A metabolically engineered spin-labeling approach for studying glycans on cells

Metabolic glycan engineering (MGE) coupled with nitroxide spin-labeling (SL) was utilized to investigate the heterogeneous environment of cell surface glycans in select cancer and normal cells. This approach exploited the incorporation of azides into cell surface glycans followed by a click reaction with a new nitroxide spin label. Both sialic acid and N-acetylglucosamine (GlcNAc) were targeted for spin labelling. Although each of these moieties experiences a diverse and heterogeneous glycan environment, their EPR spectra and hence mobility are both characterized as a linear combination of two distinct spectra where one component reflects a highly mobile or uncrowded micro-environment with the second component reflecting more restricted motion, reflective of increased crowding and packing within the glycocalyx. What differs among the spectra of the targeted glycans is the relative percentage of each component, with sialic acid moieties experiencing on average an ∼80% less crowded environment, where conversely GlcNAc/GalNAz labeled sites reported on average a ∼50% more crowded environment. These distinct environments are consistent with the organization of sugar moieties within cellular glycans where some residues occur close to the cell membrane/protein backbone (i.e. more restricted) and others are more terminal in the glycan (i.e. more mobile). Strikingly, different cell lines displayed varied relative populations of these two components, suggesting distinctive glycan packing, organization, and composition of different cells. This work demonstrates the capability of SDSL EPR to be a broadly useful tool for studying glycans on cells, and interpretation of the results provides insights for distinguishing the differences and changes in the local organization and heterogeneity of the cellular glycocalyx.

Metabolic glycan engineering (MGE) coupled with nitroxide spin-labeling (SL) was utilized to investigate the heterogeneous environment of cell surface glycans in select cancer and normal cells.     

水质评价涉及的因子权重与定权方法

水质评价涉及属性权与熵权两种权重.熵权表征因子的分类能力,由因子的隶属度向量通过计算信息熵确定.属性权表征因子重要性程度的差异,用途是使不同因子的隶属度具有"可比性",但定权方法众说不一.指出,因子重要性程度差异源于因子属性与因子取值无关,并且表征这种差异等同于对因子接重要性排序.AHP的比例标度判断矩阵为因子排序提供了合理的数据条件,但基于"一致性检验"的特征根排序法受到质疑;FAHP也因没有彻底摆脱"一致性",所以建立的排序方法有局限性.为此,通过标度变换将比例标度转化为评分标度,利用评分标度的可加性把判断矩阵中由评分标度确定的因子的序关系转化为因子排序.由此建立不受"一致性"干扰的定权方法.     

高分辨率Ⅰ-line正性光刻胶的制备及应用性能研究

利用两种不同重均分子量的改性酚醛树脂(PF)与一种三个酯化度的四羟基二苯甲酮-重氮萘醌磺酸酯光敏剂(PAC)按比例配制,加入适量助剂优化感光性能,制备出一种应用于电子触屏加工领域的Ⅰ-line正性光刻胶,其具有刻蚀精度高、工艺性能优良、单位成本较低等优势特点.     

Development and validation of an LC‐MS/MS method for the determination of mesalazine in beagle dog plasma and its application to a pharmacokinetic study

A simple, specific and sensitive LC‐MS/MS method was developed and validated for the determination of mesalazine in beagle dog plasma. The plasma samples were prepared by protein precipitation, then the separation of the analyte was achieved on a Waters Spherisorb C₆ column (150 × 4.6 mm, 5 µm) with a mobile phase consisting of 0.2% formic acid in water–methanol (20:80, v/v). The flow rate was set at 1.0 mL/min with a split ratio of 3:2. Mass spectrometric detection was achieved by a triple‐quadrupole mass spectrometer equipped with an electrospray source interface in positive ionization mode. Quantitation was performed using selected reaction monitoring of precursor–product ion transitions at m/z 154 → m/z 108 for mesalazine and m/z 285 → m/z 193 for diazepam (internal standard). The linear calibration curve of mesalazine was obtained over the concentration range 50–30,000 ng/mL. The matrix effect of mesalazine was within ±9.8%. The intra‐ and inter‐day precisions were <7.9% and the accuracy (relative error) was within ±3.5%. The validated method was successfully applied to investigate the pharmacokinetics of mesalazine in healthy beagle dogs after rectal administration of mesalazine suppository. Copyright © 2014 John Wiley & Sons, Ltd.     

Tailorable PC71BM Isomers: Using the Most Prevalent Electron Acceptor to Obtain High‐Performance Polymer Solar Cells

Despite being widely used as electron acceptor in polymer solar cells, commercially available PC₇₁BM (phenyl‐C₇₁‐butyric acid methyl ester) usually has a “random” composition of mixed regioisomers or stereoisomers. Here PC₇₁BM has been isolated into three typical isomers, α‐, β₁‐ and β₂‐PC₇₁BM, to establish the isomer‐dependent photovoltaic performance on changing the ternary composition of α‐, β₁‐ and β₂‐PC₇₁BM. Mixing the isomers in a ratio of α/β₁/β₂=8:1:1 resulted in the best power conversion efficiency (PCE) of 7.67 % for the polymer solar cells with PTB7:PC₇₁BM as photoactive layer (PTB7=poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl]]). The three typical PC₇₁BM isomers, even though sharing similar LUMO energy levels and light absorption, render starkly different photovoltaic performances with average‐performing PCE of 1.28–7.44 % due to diverse self‐aggregation of individual or mixed PC₇₁BM isomers in the otherwise same polymer solar cells.     

Loading of a Coordination Polymer Nanobelt on a Functional Carbon Fiber: A Feasible Strategy for Visible‐Light‐Active and Highly Efficient Coordination‐Polymer‐Based Photocatalysts

To improve the photocatalytic properties of coordination polymers under irradiation in the visible‐light region, coordination polymer nanobelts (CPNB) were loaded on functional carbon fiber (FCF) through the use of a simple colloidal blending process. The resulting coordination polymer nanobelt loaded functional carbon fiber composite material (CPNB/FCF) exhibited dramatically improved photocatalytic activity for the degradation of rhodamine B (RhB) under visible‐light irradiation. Optical and electrochemical methods illustrated the enhanced photocatalytic activity of CPNB/FCF originated from high separation efficiency of photogenerated electrons and holes on the interface of CPNB and FCF, which was produced by the synergy effect between them. In the composite material, the role of FCF could be described as photosensitizer and good electron transporter. For FCF, the number of functional groups on its surface has a significant influence on the photocatalytic performance of the resulting CPNB/FCF composite material, and an ideal FCF carrier was obtained as a highly efficient CPNB/FCF photocatalyst. CPNB/FCF showed outstanding stability during the degradation of rhodamine B (RhB); thus, the material is suitable for use as a photocatalyst in the treatment of organic dyes in water.     

Supramolecular hydrogel microcapsules via cucurbit[8]uril host–guest interactions with triggered and UV-controlled molecular permeability

Host–guest assembly in droplet-based microfluidics opens a new avenue for fabricating supramolecular hydrogel microcapsules with high monodispersity and controlled functionality. In this paper, we demonstrate a single emulsion microdroplet platform to prepare microcapsules with supramolecular hydrogel skins from host molecule cucurbit[8]uril and guest polymer anthracene-functionalized hydroxyethyl cellulose. In contrast to construction of microcapsules from a droplet-in-droplet double emulsion, here the electrostatic attraction between charged polymer and surfactant facilitates formation of defined supramolecular hydrogel skins in a single emulsion. Furthermore, by taking advantage of dynamic interactions and the tunable cross-linked supramolecular hydrogel network, it is possible to prepare microcapsules with triggered and UV-controlled molecular permeability. These could be potentially used in a delivery system for e.g. agrochemicals, nutraceuticals or cosmetics.