Gold Nanoparticles Capped with Polyethyleneimine for Enhanced siRNA Delivery

An efficient and safe delivery system for small interfering RNA (siRNA) is required for clinical application of RNA interfering therapeutics. Polyethyleneimine (PEI)‐capped gold nanoparticles (AuNPs) are successfully manufactured using PEI as the reductant and stabilizer, which bind siRNA at an appropriate weight ratio by electrostatic interaction and result in well‐dispersed nanoparticles with uniform structure and narrow size distribution. With siRNA binding, PEI‐capped AuNPs induce more significant and enhanced reduction in targeted green fluorescent protein expression in MDA‐MB‐435s cells, though more internalized PEI/siRNA complexes in cells are evidenced by confocal laser scanning microscopy observation and fluorescence‐activated cell sorting analyses. PEI‐capped AuNPs/siRNA targeting endogenous cell‐cycle kinase, an oncogene polo‐like kinase 1 (PLK1), display significant gene expression knockdown and induce enhanced cell apoptosis, whereas it is not obvious when the cells are treated with PLK1 siRNA using PEI as the carrier. Without exhibiting cellular toxicity, PEI‐capped AuNPs appear to be suitable as a potential carrier for intracellular siRNA delivery.     

A Novel Synthesis of Malic Acid Capped Silver Nanoparticles using Solanum lycopersicums Fruit Extract

Integration of green chemistry principles to nanotechnology is one of the key issues in nanoscience research. The development of the concept of green nanoparticle preparation has been growingly needed for environmentally benign metal nanoparticle synthesis protocols to avoid adverse effects in medical applications. Keep this in mind, in the present study, silver nanoparticles were synthesized using Solanum lycopersicums fruit extract. The prepared silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy techniques. The surface plasmon resonance peak was found at 445 nm. The synthesized silver nanoparticles were spherical in shape with the average size of 10 nm. The citric acid present in S. lycopersicums fruit extract acted as reducing agent and malic acid was responsible for capping of the bioreduced silver nanoparticles.     

PVP表面修饰不同形貌金银纳米粒子研究现状

聚乙烯吡咯烷酮(PVP)是一种重要的工业化大分子表面活性剂,由于其大分子结构的特殊性及生物适应性,使得PVP在制备金属纳米粒子过程中得到了广泛应用。近年来,有大量关于以PVP为大分子表面修饰剂制备不同形貌金属纳米粒子的文献报道。文中综述了以PVP为表面修饰剂,分别以乙二醇、乙醇、N,N-二甲基甲酰胺及水为溶剂,通过溶剂和PVP自身的还原作用,在不同反应条件下制备不同形貌金、银纳米粒子的研究现状,提出了不同溶剂体系中不同形貌金属纳米粒子的形成机理研究是未来该领域要解决的主要问题。     

Synthesis of Monodisperse Silver Nanoparticles by Sonolysis of Silver Carboxylates

Monodisperse, crystalline silver nanoparticles are synthesized by sonolytically assisted decomposition of silver oxalate and oleate precursors in dibenzylether. Oleic acid and oleylamine are used as capping agents. The diameters of the obtained particles vary from 6 to 10 nm depending on the sonification time and the precursor material. The particles are stable in non‐polar media. A 2D and 3D assembly of the as‐prepared nanoparticles is observed. Particle sizes and dispersities are characterized by transmission electron microscopy and image analysis. The decomposition characteristics of the different precursor compounds are investigated using UV–Vis spectroscopy and thermogravimetry.     

Optical Properties of Thulium-Modified Silver Nanoparticles

We have prepared silver nanoparticles in thulium-modified colloidal solutions by “green” synthesis and investigated the optical properties of the resultant mixed solutions. The thulium ions have been shown to influence the properties of the colloidal silver nanoparticles. Thulium has a strong advantageous effect on the plasmon resonance of the silver nanoparticles, whereas the components of peppermint reduce the effect. The silver nanoparticles reduce the thulium ion photoluminescence intensity.     

水热法制备纳米银颗粒的试验研究

以AgNO_3和NaHCO_3为反应原料,以PVP为保护剂,用水热法制备出纳米银颗粒。研究了AgNO_3浓度和分散剂PEG的加入对反应生成纳米银颗粒形貌的影响。结果表明,在AgNO_3浓度为0.06 mol/L,NaHCO_3浓度为0.15 mol/L,PVP为0.03 mol/L,PEG为0.05 mol/L,反应温度为200℃,反应时间4 h的工艺条件下,可得到平均粒径尺寸约50 nm、分散性好、尺寸均一的近球形纳米银颗粒。     

Toxicity of Silver Nanoparticles in Macrophages

Silver nanoparticles (nanosilver) are broadly used today in textiles, food packaging, household devices and bioapplications, prompting a better understanding of their toxicity and biological interactions. In particular, the cytotoxicity of nanosilver with respect to mammalian cells remains unclear, because such investigations can be biased by the nanosilver coatings and the lack of particle size control. Here, nanosilver of well‐defined size (5.7 to 20.4 nm) supported on inert nanostructured silica is produced using flame aerosol technology. The cytotoxicity of the prepared nanosilver with respect to murine macrophages is assessed in vitro because these cells are among the first to confront nanosilver upon its intake by mammals. The silica support facilitates the dispersion and stabilization of the prepared nanosilver in biological suspensions, and no other coating or functionalization is applied that could interfere with the biointeractions of nanosilver. Detailed characterization of the particles by X‐ray diffraction and electron microscopy reveals that the size of the nanosilver is well controlled. Smaller nanosilver particles release or leach larger fractions of their mass as Ag⁺ ions upon dispersion in water. This strongly influences the cytotoxicity of the nanosilver when incubated with murine macrophages. The size of the nanosilver dictates its mode of cytotoxicity (Ag⁺ ion‐specific and/or particle‐specific). The toxicity of small nanosilver (<10 nm) is mostly mediated by the released Ag⁺ ions. The influence of such ions on the toxicity of nanosilver decreases with increasing nanosilver size (>10 nm). Direct silver nanoparticle–macrophage interactions dominate the nanosilver toxicity at sizes larger than 10 nm.     

基于毛竹半纤维素的银纳米粒子的绿色合成

直接以碱溶性毛竹半纤维素为稳定剂、葡萄糖为还原剂,在水介质中绿色合成银纳米粒子,讨论了合成条件对银纳米粒子的形成和储存稳定性的影响,表征了银纳米粒子-半纤维素复合物经热处理后获得的Ag-C复合物的物理化学特性,并讨论了银纳米粒子的可能形成机理。在恒定其他反应条件下,延长反应时间会有更多银纳米粒子生成,但过度延长反应时间会使银纳米粒子发生团聚而生成大颗粒的粒子;高的葡萄糖浓度、反应温度和初始半纤维素用量会加快银纳米粒子的生成。银纳米粒子的平均粒径和粒径分布范围均随半纤维素用量的增大而减小,而银纳米粒子在4℃的储存稳定性随半纤维素用量的增大而增强。银纳米粒子-半纤维素复合物在空气气氛中300℃热处理1h后获得的Ag-C复合物中同时存在金属态的银和氧化态的银。半纤维素中呈电负性的大量自由羟基和少量羧基可能对银纳米粒子的形成起至关重要的作用。     

纳米银颗粒-银离子复合型导电墨水导电性研究

目的 为了减少纳米银颗粒墨水所制备图案的孔隙率,提高图案的导电性。方法 将多尺寸纳米银颗粒与银离子溶液混合制备得到纳米银颗粒-银离子复合型墨水,通过扫描电子显微镜（SEM）观察所制备图案的表面形貌,采用X-射线衍射仪（XRD）确定图案表面晶型,并对图案进行电阻率测试。结果 实验结果表明,纳米银颗粒-银离子的配比对该复合型导电墨水的导电性有重要影响。AgNPs与Ag⁺的体积比为2∶1的混合型墨水在干燥之后具有最佳导电性,电阻率为1.33×10^-3Ω·cm,该墨水中银的质量分数约为4.37%。经过热压之后,AgNPs与Ag⁺的体积比为5∶1的墨水所制备的图案导电性最好,电阻率为1.32×10^-4Ω·cm,该墨水中银的质量分数约为3.19%。结论 所制备的纳米银颗粒-银离子复合型墨水干燥后即可导电,经过热压处理之后导电性可进一步提高。该复合型墨水中银含量低,可大大降低其用于柔性器件的成本。     

Photoinduced Silver Nanoparticles/Nanorings on Plasmid DNA Scaffolds

Biological scaffolds are being actively explored for the synthesis of nanomaterials with novel structures and unexpected properties. Toroidal plasmid DNA separated from the Bacillus host is applied as a sacrificial mold for the synthesis of silver nanoparticles and nanorings. The photoirradiation method is applied to reduce Ag^I on the plasmid. The nanoparticles are obtained by varying the concentration of the Ag^I ion solution and the exposure time of the plasmid–Ag^I complex under UV light at 254 nm and room temperature. It is found that the plasmid serves not only as a template but also as a reductant to drive the silver nucleation and deposition. The resulting nanoparticles have a face‐centered cubic (fcc) crystal structure and 20–30 nm average diameter. The detailed mechanism is discussed, and other metals or alloys could also be synthesized with this method.     

粒径可控纳米银的制备研究

以次磷酸钠液相还原法制备纳米银溶胶.通过调节还原后银溶胶的pH值可以达到控制纳米银粒径的效果.研究了氨水在制备不同粒径的银粉过程中的作用.对银溶胶进行了Zeta电位测量,对制得的纳米银样品用XRD、TEM进行了表征,采用原子吸收法分析了还原后溶液中残留的银离子的浓度,确定银的还原率.分析了各种因素对纳米银制备和样品粒径的影响.通过控制适当合成反应条件,可制得10～100nm、粒径可控、高分散性、高纯度的纳米银粉.     

基于叶酸靶向的银纳米生物材料研究

采用氧化还原法制备出球状银(Ag)纳米颗粒,通过巯基化反应制备出巯基化叶酸,在水性分散剂中通过分子自组装进行银纳米颗粒的叶酸修饰;采用傅里叶变换红外光谱仪对巯基化叶酸及其中间产物进行测试表征,结果表明叶酸已成功被巯基化;通过透射电镜(TEM)、紫外-可见分光光度计(UV-Vis)、荧光分光光度计进行表征,证明巯基叶酸能够成功修饰到银纳米颗粒表面,银颗粒尺寸约50nm,修饰后复合颗粒尺寸约53nm,复合物不但能够发出紫外吸收信号且金属荧光性能增强;基于叶酸本身的荧光性能及叶酸受体的靶向功能,该复合物有望应用于肿瘤细胞检测、纳米生物探针等医用诊断领域。     

纳米银的合成及其抗菌应用研究进展

病原微生物严重威胁着人类的健康安全,纳米银作为一种新型抗菌材料,其制备与应用已成为纳米材料领域的研究热点。本文综述了纳米银的主要合成方法,包括多糖法、Tollens试剂法、辐射法、生物法和多金属氧酸盐法等,具有原料广泛、反应温和、成本低廉和环境友好等优点。基于纳米银的优异抗菌性能,总结了纳米银的抗菌机理及其抗菌应用,并展望了纳米银在抗菌涂料、抗菌包装等领域的发展前景。     

Electrochemical Preparation of Silver Polyacrylate Solutions Intended for the Synthesis of Silver Nanoparticles

Materials Science - By using the method of cyclic voltammetry, we study the anodic dissolution of silver in a sodium polyacrylate (NaPA) solution. The influence of the concentration of NaPA,...     

可反应表面修饰银纳米微粒的制备及组装

合成了功能化的修饰剂双11-十一烯基二硫代磷酸,以此为修饰剂,NaBH4还原可溶性银盐的水溶液制得了功能化的银纳米微粒,并通过氢化硅氢化反应组装银纳米颗粒薄膜。采用透射电子显微镜（TEM）、紫外-可见吸收光谱（UV-Vis）、傅立叶红外吸收光谱（FT-IR）、原子力显微镜（AFM）和X-光电子能谱（XPS）对所制的纳米微粒及组装的薄膜进行形态和结构表征,结果表明：银纳米颗粒为球形,无团聚现象,纳米微粒表面带有可反应的C=C双键不饱和官能团;组装后纳米微粒团聚长大,是通过Si-C键与基底结合。     

软模板技术制备银的各向异性纳米粒子

纳米银的光学、电学和催化活性与粒子的粒径、形貌和结构之间存在着强烈的依赖关系,研究各向异性银纳米材料的形成具有重要意义.结合软模板技术在各向异性银纳米材料制备方面的研究成果,着重讨论了银纳米棒和纳米线的制备方法和形成机理,概述了树枝状纳米银、纳米银片(盘)、纳米银立方体和三棱柱的研究进展,指出利用软模板技术可合成各种形貌的纳米银粒子,并指出了此类材料在研究中存在的不足,展望了其发展趋势.     

Ultrasonic Alloying of Preformed Gold and Silver Nanoparticles

Alloyed gold/silver nanoparticles with a core/shell structure are produced from preformed gold and silver nanoparticles during ultrasonic treatment at different intensities in water and in the presence of surface‐active species. Preformed gold nanoparticles with an average diameter of 15 ± 5 nm are prepared by the citrate reduction of chloroauric acid in water, and silver nanoparticles (38 ± 7 nm) are formed after reduction of silver nitrate by sodium borohydride. Bare binary gold/silver nanoparticles with a core/shell structure are formed in aqueous solution after 1 h of sonication at high ultrasonic intensity. Cationic‐surfactant‐coated preformed gold and silver nanoparticles become gold/silver‐alloy nanoparticles after 3 h of sonication in water at 55 W cm^?2, whereas only fusion of isolated gold and silver nanoparticles is observed after ultrasonic treatment in the presence of an anionic surfactant. As the X‐ray diffraction profile of alloyed gold/silver nanoparticles reveals split, shifted, and disappeared peaks, the face‐centered‐cubic crystalline structure of the binary nanoparticles is defect‐enriched by temperatures that can be as high as several thousand Kelvin inside the cavitation bubbles during ultrasonic treatment.