Fe3O4纳米颗粒细胞毒性的研究

为了研究Fe3O4纳米颗粒在突变细胞系的中的毒性问题，采用不同浓度Fe3O4纳米颗粒处理含有核苷酸剪切修复基因XPF突变的原代XPF细胞与HeLa细胞.细胞集落形成实验证实了Fe3O4纳米颗粒对XPF细胞的生长有显著的抑制作用，表现出了一定的细胞毒性，说明Fe3O4纳米颗粒不适合应用于有核苷酸剪切修复基因突变的人群.RT-PCR的结果发现CHEK1，RPA1，RPA2和RPA3的转录在XPF细胞内较明显地增加，说明了Fe3O4纳米颗粒通过改变XPF细胞内这些基因的转录，从而抑制其分裂和生长.     

Chemoselective hydrogenation of nitro compounds with supported gold catalysts

The selective reduction of a nitro group when other reducible functions are present is a difficult process that often requires stoichiometric amounts of reducing agents or, if H2 is used, the addition of soluble metals. Gold nanoparticles supported on TiO2 or Fe2O3 catalyzed the chemoselective hydrogenation of functionalized nitroarenes with H2 under mild reaction conditions that avoided the accumulation of hydroxylamines and their potential exothermic decomposition. These chemoselective hydrogenation gold catalysts also provide a previously unknown route for the synthesis of the industrially relevant cyclohexanone oxime from 1-nitro-1-cyclohexene.     

Gold nanoelectrodes of varied size: transition to molecule-like charging

A transition from metal-like double-layer capacitive charging to redox-like charging was observed in electrochemical ensemble Coulomb staircase experiments on solutions of gold nanoparticles of varied core size. The monodisperse gold nanoparticles are stabilized by short-chain alkanethiolate monolayers and have 8 to 38 kilodaltons core mass (1.1 to 1.9 nanometers in diameter). Larger cores display Coulomb staircase responses consistent with double-layer charging of metal-electrolyte interfaces, whereas smaller core nanoparticles exhibit redox chemical character, including a large central gap. The change in behavior is consistent with new near-infrared spectroscopic data showing an emerging gap between the highest occupied and lowest unoccupied orbitals of 0.4 to 0.9 electron volt.     

PEI介导外源基因进入植物细胞的瞬时表达

 【目的】医学方面的大量研究证实,聚乙烯亚胺（polyethylenimine,PEI）作为一种新型阳离子多聚物基因载体可以吸附和浓缩DNA,通过与细胞膜亲和粘附和细胞吞噬作用运载外源基因进入细胞并实现表达。本实验研究旨在探索PEI作为非病毒基因载体介导外源基因进入植物细胞并获得瞬时表达的可能性。【方法】制备PEI/DNA复合物,利用凝胶阻滞分析PEI与DNA的结合情况,采用电子显微镜观察PEI/DNA复合物的形态。以绿色荧光蛋白基因为报告基因研究不同N/P比条件下PEI/DNA复合物对拟南芥原生质体细胞的转化效率,并与PEG转化方法进行比较分析。【结果】PEI与DNA的质量比为5﹕1～1﹕4,PEI可以与DNA稳定结合,形成粒径约100～200 nm的球形复合物。PEI/DNA复合物对拟南芥原生质体细胞的转化效率随其N/P比的增大而提高,N/P＝5时PEI的转化效率达到最高且明显高于PEG介导的转化效率,N/P＞5时转化效率反而下降,容易使细胞破碎和变形。【结论】PEI作为一种新型的外源基因运送载体对拟南芥原生质体细胞具有良好的介导基因转移效果。     

Enhancement of the transfection efficiency of DNA into Crocus sativus L. cells via PEI nanoparticles

Over the past decade, several natural and synthetic cationic polymers have been utilized for gene delivery into cells. Among them, polyethylenimine (PEI) was used for gene therapy successfully. The present study investigated the effect of PEI and ultrasound waves on ssDNA delivery into saffron cells. Gel retardation, dynamic light scattering (DLS) and scanning electron microscopy (SEM) assays were employed to determine the physicochemical properties of PEI/f-DNA polyplex (complex of PEI and fluorescently labeled DNA). Moreover, the cytotoxicity of PEI, PEI/f-DNA polyplex and ultrasound were investigated on saffron cells at different concentrations. The gel retardation results indicated that the formation and neutralization of the PEI/f-DNA polyplex were completed at N/P=5. The particle size distribution of the polyplexes was from 50 to 122 nm. The experimental results revealed that the cytotoxicity of the PEI/f-DNA polyplex was lower than that of PEI alone, hence the cells showed both dose- and exposure duration-dependent responses. Furthermore, the viability of saffron cells declined extremely after 5 and 10 min sonication but this reduction was not significant at 2 min exposure duration. The results also indicated that the combined utilization of ultrasound and PEI nanoparticles increased the transfection efficiency of saffron cells up to two times higher than those obtained by PEI or ultrasound separately.     

Array-based electrical detection of DNA with nanoparticle probes

A DNA array detection method is reported in which the binding of oligonucleotides functionalized with gold nanoparticles leads to conductivity changes associated with target-probe binding events. The binding events localize gold nanoparticles in an electrode gap; silver deposition facilitated by these nanoparticles bridges the gap and leads to readily measurable conductivity changes. An unusual salt concentration-dependent hybridization behavior associated with these nanoparticle probes was exploited to achieve selectivity without a thermal-stringency wash. Using this method, we have detected target DNA at concentrations as low as 500 femtomolar with a point mutation selectivity factor of approximately 100,000:1.     

Stepwise evolution of spherical seeds into 20-fold twinned icosahedra

Understanding the factors that influence the growth and final shape of noble metal nanostructures is important for controlling their properties. However, relative to their single-crystalline counterparts, the growth of nanoparticles that contain twin defects can be difficult to control because multiple competitive growth pathways can yield such structures. We used spherical, cubic, and octahedral single-crystalline gold nanoparticles as dual electron microscopy labels and plasmonic seeds to track the growth of multiply twinned silver nanostructures. As the bimetallic nanostructures grew, they successively developed twin planes to ultimately form multiply twinned nanoparticles from single-crystalline seeds. Collectively, these data demonstrate how a series of nanoparticles of different shapes and internal crystal structures are interrelated and develop from one another.     

Radio-wave heating of iron oxide nanoparticles can regulate plasma glucose in mice

Medical applications of nanotechnology typically focus on drug delivery and biosensors. Here, we combine nanotechnology and bioengineering to demonstrate that nanoparticles can be used to remotely regulate protein production in vivo. We decorated a modified temperature-sensitive channel, TRPV1, with antibody-coated iron oxide nanoparticles that are heated in a low-frequency magnetic field. When local temperature rises, TRPV1 gates calcium to stimulate synthesis and release of bioengineered insulin driven by a Ca(2+)-sensitive promoter. Studying tumor xenografts expressing the bioengineered insulin gene, we show that exposure to radio waves stimulates insulin release from the tumors and lowers blood glucose in mice. We further show that cells can be engineered to synthesize genetically encoded ferritin nanoparticles and inducibly release insulin. These approaches provide a platform for using nanotechnology to activate cells.     

基于链替代扩增-纳米金比色直观检测单链核酸方法的研究

[目的]将链替代扩增技术与核酸修饰纳米金积聚变色的光学特性相结合,设计了一种新型的直观检测3′端暴露单链核酸的方法,实现对单链核酸的高灵敏度检测。[方法]设计一条含有硫代修饰酶切位点的单链核酸（ZDNA）,其酶切位点5′端是能将核酸修饰纳米金变色的Linker序列,3′端是能与Target单链核酸3′端完全互补的H序列。当无Target存在时,Linker会充分暴露,能使核酸修饰纳米金积聚呈现紫色;但是当Target存在时,会与H序列完全互补,作为ZDNA的引物进入链替代扩增循环,形成的新链不断与Linker序列互补,不能使核酸修饰纳米金积聚呈现红色,从而间接检测了Target单链核酸。[结果]通过一系列试验确定检测体系,具体为：40μl修饰纳米金溶液（0.52 nmol/L）加入10μl酶循环体系（ZDNA20 nmol/L,33 mmol/L Tris-HCl（pH值7.9）;10 mmol/L MgCl2;66 mmol/LNaCl;0.5 mmol/LdNTP;0.1 mg/ml BSA;0.05 U/μl klenow;1 U/μl Hinc II）,直观或紫外检测并绘制Target浓度与纳米金积聚程度的标准曲线,表明Target浓度在1~200 pmol/L的范围内呈现良好的线性关系,R2=0.946,最低检测限是1 pmol/L。[结论]链替代扩增-纳米金比色检测单链核酸方法简便、直观、成本低,与传统修饰纳米金比色检测DNA方法相比,灵敏度提高了104倍。     

Activity of CeOx and TiOx nanoparticles grown on Au(111) in the water-gas shift reaction

The high performance of Au-CeO2 and Au-TiO2 catalysts in the water-gas shift (WGS) reaction (H2O + CO-->H2 + CO2) relies heavily on the direct participation of the oxide in the catalytic process. Although clean Au(111) is not catalytically active for the WGS, gold surfaces that are 20 to 30% covered by ceria or titania nanoparticles have activities comparable to those of good WGS catalysts such as Cu(111) or Cu(100). In TiO(2-x)/Au(111) and CeO(2-x)/Au(111), water dissociates on O vacancies of the oxide nanoparticles, CO adsorbs on Au sites located nearby, and subsequent reaction steps take place at the metal-oxide interface. In these inverse catalysts, the moderate chemical activity of bulk gold is coupled to that of a more reactive oxide.     

水果中农药残留的表面增强拉曼光谱技术快速检测研究

为了建立水果中农药残留的快速检测方法，通过过氧化氢和浓硫酸处理制备疏水化的硅片基底，采用静电吸附法将金纳米粒子组装到硅片基底表面，形成硅片/金纳米粒子复合基底，将水果中残留的福美双、百草枯和啶虫脒等3种农药经抽提后滴加到复合基底上，采用表面增强拉曼光谱技术进行检测。结果表明，福美双、百草枯和啶虫脒的方法线性范围分别为0.20～2.00、0.05～0.50、0.20～2.00 mg/kg，最低检测浓度分别为0.20、0.05、0.20 mg/kg。该方法应用于苹果、橘子和梨等水果的农药残留量分析，回收率在94.5%～120.0%之间，相对标准偏差均在15%以下。该方法具有较高的准确度和精确度，适用于水果农药残留的快速检测。     

Nanotechnology. Color-changing nanoparticles offer a golden ruler for molecules

At a meeting here last week, a chemist reported a way to use pairs of gold nanoparticles to track the binding and unbinding of DNA.     

Photothermal imaging of nanometer-sized metal particles among scatterers

Ambient optical detection of labeled molecules is limited for fluorescent dyes by photobleaching and for semiconducting nanoparticles by "blinking" effects. Because nanometer-sized metal particles do not optically bleach, they may be useful optical labels if suitable detection signals can be found. We demonstrate far-field optical detection of gold colloids down to diameters of 2.5 nanometers with a photothermal method that combines high-frequency modulation and polarization interference contrast. The photothermal image is immune to the effects of scattering background, which limits particle imaging through Rayleigh scattering to diameters larger than 40 nanometers.     

Active nonmetallic Au and Pt species on ceria-based water-gas shift catalysts

Traditional analysis of reactions catalyzed by supported metals involves the structure of the metallic particles. However, we report here that for the class of nanostructured gold- or platinum-cerium oxide catalysts, which are active for the water-gas shift reaction, metal nanoparticles do not participate in the reaction. Nonmetallic gold or platinum species strongly associated with surface cerium-oxygen groups are responsible for the activity.     

检测牛奶中结合珠蛋白的电流型免疫传感器的研制

为构建可定量检测牛奶中结合珠蛋白(Hp)含量的电流型免疫传感器,以三电极系统中的金电极为工作电极,采用层层自组装技术将L-半胱氨酸、纳米金颗粒和抗牛Hp抗体依次组装在工作电极上,制成免疫传感器。制成的免疫传感器对Hp的线性检测范围为15～100 mg.L-1,最低检测限为0.63 mg.L-1,并具有较好的重现性和稳定性。分别采用该传感器和ELISA检测试剂盒对隐性乳房炎患牛乳样中的Hp含量进行检测的结果表明,两种检测结果间无显著差异(P>0.05)。结论:制备的免疫传感器可定量检测牛奶中的结合珠蛋白(Hp)。     

Harpin类蛋白纳米粒的制备及促生作用

Harpinx∞和Harpinxm分别来自水稻白叶枯病菌（Xanthomonas oryzae pv．oryzae,X∞）和棉花角斑病菌（Xanthomonas cirri subsp．malvacearum,Xcm）,都具有Harpin的特性。笔者将Harpinx∞和Harpinxm蛋白制成纳米粒剂型进行诱导烟草过敏性反应等研究,结果表明,这2种蛋白与其蛋白纳米粒都能在烟草叶片上激发过敏性反应和氧爆发现象,对烟草种子萌发具有促进作用,尤其Harpinx∞蛋白纳米粒能更好地激发烟草产生氧爆发,促生效果达104．5％。Harpinx∞。与Harpinxm蛋白纳米粒在释放的初始阶段即出现突释,至48h时分别达到83．9％和84．5％,起到持续性的促生效果。     

Powering fuel cells with CO via aqueous polyoxometalates and gold catalysts

Electricity was produced by catalytic oxidation of carbon monoxide (CO) by using gold catalysts at room temperature. The observed rates are faster than conventional processes operating at 500 kelvin or higher for the conversion of CO with water to produce hydrogen and carbon dioxide through the water-gas shift (WGS). By eliminating the WGS reaction, we remove the need to transport and vaporize liquid water in the production of energy for portable applications. This process can use CO-containing gas streams from the catalytic reforming of hydrocarbons to produce an aqueous solution of reduced polyoxometalate compounds that can be used to generate power. The reduced polyoxometalate can be reoxidized in fuel cells that contain simple carbon anodes.     

基于纳米金和核酸适配体的重金属离子传感器研究进展

综述了国内外基于纳米金和核酸适配体的重金属离子传感器的研究进展,从比色法、荧光法和共振散射光谱法三大类详细阐述了各类传感器的原理、技术应用及优缺点,讨论了现有传感器存在的问题和未来检测技术的发展方向。     

秦川牛胎儿骨骼肌卫星细胞的分离培养

【目的】探索胎牛骨骼肌卫星细胞分离、培养、鉴定及基因转染的方法。【方法】分别采用Ⅰ型胶原酶消化、Ⅰ型胶原酶与胰蛋白酶二步消化及链霉蛋白酶消化法对胎牛骨骼肌卫星细胞进行培养,比较了3种不同分离方法所得细胞数及其存活率的差异;利用差速贴壁法和Percoll密度梯度离心相结合的方法纯化骨骼肌卫星细胞,对纯化后的细胞进行myostatin基因RT-PCR以及结蛋白(Desmin)免疫细胞化学染色鉴定,最后通过电转染法对纯化的骨骼肌卫星细胞进行EGFP基因转染研究。【结果】3种消化培养方法中,以链霉蛋白酶消化法分离得到的胎牛骨骼肌卫星细胞数显著高于其它2种方法(P0.05),但细胞存活率较低(P0.05);而采用Ⅰ型胶原酶与胰蛋白酶二步消化法可以得到相对较高的细胞数及存活率。利用差速贴壁和Percoll密度梯度离心相结合的方法可以得到纯化的骨骼肌卫星细胞;电转染法适用于骨骼肌卫星细胞的基因转染。【结论】建立了胎牛骨骼肌卫星细胞分离、培养、纯化、鉴定及基因转染的方法,为通过转基因方法改良秦川牛产肉性能研究奠定了基础。