贵金属纳米颗粒杂化囊泡的制备及拉曼增强效果研究

以超支化聚合物囊泡为模板制备了贵金属纳米颗粒表面功能化的杂化囊泡.模板囊泡通过多巴胺修饰的超支化聚醚HSP-DA在水中自组装形成.在碱性条件下,囊泡表面的多巴胺自聚合生成聚多巴胺,实现囊泡的交联.由于聚多巴胺具有强黏附特性,因此可以将HSP-PDA交联囊泡分别与Au纳米溶胶、Ag纳米溶胶直接混合,得到Au纳米颗粒或Ag纳米颗粒功能化的杂化囊泡.分别测定了2种杂化囊泡的拉曼光谱,发现杂化囊泡产生了明显的表面增强的拉曼光谱(SERS)信号,清晰显示了对应于囊泡模板分子的拉曼信号,表明可以通过SERS来原位检测囊泡的组成.Ag纳米颗粒杂化囊泡展示出更高的SERS灵敏度,可进一步作为探针检测水中浓度为10-7mol/L罗丹明6G分子,得到了显著增强的拉曼光谱,证明所制备的Ag纳米颗粒杂化囊泡可用于目标分子的痕量检测.     

油酸囊泡尺度多分散性及二元醇对其pH窗口的影响

以油酸(OA)为模型脂肪酸, 依据目测激光丁达尔现象在pH滴定曲线上划分相区, 确定OA囊泡化pH窗口为8.2~10.1. 利用光学显微镜、 激光共聚焦显微镜和冷冻刻蚀-透射电子显微镜共同表征了OA囊泡的形貌及粒径, 发现体系中微米和亚微米级的多层囊泡以及纳米级的单层囊泡共存, 呈现尺度多分散性. 用不同链长的短链二元醇辅助OA形成囊泡, 结果表明, 短链二元醇有助于脂肪酸囊泡(FAV)的pH窗口拓宽, 拓宽的方向取决于表面氢键作用方式或疏水插入方式. 在酸性条件下二元醇与FAV相互作用后, 在囊泡表面残留的自由羟基越多, 越有助于拓宽其酸性pH窗口.     

天然松香用于制备球型纳米银的研究

以AgNO3为原料,利用天然松香中的还原性物质枞酸还原银氨络离子得到银纳米颗粒,利用油酸等与纳米颗粒的相互作用在表面形成一层保护层来防止纳米颗粒的聚集。并用UV-vis、TEM和XRD对其进行检测和表征。通过控制反应条件,可制得粒度分布较均匀、结晶性能良好的银纳米颗粒。     

石英纳米通道单磷脂囊泡的电阻-脉冲分析方法（英文）

本文报告了用于检测单囊泡及其粒径分析的石英纳米通道电阻-脉冲分析方法.采用圆柱形石英纳米通道可检测粒径为100~300 nm的单磷脂囊泡和直径为170~400 nm的聚苯乙烯纳米颗粒.单囊泡和纳米颗粒的迁移可通过检测各自产生的方波电流脉冲信号,并由此确定颗粒尺寸.结果表明,采用石英纳米通道电阻-脉冲分析方法得到的颗粒/囊泡粒径与采用动态光散射法和扫描电子显微法得到的结果完全一致.这种基于电子的分析方法具有快速简单的特点,所用的自制微传感器廉价耐用.石英通道的应用还可与其它分析方法如电流分析法和荧光显微法联用,以获得生物囊泡及人工囊泡更完全的信息.     

石英纳米通道单磷脂囊泡的电阻-脉冲分析方法

本文报告了用于检测单囊泡及其粒径分析的石英纳米通道电阻-脉冲分析方法. 采用圆柱形石英纳米通道可检测粒径为100~300 nm的单磷脂囊泡和直径为170~400 nm的聚苯乙烯纳米颗粒. 单囊泡和纳米颗粒的迁移可通过检测各自产生的方波电流脉冲信号, 并由此确定颗粒尺寸. 结果表明,采用石英纳米通道电阻-脉冲分析方法得到的颗粒/囊泡粒径与采用动态光散射法和扫描电子显微法得到的结果完全一致. 这种基于电子的分析方法具有快速简单的特点,所用的自制微传感器廉价耐用. 石英通道的应用还可与其它分析方法如电流分析法和荧光显微法联用,以获得生物囊泡及人工囊泡更完全的信息.     

类水滑石诱导囊泡的自发形成

报道了一种新的囊泡合成方法——荷电固体纳米颗粒诱导囊泡的自发形成. 研究发现, 将5.0 g/L带结构正电荷的Mg₃Al类水滑石(HTlc)溶胶和0.02 mol/L由两性表面活性剂十二烷基甜菜碱(C₁₂BE)和阴离子表面活性剂双(2-乙基己基)琥珀酸磺酸钠(AOT)组成的溶液(C₁₂BE与AOT物质的量比为3∶2)混合, 当HTlc溶胶与表面活性剂溶液的体积比在1∶9～4∶6范围内, 在HTlc纳米颗粒的诱导下可自发形成囊泡, 并获得稳定的HTlc-囊泡复合分散体系.     

银纳米颗粒@二氧化硅微球SERS基底的制备

采用溶胶-凝胶技术制备富含巯基的二氧化硅微球,在其表面原位合成银纳米颗粒,将其作为表面增强拉曼散射(Surface-enhanced Raman scattering,SERS)的活性基底材料,重点讨论了银纳米颗粒作为"热点"对SERS性能的影响。银纳米颗粒的原位生成导致微球表面粗糙化,致密的纳米颗粒能够形成更多的热点,分别采用透射电镜、扫描电镜、X射线光电子能谱、Raman等对银纳米颗粒在微球表面生长状况进行了表征。结果表明,微球表面的巯基直接导致银纳米颗粒的生长,并为银纳米颗粒的稳定性提供了还原性环境。     

低代端酯基PAMAM树形分子存在下银纳米颗粒的制备

在低代端酯基PAMAM树形分子(G1.5-COOCH₃)存在时，用氢气还原AgNO₃制备出银纳米颗粒。用透射电子显微镜(TEM)，电子衍射(ED)，紫外-可见吸收光谱(UV-Vis)和红外光谱(FT-IR)对所制备的银纳米颗粒进行了表征。实验结果表明，当用氢气作为还原剂时，以低代树形分子为保护剂，通过优化还原条件，可成功制备尺寸稳定、均一的银纳米颗粒，其粒径为2.9±0.5 nm，且所制备的银纳米颗粒的粒径分布较窄。根据树形分子的理论尺寸与制备的银纳米颗粒的粒径关系，可推断出大多数的银纳米颗粒是由多个树形分子所包围而稳定存在。     

共轭亚油酸与海藻酸钠囊泡化自组装纳米容器及其药物缓释性能

脂肪酸囊泡(FAV)是一类重要的纳米容器,然而其形成pH范围较窄且偏碱性环境,限制了其应用。 本文将共轭亚油酸(CLA)与海藻酸钠(SA)在近中性环境下共同自组装囊泡化纳米容器并提高其膜稳定性。动态激光光散射(DLS)和透射电子显微镜(TEM)结果表明,当SA质量分数为25%~50%时复合体系可在近中性条件下自组装形成50~250 nm尺寸的囊泡化纳米容器,且pH=7.4时随着质量分数增加囊泡化纳米容器直径增大。 根据SA和CLA在中性环境的物种存在形式推测,二者通过氢键作用驱动形成囊泡化纳米容器。 体外模拟释放实验表明,囊泡化纳米容器具有较高包覆率和较优缓释效果,有望应用于药物传输领域。     

胺类分子结构对油酸囊泡pH窗口的影响

基于激光丁达尔效应及浊度测定, 考察了改变二元胺的碳桥长度、 多元胺的氨基多寡、 长链伯胺的碳链长度及季铵化等因素对油酸囊泡pH窗口的影响. 结果表明, 二元胺及多元胺主要导致油酸囊泡的pH窗口向碱性方向拓宽, 而长链伯胺和十二烷基三甲基溴化铵(DTAB)不仅可使油酸囊泡的pH窗口向碱性拓宽, 而且可使油酸在酸性pH区域形成另一个介稳至稳定的新囊泡相. 氨基在不同pH下质子化和脱质子化转换是胺类分子调节油酸囊泡pH窗口的共同驱动力, 疏水作用是长链胺类的又一驱动力, 而静电吸引是季铵盐的另一种特殊驱动力. 分子间相互作用的热力学参数及结合能计算结果表明, 二乙烯三胺为代表的二元胺或多元胺在油酸囊泡表面以氢键或离子-偶极作用等非共价结合为主, 其调节功能弱于长链伯胺及DTAB与油酸的疏水共组装或DTAB与油酸的静电吸引作用.     

高效相转移法制备金属有机溶胶

Organosols of silver and gold nanoparticles stabilized by sodium oleate were prepared with high efficiency by simple phase transfer of their hydrosols to isooctane. Concentrations of sodium oleate and magnesium chloride have crucial effects on the phase transfer efficiency. UV-visible absorption spectroscopy and transmission electron microscopy have been used to characterize the nanoparticles. A possible phase transfer mechanism was proposed based on the anchoring positions of oleate deduced by molecular modeling calculations.     

A simple way of preparing large compound vesicles loaded with and without silver nanoparticles based on polystyrene-block-polyacrylonitrile

By a simple method, large compound vesicles (LCVs) and LCVs with silver nanoparticles (Ag@LCVs) are created from asymmetric polystyrene-block-polyacrylonitrile (PS-b-PAN) and silver precursor. The asymmetric PS-b-PAN is polymerized by sequential reverse atom transfer radical polymerization and atom transfer radical polymerization. Afterwards, by using N,N′-dimethylformamide as solvent and reductant for the silver precursor, LCVs and Ag@LCVs are produced through simple drop casting and evaporation of solution on the substrate. Transmission electron microscope images together with scanning electron microscopy images show that both LCVs and Ag@LCVs are flowerlike and of rough surfaces. Ultraviolet-visible spectrophotometer confirms the formation of Ag nanoparticles (Ag NPs). Specifically, the distribution of Ag NPs in Ag@LCVs is not uniform and they are principally in the center. Otherwise, adherence of simple vesicles and small hybrid nanoparticles of Ag NPs encapsulated within PS-b-PAN are observed. Finally, formation mechanisms for LCVs and Ag@LCVs are discussed.     

Effect of preformed egg phosphatidylcholine vesicles on spontaneous vesiculation of oleate micelles

An addition of oleate micellar solution to two original sizes (180 nm and 50 nm) of preformed vesicles was studied using gel exclusion chromatography, dynamic light scattering and freeze fracture electron microscopy. The effect of molar ratios of phospholipid and oleate on size distribution of newly formed vesicles was investigated by varying molar concentrations of these two components. After adding an equiamount of oleate to 180 nm-preformed vesicles or 50 nm-preformed vesicles, a relatively monodisperse population of newly formed vesicles was detected. For the high amount of oleate addition to two original sizes of preformed vesicles, the results were quite different. New large vesicles and a number of new small vesicles were observed in samples of mixed EggPC/oleate suspension in the presence of preformed vesicles with 180 nm of size, whereas, only some new large vesicles were detected in samples of mixed EggPC/oleate suspension in the presence of preformed vesicles with 50 nm of size. We assumed that the number of new small vesicles, with size close to preformed vesicles, increased in the latter case. The transformation of mixed EggPC/oleate micelles to mixed vesicles was investigated. The results showed that transformation of mixed EggPC/oleate micelles to vesicles was remarkably faster than transformation of mere oleate micelles to vesicles. The above findings suggested that new mixed EggPC/oleate vesicles with small size were presumably formed by partial solubilization.     

A biologically friendly approach for silver nanoparticle formation and their in situ attachment to lecithin vesicles

There has been a keen interest for developing a biologically friendly approach for the preparation of silver nanoparticles for their application reasons. A biocompatible, single step method is established for the preparation of silver nanoparticles in lecithin (Egg phosphatidylcholine)/water systems where lecithin itself acts as a reductant for silver nitrate to form the silver nanoparticles. In another attempt, silver nanoparticles were successfully synthesized inside the lecithin vesicles and were found attached to the bilayers of lecithin vesicles. To the best of our knowledge, this is the first report where a biological surfactant has acted as a mild reducing agent for silver nitrate by itself to form silver nanoparticles.     

Rapid Biosynthesis of Silver Nanoparticles Using Areca Nut (Areca catechu) Extract Under Microwave-Assistance

In this research paper, we report on the rapid synthesis of silver nanoparticles using dried areca nut (Areca catechu). The microwave exposed aqueous areca nut powder when treated with the aqueous silver salt solution yielded irregular shaped silver nanoparticles. The formation and morphology of the nanoparticles are studied using UV–visible spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The X-ray diffraction studies and energy dispersive X-ray analysis indicate that the particles are crystalline in nature. The understanding of capping of biological moiety is derived from Fourier transform infrared spectroscopy and the thermogravimetric analysis. The green chemistry approach for the synthesis of silver nanoparticles is modest, amenable for large scale commercial production. Further the biologically synthesized silver nanoparticles are known for their potential antibacterial activity.     

The synthesis of Cu/plate-like ZnO nanostructures and their self-assembly mechanism

A composite Cu/ZnO nanostructure with Cu nanoparticles supported on ZnO hexagonal nanoplates has been successfully fabricated by a heating approach, using their metal oleate salts as the precursors without any additives. Combined Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and other examination technologies, the structural properties and formation mechanism of as-synthesized Cu/ZnO nanocomposites are studied in detail. The results reveal that the nanostructures are plate-like with uniform shape and size, and Cu nanoparticles exhibit specific (111) plane matching with the (002) facet of ZnO, indicating a surface-induced interaction mechanism. Further characterization demonstrates that copper nanoparticles can be generated by a decomposition/self-reduction route of copper salts, and the oleate ions act as dual roles in the process: reducing and protecting agents. The difference of decomposition temperature between metal oleates also plays important roles in the formation of Cu/ZnO nanostructure. In addition, the catalytic performance of these nanocomposites is evaluated and it can be found that compared with Cu/rod-like ZnO, as-synthesized samples are highly selective for methanol.     

An efficient approach to derive hydroxyl groups on the surface of barium titanate nanoparticles to improve its chemical modification ability

Highly hydroxylated barium titanate (BaTiO(3)) nanoparticles have been prepared via an easy and gentle approach which oxidizes BaTiO(3) nanoparticles using an aqueous solution of hydrogen peroxide (H(2)O(2)). The hydroxylated BaTiO(3) surface reacts with sodium oleate (SOA) to form oleophilic layers that greatly enhance the dispersion of BaTiO(3) nanoparticles in organic solvents such as tetrahydrofuran, toluene, and n-octane. The results of Fourier transform infrared spectroscopy confirmed that the major functional groups on the surface of H(2)O(2)-treated BaTiO(3) nanoparticles are hydroxyl groups which are chemically active, favoring chemical bonding with SOA. The results of transmission electron microscopy of SOA-modified BaTiO(3) nanoparticles suggested that the oleate molecules were bonded to the surfaces of nanoparticles and formed a homogeneous layer having a thickness of about 2 nm. Furthermore, the improved dispersion capability of the modified BaTiO(3) nanoparticles in organic solvents was verified through analytic results of its settling and rheological behaviors.     

维生素E绿色还原法制备银纳米粒子的研究

采用一种绿色还原法制备银纳米粒子,以维生素E为还原剂,淀粉为稳定剂,在液相中还原硫酸银,通过改变溶液的pH值和反应时间,得到不同粒径的黄色银纳米粒子,并分别采用透射电镜、红外光谱、紫外-可见吸收光谱、扫描电镜和电化学方法对银纳米粒子进行表征。结果表明:维生素E在溶液中被氧化生成苯醌,反应得到的银纳米粒子为球形,粒径为8~25 nm;在较强碱性条件下,得到的银纳米粒子尺寸较小,分布较均匀,其平均粒径约为10 nm;不同条件下生成的银溶胶分别在417、411、409、408 nm处出现紫外吸收峰,这些吸收峰均为银纳米粒子的表面共振吸收;生成的银纳米粒子具有很好的电化学性质,并对L-半胱氨酸的电化学反应显示了良好的催化活性。     

A simple method to synthesize triangular silver nanoparticles by light irradiation

We describe a simple method to synthesize triangular silver nanoparticles by photoreducing the silver ions by citrate. A noteworthy difference of the present method as compared with the previous photo-induced methods is that good shape control over the nanoparticles can be realized in the absence of soft templates or polymer directing agents. The formation process of the silver nanoparticles was investigated by UV-vis spectroscopy and transmission electron microscopy (TEM). It was found that the concentration of reactant plays important role in the morphology control of produced silver nanoparticles. As one of the applications of these nanoparticles, they were used as surface-enhanced Raman scattering substrates and 1,4-bis[2-(4-pyridyl)ethenyl]-benzene (BVPP) was used as a Raman probe to evaluate the enhancement ability of the triangular silver nanoparticles.     

Mechanism of growth of colloidal silver nanoparticles stabilized by polyvinyl pyrrolidone in gamma-irradiated silver nitrate solution

Silver nanoparticles were prepared by using polyvinyl pyrrolidone (PVP) as a stabilizer and gamma-irradiation. Transmission electron microscopy (TEM) results showed that both the amount and the molecular weight of PVP in the irradiated solution considerably affect the average size of the silver nanoparticles. The average size of the silver nanoparticles decreases with increasing the amount of PVP in the solution, but increases with increasing its molecular weight. Further, TEM showed that the silver nanoparticles become disassembled into smaller nanoparticles after dilution with distilled water and sonication. Since the processes of dilution and sonication are not expected to result in chemical reactions or to split the silver nanoparticles, we conclude that each silver nanoparticle prepared by [Formula: see text] -irradiation consists of several smaller nanoparticles surrounded by PVP. Thus, based on these observations, we propose a three-step mechanism for the growth of the silver nanoparticles under the conditions considered here. In the first step, the silver ions interact with PVP, then in the second step the silver ions that are exposed to gamma-irradiation are reduced to silver atoms; nearby silver atoms then aggregate at close range. These aggregates are the primary nanoparticles. Finally, these primary nanoparticles coalesce with other nearby primary nanoparticles or interact with PVP to form larger aggregates which are the secondary (final) nanoparticles.