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.     

Spontaneous mode-selection in the self-propelled motion of a solid/liquid composite driven by interfacial instability

Spontaneous motion of a solid/liquid composite induced by a chemical Marangoni effect, where an oil droplet attached to a solid soap is placed on a water phase, was investigated. The composite exhibits various characteristic motions, such as revolution (orbital motion) and translational motion. The results showed that the mode of this spontaneous motion switches with a change in the size of the solid scrap. The essential features of this mode-switching were reproduced by ordinary differential equations by considering nonlinear friction with proper symmetry.     

Exponential homeomorphisms in the category of topological spaces with base point

Topologies on base point preserving function spaces are studied making use of the Brown-Booth-Tillotson C-smash product and the topologies on function spaces defined by the classes C of exponentiable spaces. Some conditions on the classes C are obtained for exponential bijections and exponential homeomorphisms in the category of topological spaces with base point. Conditions for exponential homeomorphisms are obtained for CW-complexes whose cellular structure implies precise results.     

Highly efficient asymmetric conjugate addition of 5-benzylfurfurals to nitroalkenes using a thiourea organocatalyst

The asymmetric direct bisvinylogous conjugate addition of 5-benzylfurfural derivatives to nitroalkenes using a thiourea organocatalyst resulted in a corresponding ε-regioselective addition products in high yields and up to 95% enantiomeric excess.     

New Size-Expanded Fluorescent Thymine Analogue: Synthesis,Characterization, and Application

Here, the synthesis, photophysical characterization, and application of a new size-expanded thymine nucleoside, ^diox T , is described. ^diox T has desirable qualities as a T surrogate, including excellent quantum yield (0.36) and high environmental sensitivity. When incorporated into single- and double-stranded DNA, ^diox T showed excellent photophysical characteristics including a high quantum yield (average 0.20), and unlike BgQ, demonstrated dependence on neighboring bases without significant destabilization of the duplex. Interestingly, the matched base pair of adenine (A) and ^diox T has the unique property that it exhibits higher fluorescence than mismatched base pairs, and ^diox T has self-quenching effects. As one example of the possible applications of these promising features, single nucleoside polymorphism typing is demonstrated for discrimination of A by using ^diox T . The results suggest that ^diox T can be used for a broad range of applications in chemical biology.     

Asymmetric conjugate addition of 5-benzylfurfurals to nitroalkenes using a diaminomethylenemalononitrile organocatalyst

A pyrrolidine–diaminomethylenemalononitrile organocatalyst efficiently promotes the asymmetric direct bisvinylogous Michael addition of 5-benzylfurfural derivatives to nitroalkenes, affording the corresponding ε-regioselective addition products in high yields with up to 86% ee.     

Characterization of Alumina Gel Catalysts by Emanation Thermal Analysis (ETA)

Alumina gels made from the metal alkoxide is known to have high catalyst activity for the selective reduction of NO _x by hydrocarbons. It is also reported that the fine structure of the gels effects the activity. In this study, the effect of the preparation method on the fine structure and catalyst activity of the gels was investigated. Monolithic gels were obtained by hydrolysis of Al(sec-C₄H₉O)₃. The wet gels were dried at 90°C (xerogels), supercritically dried (aerogels), or dried after immersion in an ethanol solution of methyltrimethoxysilane (modified xerogels). The changes in the microstructure during heating were discussed using the results of TG-DTA, ETA and N₂ adsorption. The ETA curves show the ²²⁰Rn-release rate, E, of the samples, previously labelled with ²²⁸Th and ²²⁴Ra, during heating. The decrease in E of the xerogel at temperatures higher than 400°C indicates a gradual decrease in the surface area and porosity. A remarkable decrease in the BET surface area of the xerogel was found after heat-treating at 500°C. On the other hand, constant E of the aerogels and modified xerogels above 450°C suggests high thermal stability. The pore radii, estimated by BJH method, and the catalyst activities at 500°C of the aerogels and the modified xerogels were higher than those of the xerogels. The temperature range in which the alumina gels are applicable as catalysts was determined.     

Synthesis of the Core Oligosaccharides of Lipooligosaccharides from Campylobacter jejuni: A Putative Cause of Guillain–Barré Syndrome

The chemical synthesis of the highly branched core oligosaccharides of lipooligosaccharides (LOSs) found in Campylobacter jejuni, which causes Guillain–Barré syndrome by a preceding infection, is described. The target LOS mimics, consisting of eight or nine monosaccharides, were classified into three groups as key building blocks: ganglioside-core tetra-/pentasaccharides (GM1-/GD1a-like), l -glycero-d -manno-heptose-containing trisaccharides, and 3-deoxy-d -manno-2-octulosonic acid (KDO) residues. These synthetic fragments were obtained from commercially available monosaccharides. Less obtainable l -glycero-d -manno-heptose and KDO residues, as key components of the LOSs, were synthesized from p-methoxyphenyl d -mannoside and di-O-isopropylidene-protected d -mannose, respectively. The synthesis of α-KDO glycoside, as one of the most difficult stereocontrolled glycosidic constructions, was achieved by treating a 2,3-ene derivative of KDO with phenylselenyl trifluoromethanesulfonate as a suitable α-directing reagent. All synthetic blocks were constructed through a convergent synthetic route, which resulted in the first synthesis of structurally challenging LOS core glycans containing ganglioside GM1 and GD1a-core sequences.     

Facile aerobic photo-oxidative synthesis of α-diketones from alkynes

We report a useful method for facile aerobic photo-oxidative synthesis of α-diketones from alkynes with MgBr₂·OEt₂. This procedure provides a practical synthetic method of α-diketones using easily handled bromine sources, harmless visible light, and molecular oxygen as terminal oxidant.