Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 2Reduction of Carbon Dioxide During the Synthesis of Metal Nano-Particles in Water(Elsevier Ltd., 2003) Polat, Hürriyet; Cohen, H; Meyerstein, D; Rusonik, I.An effort was made to synthesize "carbon-free" metal (Fe-0, Co-0, Ni-0) nano-particles via the reduction of their salts with BH4- in aqueous solutions. Surprisingly it was found that when the synthesis is carried out in the presence of CO2, e.g., in aerated solutions, the CO2 is catalytically reduced by BH(4)(-)on the surface of the metal particles. Carbon-free metals can be prepared by reduction under an inert atmosphere. Thus metal surfaces might have acted as catalysts for CO2 fixation, probably via the initial formation of carbon clusters, in the reductive atmosphere in the prebiotic era. (C) 2003 Elsevier B.V. All rights reserved.Article Citation - WoS: 169Citation - Scopus: 177Thin Film Microextraction: Towards Faster and More Sensitive Microextraction(Elsevier Ltd., 2019) Ölçer, Yekta Arya; Tascon, Marcos; Eroğlu, Ahmet Emin; Boyacı, EzelThin film microextraction (TFME) is an analytical tool that has been proven to be suitable for integrated sampling and sample preparation of a wide variety of routine and on-site applications. Compared to the traditional microextraction techniques, the most important advantage of TFME is its enhanced sensitivity due to the relatively larger extractive phase spread over a larger surface area. The technique, in this way, facilitates fast extraction kinetics and high extractive capacity. Moreover, TFME offers high versatility for device development over classical SPME technologies due to the plethora of available extractive phases, coating methods and geometry options. The goal of this review is to provide a comprehensive summary of the contemporary advances in this exciting field covering novel extractive phases, technological and methodological developments, and relevant cutting-edge applications. Finally, a critical discussion of the future trends on TFME is also presented. (C) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 29Citation - Scopus: 29Investigating Silicon Wafer Based Substrates for Dried-Droplet Analysis by Laser-Induced Breakdown Spectroscopy(Elsevier Ltd., 2019) Aras, Nadir; Yalçın, ŞerifeThis work communicates a critical assessment on the analytical capability of the three silicon wafer-based substrates; crystalline silicon (c-Si), oxide-coated silicon (SiO2-Si), and nitride-coated silicon (Si3N4-Si), for dried-droplet analysis by laser-induced breakdown spectroscopy. The methodology consists of loading, drying and analyzing steps. First, nanoliter volume of droplets are manually loaded onto the substrate and dried at room temperature. Then, the dry residue is subjected to high peak power (1.15 GW/cm(2)) laser pulses focused outside the minimum focal point condition and luminescent plasma is spectroscopically analyzed. Results revealed that nitride-coated substrate exhibits strong enhancements in signal intensity for most emission lines of the analyte species investigated: Cd, Cr, Cu, Mn, and Pb. Surface reflectivity and surface morphology were comparatively investigated to explore enhanced analytical performance of nitride-coated substrates. Experimental conditions were optimized and growth curves for all the elements are found linear with minimum regression constant of 0.96. LOD's of 62 pg Cd, 1.5 pg Cr, 0.5 pg Cu, 2 pg Mn and 11 pg Pb, in absolute amounts, were obtained. The accuracy and precision of the methodology were tested on certified reference water sample (CRM-TMDW), and ICP-multi-element standard sample (ICP-MES). The surface enhancement effect observed on Si3N4 coated substrates has improved the analytical capability of laser-induced breakdown spectroscopy for liquid analysis.Article Citation - WoS: 6Citation - Scopus: 7Development of a Water-Soluble 3-Formylbodipy Dye for Fluorogenic Sensing and Cell Imaging of Sulfur Dioxide Derivatives(Elsevier Ltd., 2019) Işık, Murat; Şimşek Turan, İlke; Dartar, SuayA new water-soluble, highly fluorogenic 3-formylBODIPY dye that enables the sensing of SO2 derivatives in aqueous buffers and cancer cells is reported. The quaternary ammonium group appended through the mesa-position of the BODIPY dye ensures water solubility. The probe exhibits high specificity for cytosolic (bi)sulfites and fluoresces brightly in human lung adenocarcinoma cells (A549). (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 34Citation - Scopus: 36Biomimetic Hybrid Scaffold Consisting of Co-Electrospun Collagen and Pllcl for 3d Cell Culture(Elsevier Ltd., 2019) Türker, Esra; Yıldız, Ümit Hakan; Arslan Yıldız, AhuElectrospun collagen is commonly used as a scaffold in tissue engineering applications since it mimics the content and morphology of native extracellular matrix (ECM) well. This report describes "toxic solvent free" fabrication of electrospun hybrid scaffold consisting of Collagen (Col) and Poly(L-lactide-co-epsilon-caprolactone) (PLLCL) for three-dimensional (3D) cell culture. Biomimetic hybrid scaffold was fabricated via co-spinning approach where simultaneous electrospinning of PLLCL and Collagen was mediated by polymer sacrificing agent Polyvinylpyrrolidone (PVP). Acidified aqueous solution of PVP was used to solubilize collagen without using toxic solvents for electrospinning, and then PVP was readily removed by rinsing in water. Mechanical characterizations, protein adsorption, as well as biodegradation analysis have been conducted to investigate feasibility of biomimetic hybrid scaffold for 3D cell culture applications. Electrospun biomimetic hybrid scaffold, which has 3D-network structure with 300-450 nm fiber diameters, was found to be maximizing cell adhesion through assisting NIH 3T3 mouse fibroblast cells. 3D cell culture studies confirmed that presence of collagen in biomimetic hybrid scaffold have created a major impact on cell proliferation compared to conventional 2D systems on long-term, also cell viability increased with the increasing amount of collagen. (c) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 16Citation - Scopus: 17Antiproliferative Activity of (r)-4 '-methylklavuzon on Hepatocellular Carcinoma Cells and Epcam(+)/Cd133(+) Cancer Stem Cells Via Sirt1 and Exportin-1 (crm1) Inhibition(Elsevier Ltd., 2019) Delman, Murat; Avcı, Sanem Tercan; Akçok, İsmail; Kanbur, Tuğçe; Erdal, Esra; Çağır, AliCytotoxic effects of (R)-4'-methylklavuzon were investigated on hepatocellular carcinoma cells (HuH-7 and HepG2) and HuH-7 EpCAM(+)/CD133(+) cancer stem cells. IC50 of (R)-4'-methylklavuzon was found as 1.25 mu M for HuH-7 parental cells while it was found as 2.50 mu M for HuH-7 EpCAM(+)/CD133(+) cancer stem cells. (R)-4'-methylklavuzon tended to show more efficient in vitro cytotoxicity with its lower IC50 values on hepatocellular carcinoma cell lines compared to its lead molecule, goniothalamin and FDA-approved drugs, sorafenib and regorafenib. Cell-based Sirtuin/HDAC enzyme activity measurements revealed that endogenous Sirtuin/HDAC enzymes were reduced by 40% compared to control. SIRT1 protein levels were upregulated indicating triggered DNA repair mechanism. p53 was overexpressed in HepG2 cells. (R)-4'methylklavuzon inhibited CRM1 protein providing increased retention of p53 and RIOK2 protein in the nucleus. HuH-7 parental and EpCAM(+)/CD133(+) cancer stem cell spheroids lost intact morphology. 3D HepG2 spheroid viabilities were decreased in a correlation with upregulation in p53 protein levels. (C) 2019 Elsevier Masson SAS. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 6Palladium-Catalyzed Coupling of 2-En Carbonates With Terminal Alkynes(Elsevier Ltd., 2018) Taç, Doğan; Artok, LeventThe first palladium-catalysed coupling of the carbonates of (E)-configured conjugated enynols with terminal alkynes is described. This method allows the synthesis of vinyl-allenynes with good yields. It has been determined that the method is not suitable for the (Z)-configured substrates.Article Citation - WoS: 16Citation - Scopus: 19Nmr Studies on Natural and Synthetic Amavadin(Elsevier Ltd., 2000) Armstrong, Elaine M.; Collison, David; Ertok, Nigar; Garner, Catherine D.The stereochemistry of isolated natural product Amavadin, which contains a 1:2 complex of V(IV) with N-hydroxyimino-2,2′-dipropionic acid (HIDPAH3), and some synthetic complexes have been investigated. Amavadin was isolated from Amanita muscaria and oxidized with [NH4]2[Ce(NO3)6]. H2[Δ-V(S,S-HIDPA)2].3H2O, H2[Δ,Λ-V(S,S-HIDPA)2].3H2O and their equivalent oxidized species have been synthesized and characterized spectroscopically. A combination of COSY, NOE, 1H, 13C-NMR and CD spectroscopy have been used to prove that the isolated natural product Amavadin consists of an almost equal mixture of the Δ- and Λ-isomers of [V(S,S-HIDPA)2]2-. The stereochemistry of isolated natural product Amavadin, which contains a 1:2 complex of V(IV) with N-hydroxyimino-2,2'-dipropionic acid (HIDPAH3), and some synthetic complexes have been investigated. Amavadin was isolated from Amanita muscaria and oxidized with [NH4]2[Ce(NO3)6]. H2[Δ-V(S,S-HIDPA)2].3H2O, H2[Δ,Λ-V(S,S-HIDPA)2].3H2O and their equivalent oxidized species have been synthesized and characterized spectroscopically. A combination of COSY, NOE, 1H, 13C-NMR and CD spectroscopy have been used to prove that the isolated natural product Amavadin consists of an almost equal mixture of the Δ- and Λ-isomers of [V(S,S-HIDPA)2]2-.Book Part Citation - WoS: 7Citation - Scopus: 14Olive Oil Adulteration With Sunflower and Corn Oil Using Molecular Fluorescence Spectroscopy(Elsevier Ltd., 2010) Öztürk, Betül; Arıkan, Aysun; Özdemir, DurmuşAdulteration of olive oil with cheaper substitutes such as sunflower and corn oil is a major concern for the public. Rapid analysis methods are required for a quick and easy screening of possible adulteration attempts. Fluorescence spectroscopy coupled with a genetic algorithm-based multivariate calibration method allows the determination of olive oil adulteration with sunflower and corn oil. Because the standard error of prediction values are all below 1.30% (w/w) for the ternary set, fluorescence spectroscopy can be used as a fast screening method for possible olive oil adulteration with cheaper vegetable oils. In addition, the genetic algorithm used in the genetic inverse least squares (GILS) method is able to select and extract the most relevant information to build successful calibration models that have high predictive ability for the independent test samples.Article Citation - WoS: 44Citation - Scopus: 53Smart Phone Assisted Detection and Quantification of Cyanide in Drinking Water by Paper Based Sensing Platform(Elsevier Ltd., 2017) İncel, Anıl; Akın, Osman; Çağır, Ali; Yıldız, Ümit Hakan; Demir, Mustafa MuammerAn organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6 μ m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN− addition from 10−2 to 10−12 M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN− concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions.