Browsing by Subject "chemical structure"
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Item Open Access Cyclodextrin functionalized poly(methyl methacrylate) (PMMA) electrospun nanofibers for organic vapors waste treatment(Elsevier BV, 2010) Uyar, Tamer; Havelund, R.; Nur, Y.; Balan, A.; Hacaloglu, J.; Toppare, L.; Besenbacher, F.; Kingshott, P.Poly(methyl methacrylate) (PMMA) nanofibers containing the inclusion complex forming betacyclodextrin (_-CD) were successfully produced by means of electrospinning in order to develop functional nanofibrous webs for organic vapor waste treatment. Electrospinning of uniform PMMA nanofibers containing different loadings of _-CD (10%, 25% and 50% (w/w)) was achieved. The surface sensitive spectroscopic techniques; X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed that some of the _-CD molecules are present on the surface of the PMMA nanofibers, which is essential for the trapping of organic vapors by inclusion complexation. Direct pyrolysis mass spectrometry (DP-MS) studies showed that PMMA nanowebs containing _-CD can entrap organic vapors such as aniline, styrene and toluene from the surroundings due to inclusion complexation with _-CD that is present on the fiber surface. Our study showed that electrospun nanowebs functionalized with cyclodextrinsmayhave the potential to be used as molecular filters and/or nanofilters for the treatment of organic vapor waste and air filtration purposes.Item Open Access Cytotoxic activities of some benzothiazole-piperazine derivatives(Taylor and Francis Ltd, 2015) Gurdal, E.E.; Durmaz I.; Cetin-Atalay, R.; Yarim, M.Synthesis, characterization and cytotoxic activities of ten benzothiazole-piperazine derivatives were reported. In vitro cytotoxic activities of compounds were screened against hepatocellular (HUH-7), breast (MCF-7) and colorectal (HCT-116) cancer cell lines by sulphorhodamine B assay. Based on the GI50 values of the compounds, most of the benzothiazole-piperazine derivatives are active against HUH-7, MCF-7 and HCT-116 cancer cell lines. Compound 1d is highly cytotoxic against all tested cancer cell lines. Further investigation of compound 1d by Hoechst Staining and Fluorescence-Activated Cell Sorting Analysis (FACS) revealed that this compound causes apoptosis by cell cycle arrest at subG1 phase. © 2014 Informa UK Ltd. All rights reserved.Item Open Access Detecting secondary structure and surface orientation of helical peptide monolayers from resonant hybridization signals(Nature Publishing Group, 2013) Alici, K. B.; Gallardo I.F.Hybridization of dominant vibrational modes with meta-surface resonance allows detection of both structural changes and surface orientations of bound helical peptides. Depending on the resonance frequency of meta-molecules, a red- or blue- shift in peptide Amide-I frequency is observed. The underlying coupling mechanism is described by using a temporal coupled mode theory that is in very good agreement with the experimental results. This hybridization phenomenon constitutes the basis of many nanophotonic systems such as tunable coupled mode bio-sensors and dynamic peptide systems driven by infrared signals.Item Open Access Direct measurement of molecular stiffness and damping in confined water layers(The American Physical Society, 2004) Jeffery, S.; Hoffmann, P. M.; Pethica, J. B.; Ramanujan, C.; Özer, H. Ö.; Oral, A.We present direct and linear measurements of the normal stiffness and damping of a confined, few molecule thick water layer. The measurements were obtained by use of a small amplitude (0.36 Å), off-resonance atomic force microscopy technique. We measured stiffness and damping oscillations revealing up to seven molecular layers separated by 2.526 ± 0.482 Å. Relaxation times could also be calculated and were found to indicate a significant slow-down of the dynamics of the system as the confining separation was reduced. We found that the dynamics of the system is determined not only by the interfacial pressure, but more significantly by solvation effects which depend on the exact separation of tip and surface. The dynamic forces reflect the layering of the water molecules close to the mica surface and are enhanced when the tip-surface spacing is equivalent to an integer multiple of the size of the water molecules. We were able to model these results by starting from the simple assumption that the relaxation time depends linearly on the film stiffness.Item Open Access Self-assembled template-directed synthesis of one-dimensional silica and titania nanostructures(2011) Acar H.; Garifullin, R.; Güler, Mustafa O.Mineralized biological materials such as shells, skeleton, and teeth experience biomineralization. Biomimetic materials exploit the biomineralization process to form functional organic-inorganic hybrid nanostructures. In this work, we mimicked the biomineralization process by the de novo design of an amyloid-like peptide that self-assembles into nanofibers. Chemically active groups enhancing the affinity for metal ions were used to accumulate silicon and titanium precursors on the organic template. The self-assembly process and template effect were characterized by CD, FT-IR, UV-vis, fluorescence, rheology, TGA, SEM, and TEM. The self-assembled organic nanostructures were exploited as a template to form high-aspect-ratio 1-D silica and titania nanostructures by the addition of appropriate precursors. Herein, a new bottom-up approach was demonstrated to form silica and titania nanostructures that can yield wide opportunities to produce high-aspect-ratio inorganic nanostructures with high surface areas. The materials developed in this work have vast potential in the fields of catalysis and electronic materials. © 2011 American Chemical Society.Item Open Access Synthesis and anticancer activity evaluation of some benzothiazole-piperazine derivatives(Bentham Science Publishers B.V., 2015) Gurdal, E.E.; Buclulgan, E.; Durmaz I.; Cetin-Atalay, R.; Yarim, M.Synthesis, characterization and cytotoxic activities of ten benzothiazole-piperazine derivatives were reported. In vitro cytotoxic activities of compounds were screened against hepatocellular (HUH-7), breast (MCF-7) and colorectal (HCT-116) cancer cell lines by sulphorhodamine B assay. Based on the GI50 values of the compounds, most of the benzothiazole-piperazine derivatives are active against HUH-7, MCF-7 and HCT-116 cancer cell lines. Aroyl substituted compounds 1h and 1j were found to be the most active derivatives. In addition, further investigation of compounds 1h and 1j by Hoechst staining and FACS revealed that these compounds cause apoptosis by cell cycle arrest at subG1 phase. © 2015 Bentham Science Publishers.Item Open Access Synthesis and dye sensitized solar cell applications of Bodipy derivatives with bis-dimethylfluorenyl amine donor groups(Royal Society of Chemistry, 2015) Çakmak, Y.; Kolemen, S.; Buyuktemiz, M.; Dede, Y.; Erten-Ela, S.Three Bodipy dyes with strong absorptivities in the visible and near infrared regions were designed, synthesized and their potential as photosensitizers for liquid electrolyte-based dye sensitized solar cells have been evaluated. For the first time Bodipy derivatives with bis-dimethylfluorenyl amine donor groups which were known for their bulky structures as donor groups have been used together. We altered our mostly used triphenylamine group with these and investigated the dye-sensitized solar cell efficiencies of this new class of Bodipy dyes. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015.Item Open Access Synthesis of novel substituted purine derivatives and identification of the cell death mechanism(Elsevier Masson SAS, 2015) Demir, Z.; Guven, E.B.; Ozbey, S.; Kazak, C.; Atalay, R.C.; Tuncbilek, M.Novel substituted adenine and purine derivatives were designed and synthesized.Compound 36 displayed the greatest cytotoxic activity with IC50 less than 1 1/4M.36 induces senescence associated cell death, which was demonstrated with SA2-Gal assay. © 2014 Elsevier Masson SAS.