金纳米粒子组装体系的表面增强拉曼光谱特性研究——表面粒子密度与拉曼光谱强度的关系

利用纳米粒子组装制备了金基底———巯基苯胺自组装膜偶联层———金纳米粒子的“三明治”结构,研究了表面粒子密度与偶连层分子的拉曼光谱强度的关系。实验结果显示,该结构对偶连层分子的拉曼光谱有很好的增强效应,增强因子可达１０５。在表面粒子密度较低时,拉曼光谱强度与表面粒子密度曲线呈线形,随着表面粒子密度的增加,曲线出现负偏差并在粒子密度较高区域出现一个平台。     

金纳米粒子组装体系的表面增强拉曼光谱特性研究：表面粒子密度与？…

利用纳米粒子组装制备了金基底－－巯基苯胺自组装膜偶联层－－金纳米粒子的“三明治”结构,研究了表面粒子粒子密度与偶连层分子的拉曼光谱强度的关系。结果 偶连层分子的拉曼光谱有很好的增强效应,增强因子可达１０＾５。在表面粒子密度较低时,拉曼光谱强讧民表面粒子密度曲线呈线形,随着表面粒子密度的增加,曲线出现偏差并在粒子密度较高区域出现一个平台。     

偶联分子对金纳米粒子在玻片上组装的影响

将金纳米粒子组装在用3-氨基丙基-三乙氧基硅烷(APES)修饰的普通玻片上,再分别用偶联分子对巯基苯胺、1,4-二巯基苯在该基底上再次组装金纳米粒子,结果表明用对巯基苯胺作为组装的偶联分子得到双层金纳米粒子结构,对巯基苯胺的表面增强拉曼光谱信号得到增强,而用1,4-二巯基苯作为组装的偶联分子得到单层金纳米粒子结构。     

DNA诱导金纳米粒子自组装及其SERS表征

首先将巯基DNA分子与金纳米粒子偶联,并用琼脂糖凝胶电泳分离出含不同DNA分子数目的金纳米粒子,最后将修饰有互补DNA链的Au纳米粒子进行组装,得到组装体(五聚体)。透射电子显微镜(TEM)研究表明,DNA-Au纳米组装体被成功地获得;表面增强拉曼光谱(SERS)研究表明,与未组装的金纳米粒子相比,DNA-Au纳米组装体具有更强的SERS活性。     

金纳米粒子自组装薄膜的光谱学研究

采用柠檬酸钠还原氯金酸制备了金胶体，通过静电自组装制备了金纳米粒子薄膜，利用紫外-可见光吸收光谱等对金纳米粒子薄膜进行了光谱学研究，紫外-可见光吸收光谱表明所制备的金溶胶为单分散体系，根据自组装薄膜的X-射线衍射谱，由谢乐公式估算金纳米粒子的粒径约为21nm；X-射线光电子能谱显示氯金酸的还原反应比较完全，金主要以Au^0的价态存在，金胶体粒子通过静电吸引机制组装到PDDA改性的衬底表面；紫外-可见光吸收光谱和表面增强拉曼光谱显示，由于粒子间的电磁耦合，自组装金纳米粒子薄膜表现出协同等离子体共振吸收行为和表面增强拉曼散射效应。     

微波合成银包覆金纳米粒子膜的拉曼散射活性研究

采用微波加热加压法和静电吸附自组装法在石英玻璃表面制备了银包覆金纳米粒子薄膜,利用原子力显微镜分析了薄膜的表面形态和结构,测定结晶紫分子在薄膜表面的拉曼光谱。结果表明,银包覆金纳米粒子薄膜具有很强的表面增强拉曼散射效应(SERS)活性和稳定性。     

金银纳米粒子的电化学性质及联苯胺的SERS研究

采用柠檬酸钠还原氯金酸,硼氢化钠还原硝酸银分别制备了较小粒径的金、银纳米粒子.运用紫外可见吸收光谱(UV-Vis)、扫描电子显微镜(SEM)、循环伏安法(CV)对金、银纳米粒子进行了表征.结果表明:所得金、银纳米粒子粒径分别约为16和10 nm,并能以亚单层形式组装于导电玻璃(ITO)表面;CV图显示金、银纳米粒子分别有一对不对称的氧化还原峰,而且纳米粒子的浓度对其氧化还原电位存在一定的影响.采用自组装方法,以联苯胺为偶联分子,在粗糙金基底表面构筑了金/银纳米粒子的双层有序结构.表面增强拉曼光谱研究表明,在有序金银纳米粒子组装体中偶联分子的拉曼散射得到了增强.     

不同形貌金纳米粒子的制备及其表面增强拉曼散射效应的研究

不同形状的金纳米粒子在表面增强拉曼散射(surface enhanced Raman scattering,SERS)中有不同的增强效果,多面体金纳米粒子具有多角结构,显示出比金纳米板更为明显的增强效果,近年来对其合成和性质的研究备受关注。该研究探究了十二面体,二十面体,三角板,球形四种形状的金纳米粒子在SERS中不同的增强效果。分别采用硼氢化钠还原法和以N,N-二甲基甲酰胺(DMF)为还原剂制备金三角纳米片和二十面体金纳米粒子,又以二十面体金纳米粒子为种子制备出十二面体金纳米粒子,并分别以以上三种不同形貌的金纳米粒子及球形金溶胶为基底,4-巯基吡啶,对巯基苯甲酸为探针分子检测了其在不同激发波长下的增强效果。透射电子显微镜结果表明金三角纳米板的平均边长为130nm,二十面体和十二面体金纳米粒子的粒径分别为100和120nm。三者的紫外可见吸收峰分别在589,598和544nm处。表面增强拉曼散射结果表明金多面体比金三角纳米板表现出更好的增强效果。     

银纳米粒子自组装复合LB膜的结构与性质

纳米粒子的自组装和有序组装膜的结构与性质近年来受到了人们的广泛关注,纳米粒子的表面结构与性质对由其组装成的有序膜的结构与性质有直接的影响。文章报道了利用自组装技术制备的银纳米粒子与双亲有机分子的单层和多层复合LB膜,通过吸收光谱和表面增强拉曼光谱研究了银纳米粒子与吸附分子间的相互作用,探讨了复合膜的成膜特性及银纳米粒子的拉曼增强特性。十八胺／银粒子复合LB膜的吸收光谱及拉曼光谱显示,十八胺分子与银纳米粒子表面的活位通过NH2中的氮原子以复合体的形式结合;同时,在激发光的作用下复合体可能存在光催化过程。根据银粒子复合LB膜的实验结果,十八胺和十八酸之间的反应产物在复合膜中起空间位阻作用,与银粒子表面的相互作用较弱。     

溶液酸碱性对金纳米粒子在端基功能化单分子膜表面组装影响的SERS光谱研究

在4,4’-二硫联吡啶在Au表面形成自组装单分子层膜的基础上,采用表面增强拉曼散射光谱(SERS)研究了在不同pH值条件下金纳米粒子在4,4’-二硫联吡啶自组装单分子膜/Au体系表面的组装。研究结果表明,由于处于单分子膜表面的吡啶环中氮原子的质子化程度随溶液环境中pH值的变化而变化,使得金纳米粒子与单分子膜表面间的结合作用程度不同,由此会引起金纳米粒子在单分子膜表面的覆盖度存在差异,并最终导致所观测到的4-巯基吡啶自组装单分子膜的SERS光谱强度存在明显的差异。而且,令人感兴趣的是,所观测到的SERS谱峰强度随金纳米粒子组装时pH值的变化呈现出明显的规律性。结合分子结构特征的分析,初步阐明了SERS谱峰强度随pH值这一组装条件的改变而发生规律性变化的内在原因。     

Surface enhanced Raman spectroscopic readout on heavy metal ions based on surface self assembly

A new method is reported for detecting heavy metal ions by using the self assembled monolayer (SAM) technique and surface enhanced Raman spectroscopy (SERS). The p‐mercaptobenzoic acid (MBA) served as the SERS readout molecule and the modified tag to attach on the smooth gold substrate as well as the tag of nanoparticles by the SAM method. Two carboxyl groups from MBA molecules which were attached respectively to gold substrate and gold nanoparticles were linked through the heavy metal ions (Cu²⁺, Pb²⁺ and Zn²⁺) as bridge, and thus sandwich structure of ‘MBA modified gold substrate/heavy metal ions/MBA modified gold nanoparticles’ was built for detection. The observation of the oxidation peak of metal nanoparticles from cyclic voltammetry (CV) curve, gold nanoparticles from scanning electron microscopy (SEM) images and SERS signal of MBA from the sandwich structure indicated the existence of heavy metal ions. The difference in the wavenumbers of vibrational modes from MBA in the sandwich structure constructed by different could be used to identify different heavy metal ions. The assembled structure was rinsed by strong chelator of EDTA solution to remove the heavy metal ions from the sandwich structure and thus to obtain a fresh gold substrate modified with MBA for the cyclic detection. Copyright © 2007 John Wiley & Sons, Ltd.     

琼脂糖凝胶/纳米金复合结构的制备及其表面增强拉曼性质

以琼脂糖凝胶为模板,将预先制备好的胶体金颗粒负载在琼脂糖凝胶的网状结构中,制备了琼脂糖凝胶/纳米金复合膜结构,采用透射电子显微镜、扫描电子显微镜、紫外-可见-近红外光谱仪对复合膜的结构和光学性质进行了表征,实验数据表明纳米金颗粒均匀的分散在琼脂糖凝胶膜上,并且呈现出优异的光学吸收特性。基于琼脂糖凝胶的溶胀收缩特性和纳米金颗粒可调的表面等离子体共振吸收特性,将琼脂糖凝胶/纳米金复合膜作为表面增强拉曼(SERS)基底材料,研究了其对拉曼信号分子尼罗蓝A(NBA)的SERS检测效果。结果表明,琼脂糖凝胶的多孔网状结构为纳米金颗粒的富集提供了良好的载体,随着琼脂糖凝胶在空气中失水收缩,纳米金颗粒间距离逐渐缩短,产生动态的热点效应,对拉曼信号分子具有良好的增强效应。     

桑色素修饰金纳米粒子自组装膜的制备及其性能研究

采用水相硅烷化方法,将γ-氨基丙基三乙氧基硅烷[H₂N(CH₂)₃Si(OC₂H₅)₃](APES)组装在石英表面,在基底表面修饰上氨基为末端的单层膜,并进一步在这种功能化的单层膜基底上组装金纳米粒子得到金纳米粒子/APES/石英的纳米复合结构。以制备的金纳米粒子自组装膜修饰石英为基底及DL-半胱胺酸为中介,利用桑色素(Morin)和DL-半胱胺酸的化学吸附作用,将桑色素间接组装在金纳米粒子自组装膜修饰石英基底表面,所构建的桑色素修饰金纳米粒子自组装膜对三苯基锡有灵敏的荧光识别作用。文章着重研究了桑色素修饰金纳米粒子自组装膜的制备以及组装条件对其荧光行为的影响,探讨了膜的响应特性及响应机理。     

Sensitive surface-enhanced Raman scattering substrates based on anti-pyramidal gold architectures decorated with silver nanoparticles

Abstract

A micro-structured gold surface, consisting of a periodic square–based anti–pyramidal array (Klarite) with a smooth boundary surface on which silver nanoparticles (diameter: 60?nm) were deposited, produced an active surface enhanced Raman scattering substrate. With p-aminothiophenol as a probe molecule, the Raman activity of the micro–structured surface was compared before and after deposition of the silver nanoparticles. Experimental results show that the Raman spectra on the silver/p-aminothiophenol/Klarite structure is stronger than that on the silver/p-aminothiophenol/gold film and the Raman spectra on the silver/p-aminothiophenol/gold film is stronger than that on silver/p-aminothiophenol, p-aminothiophenol/Klarite structure, p-aminothiophenol/gold film, which is confirmed by numerical simulations. A similar result is obtained with crystal violet as test molecule.     

Surface enhanced Raman scattering of molecules related to highly ordered gold cavities

We presented a controlled particles‐in‐cavity (PIC) pattern for surface‐enhanced Raman scattering (SERS) detection. The periodic gold cavity array was fabricated by electrodeposition using highly ordered polystyrene spheres as a template. The as‐prepared gold cavities can be used as a SERS active substrate with significant spectral enhancement and reproducibility, which was evaluated by SERS signals using 4‐mercaptobenzoic acid (4‐MBA) as probe molecules. The surface of these gold cavities was further functionalized with cetyltrimethylammonium bromide molecules, which may immobilize the 4‐MBA‐modified silver nanoparticles in the gold cavity to form a PIC structure via the electrostatic interaction. We have demonstrated that there exists a pH window for the immobilization of the nanoparticles inside cavities. Therefore, the silver nanoparticles can be selectively immobilized into the functionalized gold cavities under the optimized pH value of the media. Further enhancement of the Raman scattering of the labeled molecules can be achieved due to the interconnection between the silver nanoparticles and gold cavity. Copyright © 2013 John Wiley & Sons, Ltd.     

Raman spectroscopy of combinatory anticancer drug release from gold nanoparticles inside a single leukemia cell

Combinatory anticancer drug release from gold nanoparticles (AuNPs) in K562 human myeloid leukemia cells was performed using Raman spectroscopy. We fabricated the anticancer drug of imatinib as a BCR‐ABL tyrosine kinase inhibitor on AuNP surfaces along with a transferrin (Tf)‐targeting moiety to treat the leukemia cells. DNA topoisomerase I inhibitor topotecan was also assembled to monitor its fluorescence onto AuNPs. The linker group of 4‐carboxylic benzoic acid was used to conjugate to targeting the Tf protein. Our Raman data indicated that the drug molecules were not detached in the cell culture media but released after treatment with glutathione (2 mM). Intracellular distribution and release of the anticancer drug–AuNP conjugates in K562 cells were examined by both fluorescence microscopy and dark‐field microscopy with surface‐enhanced Raman scattering. Copyright © 2013 John Wiley & Sons, Ltd.     

Gold nanoparticles produced by laser ablation in water and in graphene oxide suspension

The comparison between two different approaches based on the use of the laser ablation in medium to synthetise gold nanoparticles is presented and discussed. Deionised water as well as a graphene oxide (GO) suspension in deionised water have been employed as solution to produce gold nanoparticles by laser ablation. In the former case, the nanoparticles assembly has been stabilised by using surfactants, but in the latter case to avoid undesired effects the use of chemicals was not necessary and Au reduced graphene oxide (Au-rGO) nanocomposites have been obtained. The structure, size and composition of the gold nanoparticles and of the Au–rGO nanocomposites have been monitored by UV–Vis–NIR absorption spectroscopy and Raman spectroscopy, the transmission and scanning electron microscopies and the X-ray energy-dispersive spectroscopy. The presented methodology of Au rGO nanocomposites preparation could represent a green alternative on the production of metallic nanoparticles in biocompatible environment.