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Öğe Carboxylated-Graphene Decorated Pencil Graphite Electrode as a Platform for Voltammetric Detection of DNA(Electrochemical Soc Inc, 2017) Zor, Erhan; Eksin, Ece; Findik, Mukerrem; Bingol, Haluk; Erdem, ArzumContinuous technology miniaturization using nanoscale materials allows the design of DNA sensing platforms with not only far larger surface areas but alsomore effective characteristics. We herein synthesized benzoic acid-functionalized graphene oxide (GOB), characterized by FT-IR, XPS, Raman Spectroscopy, TGA, SEM, TEM techniques and then it was utilized as a supporting material. Due to the benzoic acid groups available on the surface of GOB, fsDNA was directly immobilized onto the disposable pencil graphite electrode (PGE). The limit of detection (LOD) for fish sperm DNA (fsDNA) concentration was estimated to be 1.11 mu g/mL by using differential pulse voltammetry (DPV) technique. It can be assumed that this simple modification protocol offers an alternative for the quick and robust monitoring of sequence-specific nucleic acids avoiding the need of complex or expensive requirements, and it can pave the way for new opportunities to design more novel DNA sensing strategies and applications on disposable platforms. (c) 2017 The Electrochemical Society. All rights reserved.Öğe Catalytic degradation of organic dye using reduced graphene oxide-polyoxometalate nanocomposite(Elsevier Science Sa, 2017) Ucar, Asuman; Findik, Mukerrem; Gubbuk, I. Hilal; Kocak, Nuriye; Bingol, HalukSilicotungstic acid (SiW) decorated reduced graphene oxide (rGO) nanocomposite (rGO-SiW) has been prepared and evaluated as a heterogeneous nanocatalyst for the degradation reactions of methylene blue (MB) and rhodamine B (RhB). The structural and morphological properties of rGO-SiW nanocomposite were investigated by various techniques such as Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), Atomic force microscopy (AFM) and Scanning electron microscope (SEM), which revealed the homogeneous and noncovalent anchoring of SiW nanoparticles on rGO sheets. The catalytic activity of rGO-SiW nanocomposite on the degradations of MB and RhB has been monitored using UV-visible absorption spectrometry in the presence of NaBH4 as the reducing agent at room temperature in water. The reduction reactions followed pseudo-first order kinetics and degradation were achieved in 34 min for MB and 81 min for RhB using rGO-SiW as catalysts. (C) 2017 Elsevier B.V. All rights reserved.Öğe Cytotoxic effects, microbiological analysis and inhibitory properties on carbonic anhydrase isozyme activities of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its Cu(II), Co(II), Zn(II) and Mn(II) complexes(Springer, 2021) Ucar, Asuman; Findik, Mukerrem; Kuzu, Muslum; Pehlivanoglu, Suray; Sayin, Ulku; Sayin, Zafer; Akgemci, Emine GulerMetal complexes of thiosemicarbazones have been receiving considerable attention in biological applications such as antimicrobial and anticancer therapies. In this work, Co(II), Zn(II) and Mn(II) complexes of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone (HMAT) were synthesized for the first time and characterized by EPR, FT-IR, NMR, UV-Vis spectroscopies, TG/DSC and elemental analysis. X-ray powder diffraction analysis was carried out for Zn(II) complex. HMAT and its Cu(II), Co(II), Zn(II) and Mn(II) complexes were tested as enzyme inhibitory agents. All compounds are effective inhibitor of cytosolic carbonic anhydrase I and II isoforms (hCA I and II) enzymes. IC(50)values of HMAT and its Cu(II), Co(II), Zn(II) and Mn(II) complexes were determined as 93.35, 324.46, 25.67, 1.06 and 22.36 mu M for CA I isozyme and 99.02, 86.64, 57.76, 10.34 and 36.48 mu M for CA II isozyme, respectively. The evaluation of potential cytotoxic effects of the compounds was performed against normal epithelial breast mammary gland CRL-4010, estrogen-positive low metastatic MCF-7 and triple negative highly metastatic MDA-MB-231 breast adenocarcinoma cell lines by MTT assay. The results showed that the tested metal complexes have high cytotoxic effects than their ligand molecule. In particular, the Cu(II) complex displayed preciously high cytotoxic properties different from the others. Given these facts, the Cu(II) complex could be debated as potential chemotherapeutic molecule against drug-resistant breast cancer cells. Minimum inhibitory concentrations of the compounds against the test organisms were also detected for the microbiological analysis.Öğe Electrochemical detection of interaction between daunorubicin and DNA by hybrid nanoflowers modified graphite electrodes(Elsevier Science Sa, 2021) Findik, Mukerrem; Bingol, Haluk; Erdem, ArzumIn this study, two types of hybrid nanoflowers (NFs) modified disposable electrodes were developed to investigate the electrochemical behavior of anticancer drug-DNA interaction. Biocompatible hybrid NFs were synthesized by amino acids (L-glutamic acid and L-cysteine) via a simple, rapid and cost-effective methods. Structural characterizations of the synthesized hybrid NFs were performed with Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), while morphological characterizations were performed using scanning electron microscopy (SEM) and energy diffuser X-ray (EDX) spectroscopy techniques. As the sensing platform in electrochemical studies, pencil graphite electrode (PGE) has been used because of its advantages such as low cost, easy-to-handle, portable and disposable. After PGEs modified with NFs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, differential pulse voltammetry (DPV) technique was used in the determination of calf thymus double stranded DNA (ctdsDNA) and also daunorubicin (DNR) as well as DNA-DNR interaction. The detection limits as a result of ctdsDNA determination were found to be 0.93 mu g/mL by using Lcysteine NFs modified PGE (c-NFs-PGE) and 2.37 mu g/mL by using L-glutamic acid modified PGE (ga-NFs-PGE). The detection limits obtained for the determination of DNR were found as 2.93 mu M and 2.06 mu M with c-NFs-PGE and ga-NFs-PGE, respectively. The optimum interaction time between DNR and ctdsDNA was determined by cNFs-PGE, which showed higher sensitivity performance against oxidation of guanine signals.Öğe Fluorogenic ferrocenyl Schiff base for Zn2+ and Cd2+ detection(Springer, 2017) Findik, Mukerrem; Ucar, Asuman; Bingol, Haluk; Guler, Ersin; Ozcan, EmineA novel sensor based on acetylferrocene-containing Schiff base (ASB) was synthesized by reaction of alpha-chloroacetylferrocene and N-(salicylidene)-l-valinmethylester. The structure of the compound was characterized by using elemental analysis and Fourier-transform infrared (FT-IR), H-1 nuclear magnetic resonance (NMR), and C-13 NMR spectroscopy. Its metal-cation-sensing properties were investigated spectrofluorometrically. ASB served as selective chemosensor for Zn2+ and Cd2+ towards alkali, alkaline-earth, and various heavy-metal ions. It showed significant fluorescence enhancement for Zn2+ and Cd2+ ions, stemming from C=N isomerization and chelation-enhanced fluorescence. The binding modes of the complexes were determined to have 1:1 complexation stoichiometry, and the binding constants were calculated as (6.93 +/- 0.25) x 10(6) M-1 for ASB center dot Zn (2+) and (7.49 +/- 0.18) x 10(5) M-1 for ASB center dot Cd (2+) using the nonlinear curve-fitting method.Öğe Hybrid nanoflowers modified pencil graphite electrodes developed for electrochemical monitoring of interaction between Mitomycin C and DNA(Elsevier, 2021) Findik, Mukerrem; Bingol, Haluk; Erdem, ArzumIn the present study, biocompatible hybrid nanoflowers (NFs) were synthesized by amino acids (glycine, L-lysine) via a simple, rapid and cost-effective methods. NFs were characterized by using FT-IR, Raman spectroscopy, XPS, SEM and EDX techniques. Modified pencil graphite electrode (PGE) surfaces with well-defined NFs were developed to electrochemical monitoring of calf thymus double stranded DNA (ctdsDNA) using differential pulse voltammetry (DPV) for the first time. SEM, EDX, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods were used to characterize the surfaces obtained after modification. In comparison to L-lysine NFs (LNFs-PGE), glycine NFs (GNFs-PGE) exhibited a higher sensitivity performance towards the oxidation of guanine moiety signals. The interaction time between anticancer drug Mitomycin C (MC) and ctdsDNA was aslo investigated with GNFs-PGE.Öğe New copper(II) complex based-thiosemicarbazone and phenanthroline: DNA/BSA binding, antiproliferative activity, DFT and docking studies(Elsevier, 2023) Findik, Mukerrem; Turkkan, Ercan; Pehlivanoglu, Suray; Sayin, Ulku; Ceylan, Umit; Akgemci, Emine GulerA new copper(II) complex {Cu(HPP)}, bromo(1,10-phenanthroline)(triphenylphosphine)copper(I) with 2-hydroxy-5-methoxyacetophenone thiosemicarbazone (HMAT) was synthesized and characterized by experimental FT-IR, Raman, UV-vis, TGA and EPR spectral analysis. The Cu(HPP) was theoretically modeled using the B3LYP/VTZ method/basis set and the values of the spectroscopic parameters were calculated by the DFT method. The coordination geometry around the Cu(II) in the compound was predicted as an elongated octahedral. Spectroscopic investigations showed the intercalative binding mechanism of the Cu(HPP) with calf-thymus deoxyribonucleic acid (ct-DNA). Spectroscopic techniques were also used to evaluate the interaction of the Cu (HPP) with bovine serum albumin (BSA), which revealed that the Cu(HPP) could bind to BSA significantly. In addition, the molecular docking between the Cu(HPP) and BSA was investigated to support the bonding mechanism. Further, we studied the anticancer activity of the Cu(HPP) in drug resistant breast cancer cell line (MDA-MB-231), with a focus on the proliferative characteristics. Our findings emphasize that this newly synthetized complex has a significant cytotoxic effect on the cells and can be utilized as a candidate chemotherapeutic agent to effectively target breast cancer.Öğe Organometallic chiral Schiff base for enantio-selective fluorescent recognition of methionine(Springer International Publishing Ag, 2017) Ucar, Asuman; Findik, Mukerrem; Bingol, Haluk; Guler, Ersin; Ozcan, EmineHerein, the synthesis and characterization of a novel chiral Schiff bases derived from ferrocene, coded as 3, have been reported. The sensing behavior of the synthesized compound has been examined towards the enantiomers of some amino acids (methionine, alanine, serine, histidine, and threonine) by spectrofluorimetric method. The fluorescence response of compound 3 showed noticeable enhancement upon addition of d-methionine compared to l-methionine and kept nearly linear correlation with the concentration of d-methionine. The value of enantiomeric fluorescence difference ratio (ef) has been determined to be 1.54 when d - and l- methionine amount is 100 times more than compound 3. The results showed that the compound 3 can be used as a sensor for enantio-selective recognition of d-methionine.Öğe Self-assembly of a new building block of {BMo12O40} with excellent catalytic activity for methylene blue(Pergamon-Elsevier Science Ltd, 2019) Findik, Mukerrem; Ucar, Asuman; Colak, Alper Tolga; Sahin, Onur; Bingol, Haluk; Sayin, Ulku; Kocak, NuriyeA novel organic-inorganic hybrid of 2,2'-bipyridyl (2,2'-bipy) linked covalently with the first inorganic framework based on boron-containing Keggin-type heteropolymolybdate anion [BMo12O40](5-) has been hydrothermally synthesized in aqueous solution. The crystal structure was fully characterized by elemental analyses, single crystal X-ray diffraction, Fourier-transform infrared spectrum (FT-IR), powder X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis) and electron paramagnetic resonance (EPR) analysis. The catalytic performance of the synthesized catalyst was studied in degradation of methylene blue (MB) at ambient temperature. The catalyst exhibited excellent degradation against MB with a rate constant of 0.506/m, which was much higher than those by other polyoxometalate catalysts. Moreover, it was found to be easily separated from the reaction solution and recycled up to five times without significant loss of degradation activity. (C) 2019 Elsevier Ltd. All rights reserved.Öğe Synthesis of anti-4-phenoxyphenylaminoglyoxime and its some transition metal complexes: Spectral, DFT, electrochemical and anticancer activity studies(Elsevier, 2020) Findik, Mukerrem; Ucar, Asuman; Turkkan, Ercan; Pehlivanoglu, Suray; Ozcan, Emineanti-4-phenoxyphenylaminoglyoxime (LH2) was synthesized starting from 4-aminodiphenylether and anti-chloroglyoxime in absolute ethanol. Then, mononuclear complexes [Ni(II) and Cu(II)] of LH2 were synthesized with the metal:ligand ratio of 1:2. The LH2 and its complexes [Ni(LH)(2) and Cu(LH)(2)] were characterized by elemental analysis, FT-IR, Raman, UV-vis, thermogravimetric analysis (TGA), H-1 NMR, C-13 NMR, heteronuclear multiple bond correlation (HMBC) spectroscopy and theoretical DFT studies. Also, redox properties of the ligand and its complexes were investigated by cyclic voltammetry in DMSO solution at room temperature. Conformational space was scanned with molecular mechanic simulations and then the possible stable conformers of LH2 ligand were determined by B3LYP/6-311++G (d,p) level calculations. The Ni(LH)(2) and Cu(LH)(2) metal complexes were modeled theoretically using B3LYP/LanL2DZ level. The theoretical vibrational frequencies were calculated by using optimization calculation levels. The NMR parameters of LH2 ligand, Cu(LH)(2) and Ni(LH)(2) metal complexes were calculated at mPW1PW91/6-311 + G (2d,p) level. Theoretically calculated values were compared with the related experimental values. The DFT calculation results have been used to predict and interpret the molecular structures of LH2 ligand and its complexes. The geometry around nickel in Ni(LH)(2) and around cupper in Cu(LH)(2) complex are almost square planar. In addition, we evaluated the efficacy of LH2 ligand and its Ni(LH)(2) and Cu(LH)(2) complexes in the breast adenocarcinoma cell line (MCF7). Our data showed that the metal compounds affect positively the cytotoxic activity of the ligand (LH2). The metal complexes, especially Ni(LH)(2) complex, exhibited noteworthy biological activity against the viability of MCF7 cells. (C) 2020 Elsevier B.V. All rights reserved.Öğe 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 OzgurIn 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.
