- Preparation and characterization of phase-segregated vesicles of photopolymerizable diacetylene mixed with nonpolymerizable amphiphiles
-
A mixture of sodium 1,2-di(hexadecyloxycarbonyl)ethanesulfonate (2C16S) with photopolymerizable 1,2-di(10,12- tricosadiynoyl)-sn-glycerol 3-phosphocholine (DTPC) in a 2:100 ratio was treated by modified thin-film hydration to give an aggregate which became polymerized giant vesicles (GVs) under irradiation at 254 nm. The autofluorescence of the GVs was analyzed with a confocal laser scanning microscope at the cross section, revealing a 3.8-μm diameter ring shape and the presence of a dark part of ca. 1 μm in the ring. When octadecylrhodamine B (RhB) as an amphiphilic fluorescence probe was added to the GV, the fluorescence of RhB was emitted from the whole ring. Therefore, phase segregation of 2C16S from DTPC was confirmed. Similarly, mixed vesicles of N,N-di(2-hexadecanoyloxyethyl)dimethylammonium iodide with DTPC were found to be 3.7-μm diameter phase-segregated vesicles with a dark portion of ca. 1 μm on the ring in the cross sectional image. On the other hand, DTPC vesicles mixed with 1,2-di(dodecyloxycarbonyl)ethanesulfonate, N,N-di(2- dodecanoyloxyethyl)dimethylammonium iodide, and N,N-di(2-tetradecanoyloxyethyl) dimethylammonium iodide formed sphere structures filling the inside of the vesicles. The segregation mechanism was explained by the difference in the main phase transition temperature of each amphiphile.
- Matsumoto, Jin,Yoneda, Koshiro,Tasaka, Jun,Shiragami, Tsutomu,Yasuda, Masahide
-
experimental part
p. 1551 - 1557
(2011/03/16)
-
- Generation of quinone methide from aminomethyl(hydroxy)arenes precursors in aqueous solution
-
o-Quinone methides (QMs) are an important reactive intermediate for organic synthetic and biological standpoints of view. Photochemical and thermal transformation of N,N-dialkyl-9-aminomethyl-10-phenanthrols and their naphthalene analogs, which act as QM precursors, has been studied. These precursors readily reacted with alkyl vinyl ethers to give 2-alkoxydibenzo[f,h] chroman and 2-alkoxybenzo[f]chroman, respectively. Thermal and photochemical generation of QM was accelerated by the presence of water molecule in reaction solvents and by the formation of anionic micelle and vesicle.
- Matsumoto, Jin,Ishizu, Masayuki,Kawano, Ryu-Ichiro,Hesaka, Daisuke,Shiragami, Tsutomu,Hayashi, Yoshimi,Yamashita, Toshiaki,Yasuda, Masahide
-
p. 5735 - 5740
(2007/10/03)
-
- Raman and IR spectroscopic studies of the interaction between counterion and polar group in self-assembled systems of AOT-homologous 'sodium dialkyl sulfosuccinates'
-
Headgroup-counterion interactions have been studied for a homologous series of sodium dialkyl sulfosuccinates (SDAS) with propyl, butyl, hexyl, octyl, decyl, undecyl and dodecyl chains as Aerosol-OT analogues. Raman scattering and IR absorption spectra were recorded and compared with those for dimethyl sulfosuccinate monohydrate, diethyl sulfosuccinate trihydrate and diheptyl sulfosuccinate dihydrate, whose crystal structures are known. The spectral features of the C=O and SO3- stretch modes directly reflect the interaction between the polar group and the Na+ ion and depend strongly upon the environment of hydration. The results may be summarized as follows. For the SDAS monohydrates in the solid state, there exists a strong interaction between the β C=O group and the Na+ ion, as a consequence of coordination of the β C=O to the Na+ ion, resulting in splitting of the C=O stretch modes. In particular, the common Raman (IR) bands observed at 1705- 1707 (1706-1708) and 1730-1732 (1732-1733) cm-1 may be assigned to the β C=O group coordinated to the Na+ counterion and the hydrated α C=O group, respectively. The extent of splitting of these bands is a measure of the strength of this C=O···Na+ interaction. Coordination of the β C=O to the Na+ ion also affects the C=O deformation modes of the O-C=O linkage. An increased hydration number and longer hydrocarbon chains induce a weak interaction between the C=O group and the Na+ ion. The SO3-···Na6+ interaction reflects the SO3- stretch modes, depending upon the extent of hydration. Furthermore, for the SDAS samples in the organic and aqueous microphases, Raman (IR) bands characteristic of the C=O and SO3-1 groups have been used successfully to account for the interaction between the polar group and the Na+ ion.
- Nagasoe, Yasuyuki,Ichiyanagi, Naoki,Okabayashi, Hirofumi,Nave, Sandrine,Eastoe, Julian,O'Connor, Charmian J.
-
p. 4395 - 4407
(2007/10/03)
-
- Simple transphosphatidylation of phospholipids catalysed by a lipid-coated phospholipase D in organic solvents
-
A lipid-coated phospholipase D (PLD) was prepared by mixing aqueous solutions of PLD and lipids.The lipid-coated PLD showed a high catalytic activity for transphosphatidylation of egg yolk phosphatidylcholine (egg-PC) with alcohols in two-phase benzene-acetate buffer solution.Since both substrates and enzymes are soluble in the organic phase, the reaction proceeded in the benzene phase and the aqueous phase is required to remove the produced choline moiety from the organic phase.When a native PLD was employed instead of the lipid-coated PLD, the reaction was very slow (ca. 1/300 that of the lipid-coated PLD) because the reaction occurs at the interface of the lipophilic substrates and water-soluble enzymes.The transphosphatidylation catalysed by a lipid-coated PLD could be applied in a manner widely independent of the nature of the head groups of the coating lipids and the polarity of the organic solvents, and could be applied also on a large-scale (yield 1-2 g) synthesis to introduce various alcohols, sugars, and nucleic acids at the head groups of phospholipids.We have determined substrate selectivity and Michaelis-Menten kinetics for a lipid-coated PLD and compared the results with those for the native PLD.
- Okahata, Yoshio,Niikura, Ken-ichi,Ijiro, Kuniharu
-
p. 919 - 926
(2007/10/02)
-