Reversible Re‐programing of Cell–Cell Interactions

The ability to engineer and re‐program the surfaces of cells would provide an enabling synthetic biological method for the design of cell‐ and tissue‐based therapies. A new cell surface‐engineering strategy is described that uses lipid‐chemically self‐assembled nanorings (lipid‐CSANs) that can be used for the stable and reversible modification of any cell surface with a molecular reporter or targeting ligand. In the presence of a non‐toxic FDA‐approved drug, the nanorings were quickly disassembled and the cell–cell interactions reversed. Similar to T‐cells genetically engineered to express chimeric antigen receptors (CARS), when activated peripheral blood mononuclear cells (PBMCs) were functionalized with the anti‐EpCAM‐lipid‐CSANs, they were shown to selectively kill antigen‐positive cancer cells. Taken together, these results demonstrate that lipid‐CSANs have the potential to be a rapid, stable, and general method for the reversible engineering of cell surfaces and cell–cell interactions.     

Silver‐Catalyzed Decarboxylative Trifluoromethylthiolation of Aliphatic Carboxylic Acids in Aqueous Emulsion

A silver‐catalyzed decarboxylative trifluoromethylthiolation of secondary and tertiary carboxylic acids under mild conditions tolerates a wide range of functional groups. The reaction was dramatically accelerated by its performance in an aqueous emulsion, which was formed by the addition of sodium dodecyl sulfate to water. It was proposed that the radical, which was generated from the silver‐catalyzed decarboxylation in the “oil‐in‐water” droplets, could easily react with the trifluoromethylthiolating reagent to form the product.     

Discovery of Cell‐Permeable Inhibitors That Target the BRCT Domain of BRCA1 Protein by Using a Small‐Molecule Microarray

BRCTs are phosphoserine‐binding domains found in proteins involved in DNA repair, DNA damage response and cell cycle regulation. BRCA1 is a BRCT domain‐containing, tumor‐suppressing protein expressed in the cells of breast and other human tissues. Mutations in BRCA1 have been found in ca. 50 % of hereditary breast cancers. Cell‐permeable, small‐molecule BRCA1 inhibitors are promising anticancer agents, but are not available currently. Herein, with the assist of microarray‐based platforms, we have discovered the first cell‐permeable protein–protein interaction (PPI) inhibitors against BRCA1. By targeting the (BRCT)₂ domain, we showed compound 15 a and its prodrug 15 b inhibited BRCA1 activities in tumor cells, sensitized these cells to ionizing radiation‐induced apoptosis, and showed synergistic inhibitory effect when used in combination with Olaparib (a small‐molecule inhibitor of poly‐ADP‐ribose polymerase) and Etoposide (a small‐molecule inhibitor of topoisomerase II). Unlike previously reported peptide‐based PPI inhibitors of BRCA1, our compounds are small‐molecule‐like and could be directly administered to tumor cells, thus making them useful for future studies of BRCA1/PARP‐related pathways in DNA damage and repair response, and in cancer therapy.     

Auto‐Oxidative Coupling of Glycine Derivatives

The unprecedented title reaction between glycine derivatives and indoles, as well as the auto‐oxidative Povarov/aromatization tandem reaction of glycine derivatives with olefins are described. The reactions were performed in the absence of redox‐active catalysts and chemical oxidants under mild reaction conditions. Only simple organic solvents and air (or O₂) were required.     

A Small‐Molecule FRET Reporter for the Real‐Time Visualization of Cell‐Surface Proteolytic Enzyme Functions

Real‐time imaging of cell‐surface‐associated proteolytic enzymes is critical to better understand their performances in both physiological and pathological processes. However, most current approaches are limited by their complexity and poor membrane‐anchoring properties. Herein, we have designed and synthesized a unique small‐molecule fluorescent probe, which combines the principles of passive exogenous membrane insertion and Förster resonance energy transfer (FRET) to image cell‐surface‐localized furin‐like convertase activities. The membrane‐associated furin‐like enzymatic cleavage of the peptide probe leads to an increased fluorescence intensity which was mainly localized on the plasma membrane of the furin‐expressed cells. This small‐molecule fluorescent probe may serve as a unique and reliable reporter for real‐time visualization of endogenous cell‐surfaceassociated proteolytic furin‐like enzyme functions in live cells and tissues using one‐photon and two‐photon microscopy.     

Photochemical Behavior of Single‐Walled Carbon Nanotubes in the Presence of Propylamine

This report describes the photochemical behavior of single‐walled carbon nanotubes (SWNTs) in the presence of propylamine. The SWNTs are characterized by absorption and Raman spectroscopy. The spectral changes due to photoirradiation indicate that reactions occur predominantly with the metallic SWNTs and small‐diameter SWNTs. The detection of amine radicalcation species by ESR spectroscopy reveals photoinduced electron transfer from the amine to the excited SWNTs. After exposure of the photoirradiated SWNTs to air, the characteristic spectra were recovered, except for that of the small‐diameter SWNTs. The results suggest that, after photoreduction of the SWNTs, subsequent selective sidewall functionalization of the small‐diameter SWNTs occurs.     

Self‐Propelled Janus Mesoporous Silica Nanomotors with Sub‐100 nm Diameters for Drug Encapsulation and Delivery

The synthesis of an innovative self‐propelled Janus nanomotor with a diameter of about 75 nm that can be used as a drug carrier is described. The Janus nanomotor is based on mesoporous silica nanoparticles (MSNs) with chromium/platinum metallic caps and propelled by decomposing hydrogen peroxide to generate oxygen as a driving force with speeds up to 20.2 μm s^?1 (about 267 body lengths per second). The diffusion coefficient (D) of nanomotors with different H₂O₂ concentrations is calculated by tracking the movement of individual particles recorded by means of a self‐assembled fluorescence microscope and is significantly larger than free Brownian motion. The traction of a single Janus MSN nanomotor is estimated to be about 13.47×10^?15 N. Finally, intracellular localization and drug release in vitro shows that the amount of Janus MSN nanomotors entering the cells is more than MSNs with same culture time and particle concentrations, meanwhile anticancer drug doxorubicin hydrochloride loaded in Janus MSNs can be slowly released by biodegradation of lipid bilayers in cells.     

Boron‐Double‐Ring Sheet,Fullerene, and Nanotubes: Potential Hydrogen Storage Materials

Similar to carbon‐based graphene, fullerenes and carbon nanotubes, boron atoms can form sheets, fullerenes, and nanotubes. Here we investigate several of these novel boron structures all based on the boron double ring within the framework of density functional theory. The boron sheet is found to be metallic and flat in its ground state. The spherical boron cage containing 180 atoms is also stable and has I symmetry. Stable nanotubes are obtained by rolling up the boron sheet, and all are metallic. The hydrogen storage capacity of boron nanostructures is also explored, and it is found that Li‐decorated boron sheets and nanotubes are potential candidates for hydrogen storage. For Li‐decorated boron sheets, each Li atom can adsorb a maximum of 4 H₂ molecules with g_d=7.892 wt %. The hydrogen gravimetric density increases to g_d=12.309 wt % for the Li‐decorated (0,6) boron nanotube.     

印章印文的鉴定方法

对印章印文的鉴定方法进行了综述,内容包括显微镜观察印文特征、计算机辅助人工比对、印油的渗散程度测定和仪器分析方法(包括紫外-可见导数光谱法、荧光光谱法、红外光谱法、拉曼光谱法、薄层色谱法、液相色谱法、气相色谱法和质谱法)等(引用文献64篇)。     

高效液相色谱法测定咪唑中2-甲基咪唑和4-甲基咪唑

采用高效液相色谱法测定咪唑中2-甲基咪唑和4-甲基咪唑的含量。采用XDB C18色谱柱为分离柱,以pH 3.5的0.05mol·L-1磷酸二氢钾缓冲溶液与甲醇以体积比95比5组成的混合溶液为流动相,流量为1.0mL·min-1,在波长210nm处进行二极管阵列检测。2-甲基咪唑和4-甲基咪唑均在0.10~25.0mg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)分别为20,40mg·kg-1。在1.00,5.00,20.0mg·L-1 3个浓度水平进行加标回收试验,回收率在89.0%~103%之间,测定值的相对标准偏差(n=7)在0.58%~3.0%之间。