Simultaneously photodeposited rhodium metal and oxide nanoparticles promoting photocatalytic hydrogen production

Photodeposition of a Rh cocatalyst under atmospheric conditions could simultaneously provide both Rh metal and oxide nanoparticles on a K(2)Ti(6)O(13) photocatalyst, both of which cooperatively promoted the photocatalytic hydrogen production from water and methane.     

Formation and regulation of fullerene-incorporation in liposomes under the phase transition temperature

The fullerene-exchange reaction from a cyclodextrin cavity to liposomes represents one of the best methods to prepare lipid membrane-incorporated [70]fullerenes (C(70)). The C(70)-exchange reaction occurred completely at temperatures above the phase transition temperature (T(m)) of the liposomes; however, lowering the temperature to below the T(m) led to C(70) aggregation outside the liposomes. This observation has limited the development of more functional LMIC(70) using a variety of liposome compositions. In this paper, this reaction was found to occur efficiently by the addition of small amounts of lipids bearing a π-moiety. The π-moieties act as a gate when hydrophobic C(70) migrates into the hydrophilic liposome surface. Therefore, the π-moieties should exist in the polar head groups of the lipids and the C(70)-exchange reaction can be controlled by pH.     

Remarkable birefringence in a TiO2-SiO2 composite film with an aligned mesoporous structure

Mesoporous titania-silica composite films with highly aligned cylindrical pores are prepared by the sol-gel method using a substrate with structural anisotropy. The strong alignment effect of a rubbing-treated polyimide film on a substrate provides a narrow alignment distribution in the plane of the film regardless of the fast condensation rate of titania precursors. The collapse of the mesostructure upon the surfactant removal is effectively suppressed by the reinforcement of the pore walls with silica by exposing the as-deposited film to a vapor of a silicon alkoxide. The existence of a silica layer on the titania pore wall is proved from the distributions of Ti and Si estimated by the elemental analysis in high resolution electron microscopy. The obtained mesoporous titania-silica composite film exhibits a remarkable birefringence reflecting the highly anisotropic mesoporous structure and the high refractive index of titania that forms the pore wall. The Δn value estimated from the optical retardation and the film thickness is larger than 0.06, which cannot be achieved with the conventional mesoporous silica films with uniaxially aligned mesoporous structure even though the alignment of the pores in the films is perfect. These inorganic films with mesoscopic structural anisotropy will find many applications in the field of optics as phase plates with high thermal/chemical/mechanical stabilities.     

Columnarly assembled liquid-crystalline peptidic macrocycles unidirectionally orientable over a large area by an electric field

Being inspired by naturally occurring peptidic macrocycles, we developed liquid-crystalline (LC) compounds 1 and 2 that are capable of self-assembling into hexagonal columnar mesophases over a wide temperature range that includes room temperature. Their bowl-shaped macrocyclic cores are conformationally robust because of the presence of internal H-bonds, while the columnar assembly is ensured by intermolecular H-bonding interactions involving the exocyclic amide units. When an electric field was applied to their LC films from a direction orthogonal to the film plane, the columns were oriented homeotropically over a large area.     

Improvements in transfection efficiency with chitosan modified poly(DL-lactide-co-glycolide) nanospheres prepared by the emulsion solvent diffusion method, for gene delivery

This study sought to evaluate the in vitro transfection efficiency of plasmid DNA (pDNA)-loaded chitosan-modified poly(DL-lactide-co-glycolide) nanospheres (CS-PLGA NS) in a gene-delivery system. Using the emulsion solvent diffusion (ESD) method, pDNA-loaded PLGA NS was prepared and the surface of the PLGA NS was modified by binding to CS. Gene transfection ability of CS-PLGA NS was examined in A549 cells. The luciferase gene was used as a reporter gene. The pattern of luciferase activity by pDNA-loaded CS-PLGA NS was initially weak, but gradually grew stronger before decreasing activity. These phenomena should be in accordance with the sustained-release profile of pDNA from PLGA NS in the cytosol and the pDNA protection against DNase. Positively charged CS-PLGA NS was found, by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay, not to exhibit cytotoxicity on A549 cells. These results suggest that CS-PLGA NS are potential contributors to efficient pDNA delivery due to their increased interactions with cells and lack of cytotoxic effects.     

Hydrophobic labeling of amino acids: transient trapping-capillary/microchip electrophoresis

Transient trapping (tr-trapping) was developed as one of the on-line sample preconcentration techniques to improve a low concentration-sensitivity in microchip electrophoresis (MCE), providing highly effective preconcentration and separation based on the trap-and-release mechanism. However, a poor performance to hydrophilic analytes limited the applicability of tr-trapping. To overcome this drawback, tr-trapping was combined with a sample labeling using a hydrophobic reagent in CE. Three commercially available fluorescent dyes, fluorescein isothiocyanate, succinimidyl esters of Alexa Fluor 488 and BODIPY FL-X, were tested as derivatization reagents to increase the hydrophobicity of amino acids (AAs) that were undetectable due to no fluorescence/UV-absorbance. As a result, it was confirmed that BODIPY labeling allowed various AAs to be analyzed in tr-trapping-micellar electrokinetic chromatography (tr-trapping-MEKC) by the increase in the hydrophobicity. In tr-trapping-MEKC, both the improvement of the resolution and 106-125-fold enhancements of the detectability of labeled AAs were achieved relative to the conventional capillary zone electrophoresis. The limit of detection of labeled phenylalanine was improved from 800 to 5 pM by applying tr-trapping-MEKC. In tr-trapping-microchip MEKC, furthermore, an 80-160-fold enhancement of the peak intensity and a baseline separation was also achieved within 30 s. These results clearly demonstrate that the tr-trapping technique with hydrophobic labeling will make CE/MCE more sensitive for various analytes.     

Phase space geometry of dynamics passing through saddle coupled with spatial rotation

Nonlinear reaction dynamics through a rank-one saddle is investigated for many-particle system with spatial rotation. Based on the recently developed theories of the phase space geometry in the saddle region, we present a theoretical framework to incorporate the spatial rotation which is dynamically coupled with the internal vibrational motions through centrifugal and Coriolis interactions. As an illustrative simple example, we apply it to isomerization reaction of HCN with some nonzero total angular momenta. It is found that no-return transition state (TS) and a set of impenetrable reaction boundaries to separate the "past" and "future" of trajectories can be identified analytically under rovibrational couplings. The three components of the angular momentum are found to have distinct effects on the migration of the "anchor" of the TS and the reaction boundaries through rovibrational couplings and anharmonicities in vibrational degrees of freedom. This method provides new insights in understanding the origin of a wide class of reactions with nonzero angular momentum.     

Electrochemically monitoring the binding of concanavalin A and ovalbumin

To evaluate protein-protein interactions, a new voltammetric method was developed using a protein labeled with an electroactive compound. Concanavalin A (ConA), which is a lectin, recognizes α-mannose residues. Because the ConA was to be bound to ovalbumin (OVA), which has a high-mannose sugar chain, ConA labeled with daunomycin was prepared as the probe to monitor the binding. The binding to OVA was caused by the label modification of the ConA. As a result, the electrode response of the labeled ConA decreased as the OVA concentration increased. The electrode response of the labeled ConA was linearly over the range of 1.5 × 10⁻¹⁰ and 1.5 × 10⁻⁹ M OVA. The relative standard deviation of 1.5 × 10⁻⁸ M labeled ConA and 1.5 × 10⁻¹⁰ M OVA was 6.9% (n = 5). The labeled ConA-OVA binding could then be conveniently monitored based on the change in response. In contrast, interactions between the labeled ConA and a protein with no specific sugar chain also were investigated. Incubation scarcely influenced the peak current of the labeled ConA. When several concentrations of OVA were added to a serum, good recovery determined it. Consequently, this method could be applied to the measurement of protein-protein interactions.     

Synthesis of chiral 1-substituted tetrahydroisoquinolines by the intramolecular 1,3-chirality transfer reaction catalyzed by Bi(OTf)3

The intramolecular 1,3-chirality transfer reaction of chiral amino alcohols 1 with 99% ee was developed to construct chiral 1-substituted tetrahydroisoquinoline 2. Bi(OTf)(3) (10 mol %)-catalyzed cyclization of 1 (R = H) afforded (S)-1-(E)-propenyl tetrahydroisoquinoline 2 (R = H) in 83% yield with a ratio of 98:2. The stereochemistry at the newly formed chiral center was produced by a syn S(N)2'-type process. In this reaction, the substituent on the benzene ring of 1 significantly affected the reactivities and selectivities. A plausible reaction mechanism was proposed.