Synthesis of (--)-Muricatacin via alpha- and alpha'-C-H bond functionalization of tetrahydrofuran

(--)-Muricatacin, a potent cytotoxic (4R,5R)-5-hydroxyheptadecan-4-olide, has been synthesized through alpha-C--H hydroxyalkylation and alpha'-C--H oxidation of tetrahydrofuran. This study presents a novel method for C--H bond functionalization as a means for preparing gamma-(hydroxyalkyl)-gamma-butyrolactones.     

光谱法研究1,3-硫杂杯[4]罗丹明乙二胺酰胺衍生物对Fe3+的探针性能

利用硫杂杯[4]芳烃衍生物与罗丹明乙二胺发生酰化反应,合成了2个具有双罗丹明基团的1,3-硫杂杯[4]罗丹明乙二胺酰胺衍生物.在实验条件下,衍生物与Fe3+均能形成1:1配合物,配合物的形成诱导了衍生物分子中罗丹明基螺环开环,而表现出良好的荧光和比色探针性能.1,3-硫杂杯[4]罗丹明酰胺-2,4-酯对Fe3+的选择性...     

Analysis of oxidation process of cholecystokinin octapeptide with reactive oxygen species by high‐performance liquid chromatography and subsequent electrospray ionization mass spectrometry

The C‐terminal octapeptide of cholecystokinin (CCK8) includes some easily oxidizable amino acids. The oxidation of CCK8 by reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) and hydroxyl radicals (OH^?) was investigated using reversed‐phase high performance liquid chromatography (RP‐HPLC) and subsequent electrospray ionization mass spectrometry. The mechanism of oxidation of CCK8 in the H₂O₂ system differed from that of CCK8 in the Fenton system, in which OH^? are produced. In the H₂O₂ system, ²⁸Met and ³¹Met were oxidized to methionine sulfoxide, and no further oxidation or degradation/hydrolysis occurred. On the other hand, in the Fenton system, ²⁸Met and ³¹Met residues were oxidized to methionine sulfone via the formation of methionine sulfoxide. In addition, the oxidized product was observed at the Trp residue but not at the Tyr residue, and small peptide fragments from CCK8 were observed in the Fenton system. From these results, it was concluded that ²⁸Met and ³¹Met residues of CCK8 are susceptible to oxidation by ROS. Copyright © 2009 John Wiley & Sons, Ltd.     

Large‐scale SPH simulations of droplet impact onto a liquid surface up to the consequent formation of Worthington jet

In this study, the whole process of liquid droplet impact onto a liquid surface up to the consequent formation of the central column was simulated using the smoothed particle hydrodynamics method (SPH), and compared with an experiment using a high‐speed video camera. The surface tension tensor for the particle‐based expression was adequately included as the gradient of the surface tension and that enabled the simulation leading to the formations of crater and crown as well as the consequent central column. The simulated time series of the crater depth and diameter and crown height corresponded quantitatively well with the experimental result up to the rebound motion while discrepancies remained as a lower central column height in the simulation, and this seemed to be ascribed to the difficulty in realizing the complex surface structure that inevitably appeared in the fast rebound motion. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of a microfluidic platform for single-cell secretion analysis using a direct photoactive cell-attaching method

A precise understanding of individual cellular processes is essential to meet the expectations of most advanced cell biology. Therefore single-cell analysis is considered to be one of possible approach to overcome any misleading of cell characteristics by averaging large groups of cells in bulk conditions. In the present work, we modified a newly designed microchip for single-cell analysis and regulated the cell-adhesive area inside a cell-chamber of the microfluidic system. By using surface-modification techniques involving a silanization compound, a photo-labile linker and the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer were covalently bonded on the surface of a microchannel. The MPC polymer was utilized as a non-biofouling compound for inhibiting non-specific binding of the biological samples inside the microchannel, and was selectively removed by a photochemical reaction that controlled the cell attachment. To achieve the desired single-macrophage patterning and culture in the cell-chamber of the microchannel, the cell density and flow rate of the culture medium were optimized. We found that a cell density of 2.0 × 10(6) cells/ml was the appropriate condition to introduce a single cell in each cell chamber. Furthermore, the macrophage was cultured in a small size of the cell chamber in a safe way for 5 h at a flow rate of 0.2 μl/min under the medium condition. This strategy can be a powerful tool for broadening new possibilities in studies of individual cellular processes in a dynamic microfluidic device.     

Synthesis, structure and inclusion properties of cone-tris{[(5′-methyl-2,2′-bipyridyl)-5-yl]oxycarbonylmethoxy}hexahomotrioxacalix[3]arene

Hexahomotrioxacalix[3]arene having [(5′-methyl-2,2′-bipyridyl)-5-yl]oxycarbonylmethoxy group with cone conformation was prepared, which shows strong Ag⁺ affinity and acts as a ditopic receptor for Ag⁺ and nBuNH₃ ⁺. A conformational change of 2,2′-bipyridyl moiety from the original outward orientation of the ring nitrogen to the inside orientation toward the thiacalixarene cavity was observed in the process of Ag⁺ complexation.     

Extended nanospace chemical systems on a chip for new analytical technology

Integration of chemical processes on a microchemical chip has gained much attention in the past decade, and the basic concepts of micro-integration and the supporting technologies have been intensively developed. As a result, many analytical and chemical synthesis applications were demonstrated. The superior performances were verified including shortening analysis time, decrease of sample and reagent volume, and easy chemical operations. Now, the micro-technologies are moving toward practical applications by establishing the systems in which the microchemical chip works as chemical central processing unit. Recently, as a new research field, integration is further proceeding to the 10(1)-10(3) nm scale, which we call extended nanospace. The extended nanospace locates the gap between the targets of conventional nanotechnology (10(0)-10(1) nm) and micro-technology (>1 μm), and the fluidics and chemistry have not been explored well due to a lack of fundamental technologies. For these purposes, many methodologies were established in recent years. Unique liquid properties were reported, which were quite different from those in microspace. Some properties can be expected by considering the characteristics of microspace and the downscaling, and the others are unexpected or are difficult to predict. These properties enabled new chemical operations which will be quite important as the next analytical technologies. Now, chemistry and fluidics in the extended nanospace are forming a new research field. In this review, we survey the fundamental technologies for extended nanospace researches and introduce several unique liquid properties. Finally, unique chemical operations are also illustrated leading to new analytical operations.