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841.
Ishii T Otsuka H Kataoka K Nagasaki Y 《Langmuir : the ACS journal of surfaces and colloids》2004,20(3):561-564
PEGylated gold nanoparticles with biotin moieties installed at the distal end of the PEG tethered chains were prepared by the autoreduction of HAuCl4 catalyzed by alpha-biotinyl-PEG-block-poly[2-(N,N-dimethylamino)ethyl methacrylate] (biotinyl-PEG/PAMA) in aqueous medium at room temperature. The size of the gold nanoparticles was controllable in a range of 6-13 nm by changing the initial Au3+/polymer ratio, while retaining their narrow size distribution. The dispersion stability of the nanoparticles in aqueous medium was extremely high even under the condition of salt concentration as high as I = 2.0. Biotinyl-PEG/PAMA-anchored gold nanoparticles underwent specific aggregation in the presence of streptavidin, revealing their promising utility as colloidal sensing systems applicable under biological condition. 相似文献
842.
Okamurallene (), a novel nonterpenoid C15 bromoallene containing cyclopropane ring, has been isolated from the red alga Laurencia okamurai Yamada and its structure was determined by the spectral evidence. 相似文献
843.
Takeshi?Sakura Tadahito?Takahashi Kazunori?Kataoka Yukio?NagasakiEmail author 《Colloid and polymer science》2005,284(1):97-101
We have developed a rapid and simple method for the preparation of nearly mono-dispersed gold colloids with a fairly high concentration above 10 mM using hydroxylamine as the reducing agents, in the presence of α-methoxy-ω-mercaptoethyl-poly(ethylene glycol)(MeO-PEG-SH). It was found that a hydroxylamine acted not only as a reducing agent, but also as a nucleation agent under alkaline reaction conditions. Though the colloid concentration was fairly high, the dispersion stability was remarkably improved even in a high ionic strength in the range greater than 1 M NaCl, in which conventional citrate gold colloids immediately flocculate and precipitate. The obtained colloid was successfully re-dispersed in aqueous media after lyophilization. In addition, the prepared gold colloid reduced a protein adsorption significantly on its surface. Concerning these results, the obtained colloidal dispersion may be suitable for biological applications, since a regionally concentrated colloidal dispersion with dispersion stability is required for bio-labeling and bio-imaging systems.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
844.
Matsuura K Yamashita T Igami Y Kimizuka N 《Chemical communications (Cambridge, England)》2003,(3):376-377
DNA three-way junctions formed from three 30-mer oligonucleotides that contain single-chained self-complementary sticky ends spontaneously self-assemble into 'nucleo-nanocages': the exo- and endo-nuclease digestion experiments indicate that defects such as the single and double strand end structures are absent on the spherical nano-assemblies, providing clear evidence for the closed nanocage structure. 相似文献
845.
Kasai HF Tsubuki M Takahashi K Shirao M Matsumoto Y Honda T Seyama Y 《Journal of chromatography. A》2002,977(1):125-134
The direct separation of several stereoisomers (enantiomers and geometrical isomers) of furan derivatives, important intermediates for the synthesis of physiologically active natural products, was achieved using capillary gas chromatography/mass spectrometry with a per-O-methyl-beta-cyclodextrin, supercritical fluid chromatography and high-performance liquid chromatography with a tris(3,5-dimethylphenylcarbamate) of cellulose or amylose for the chiral stational phases, respectively. The temperature dependence of the peak resolution (Rs) and the retention factor (k) over the range of 110-130 degrees was studied using crotyl furfuryl ether in gas chromatography. Successive increases in the Rs value and of the difference between the k value of the E-isomer and the k value of the Z-isomer were observed when the gradient temperature was decreased. The per-O-methyl-beta-cyclodextrin column was suitable for use with volatile furan ethers whose molecular masses are between 150 and 180. In conclusion, the separation of thermally unstable furan derivatives was accomplished using supercritical fluid chromatography and high-performance liquid chromatography. 相似文献
846.
Solvent versatility of immobilized 3,5-dimethylphenylcarbamate of amylose in enantiomeric separations by HPLC 总被引:3,自引:0,他引:3
Zhang T Kientzy C Franco P Ohnishi A Kagamiharb Y Kurosawa H 《Journal of chromatography. A》2005,1075(1-2):65-75
CHIRALPAK IA is a new chiral stationary phase containing amylose 3.5-dimethylphenylcarbamate immobilized onto silica gel. It is compatible with the whole range of organic solvents. Its solvent versatility has been thoroughly investigated. The option to use a wide range of solvents, especially the "non-standards" ones, in the mobile phase enables the enhancement of chiral separation methods in terms of enantioselectivity, resolution, analysis time, sample injection and sample solubility. Parameters such as the mobile phase type, the nature of modifier and eluting strength of various solvents are examined and discussed. A guideline for method development and optimization on CHIRALPAK IA is also proposed. 相似文献
847.
Kiyomi Kakiuchi Koichi MinatoKen Tsutsumi Tsumoru MorimotoHideo Kurosawa 《Tetrahedron letters》2003,44(9):1963-1966
Radical ring-opening reactions of bicyclo[4.2.0]octanones, its C6 alkyl derivatives, and tricyclic ketones promoted by SmI2 gave cyclohexanones via fission of the external cyclobutane bond. The CO2Me, CN, and phenyl derivatives led to the production of the eight-membered ring compounds through cleavage of the central cyclobutane bond. Using this regioselective reaction, the synthesis of (±)-acorenone was achieved. 相似文献
848.
N Hazemoto S Ishizaka M Haga Y Kato S Kurosawa N Kamo Y Kobatake 《Chemical & pharmaceutical bulletin》1989,37(8):2153-2154
Ion-selective electrodes (ISEs) responsive to the antitussives dextromethorphan and dimemorfan were constructed by the fixation of an ion-exchanger, ammonium tetraphenylborate, on a Millipore membrane by means of a plasma-polymerization technique. The electrodes showed a Nernstian response over the range of 10(-5)-10(-2) M dextromethorphan and dimemorphan, and the working pH range was 5-7. The interference from common cations such as Na+, K+ and Ca2+ was negligible but some organic cations interfered weakly. The electrodes were applied successfully for the determination of the drugs in pharmaceutical preparations. 相似文献
849.
Chang-Yi Qian Jun-Ichi Hirose Hiroshi Nishino Kazu Kurosawa 《Journal of heterocyclic chemistry》1994,31(5):1219-1227
Thirteen new 2,3,5-trisubstituted furans were prepared by the acid-catalyzed decomposition of 6,6-di-substituted 1,2-dioxan-3-ols in 57-93% yields. The reaction could be accounted for as the consequence of an oxygen-oxygen bond cleavage by acid and the migration of a phenyl group at the C-6 position followed by cyclization and elimination of a phenol. The migratory aptitude was in the order of 4-MeOC6H4- > 4-MeC6H4- > Ph- = 4-FC6H4- > 4-ClC6H4- = 4-BrC6H4- that was found from the competitive phenyl migration in the reaction of 1,2-dioxan-3-ols bearing two different substituents at the C-6 position. 相似文献
850.
Mamoru Hashimoto Nobuko Izuchi Kazunori Sakata 《Journal of heterocyclic chemistry》1988,25(6):1705-1708
A novel macrocycle, 5,14-dihydro-7,16-diethyldipyrazo[b,i][1,4,8,11]tetraazacyclotetradecine, has been synthesized from 1,2-diaminopyrazine and 2-ethyl-3-ethoxyacrolein. The absorption bands appearing in the energy range greater than 20000 cm?1 were attributable to the π → π transitions. The bands in the range of the 20100–23300 cm?1 show more bathochromic shift and greater intensity than those observed for corresponding 5,14-dihydro-7,16-diethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine and/or 5,14-dihydro-7,16-diethyl-(Z)-dipyrido[b,i][1,4,8,11]tetraazacyclotetradecine. The nickel(II), copper(II) and palladium(II) complexes of 5,14-dihydro-7,16-diethyldipyrazo[b,i][1,4,8,11]tetraazacyclotetradecine have been synthesized using a metal template reaction. In 1H and 13C nmr spectra, the signals of annulene skeleton for metal-free ligand and its complexes were found to observe in the lower field than those of the dibenzoanalogue. 相似文献