Solution behavior of aerosol ot/water/oil system

The phase diagrams of water-cyclohexane containing 5, 10, and 20 wt% sodium 1,2-bis(2-ethylhexyloxycarbonyl)-1-ethanesulfonate (Aerosol OT, AOT) as a function of temperature were studied. There is the water phase in which AOT is dissolved and a large amount of oil is solubilized at higher temperature, and the oil phase in which AOT is dissolved and a large amount of water is solubilized at lower temperature. It is evident from the phase behavior that the hydrophile-lipophile property of AOT is well balanced. Accordingly, the phase diagram and properties of AOT solution are affected rather sensitively by the addition of a small amount of hydrophilic or lipophilic additive or by temperature. Careful elimination of inorganic salts also influences markedly the solution properties of AOT. Thus, the addition or removal of known amounts of inorganic salts, such as Na₂SO₄ is also very important to control the solution properties related to practical applications. In this context phase diagrams of both carefully purified and commercial AOT with or without additives have been determined.     

Komplexbildung von Poly-L-lysin mit Polyacrylsäure

Ohne Zusammenfassung     

Komplexbildung von Poly-L-lysin mit Polyacryls?ure

Ohne Zusammenfassung     

Molecular dynamics simulation of an archaeal lipid bilayer with sodium chloride

We have performed molecular dynamics simulations of a bilayer formed by the synthetic archaeal lipid, diphytanyl phosphatidylcholine, in NaCl electrolyte solution at four different concentrations (0-4 M) to investigate how structural and dynamic properties of the model archaeal membrane are changed due to the ionic strength of the solution. The archaeal lipid bilayer shows minor changes in their physical properties, indicating the unusual high stability of the membrane against salt, though small reductions of molecular area and lateral diffusion of the lipid are detected at the highest electrolyte concentration of 4 M. Sodium ions penetrate to the ether-rich region, where the ions are likely bound to the ether oxygen in the sn-1 chain rather than to that in the sn-2 chain. The observed salt bridges among two or three neighboring lipids account for the small reduction in the molecular area. The bound ions together with the counter (chloride) ions give rise to a diffusive electric double layer; as a result, the membrane dipole potential is slightly increased with increasing NaCl concentration.     

PHASE BEHAVIOR IN SYSTEMS OF NONIONIC SURFACTANT/ WATER/ OIL AROUND THE HYDROPHILE-LIPOPHILE-BALANCE-TEMPERATURE (HLB-TEMPERATURE)

The phase diagram of the C₁₂H₂₅(OCH₂CH₂)₅OH/water/tetradecane system was studied around the critical solution temperatures of surfactant-water and surfactant-oil phases. Although the phase behavior is very complicated due to the formation of liquid crystalline phase, basic phase-changes around the three-phase region, consisted of a water, a surfactant and an oil phases, are the same as those in a short-chain nonionic surfactant system.     

Proteo-dendrimers designed for complementary recognition of cytochrome c: dendrimer architecture toward nanoscale protein complexation

"Proteo-dendrimers" in which polyanionic hepta(glutamic acids), fluorescent zinc porphyrinate cores, hydrophilic polyether surfaces, and nonpeptide hydrophobic dendrons are combined, were developed as a new series of synthetic receptors for protein recognition. They have polyanionic "patch" structures on their surfaces and undergo complementary electrostatic interactions with a positively charged cytochrome c patch, as observed in biological protein-protein recognition systems. Stability constants of the resulting supramolecular complexes were determined in phosphate buffer (pH 7) by monitoring the fluorescence quenching of the zinc porphyrinates. These proteo-dendrimer receptors exhibited higher affinities with cytochrome c proteins in aqueous solutions than with biological cytochrome b5. Furthermore, they effectively blocked complexation of biological cytochrome b5 with cytochrome c, indicating that the proteo-dendrimers and cytochrome b5 similarly occupy the polycationic patch of cytochrome c.     

Thermal polymerizations of alkali 4-(1-bromoethyl)benzoates

Thermal reactions of alkali salts of 4-(1-bromoethyl)benzoic acid in bulk were investigated. These reactions were found to produce unexpectedly the graft copolymer, poly(4-vinylbenzoate)-graft-oligo(oxycarbonyl-1,4-phenylenethylidene) ( 1 ). The relative reactivity of the oligocondensation as well as the vinyl polymerization of the salts decreased in the following order: K > Na > Li. The reaction polymerization rate proceeded rapidly during the initial 15 min, and then slowed down.