透射电镜三维重构确定金纳米粒子的立体结构

贵金属纳米颗粒具有局域表面等离激元这一特性使其具有丰富的光学性质,而这一特性受制于纳米颗粒所形成的立体几何形状,而透射电镜和扫描电镜的二维图像不能真切地观测和确定纳米颗粒所形成的立体几何结构。透射电镜三维重构技术可作为一种确定纳米颗粒立体结构的直观有效的方法。本文利用透射电镜的三维重构技术,选择合适的参数进行二维图像的采集、图像匹配对中及重构、立体模型的构建,从而通过构建的模型对两种金纳米颗粒样品的不同几何形状所产生的边界形态进行了确认和分析。     

聚合物对还原法合成Pt纳米粒子过程的影响

用H_2还原K_2PtCl_4溶液的方法在常温下合成了Pt纳米粒子，考察了poly(N- isopropylacrylamide)(PNIPA), poly(N-vinylacetamide)(PNVA)和poly (vinylalcohol)(PVA)等三种可溶于水的聚合物对Pt纳米粒子大小和溶胶稳定性的 影响。TEM和溶胶中加入KCl电解质溶液后溶胶稳定性测定结果表明，以PNIPA为稳 定剂可获得粒径最小的Pt粒子，且溶胶最为稳定。较高的PNIPA/Pt~(2+)摩尔比对 合成小颗粒的Pt纳米粒子有利，而聚合物的分子量对粒子影响不大。Pt晶粒在H_2 气氛下生长过程较为缓慢，停止通入还原气体H_26h后，晶粒生长才基本完成，但 溶胶在6个月后仍保持良好的稳定性。     

基于AFM纳米氧化技术的金纳米粒子定点组装

二维纳米粒子矩阵列在纳米电子器件^[1,2]、表面增强喇曼活性基底^[3,4]、刻蚀掩模^[5]等领域具有广泛的应用前景。在这些纳米粒子阵列为内部,纳米粒子的排布是随机、无序的。这一缺点已经妨碍了纳米粒子阵列在上述领域中的进一步应用。基于此,人们开始关注纳米粒子的可控组装。传统的光刻技术^[6]、微接触印刷技术^[7]以及生物分子模板技术^[8]都被用来实现纳米粒子在固体表面上的可控组装,本实验室在纳米粒子的合成及可控组装方面也进行了研究^[7,9,11]。本文力图精确控制单个纳米粒子在基底表面上的组装位置。利用AFM纳米氧化技术。在硅表面构建了纳米级的化学图形化表面,通过不同的化学官能团,如甲基、氨基对金纳米粒子亲和性质的差异,实现了纳米粒子在固体表面的定点组装。     

CO_2激光辐照石墨产生的碳纳米结构

用高分辨透射电子显微镜（HRTEM）检查连续波CO_2激光束（波长10.6 μm, 功率300 W）辐照石墨后发现,不但有通常所见的碳纳米多面体（polyhedrons), 纳米洋葱（onions)和纳米管,而且也罕见的腔内充填大小不等空心洋葱（hollow onions, HOs）的碳纳米袋（nano-bags)。同时,在纳米袋中一些结构相似的碳 HO聚生成为HO团簇。根据这些团簇的排布情况,我们认为这种聚生物有可能是HO结 晶晶格生长的前体（precursor)。     

硅基底金纳米粒子微阵列电极的制备及其电化学性质的研究— 多孔硅电致发光 生物传感器研究的前期探索

用Frens法制备了不同粒径的金纳米粒子,并用透射电镜、紫外可见分光光度法进行了表征。用自组装技术得到了金膜电极表面的金纳米粒子二维阵列电极,用扫描电镜、电化学等方法对该微阵列电极进行了表征。结果表明,当金电极表面被自组装膜完全覆盖后,电化学反应不再发生,而将金纳米粒子组装到膜上以膈,才得到电化学信号。我们认为,金纳米粒子在这里对电荷的跨膜转移有很强的促进作用。对于该过程的研究,用助于理解电荷的转移机制,对进一步理解电荷隧穿过程有一定的指导意义。     

金纳米粒子组装体的连续离散型纳米结构控制

采用柠檬酸钠还原氯金酸的方法,制备出粒径均一的金纳米粒子(AuNPs),通过加入二水合双(对-磺酰苯基)苯基膦化二钾盐(BSPP),增强了AuNPs体系的分散性与稳定性.选用直径为15和40nm的AuNPs,用不同序列巯基修饰的单链DNA连接到其表面,通过DNA链的杂交,形成不同结构的金纳米粒子组装体.通过改变加入DNA延长连接单元的比例,可以控制金纳米粒子组装体具有连续离散型的1∶1,2∶1和3∶1纳米结构.     

金纳米粒子通过形成Au-S键的组装

利用湿化学法以纳米粒子为基本单元构筑各种纳米复合结构,具有灵活简便、通用性强等特点,近年来受到了广泛的重视．Ｎａｔａｎ［１-４］等最先开展了在固体表面上制备金纳米粒子单层膜的研究,他们借助双官能团硅烷化试剂对硅氧化物基底（如玻璃、石英等）进行表面修饰?..     

金纳米粒子组装体系粒子密度与SERS强度的关系

利用纳米粒子组装技术制备出金基底／巯基苯胺自组装膜偶联层／金纳米粒子的“三明治”结构。实验结果显示,该结构对偶联层分子的喇曼光谱显示出很好的增强效应,增强因子可达１０＾５;在表面粒子密度（粒子覆盖度）较低时,表面增强喇曼散射（ＳＥＲＳ）强度与表面粒子密度近似呈线性关系;随着表面粒子密度的增加,这种线性关系出现负偏差并在表面粒子密度较高区域出现一个平台;在６０￣１１０ｎｍ范围内大粒径金粒子对喇曼光谱     

硫化亚锡有序纳米孔道阵列薄膜的制备与表征

以阳极氧化铝为模板,采用两步复型技术首次制备了一种SnS有序纳米孔道阵列薄膜。SEM和TEM测试结果显示此SnS有序多孔薄膜具有几乎均一的、紧密堆积的、直形的纳米孔道阵列结构,孔道直径约200mm,长度约1μm。EDS,XPS和XRD分析结果表明此SnS有序多孔薄膜的SnS骨架具有正交SnS的晶体结构,薄膜中锡与硫的原子比接近化学计量比1:1。     

金纳米粒子组装结构中的表面重组现象

以纳米粒子为基本结构单元构筑的各种二维或三维超晶格结构受到了广泛的重视［１］．人们的兴趣一方面来源于在纳米尺度上控制材料结构 ,另一方面则因为组织化的纳米材料或结构具有独特的性质 ,以期在非线性光学、纳米电子学等前沿领域得到应用［２］．当前研究最多的结构形式是固体表面上的纳米粒子阵列或单层薄膜 ,通常是胶体粒子靠某种特殊相互作用吸附或沉积在固体表面上（亦称为“纳米粒子在表面上的组装［３］”） ,因此对纳米粒子及固体表面进行功能化的修饰 ,从而控制纳米粒子在表面上的排列和聚集状态 ,是制备这类复合结构的核心问…     

电化学沉积法制备金（核）-铜（壳）纳米粒子阵列

以组装在有机分子自组装膜/金基底电极上的Au纳米粒子阵列为电化学沉积模板,制备了金(核)-铜 (壳)纳米粒子阵列.选用巯基十一胺（AUDT）和巯基癸烷（DT）混合自组装膜作为基底电极与Au纳米粒子的耦联层,可以在一定的电位下实现金属Cu在Au纳米粒子上的选择性沉积.将沉积电位控制在－0.03 V（vs SCE）时,沉积初期（t ≤ 15 s,沉积粒子粒径 ≤ 20 nm ）金(核)-铜 (壳)粒子具有良好的单分散性和近似球形,而且粒径实验值同计算值非常吻合.     

Controlled Assembly of Au,Ag, and Pt Nanoparticles with Chitosan

Working on the chain gang : A simple method for the controlled assembly of metal nanoparticles (Au, Ag, and Pt) into 1D chains (see figure) has been developed based on the electrostatic interaction of negatively charged carboxylic groups on the citrate ions surrounding the NPs and the positively charged chitosan polymer.

     

Directed Assembly of Soft Anisotropic Nanoparticles by Colloid Electrospinning

Directed assembly of triblock copolymer worms to produce nanostructured fibers is achieved via colloid electrospinning. These copolymer worms are conveniently prepared by polymerization‐induced self‐assembly in concentrated aqueous dispersion. Addition of a second water‐soluble component, poly(vinyl alcohol), is found to be critical for the production of well‐defined fibers: trial experiments performed using the worms alone produce only spherical microparticles. Transmission electron microscopy studies confirm that the worm morphology survives electrospinning and the worms become orientated parallel to the main axis of the fibers during their generation. The average deviant angle (θ_dev) between the worm orientation and fiber axis decreases from 17° to 9° as the worm/PVA mass ratio increases from 1.15:1 to 5:1, indicating a greater degree of worm alignment within fibers with higher worm contents and smaller fiber diameters. Thus triblock copolymer fibers of ≈300 ± 120 nm diameter can be readily produced that comprise aligned worms on the nanoscale.

     

纳米粒子的不对称修饰与可控组装

控制纳米构筑单元的组装是发展纳米材料和器件的关键问题之一,近年来发展了一系列针对纳米粒子的不对称修饰方法,为可控组装纳米粒子提供了一种新颖而有效的策略。这些方法可以将本身各向同性的纳米粒子修饰成各向异性,使得常见的功能性纳米粒子成为所需的构筑单元。本文旨在结合最近一些创新性的研究成果,介绍并总结纳米粒子不对称修饰的方法以及基于此的可控组装,讨论了当前研究中的主要发展方向和仍需要解决的问题,并对其应用前景做了展望。     

金纳米粒子组装体系SERS化学增强的研究

Gold nanoparticles were assembled on gold substrates with the self-assembled monolayer(SAM) of p-minothiophenol(PATP). AFM measurements disclose that gold nanoparticles are scattered over the surface of the substrate with a submonolayer coverage. The Raman signal of the coupling layer, the SAM of PATP, can be well observed. Potential-dependent measurements were performed to study the chemical enhancement in SERS of such a system. Based on the supposition that the direction of charge transfer is from gold nanoparticles to PATP, it is deduced that Herzberg-Teller contribution has ruled in the SERS of such a system.     

建立在硫醇分子电化学替换组装基础上的纳米粒子区域化组装

利用金基底电位变化时硫醇自组装膜的吸脱附性质, 通过改变基底电位和组装溶液, 用电化学方法在金基底上实现了传统自组装技术难以实现的硫醇分子的替换组装; 通过金基底的分区化设计, 用控制电位的组装技术在基底的不同微区内制备了不同末端官能团的硫醇及其衍生物自组装膜; 并在此基础上实现了纳米粒子的区域化组装.     

单分散磁性纳米颗粒的制备及生物高分子在其上的组装

磁性纳米颗粒因其潜在的生物医学应用价值而成为纳米生物材料领域研究的前沿。本文综述了单分散磁性纳米颗粒的制备方法以及生物高分子在磁性纳米颗粒上的组装的研究进展。     

Amphiphilic Janus Gold Nanoparticles Prepared by Interface‐Directed Self‐Assembly: Synthesis and Self‐Assembly

Materials with Janus structures are attractive for wide applications in materials science. Although extensive efforts in the synthesis of Janus particles have been reported, the synthesis of sub‐10 nm Janus nanoparticles is still challenging. Herein, the synthesis of Janus gold nanoparticles (AuNPs) based on interface‐directed self‐assembly is reported. Polystyrene (PS) colloidal particles with AuNPs on the surface were prepared by interface‐directed self‐assembly, and the colloidal particles were used as templates for the synthesis of Janus AuNPs. To prepare colloidal particles, thiol‐terminated polystyrene (PS‐SH) was dissolved in toluene and citrate‐stabilized AuNPs were dispersed in aqueous solution. Upon mixing the two solutions, PS‐SH chains were grafted to the surface of AuNPs and amphiphilic AuNPs were formed at the liquid–liquid interface. PS colloidal particles decorated with AuNPs on the surfaces were prepared by adding the emulsion to excess methanol. On the surface, AuNPs were partially embedded in the colloidal particles. The outer regions of the AuNPs were exposed to the solution and were functionalized through the grafting of atom‐transfer radical polymerization (ATRP) initiator. Poly[2‐(dimethamino)ethyl methacrylate] (PDMAEMA) on AuNPs were prepared by surface‐initiated ATRP. After centrifugation and dissolving the colloidal particles in tetrahydrofuran (THF), Janus AuNPs with PS and PDMAEMA on two hemispheres were obtained. In acidic pH, Janus AuNPs are amphiphilic and are able to emulsify oil droplets in water; in basic pH, the Janus AuNPs are hydrophobic. In mixtures of THF/methanol at a volume ratio of 1:5, the Janus AuNPs self‐assemble into bilayer structures with collapsed PS in the interiors and solvated PDMAEMA at the exteriors of the structures.     

Surfactant-Assisted Assembly of Dipeptide Forming a Broom-like Structure

Understanding the influence of surfactants on the assembly of peptides has a considerable practical motivation. In this paper, we systematically study the anionic surfactant-assisted assembly of diphenylalanine (FF). FF forms broom-like structures in a concentration of sodium cholate (NaC) around the CMC, and assembles into linear and unidirectional rods in the presence of low and high surfactant concentrations. FF’s improved hydrogen bonding and controlled assembly rates are appropriate for other anionic surfactants. At this stage, the use of FF as the simplest protein consequence can be helpful in the investigation of further protein–surfactant interactions.     

Binary Assembly of Au Nanoparticles with Controllable Two‐dimensional Architecture Directed by Phosphate Backbone Modified Oligonucleotide

A three complementary strand oligonucleotide system was employed to assemble two different‐sized, 15 and 25 nm, Au nanoparticles into binary two‐dimensional (2D) structures. First, two non‐complementary strands of phosphate backbone modified oligonucleotides (PM oligo‐DNA) were loaded on the surface of the 15 and 25 nm Au nanoparticles, respectively. Upon the addition of the third linker DNA, which was half complementary to each of the modified DNA, the Au nanoparticles would be assembled to binary 2D aggregates. The number of the 15 nm Au nanoparticles around a 25 nm Au naoparticle can be readily controlled by the length of the DNA helix used.