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71.
Kazuaki Miyashita Masami Kamigaito Mitsuo Sawamoto Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1994,32(13):2531-2542
The end-functionalization of living polymers with bases (methanol, benzylamine, diethyl sodiomalonate, and sodium methoxide) and organosilicon compounds [X ? Si(CH3)3;X ? : CH2?C(CH3)COO? , CH3COO? , CH2?CHCH2? , C6H5? ] was investigated in the living cationic polymerization of styrene initiated with the 1-phenylethyl chloride/SnCl4/nBu4NCl system in CH2Cl2 at ?15°C. The four bases and C6H5SiMe3, independent of their structures, were apparently incapable of reacting with the living end and invariably led to polystyrenes with the ω-end chlorine [~ ~ ~ CH2CH(Ph)Cl] originated from the initiating system. The number-average end-functionality (F?n) of the chloride, determined by 1H-NMR, was close to unity (F?n > 0.9). The presence of chlorine in the polymer was also confirmed by elemental analysis. In contrast, the quenching by the trimethylsilyl compounds with X = methacryloxy, acetoxy, and allyl gave ω-end-functionalized polystyrenes with the corresponding terminal groups (X) for which the F?n values were close to unity (F?n > 0.9). The effects of the structure of silyl compounds on end-capping are also discussed. © 1994 John Wiley & Sons, Inc. 相似文献
72.
Complanine, an inflammation-inducing substance isolated from the marine fireworm Eurythoe complanata
Nakamura K Tachikawa Y Kitamura M Ohno O Suganuma M Uemura D 《Organic & biomolecular chemistry》2008,6(12):2058-2060
The marine fireworm, Eurythoe complanata, is known as a dangerous animal for humans because it induces skin inflammation through its small setae. Here, the inflammation-inducing substance was successfully isolated from the whole body using a methanolic extraction, and the inflammatory activity was determined using a bioassay. The structure was spectroscopically revealed to be a trimethylammonium with an unsaturated carbon chain and was named complanine. Complanine enhanced PKC activity in combination with TPA in vitro. This may explain the molecular mechanism behind its inflammation-inducing activity. 相似文献
73.
Uemura S Aono M Komatsu T Kunitake M 《Langmuir : the ACS journal of surfaces and colloids》2011,27(4):1336-1340
Self-assembled structures of melamine and the condensed melamine derivative melem were investigated at aqueous solution-Au(111) interfaces by cyclic voltammetry and in situ scanning tunneling microscopy (STM) observation. The adsorption/desorption behaviors of both molecules on Au(111) surfaces could be controlled by varying the electrochemical potential and solution concentration. In the negative potential region, self-assembled structures of melem and melamine were constructed by double hydrogen bonding systems between nitrogen atoms of triazine rings and amine groups. In addition, melem formed a closely packed structure at potentials of between -0.3 and -0.15 V or in solutions at higher concentrations. 相似文献
74.
Aoyagi Y Kuroda M Asada S Bujo H Tanaka S Konno S Tanio M Ishii I Aso M Saito Y 《Experimental & molecular medicine》2011,43(3):161-167
The development of clinically applicable scaffolds is important for the application of cell transplantation in various human diseases. The aims of this study are to evaluate fibrin glue in a novel protein replacement therapy using proliferative adipocytes and to develop a mouse model system to monitor the delivery of the transgene product into the blood and the fate of the transduced cells after transplantation. Proliferative adipocytes from mouse adipose tissue were transduced by a retroviral vector harboring the human lecithin-cholesterol acyltransferase (lcat) gene, and were subcutaneously transplanted into mice combined with fibrin glue. The lcat gene transduction efficiency and the subsequent secretion of the product in mouse adipocytes were enhanced using a protamine concentration of 500 μg/ml. Adipogenesis induction did not significantly affect the lcat gene-transduced cell survival after transplantation. Immunohistochemistry showed the ectopic enzyme production to persist for 28 days in the subcutaneously transplanted gene- transduced adipocytes. The increased viability of transplanted cells with fibrin glue was accompanied with the decrease in apoptotic cell death. The immunodetectable serum LCAT levels in mice implanted with the fibrin glue were comparable with those observed in mice implanted with Matrigel, indicating that the transplanted lcat gene-transduced adipocytes survived and functioned in the transplanted spaces with fibrin glue as well as with Matrigel for 28 days. Thus, this in vivo system using fibrin is expected to serve as a good model to further improve the transplanted cell/scaffold conditions for the stable and durable cell-based replacement of defective proteins in patients with LCAT deficiency. 相似文献
75.
Saito S Nakano Y Hikichi A Suzuki R Yoshimoto K Maeda M Aoyama M Shibukawa M 《The Analyst》2011,136(13):2697-2705
Novel fluorescent probes have been developed for the ultratrace detection of heavy metal ions by capillary electrophoresis using laser-induced fluorescence detection. Based on a molecular design, the probes are composed of an octadentate chelating moiety, a macrocyclic DOTA (tetraazacyclododecanetetraacetic acid) and an acyclic DTPA (diethylenetriaminepentaacetic acid) frame, a spacer and a fluorophore (fluorescein). These were chosen on the basis of their ability to form kinetically inert and highly emissive complexes, and to prevent a quenching effect even with heavy and paramagnetic metal ions. Addition of a cationic polymer, polybrene, in the separation buffer provided high resolution and simultaneous detection of Ca(2+), Mg(2+), Cu(2+), Zn(2+), Ni(2+), Co(2+), Mn(2+), Cd(2+) and Pb(2+). The direct fluorescence detection of these metal ions with high sensitivity at lower ppt levels, typically 2-7 × 10(-11) M (potentially sub-ppt), was successfully achieved. While separation of anionic compounds using a counter cation ("Ion Association (IA)" mode) is typically controlled by the ion association equilibrium constants, K(ass), it was found that differences in the mobilities, μ(ep(IAC)), of the ion association complexes formed between the probe complexes and counter cations are the driving forces for separation in this new method. This suggests that each of the polybrene-probe complexes has different chemical structures among metal ions, which were able to be determined by CD spectra in this investigation. This novel separation mode was termed the "Ion Association Complex (IAC)" mode, distinct from the IA mode. 相似文献
76.
77.
Fujii S Mochizuki M Aono K Hamasaki S Murakami R Nakamura Y 《Langmuir : the ACS journal of surfaces and colloids》2011,27(21):12902-12909
Polystyrene (PS) latex particles carrying pH-responsive poly[2-(diethylamino)ethyl methacrylate] (PDEA) hair (PDEA-PS particles) were synthesized by dispersion polymerization and characterized in terms of diameter, diameter distribution, morphology, chemical composition, surface chemistry, and pH-response using scanning electron microscopy (SEM), elemental microanalysis, (1)H nuclear magnetic resonance spectroscopy, the laser diffraction method, and zeta potential measurements. The hairy particles can act as pH-responsive stabilizers of aqueous foams by adsorption at the air-water surface. Above pH 8.0, where particles have nonprotonated PDEA hair, which is relatively hydrophobic, particle-stabilized foams are stable for at least 1 month. Optical microscopy and SEM confirmed that flocculated PDEA-PS latex particles were adsorbed at the air-water interface and stabilized the aqueous foams. At pH 6.1 and 7.1, relatively stable foams can be prepared that remain stable for at least 24 h. SEM studies indicated that the PDEA-PS particles were adsorbed at the air-water interface as a monolayer at pH 6.1. At pH 5.1 and 3.1, where the particles have cationic water-soluble PDEA hairs with hydrophilic character, no foam was formed. Rapid defoamation can be induced by lowering the solution pH; the addition of acid caused the in situ protonation of 2-(diethylamino)ethyl methacrylate residues, which impart water-soluble hydrophilic character to the PDEA hair, and the PDEA-PS particles desorbed from the air-water interface. The foaming and defoaming cycles could be repeated at least five times. 相似文献
78.
Masami Sawada Yasuo Okumura Hitoshi Yamada Yoshio Takai Shigetoshi Takahashi Takahiro Kaneda Keiji Hirose Soichi Misumi 《Journal of mass spectrometry : JMS》1993,28(12):1525-1528
Using fast atom bombardment (FAB) mass spectrometry (MS), cross-chiral relationships were confirmed for the first time for the diasteromeric host-guest complexations between the chiral crown ether host (1) and the chiral organic ammonium ion guest (2) on the basis of the relative peak intensities (RPI). Both host–guest combinations (R, R, R, R) – 1, (R) – 2 and (S, S, S, S) – 1, (S) – 2 obviously provided larger RPI values than the combination of both (R, R, R, R) – 1, (S) – 2 and (S, S, S, S) – 1, (R) – 2 by a factor of 1.6 as an averaged value: 1.87 (n = 4)/1.16 (n = 4) = 1.6. These results are consistent with the expected stabilities of the host-guest complexations by CPK model examinations. Successfully observed cross-chiral examinations strongly suggest a potentially useful FABMS/RPI methodology for rapidly searching newly designed and synthesized crown ether-like host compounds with a higher degree of enantioselectivity. 相似文献
79.
Masami Kamigaito Mitsuo Sawamoto Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1993,31(12):2987-2994
Phosphoric and phosphinic acid derivatives (R1R2PO2H; R1, R2 = OPh, OPh; OnBu, OnBu; Ph, Ph; Ph, H) in conjunction with zinc chloride (ZnCl2) led to living cationic polymerization of isobutyl vinyl ether (IBVE) in toluene below 0°C. The number-average molecular weights (M?n) of the polymers (M?n > 2 × 104) were directly proportional to monomer conversion and in excellent agreement with the calculated values assuming that one polymer chain forms per R1R2PO2H molecule. Throughout the reaction, the molecular weight distributions (MWDs) stayed narrow (M?w/M?n ? 1.1). A dibasic acid, PhOP (O) (OH)2, coupled with ZnCl2, also induced living cationic polymerization of IBVE where one molecule of the acid generated two living polymer chains. The polymerization by (PhO)2PO2H/ZnCl2 and its model reactions were directly analyzed by 31P and 1H-NMR spectroscopy. The analysis showed that the acid initially forms the adduct [CH3CH(OiBu)OP(O)(OPh)2], the phosphate linkage of which is in turn activated by ZnCl2 so as to initiate living propagation. The finding thus indicates that (PhO)2PO2H indeed acts as an initiator in the living polymerization. The NMR analysis also suggested that an exchange reaction occurs between the phosphate group at the polymer terminal and the chlorine in ZnCl2. The occurrence of living IBVE polymerization with these various R1R2PO2H/ZnCl2 systems shows that phosphoric and phosphinic acids are another general class of protonic acids which are effective initiators for the living cationic polymerization assisted by Lewis acids. © 1993 John Wiley & Sons, Inc. 相似文献
80.
Dai Kato Atsumu Oda Mutsuo Tanaka Seiichiro Iijima Tomoyuki Kamata Masami Todokoro Yasuo Yoshimi Osamu Niwa 《Electroanalysis》2014,26(3):618-624
We developed an electrochemical system for detecting lipopolysaccharide (LPS) that uses an ultraflat nanocarbon film electrode modified with poly‐ε‐lysine with a high affinity to LPS. LPS was captured on the modified electrode, and then ferrocene labeled polymyxin B (FcPMB) was captured on the LPS adsorbed electrode via the LPS‐PMB affinity interaction. The adsorbed FcPMB provided an amplified response with Fe2+ ions, and the current response was dependent on the amount of captured LPS (LOD=2.0 ng/mL). This was due to the efficient accumulation of the obtained current for LPS and the very low noise made possible by the ultraflat surface. 相似文献