在线性壳聚糖膜内原位还原制备银纳米粒子及银单晶体

采用光还原方法，在线性壳聚糖膜内原位还原获得球形银粒子(粒径10～30 nm)和外观呈三角形、六边形的银单晶体(边长200～2000 nm)；采用电化学方法，在壳聚糖膜内制备了球形银纳米粒子，粒径为5～8 nm.用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、红外光谱(IR)和X射线衍射(XRD)等测试技术对壳聚糖/银复合物进行了表征，对光还原过程中银晶体结构由多晶到单晶的转变原因进行了初步的分析和探讨.     

儿茶素-银纳米复合材料的制备及其应用

探索了以植物活性成分儿茶素作为还原剂和保护剂一步水热法合成儿茶素-银纳米复合材料,并进一步测试了纳米复合材料的抑菌活性。 紫外可见吸收光谱(UV-Vis)和红外光谱(FTIR)测定证明制备得到了儿茶素包裹的银纳米粒子。 透射电子显微镜(TEM)和X射线衍射(XRD)结果显示银纳米粒子的平均粒径为22.7 nm,并具有面心立方晶体结构。 抑菌活性实验结果表明,儿茶素-银纳米复合粒子对大肠杆菌、金黄色葡萄球菌以及白色念球菌都有很强抑制作用,尤其对白色念球菌的抑制作用最强,其最低抑制浓度(MIC)和最低杀菌浓度(MBC)分别为19.63和39.26 μg/mL。 儿茶素-银纳米粒子强抑菌活性可归因于其表面银离子的持续释放,有望应用于长效抑菌制剂产品。     

银纳米粒子的绿色合成及其对荧光素室温磷光的增强效应

以β-环糊精(β-CD)作为稳定剂, 葡萄糖为还原剂, 银氨溶液为前驱体, 实现了绿色化学方法合成银纳米粒子. 利用紫外-可见分光光度法(UV-Vis)、高分辨透射电镜(HRTEM)、红外光谱法(FTIR)对产物进行了表征. 将银纳米粒子引入滤纸表面增强室温磷光(RTP)的研究, 发现银纳米粒子对醋酸铅诱导荧光素(FL)所得的RTP具有明显的增强效应, 并且随着银纳米粒子加入量的增加具有先增强后猝灭的趋势. 对β-CD与银纳米粒子的相互作用机理及银纳米粒子对FL RTP增强效应的作用机理进行了初步讨论.     

血清白蛋白与银纳米粒子相互作用的滞后效应

用透射电子显微镜、圆二色和紫外-可见光谱研究血清白蛋白与银纳米粒子的相互作用及其相关效应. 透射电子显微镜观测到血清白蛋白对银纳米粒子的包覆作用. 表面等离子体共振吸收峰的研究表明, 静电力和亲水力是血清白蛋白与银纳米粒子之间主要的作用力之一; 血清白蛋白对平均粒径为60 nm的银纳米粒子单层包覆比为6.7×10⁵. 拟合计算远紫外圆二色光谱数据发现,银纳米粒子诱导血清白蛋白中α-螺旋含量减少,而β-折叠、转角和无规卷曲等结构含量增加; 血清白蛋白的构象在作用后变得更为松散和伸展. 通过时间扫描吸收光谱跟踪研究发现, 在血清白蛋白与银纳米粒子相互作用的过程中,银纳米粒子的包覆与聚集、血清白蛋白的构象变化具有双重滞后效应,并对此过程的速度常数及热力学参数进行了估算.     

多核核壳结构银胶粒的制备及其抑菌特性

银纳米粒子具有广谱抗菌性,但自身由于具有较高的表面能容易发生团聚.本文以聚醚胺为还原剂和稳定剂,利用光化学还原法,合成了聚乙二醇包覆的银纳米粒子.通过透射电子显微镜分析表明该胶体粒子具有多核核壳结构,聚乙二醇包裹的银纳米颗粒粒径在14 nm左右,整个胶体粒子粒径在45 nm左右.抑菌实验结果表明这种银纳米胶体对大肠杆菌和金黄色葡萄球菌有明显的抑菌效果.     

Preparation and Storage of Silver Nanoparticles in Aqueons Polymers

以水溶性聚合物为保护剂,采用化学还原法制备了银纳米粒子,分别利用透射电子显微镜、紫外可见光谱、同步光散射光谱等手段对其进行了表征,并探索了制备银纳米粒子的最佳实验条件。通过将银纳米粒子-聚合物溶液进行脱水,得到含有银纳米粒子的固态聚合物膜。将固态聚合物膜重新溶解于水,其水溶液的紫外可见光谱与脱水前的溶液进行了比较,发现两者性质并无明显差异。因此,将银纳米粒子分散固定在聚合物膜中是一种崭新而有效的银纳米粒子制备和存储方法。     

银纳米粒子-介孔菱沸石-无纺布复合材料的构建及其止血和抗菌性能分析

以无纺布(NW)为基质,采用原位生长法制备了介孔菱沸石-无纺布(mCHA-NW),再以其为载体,复合银纳米粒子(AgNPs),最终得到银纳米粒子-介孔菱沸石-无纺布(AgNPs-mCHA-NW)复合材料.利用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、X射线光电子能谱仪(XPS)、全自动物理吸附仪(BE...     

邻苯二甲酸和酞嗪对干法制备银纳米粒子形貌的影响

以硬脂酸银为前驱体,采用干式热还原方法制备银纳米粒子,并研究了邻苯二甲酸(Phthalic acid, H₂PA)和酞嗪(Phthalazine,PHZ)对银粒子形貌的影响.结果表明:H₂PA在直接热显影(Thermograhic, TG)模拟体系及光敏热成像(Photothermographic,PTG)体系中均促进颗粒状银纳米粒子的形成,而PHZ在TG模拟体系及PTG体系中分别促进颗粒状银粒子及丝状银的形成.调色剂的添加顺序对显影银形貌有很大影响.调色剂组合及光敏催化剂的协同作用是PTG体系中产生"树枝状"银的关键因素,探讨了不同形貌银纳米粒子的形成机理.     

聚丙烯腈纳米纤维载银复合膜绿色制备及其催化性能

采用静电纺丝技术和化学镀方法相结合的方法,用聚丙烯腈(PAN)纳米纤维作为载体,以绿色环保的胺化改性替代化学镀传统的敏化、活化前处理,再化学镀银制备胺化聚丙烯腈纳米纤维载银复合膜(Ag/APAN).SEM、XPS、XRD、FTIR等结果表明,银离子能够吸附在经胺化处理后的PAN纳米纤维表面,且能够在纤维表面生成少量单质银;单质银作为催化活性中心,有效地促进化学镀银的进行,在PAN纳米纤维表面生成均匀致密的银纳米粒子层,制备出了以PAN纳米纤维为核,银层为壳的核壳结构复合膜.银纳米粒子附着在纳米纤维表面,可以使银纳米粒子的催化性能得到充分发挥.通过对催化邻-硝基苯胺与硼氢化钠之间氧化还原反应的研究表明,所制备的Ag/APAN纳米纤维复合膜具有很好的催化效果,且不会造成反应体系的二次污染.     

牛血红蛋白与银纳米粒子相互作用的光谱研究

运用紫外-可见吸收光谱(UV-Vis)、荧光光谱、同步荧光光谱、圆二色光谱(CD)及傅立叶变换红外光谱(FTIR)等手段, 研究牛血红蛋白(Bovine Hemoglobin, 简称BHb)与银纳米粒子的相互作用. 结果表明, BHb能吸附在银纳米粒子的表面, 使其415 nm处的特征等离子体共振吸收峰强度下降, 峰位红移. 随银纳米粒子的浓度增大, BHb分子中Soret带的吸收持续降低, 说明银纳米粒子可能使部分血红素辅基从它们的键腔中脱离出来. Stern-Volmer方程分析表明, 银纳米粒子静态猝灭BHb的内源荧光. 由UV-Vis和荧光光谱的变化, 计算BHb与银纳米粒子的结合常数, 其数量级达到10⁹～10¹⁰. 同步荧光光谱的蓝移说明, 银纳米粒子扰动BHb分子内部的酪氨酸、色氨酸残基所处的微环境, 使之包埋于疏水腔中. 拟合计算远紫外CD数据发现, 银纳米粒子诱导BHb产生轻微的二级结构改变, α-螺旋含量降低. FTIR光谱结果提示, BHb中半胱氨酸残基的硫、羧基氧、酰胺及氨基酸残基中的氮原子与银纳米粒子可能有表面键合作用.     

以葡聚糖-乙二胺聚合物为载体制备纳米银

以葡聚糖-乙二胺聚合物为载体制备纳米银.首先合成葡聚糖-乙二胺聚合物,并用紫外光谱红外光谱对聚合物进行表征;该聚合物与硝酸银反应生成葡聚糖-乙二胺聚合物-银配合物,再通过化学还原或光化学还原法使配合物中的银离子转变成单质银纳米粒,以透射电子显微镜激光纳米测定仪对制备的纳米银进行测定.结果表明制备出了粒径为23.1nm的纳米单质银.以葡聚糖-乙二胺聚合物为载体制备纳米银的方法是可行的.     

单分散性银纳米粒子的可控制备

以卤化银或氧化银作为前驱体,室温下以水为溶剂,在较高溶液浓度下,利用化学还原法制备了单分散性银纳米粒子,并通过改变前驱体的种类,实现了粒径可控制备。采取扫描电子显微镜（SEM）、紫外-可见光谱仪（UV-Vis）、X射线-粉末衍射仪（XRD）、X射线-光电子能谱仪（XPS）等对所制备的银纳米粒子的形貌及成分进行了表征。结果显示,所制备的银纳米粒子具有较高的单分散性,粒径在40~150 nm之间,具有面心立方多晶结构。该方法制备的银纳米粒子可用于喷墨打印RFID天线。     

Preparation and characterization of silver colloids with different morphologies under ultrasonic field

In the ultrasonic field, stable silver colloids were produced by the reduction of AgNO₃ with the protection of PVP using KBH₄ or N₂H₄·H₂O as reductant. The main factors affecting the morphology of silver nanoparticles, such as distribution of the ultrasonic field, ultrasonic time, ultrasonic power, and the species of reductant, were studied. The silver colloids were identified by TEM and spectrophotometry. The results indicate that the factors such as distribution of the ultrasonic field, ultrasonic time, ultrasonic power, and the species of reductant have a great impact on the morphology of the silver nanoparticles. The size of the silver nanoparticles decreases with the ultrasonic power and ultrasonic time increasing. Ag nanoparticles prepared in standing wave field preferentially grow in a certain direction, which is propitious for forming hexagonal-and spherical-like silver nanoparticles. Monodispersed spherical silver nanoparticles are easily synthesized in the diffusion field. The stability of silver colloid becomes improved by ultrasonic treatment. For example, precipitate is not found after several weeks for the silver colloid prepared with an ultrasonic treatment time of 180 min. The silver nanoparticles prepared without ultrasonic treatment are large spherical-like and hexagonal. Well-dispersed spherical silver particles with a mean size of about 20 nm have been prepared under ultrasonic treatment. Spherical, spherical-like, and hexagonal silver nanoparticles can be obtained by changing the reductants. __________ Translated from Journal of Tianjin University, 2006, 39(1) (in Chinese)     

石墨烯量子点负载银纳米粒子制备及氧还原电催化活性

银基氧还原电催化剂具有较高的电催化活性且价格相对低廉,因而受到广泛关注. 本文采用简单、预先合成的石墨烯量子点作为载体和还原剂,制得了负载于石墨烯量子点、且无保护剂和表面活性剂的表面洁净银纳米粒子（Ag NPs/GQDs）. 电化学研究表明,Ag NPs/GQDs复合电催化剂的氧还原有较高的电催化活性,氧在碱性溶液中可经4电子途径还原为水. 与商业铂碳电极（Pt/C）相比,AgNPs/GQDs电极具有高催化电流密度、良好稳定性和极佳抗甲醇性能. 该银纳米粒子对开发高性能和低成本的非铂氧还原电催化剂有潜在的应用前景.     

Green synthesis of silver nanoparticles using green alga (Chlorella vulgaris) and its application for synthesis of quinolines derivatives

Nanoparticles have been used century ago but have regained their importance in recent years being simple, ecofriendly, pollutant free, nontoxic, low-cost approach, and due good atom economy. In this report, we have demonstrated the synthesis of silver nanoparticles using green algae (Chlorella vulgaris) which in turn was used for synthesis of biologically important quinolines. Algal extract was prepared and treated with silver nitrate solution for the synthesis of silver nanoparticles. Synthesized nanoparticles were characterized with the help of analytical tools like UV, FTIR, X-ray, and SEM and used as a catalyst for the synthesis of quinolines.     

Fabrication of flower-like silver nanoparticles for surface-enhanced Raman scattering

The flower-like silver nanoparticles have been synthesized by reducing silver nitrate (AgNO₃) with ascorbic acid (AA) as the reductant and polyvinyl pyrrolidone (PVP) as the capping agent under vigorous stirring. Such flower-like nanoparticles are aggregates of small nanoplates and nanorods. They were tested as substrates for the surface-enhanced Raman scattering (SERS), showing high sensitivity for detecting Rhodamine 6G (R6G) at a concentration as low as 10^-7 mol/L. It has been found that replacing mechanical stirring with ultrasound sonication would drastically change the particle morphology, from flower-like nanoparticles to well-dispersed smaller nanoparticles. Furthermore, when trace amounts of NaCl were added into the reagents, well-dispersed Ag nanoparticles formed even in vigorous stirring. These phenomena can be explained with the diffusion and reactant supply during nucleation and growth of Ag nanoparticles.     

Molecular recognition of nucleobases and amino acids by sulphonato-calixnaphthalene-capped silver nanoparticles

The plasmon resonances of sulphonato-calixnaphthalene-capped silver nanoparticles have been used to study the complexation of the nanoparticles with nucleobases and amino acids. Only in the case of the nanoparticles capped with oxacalix[4]naphthalenesultone, does complexation of both nucleobases and certain amino acids occur. The complexation of the aromatic amino acids, phenylalanine and tryptophan, has previously not been observed for calixarene-capped silver nanoparticles.     

Structure and morphology of nanocomposite films prepared from polyvinyl alcohol and silver nitrate: Influence of thermal treatment

Hybrid organic/inorganic films have been prepared from an aqueous solution of polyvinyl alcohol (PVA) and silver nitrate (AgNO₃). The silver nanoparticles have been generated in the PVA matrix by thermal treatments. The structure and the morphology of the hybrid films have been studied as a function of the silver precursor concentration and of the annealing conditions for a wide range of annealing temperatures. It was shown that in the uncured hybrid film most of the silver ions were initially coordinated with the polymer OH groups to form a chelate structure. A nanostructuration effect leading to the formation of crystalline silver nanoparticles was evidenced for annealing treatments performed at temperatures higher than 90 °C. For a curing temperature equal to 110 °C, the sizes of the formed nanoparticles were only slightly increasing as a function of annealing time and the effect of AgNO₃ complex amount in this curing condition was also significant, but slight. Annealing at a temperature equal to 160 °C thus at a temperature for which a part of the crystalline phase of PVA was melt led to an important increase of the size of the generated metal nanoparticles. The evolution of the morphology was discussed for each curing temperature as a function of the kinetics of the nanostructuration, of the size of the matrix amorphous lamellae and of the polymer chain mobility. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2657–2672, 2007     

纳米银对表面吸附荧光素的荧光增强和荧光猝灭效应及KCl的荧光猝灭释放效应

制备了两种不同粒径的纳米银溶胶，研究了在水溶液条件下其对表面吸附荧光素(FL)的荧光性能的影响及KCl电解质对该体系荧光性能的影响。FL溶液中加入纳米银，FL分子吸收峰位发生红移。随着纳米银浓度的增加，FL分子荧光先出现增强，而后又逐渐猝灭。粒径较大的纳米银产生最大荧光增强比率所需浓度较低。在纳米银猝灭FL分子荧光的溶液中加入KCl电解质，随着KCl浓度的增加，荧光逐渐增强，出现了荧光猝灭释放效应。研究结果表明，纳米银对表面吸附FL的荧光作用与FL分子附近局域电磁场增强和分子到金属表面无辐射跃迁能量转移过程决定并与纳米银的浓度、尺寸及电解质等密切相关。     

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。