Supramolecular Science最新文献

We characterized topological orientation of bacterial photosynthetic membranes (chromatophores) from Rhodopseudomonas viridis using antibodies against H- and C-subunit of photosynthetic reaction center protein (RC). About 40% of the membranes were unsealed vesicles in the inside-out orientation exposing the cytoplasmic side whereas 20% of those were unsealed vesicles in the right side-out orientation expo-sing the periplasmic side. The residual 20% was in the form of a flat sheet structure. We immobilized the chromatophore membranes onto an indium–tin-oxide (ITO) electrode by the electro-deposition method. The electro-deposited film (ED film) showed photocurrent and photovoltage between different electrodes such as ITO and gold (Au). Addition of buffer salts such as sodium phosphate enhanced very much the photoelectrical response in the ED film.

Inorganic nanoparticles Fe₂O₃ 3–5 nm in diameter were assembled on the surface of polymer microspheres and then encapsulated in the polymer to form a trilayer composite structure. The capacitance–voltage (C–V) curve of the composite microsphere monolayer shows the presence of a plateau. The electron transportation process in the special structure was investigated combining with the energy band model. The results show that Fe₂O₃ layer acts as a charge trap between polymer layers which are regarded as potential barriers.

Self-assembly of hydrogen-bonding recognition complexes—2.5-bis(alkylamino)-1,4-benzoquinones were studied, and thermotropic liquid crystalline behavior of 2.5-bis(dodecylamino)-1,4-benzoquinone was further investigated. The obtained results showed that a ribbon-like backbone in this system plays an important role in keeping the layered supramolecular structure.

Aminotri-tert-butyl phthalocyanine (AmBuPc) is a new asymmetrical phthalocyanine, which possesses three tert-butyl groups and one amino-group. All the substituents are electron-donating ones and have a strong electron-donating ability when they interact with oxidizing gases, such as NO₂. We report its synthesis and its gas sensitivity to nitrogen dioxide, and reveal the electrochemical properties of this compound.

Monolayers of a chiral biphenyl liquid crystalline polysiloxane and its monomer have been studied by π–A isotherms and hysteresis measurements. Both of them can form monolayers at different temperatures. The molecular packing in the monolayers are temperature-dependent for the monomer but not for the polymer. The molecular orderings are dominated by the packing of the biphenyl mesogens. Metastable monolayers with different ordering and thickness of domains have been directly observed by Brewster Angle Microscopy (BAM) in monomer monolayers. Both of them show characteristics of rigid monolayers. A broken process of the monolayers can be observed during expansion.

Photocatalytic TiO₂ nanoparticles are effective photocatalyzers which can damage the cellular membranes and genetic supramolecules such as DNA. In this experiment, we observed the lesion efficacy of the photocatalytic TiO₂ nanoparticles upon the cellular membrane and genetic molecule by transmission electron microscopy and single cell gel electrophoresis assay, and the mechanisim of the cell death by photocatalytic TiO₂ nanoparticles.

Function follows conformation in biological macromolecules. In general there are a number of possible conformational states. Which state is favored is determined by physicochemical context. The fusion of the features that comprise this context to form a particular conformational state is at the core of cellular control and biological information processing. We have developed a simulation system to investigate the information processing capabilities of networks of context-sensing macromolecules (to be illustrated by a simple example).

The cosensitization of a nanostructured titanium dioxide (TiO₂) electrode with tetrasulphonated porphyrins (MTsPP M=Zn H₂) is reported. Cosensitization greatly enhances the photocurrent response at the Q-band of H₂TsPP and markedly decreases the photocurrent response in the Soret band of ZnTsPP. The photoelectric behavior of the cosensitized TiO₂ electrode is attributed to the formation of heteroaggregates between H₂TsPP and ZnTsPP molecules on the positively charged TiO₂ electrode by charge-transfer interaction resulting in the decrease of the surface concentration of the H₂TsPP dimer and the presence of the low-lying charge-transfer state.

C-reactive protein (CRP) is an acute phase reactive protein, which has been shown to specifically bind to phosphorylcholine (PC) and phosphorylethanoamine (PE) moieties in the presence of calcium. In order to investigate the effect of steric hindrance on the specific binding of CRP to membranes, we designed and synthesized six phospholipids, each containing a long-arm spacer of 3, 6 or 8 atoms between the head group and hydrophobic tail. By mixing synthesized lipids and natural lipids the ligand-containing monolayers were prepared, which have PC or PE groups protruding out of the membrane surface. To characterize of the synthesized phospholipids, the thickness of the lipid monolayers was measured by surface plasmon resonance (SPR) technique, the phase behavior of the lipid monolayer at air/water interface was studied by pressure–area analysis, and the specific binding of rabbit C-reactive protein to the synthesized lipid containing membranes was studied by imaging ellipsometry.

Neural network architecture of devices based on reaction–diffusion media is discussed. Image processing operations performed by these media are similar to first steps of human vision mechanism.