Yazar "Saf, Ahmet Ozgur" seçeneğine göre listele

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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.
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    Green synthesis of reduced graphene oxide/nanopolypyrrole composite: characterization and H2O2 determination in urine
    (Royal Soc Chemistry, 2014) Zor, Erhan; Saglam, Muhammed Esad; Akin, Ilker; Saf, Ahmet Ozgur; Bingol, Haluk; Ersoz, Mustafa
    Here we report on a novel, simple and eco-friendly approach for the fabrication of a reduced Graphene Oxide/nanopolypyrrole (rGO/nPPy) composite material and its electrochemical performance for detection of hydrogen peroxide on a glassy carbon electrode. The characterization of the as-prepared rGO/nPPy composite was investigated by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet-visible spectroscopy, scanning electron microscopy, contact angle measurement, cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry, differential pulse voltammetry and chronoamperometry techniques were used to investigate and optimize the performance of the developed electrochemical biosensor. The proposed biosensor showed excellent analytical response towards the quantification of H2O2 at pH 7.40. Under the optimized conditions, the biosensor shows a linear response range from 1.0 x 10(-7) to 4.0 x 10(-6) M concentrations of H2O2. The limit of detection was determined to be 34 nM. Reproducibility, sensitivity, stability and anti-interference capability of the fabricated biosensor for the detection of H2O2 were examined. The biological relevance of the developed electrochemical biosensor was further studied by the determination of H2O2 in urine samples. The real sample analysis of H2O2 was achieved before and after drinking coffee in urine samples. The successful and sensitive determination of H2O2 urine samples indicates that the proposed electrochemical biosensor can be applied to the quantification analysis of H2O2 in real samples.
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    A newly synthesized thiazole derivative as a fluoride ion chemosensor: Naked-eye, spectroscopic, electrochemical and NMR studies
    (Pergamon-Elsevier Science Ltd, 2014) Sariguney, Ahmet Burak; Saf, Ahmet Ozgur; Coskun, Ahmet
    2,3-Indoledione 3-thiosemicarbazone (TSCI) and a novel compound 3-(2-(4-(4-phenoxyphenyl)thiazol-2-yl)hydrazono)indolin-2-one (FTHI) were synthesized with high yield and characterized by spectroscopic techniques. The complexation behaviors of TSCI and FTHI for various anionic species (F-, Cl-, Br-, l(-), NO2-, NO3-, BzO(-), HSO4-, ClO4-) in CH3CN were investigated and compared by UV-vis spectroscopy, cyclic voltammetry and H-1 NMR titration techniques. FTHI showed high degree of selectivity for fluoride over other anions. This selectivity could be easily observed by the naked eye, indicating that FTHI is potential colorimetric sensor for fluoride anion. (C) 2014 Elsevier B.V. All rights reserved.
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    Preparation of a novel PSf membrane containing rGO/PTh and its physical properties and membrane performance
    (Royal Soc Chemistry, 2015) Saf, Ahmet Ozgur; Akin, Ilker; Zor, Erhan; Bingol, Haluk
    Recent advances in the fabrication of nanostructures such as graphene-related materials have received a lot of attention in membrane technology for the future of water supplies. Herein, we report the synthesis of a reduced graphene oxide/polythiophene (rGO/PTh) composite material using an in situ enzymatic polymerization reaction, which is an eco-friendly and a simple way to construct a nanocomposite material. Polysulfone (PSf) mixed matrix composite membranes containing rGO and rGO/PTh were prepared via a phase inversion method. The morphology of the membranes was evaluated by various characterization methods, including SEM, AFM, contact angle and porosity measurements. The performance and antifouling properties of the membranes were examined in detail. The PSf-rGO/PTh membrane showed a significant improvement in water flux permeability due to the enhancement of hydrophilicity and porosity. Moreover, the PSf-rGO/PTh membrane exhibited an approximately 10 times higher improved water flux than that of the rGO membrane as the pressure was increased. The fouling resistance ratio (FRR) and antifouling properties of the membranes were tested using two different protein solutions: bovine serum albumin (BSA) and cytochrome c (Ctc). The antifouling and FRR properties of the PSf-rGO/PTh membrane decreased due to not only the interactions between the functional groups on the membrane surface and fouling materials, but also the morphological properties of the membrane.
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    Spectrophotometric, voltammetric and cytotoxicity studies of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its N(4)-substituted derivatives: A combined experimental-computational study
    (Pergamon-Elsevier Science Ltd, 2015) Akgemci, Emine Guler; Saf, Ahmet Ozgur; Tasdemir, Halil Ugur; Turkkan, Ercan; Bingol, Haluk; Turan, Suna Ozbas; Akkiprik, Mustafa
    In this study, 2-hydroxy-5-methoxyacetophenone thiosemicarbazone (HMAT) and its novel N(4) substituted derivatives were synthesized and characterized by different techniques. The optical band gap of the compounds and the energy of HOMO were experimentally examined by UV-vis spectra and cyclic voltammetry measurements, respectively. Furthermore, the conformational spaces of the compounds were scanned with molecular mechanics method. The geometry optimization, HOMO and LUMO energies, the energy gap of the HOMO LUMO, dipole moment of the compounds were theoretically calculated by the density functional theory B3LY10/6-3114-+G(d,p) level. The minimal electronic excitation energy and maximum wavelength calculations of the compounds were also performed by TD-DFT//B3LYP/6-311++G(d,p) level of theory. Theoretically calculated values were compared with the related experimental values. The combined results exhibit that all compounds have good electron-donor properties which affect anti-proliferative activity. The cytotoxic effects of the compounds were also evaluated against HeLa (cervical carcinoma), MCF-7 (breast carcinoma) and PC-3 (prostatic carcinoma) cell lines using the standard MIT assay. All tested compounds showed antiproliferative effect having IC50 values in different range. In comparison with that of HMAT, it was obtained that while ethyl group on 4(N)-substituted position decreased in potent anti-proliferative effect, the phenyl group on the position increased in anti-proliferative effect for the tested cancer cell line. Considering the molecular energy parameters, the cytotoxicity activities of the compounds were discussed. (C) 2014 Elsevier B.V. All rights reserved.
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    Synthesis of Carbazole-Substituted thiosemicarbazone and its Cu(II) Complex, DNA/Protein Binding, Cytotoxic, antiproliferative activities and molecular docking studies
    (Elsevier, 2023) Findik, Mukerrem; Kuzu, Burak; Pehlivanoglu, Suray; Kaya, Serdal; Sayin, Ulku; Akgemci, Emine Guler; Saf, Ahmet Ozgur
    In this study, 9-ethyl-3-carbazolecarboxaldehyde-4-ethyl-thiosemicarbazone (ECCAET) and its copper(II) com-plex (Cu(ECCAET)2) were firstly synthesized and characterized. DFT and EPR studies confirmed that the complex is mononuclear and has square planar geometry. The interaction of all synthesized compounds with calf thymus DNA (CT-DNA) was examined by absorption and fluorescent spectroscopy. The experimental results showed that Cu(ECCAET)2 interacts with DNA via an intercalative binding mode. The binding interactions of the complex with CT-DNA have been confirmed through viscosity measurements revealing that the complex interacts with DNA via intercalation. Furthermore, the protein binding ability of ECCAET and Cu(ECCAET)2 was investigated using BSA via electronic absorption spectral titration, fluorescence quenching, and synchronous fluorescence spectrum studies, which revealed that the Cu(ECCAET)2 strongly bound to BSA over the ligand. Molecular docking studies were also performed to support the bonding mechanism of ECCAET and Cu(ECCAET)2 with DNA and BSA. The biological activity studies of ECCAET and Cu(ECCAET)2 against cancer cells were also investigated. A panel of cancer cell lines, including A2780 human ovarian adenocarcinoma, MDA-MB-231 human triple-negative breast adenocarcinoma, and as a control non-cancerous L929 fibroblast cell lines were also used to test the compounds' anticancer activities. Cytotoxic and antiproliferative properties of Cu(ECCAET)2 were visibly higher than its ligand (ECCAET) for all tested cell lines. The Cu(ECCAET)2 had a distinctive biological effects on A2780, and MDA-MB-231 cells compared to non-cancerous cells. Within these results, Cu(ECCAET)2 was found a promising drug candidate against gynecologic cancer diseases.