Dynamic Structural Transformation of Resveratrol‐Modified Stearate Liposomes Led to a Spontaneous Drug Release System

A mono‐substituted resveratrol derivative, resveratrol‐modified stearate (RMS), was synthesized by selectively coupling of stearic acid to the monohroxyphenyl of resveratrol in order to enhance both the stability and bioavailability of resveratrol. The RMS self‐assembles into liposomes and a series of suprastructural transformations into metastable helical ribbon, linear wire‐like structures, and inert spherical nanoparticles were detected that may be induced by the hydrogen‐bonding interactions. As a model for drug‐release investigations, gold nanoparticles (AuNPs) were encapsulated successfully by RMS to generate vesicles and succeed to release AuNPs druing the transformation to a ribbon‐like metastable stucture at ambient temperature.     

Preparation of electroactive silica mesopores by encapsulating polyaniline chains into silica framework via nonsurfactant templating sol-gel route

Electroactive silica mesopores have been synthesized by encapsulating different loadings of polyaniline chains into a silica network through sol-gel reactions of TEOS in the presence of polyaniline latex with D-glucose. It should be noted that the electroactive silica mesopores at higher polyaniline loading was found to reveal higher surface areas, larger pore volume, and slightly larger pore diameters as compared to that of neat non-electroactive silica mesopores.     

Pseudoalteromone A: a novel bioactive ubiquinone from a marine bacterium Pseudoalteromonas sp. CGH2XX (Pseudoalteromonadaceae)

A novel ubiquinone derivative, pseudoalteromone A (1), possessing a 9C nor-monoterpenoid moiety was produced from a marine bacterium Pseudoalteromonas sp. CGH2XX. This bacterium is originally isolated from a cultured-type octocoral Lobophytum crassum. The structure of ubiquinone 1 was established by spectroscopic methods. Pseudoalteromone A (1) exhibited significant cytotoxicity toward the MOLT-4 (human acute lymphoblastic leukemia, IC₅₀ = 3.764 μg/mL) cells and displayed a significant inhibitory effect (inhibition rate 45.1%) on the release of elastase by human neutrophils at a concentration of 10 μg/mL.     

Determination of metformin in rat plasma by HILIC-MS/MS combined with Tecan automation and direct injection

Metformin is a well‐known oral antihyperglycemic drug used in treatment of type II diabetes. Analysis of metformin in biological fluids is a challenge owing to its high polarity and small molecular size, which lead to poor retention of metformin on reversed‐phase liquid chromatographic columns. A high‐throughput method was developed and validated for the determination of metformin in rat plasma in support of preclinical toxicology studies, using hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC‐MS/MS) and Tecan automated sample preparation. Extracted samples were directly injected onto the unbounded silica column with an aqueous–organic mobile phase. This HILIC‐MS/MS method was validated for accuracy, precision, sensitivity, stability, matrix effect, recovery and calibration range. Acceptable intra‐run and inter‐run assay precision (coefficient of variation ≤ 3.9%) and accuracy (99.0–101.8%) were achieved over a linear range of 50–50,000 ng/mL. Metformin is stable in rat plasma for at least 6 h at room temperature, 147 days at ?70°C and through three freeze (?70°C) and thaw cycles. Metformin is also stable in rat whole blood for at least 2 h at room temperature and in an ice–water bath. The validated method was successfully used in support of several preclinical studies where metformin is dosed together with an investigational drug substance. The ruggedness of the validated method was demonstrated by the incurred sample reproducibility test. Copyright © 2011 John Wiley & Sons, Ltd.     

Kinetics and mechanisms for the adsorption, dissociation, and diffusion of hydrogen in Ni and Ni/YSZ slabs: a DFT study

The adsorption, dissociation, and diffusion of hydrogen in Ni(100) and Ni(100)/YSZ(100) slabs with two different interfaces (Ni/cation and Ni/O interface) have been studied by the density functional theory (DFT) with the Perdew-Wang functional. The H(2) molecule is found to preferentially absorb on a Top (T) site with side-on configuration on the Ni(100) surface, while the H-atom is strongly bound at a fcc Hollow (H) site. The barrier for the H(2) dissociation on both surfaces is calculated to be only ~0.1 eV. The potential energy pathways of H diffusion on pure Ni and Ni/YSZ with the two different interfaces are studied. Our calculated results show that the H-atom diffusion occurs via surface path rather than the bulk path. For the bulk path in Ni/YSZ, H-atom migration can occur more readily at the Ni/cation interface compared to the Ni/O interface. The existence of vacancy in the interface region is found to improve the mobility of H-atoms at the interface of Ni/YSZ slab. The rate constants for hydrogen dissociation and diffusion in pure Ni and Ni/YSZ are predicted.     

介孔磷酸铌一锅法高效催化木糖制备糠醛

木糖转化到糠醛一般包括两步: 首先在酶、碱或路易斯(L)酸的催化作用下异构化木糖到木酮糖, 接下来木酮糖在酸的作用下脱水得到糠醛. 针对木糖水相脱水一步制备糠醛, 利用十六烷基三甲基溴化铵(CTAB)为模板剂, 借助软模板合作策略制备了一种抗水的新型固体酸催化剂, 介孔磷酸铌, 并利用X射线衍射(XRD)、N₂吸脱附、透射电镜(TEM)、氨气程序升温脱附(NH₃-TPD)和吡啶吸附傅里叶变换红外(Py-FTIR)光谱对材料的结构和酸性质进行了表征. 研究发现介孔磷酸铌不仅具有很高的比表面积(>200 m²·g^-1), 比较窄的孔径分布(3.5nm), 同时还具有很强的L酸性和布朗斯特(B)酸性. 通过L酸催化的木糖异构化为木酮糖/来苏糖和B酸催化的木酮糖/来苏糖进一步脱水得到糠醛, 实现了一步由木糖到糠醛的高效转化. 为了优化反应条件, 考察了水溶液中反应温度、投料质量比及反应时间对木糖转化率和糠醛收率的影响, 在最佳的反应条件下, 木糖的转化率为96.5%, 糠醛的收率达49.8%. 进一步地, 为了提高收率且易于分离, 利用4-甲基-2-戊酮(MIBK)/NaCl水溶液(体积比为7:3)作为反应混合溶剂, 使糠醛收率提高到68.4%.     

以主族元素为桥的梯形化合物的光电性质

梯形化合物具有大的平面π共轭结构, 不会产生构象扭曲, 可以有效增加π共轭长度, 因而表现出非常好的光电性质. 将主族元素引入到梯形化合物骨架中作为桥接单元不仅可以固定其结构而且由于主族元素和π共轭骨架之间的轨道相互作用, 可以实现对这类化合物光电性质的调节. 采用密度泛函理论对一系列主族元素桥的梯形化合物的结构和光电性质进行了理论研究, 从而可更好地理解和预测这类化合物的性质. 研究发现, 这类化合物的电子结构可以通过引入主族元素进行调节. 由于具有更大的π共轭程度, 四主族元素桥化合物的吸收与双主族元素桥化合物相比有明显的红移, 而且荧光寿命较短. 另外, 通过计算离子化势(IPs)、电子亲和能(EAs)和重组能(λ)考察了这类化合物的电子和空穴注入及传输性质. 研究发现, 四主族元素桥化合物表现出更强的电子和空穴注入能力.     

Discovery of antagonist peptides against bacterial helicase-primase interaction in B. stearothermophilus by reverse yeast three-hybrid

Developing small-molecule antagonists against protein-protein interactions will provide powerful tools for mechanistic/functional studies and the discovery of new antibacterials. We have developed a reverse yeast three-hybrid approach that allows high-throughput screening for antagonist peptides against essential protein-protein interactions. We have applied our methodology to the essential bacterial helicase-primase interaction in Bacillus stearothermophilus and isolated a unique antagonist peptide. This peptide binds to the primase, thus excluding the helicase and inhibiting an essential interaction in bacterial DNA replication. We provide proof of principle that our reverse yeast three-hybrid method is a powerful "one-step" screen tool for direct high-throughput antagonist peptide selection against any protein-protein interaction detectable by traditional yeast two-hybrid systems. Such peptides will provide useful "leads" for the development of new antibacterials.