and S. gallinarum. The f parameters obtained experimentally by EPR support the antimicrobial activity properties results of the complexes. The evaluations of potential anticancer activity of these complexes were carried out against highly metastatic MDA-MB-231 breast adenocarcinoma cell line by MTT assay. Our results suggest that all tested copper complexes have high cytotoxic effects with the range of 1.76-3.53 mu M IC50 values in vitro. These copper complexes could be considered as potential anticancer agents to counteract drug resistance of metastatic cancer cells. (C) 2016 Elsevier B.V. All rights reserved.
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    An electrochemical chiral sensor based on electrochemically modified electrode for the enantioselective discrimination of D-/L-tryptophan
    (Springer, 2019) Erbilen, Nesibe; Zor, Erhan; Saf, Ahmet Ozgur; Akgemci, Emine Guler; Bingol, Haluk
    Chirality is a universal characteristic of natural systems and discrimination of enantiomers of a chiral molecule plays a major role particularly in chemical biology and in pharmacology. In this study, a novel electrochemical chiral sensor was developed for direct discrimination of D- and L-tryptophan (Trp) in an aqueous medium. The chiral sensor was produced by hierarchical modification of reduced graphene oxide, gold nanoparticles, poly-L-cysteine, and poly-L-phenylalanine methyl ester on the glassy carbon electrode. Each of the layers was produced by electrochemical techniques, such as electrochemical reduction and polymerization. After structural and morphological characterizations, the electrochemical behaviors of the enantiomeric pairs of Trp at the modified electrode were investigated by cyclic voltammetry and square wave voltammetry. A distinctive separation between the oxidation peak potentials of D- and L-Trp was observed at 0.73 and 0.83 V, respectively. In order to investigate the amperometric response towards D- and L-Trp, chronoamperometry technique was also used in the concentration range of 0.1-0.8 mM. Furthermore, the electrochemical performance of the modified electrodes was investigated in a mixed solution of D- and L-Trp. The results showed that the prepared electrode could be used as an electrochemical chiral sensor for Trp enantiomers.