纳米发光银簇的合成与应用研究进展EI北大核心CSCD

纳米发光银簇作为一类新型荧光金属纳米材料,具有优异的光物理性质以及良好的生物相容性,在生物传感和生物显像领域受到了越来越多的关注。本文主要以纳米发光银簇为研究对象,围绕纳米发光银簇的不同合成模板、合成方法及其在不同领域的应用进展作一综述。     

银纳米簇在生物成像及生物检测中的研究进展

由于银纳米簇的尺寸接近电子的费米能级,其能级不连续而发生能带分裂。通过与光的相互作用,能级之间发生不连续的电子跃迁,使银纳米簇表现出强烈的荧光性质。银纳米簇凭借其易合成、荧光量子产率高、可调荧光发射波长(从可见光区到近红外区)、光稳定性和生物相容性良好等优势在生物成像及生物检测等领域引起了越来越多的关注。本文结合近年来关于银纳米簇的研究,详述了其在这两方面的以下几个部分的应用研究进展:DNA调控或标记的银纳米簇的生物成像、有其他金属掺杂的银纳米簇的生物成像、以蛋白为模板合成的银纳米簇的生物成像、利用银纳米簇的荧光特性对生物酶、蛋白、肽、氨基酸、基因、DNA、腺苷、细菌以及抗菌活性等的检测,并对银纳米簇的应用所面临的挑战和发展趋势进行了展望。     

纳米发光银簇的合成与应用研究进展

纳米发光银簇作为一类新型荧光金属纳米材料,具有优异的光物理性质以及良好的生物相容性,在生物传感和生物显像领域受到了越来越多的关注。本文主要以纳米发光银簇为研究对象,围绕纳米发光银簇的不同合成模板、合成方法及其在不同领域的应用进展作一综述。     

碱性环境下硫脲协调铬黑T稳定的银纳米簇的制备

银纳米簇因有特殊的物理和化学性质,具有广泛的应用前景和研究价值。由于其易发生团聚,探索制备具有强荧光特性、稳定存在、粒径小的银纳米簇的方法具有重要的意义。本文发展了以铬黑T为稳定剂、硫脲为协调稳定剂,在碱性环境中快速制备银纳米簇的方法。在最优条件下,制备的银纳米簇的平均粒径为1.67 nm,粒径主要分布在0.74~3.33 nm,晶格间距为0.2157 nm,晶格类型为(102)型;具有蓝绿色荧光,其最大激发波长为380 nm,最大发射波长为463 nm,量子产率为1.64%。     

化学还原法制备多形貌银纳米材料

银纳米材料因具有导热导电性能好、光电性能优良及抗菌能力强等优点而引起广泛关注,近年来其制备方法得到广泛研究。已报道的制备方法可分为化学法、物理法和生物法等,其中化学还原法可以通过使用不同的还原剂、包裹试剂及助剂,实现不同形貌及粒径的银纳米材料的快速制备。本文综述了化学还原法制备颗粒状、线形、片状、立方体及其它形貌的银纳米材料的原理及应用,并展望了银纳米材料工业化制备及应用研究的发展趋势。可控制备多形貌银纳米材料对于电子行业、医药生物以及传感器等相关领域的发展具有重要意义。     

紫外光辐照下以PAMAM树形分子为模板制备Ag纳米簇及光致发光性能研究

以G5.0-OH PAMAM树形分子为模板,用紫外光辐照法制备银纳米簇.用透射电子显微镜、紫外-可见吸收光谱和共振散射光谱等对所制备的银纳米簇进行了表征.结果表明:用紫外光辐照法可以制备尺寸分布均匀、稳定的银纳米簇;且辐照时间、PAMAM树形分子的浓度及Ag⁺/PAMAM树形分子的摩尔比都会对所制备的银纳米簇产生较大的影响.由于所制备的银纳米簇的粒径小于树形分子的流体力学半径,表明树形分子起到了“内模板”作用.同时研究了银纳米簇的尺寸对其光致发光性能的影响,发现通过调节银纳米簇的尺寸可实现其光致发光的可调性.     

温敏型铜银荧光纳米簇的绿色制备及细菌成像研究

在温和条件下以D-青霉胺为配体,通过一步法制备出水溶性的具有红色荧光的铜银纳米簇(CuAgNCs),并对其形貌、结构、荧光性能等进行了表征。结果表明,制备得到的纳米簇的量子产率可达9. 6%;在279~355 K温度范围内,该纳米簇的荧光强度与温度之间呈良好的线性关系,荧光强度随着温度的增加而减弱。此外,细胞毒性噻唑蓝(MTT)实验结果表明,合成的Cu-AgNCs显示出低毒性和较好的生物相容性,它们可以渗透大肠杆菌进行细胞成像。采用共聚焦荧光成像方法在293~313 K的生理温度范围内进行细菌体内温度测量,结果表明,制备的Cu-AgNCs有望作为光致发光温度计和生物传感器应用于荧光成像等领域。     

一种新型聚集诱导发光的片状银纳米簇聚集体的合成

具有聚集诱导发光的片状银纳米簇聚集体在生物传感、生物成像等多个领域表现出良好的应用前景。以D-青霉胺(RSH)为配体，在室温下和硝酸银反应，以高产率96%合成了银纳米簇聚集体，并通过红外光谱、X-射线光电子能谱、热重分析、质谱、X-射线衍射、扫描电镜和透射电镜对其结构进行了表征。结果表明：银纳米簇聚集体是银纳米簇通过氢键网络连接形成的微米尺度的片状结构，化学组成是(AgSR)_n。紫外可见吸收光谱和发光光谱研究发现，银纳米簇聚集体最大吸收波长在253 nm,最大发射波长在564 nm;在相同浓度下，银纳米簇聚集体的水溶液不发光，但随着乙醇体积分数的增加，发光逐渐增强，显示出聚集诱导发光行为。     

淀粉功能化Fe_3O_4纳米簇球的制备与表征

以淀粉为表面活性剂,利用乙二醇溶剂热法一步制备了Fe3O4纳米簇球.采用X射线衍射仪、傅立叶变换红外光谱仪、扫描电镜等分析了产物的结构;采用热重分析仪测定了其热稳定性.结果表明:所得产物为直径约为230nm的簇球结构,构成簇球的纳米粒子直径约为10nm;引入淀粉成功地改善了产物的纳米结构和表面性能.合成的Fe3O4纳米簇球具有独特的结构和表面性能,在生物领域具有潜在的应用前景.     

多彩金纳米簇:从结构到生物传感和成像

金纳米簇是一种具有发光性能的“类分子”新兴纳米材料。通过调控金原子数目和配体组成性质,金纳米簇可以实现同激发光下不同波段发射,从而展现出“五彩缤纷”的发光特性,这使其被广泛应用于光催化、光学器件、传感和成像等多个领域。因此,开发和优化具有优异发光性能的金纳米簇一直是化学、材料和生物学科的研究热点。本文立足于金纳米簇的发光色彩,根据不同发光颜色总结了相应金纳米簇的合成原理和方法,并对影响金纳米簇发光性能的因素进行了探究。同时,也总结了近年来这些“多彩”金纳米簇在生物传感和生物成像方向的应用,并对金纳米簇发展面临的挑战及发展的趋势分别进行了探讨和展望。     

银/聚合物纳米复合材料

银/聚合物纳米复合材料是一种典型的聚合物基复合材料, 其结构和性能依赖于合成方法,因此开发材料的优异性能必须以深入研究纳米材料的先进合成技术为前提。本文综述了纳米银粒子及其与聚合物形成的纳米复合材料的最新合成进展, 重点介绍了基于液相化学还原方法合成纳米银粒子的新方法, 如溶胶-凝胶法、沉淀法、微乳液法和离子液体法, 以及纳米银粒子的分散技术和原位法合成银/聚合物纳米复合材料的新技术, 并介绍了纳米银复合材料的电绝缘性、表面增强拉曼散射性能、抗菌性及其在生物医学等领域中的应用。     

Silica-metal core-shell nanostructures

Silica-metal nanostructures consisting of silica cores and metal nanoshells attract a lot of attention because of their unique properties and potential applications ranging from catalysis and biosensing to optical devices and medicine. The important feature of these nanostructures is the possibility of controlling their properties by the variation of their geometry, shell morphology and shell material. This review is devoted to silica-noble metal core-shell nanostructures; specifically, it outlines the main methods used for the preparation and surface modification of silica particles and presents the major strategies for the formation of metal nanoshells on the modified silica particles. A special emphasis is given to the St?ber method, which is relatively simple, effective and well verified for the synthesis of large and highly uniform silica particles (with diameters from 100 nm to a few microns). Next, the surface chemistry of these particles is discussed with a special focus on the attachment of specific organic groups such as aminopropyl or mercaptopropyl groups, which interact strongly with metal species. Finally, the synthesis, characterization and application of various silica-metal core-shell nanostructures are reviewed, especially in relation to the siliceous cores with gold or silver nanoshells. Nowadays, gold is most often used metal for the formation of nanoshells due to its beneficial properties for many applications. However, other metals such as silver, platinum, palladium, nickel and copper were also used for fabrication of core-shell nanostructures. Silica-metal nanostructures can be prepared using various methods, for instance, (i) growth of metal nanoshells on the siliceous cores with deposited metal nanoparticles, (ii) reduction of metal species accompanied by precipitation of metal nanoparticles on the modified silica cores, and (iii) formation of metal nanoshells under ultrasonic conditions. A special emphasis is given to the seed-mediated growth, where metal nanoshells are formed on the modified silica cores with deposited metal nanoparticles. This strategy assures a good control of the nanoshell thickness as well as its surface properties.     

Silver cluster-biomolecule hybrids: from basics towards sensors

We focus on the functional role of small silver clusters in model hybrid systems involving peptides in the context of a new generation of nanostructured materials for biosensing. The optical properties of hybrids in the gas phase and at support will be addressed with the aim to bridge fundamental and application aspects. We show that extension and enhancement of absorption of peptides can be achieved by small silver clusters due to the interaction of intense intracluster excitations with the π-π* excitations of chromophoric aminoacids. Moreover, we demonstrate that the binding of a peptide to a supported silver cluster can be detected by the optical fingerprint. This illustrates that supported silver clusters can serve as building blocks for biosensing materials. Moreover, the clusters can be used simultaneously to immobilize biomolecules and to increase the sensitivity of detection, thus replacing the standard use of organic dyes and providing label-free detection. Complementary to that, we show that protected silver clusters containing a cluster core and a shell liganded by thiolates exhibit absorption properties with intense transitions in the visible regime which are also suitable for biosensing applications.     

Paper surfaces functionalized by nanoparticles

Nanomaterials with unique electronic, optical and catalytic properties have recently been at the forefront of research due to their tremendous range of applications. Taking gold, silver and titania nanoparticles as examples, we have reviewed the current research works on paper functionalized by these nanoparticles. The functionalization of paper with only a very small concentration of nanoparticles is able to produce devices with excellent photocatalytic, antibacterial, anti-counterfeiting, Surface Enhanced Raman Scattering (SERS) and Surface Plasmon Resonance (SPR) performances. This review presents a brief overview of the properties of gold, silver and titania nanoparticles which contribute to the major applications of nanoparticles-functionalized paper. Different preparation methods of the nanoparticles-functionalized paper are reviewed, focusing on their ability to control the morphology and structure of paper as well as the spatial location and adsorption state of nanoparticles which are critical in achieving their optimum applications. In addition, main applications of the nanoparticles-functionalized papers are highlighted and their critical challenges are discussed, followed by perspectives on the future direction in this research field. Whilst a few studies to date have characterized the distribution of nanoparticles on paper substrates, none have yet optimized paper as a nanoparticles' substrate. There remains a strong need to improve understanding on the optimum adsorption state of nanoparticles on paper and the heterogeneity effects of paper on the properties of these nanoparticles.     

pH调控的变色酸2R稳定的银纳米簇的合成

银纳米簇(Ag NCs)具有特殊的物理和化学性质,其具有广泛的应用前景和研究价值。 本文探索了以变色酸2R为稳定剂,经过两次pH调节构建一种快速制备具有强荧光特性、稳定存在且粒径小的Ag NCs的方法。 在最优实验条件下,运用该方法制备得到的Ag NCs的最大发射波长为450 nm,最大激发波长为336 nm,平均粒径为1.74 nm,主要粒经分布在0.68~2.99 nm区域内,该Ag NCs的晶格间距为0.223 nm,晶格类型为(102)。 该Ag NCs可作为探针应用于溶液中微量重金属离子和非金属离子的测定,小分子、弱酸溶液浓度等方面的检测,也可以用于细胞成像等方面。     

Electronic properties of the silver-silver chloride cluster interface

The objective of this study was to gain insight into the electronic structure of silver-silver chloride cluster composites and especially into the metal-semiconductor interface. For this purpose a theoretical study of (AgCl)(n) (n=4, 32, 108, 192, and 256), of Ag(m) (m=1-9, 30, 115, 276, and 409), and of the cluster composites Ag(115)-(AgCl)(192) and Ag(409)-(AgCl)(192) has been carried out. Density of levels (DOL), local density of levels (l-DOL), and projection of surface states, as well as projection of properties of individual atoms or groups of atoms obtained in molecular orbital calculations, are shown to be powerful tools for gaining deep insight into the properties of these large systems. The Ag(115)-(AgCl)(192) aggregate, consisting of a cubic Ag(115) cluster without corner atoms on top of a cubic (AgCl)(192) cluster, was found to be remarkably stable with a cluster-to-cluster distance of about 280 pm, and a geometry in which the number of bonding interactions between the silver atoms of Ag(115) and the chloride ions of (AgCl)(192) is at its maximum. A sharp jump in charge distribution occurs at the Ag(115)-(AgCl)(192) composite interface. The first AgCl slab picks up negative charge from the two adjacent silver slabs, so that in total the silver cluster is positively charged. In addition, the core of the silver cluster is positively charged with respect to its outermost layer. The main reason for the charge transfer from the silver cluster to the silver chloride is the newly formed MIGS (metal induced gap states) in the energy-gap range of the silver chloride and the MIdS (metal induced d states) in the d-orbital region. Their wave functions mix with orbitals of the silver cluster and with both the orbitals of the silver and the chloride ions of the silver chloride. The MIGS and the MIdS are of a quite localized nature. In them, nearest neighbor interactions dominate, with the exception of close-lying silver chloride surface states-which mix in to a large extent. We conclude that especially the MIGS not only influence the photochemical properties of silver chloride, but that their existence might be probed by appropriate spectroscopic measurements.     

Quantum chemical investigations of the latent image formation

Having studied free silver clusters by quantum chemical calculations we now present a method to take into account the influence of a silver halide surface on adsorbed silver clusters. The model for the surface will be a silver halide cluster as frozen crystal section. The interactions are discussed in detail; a new bromide pseudopotential may be of special interest. Results with this method will be given in subsequent papers.     

Generation of large gas-phase silver cluster ions by laser desorption/ionization of silver-containing salts

This work is the first to demonstrate the direct generation of large silver cluster ions through laser desorption/ionization of silver-containing salts without the assistance of a molecular beam. Both positively and negatively charged silver clusters up to 100-mer have been produced using this approach. It was observed that the silver cluster distributions produced by this method are similar to those produced using the beam-based approaches, namely there are two special features in the mass spectra. The first is that the cluster intensity distribution displays an odd–even alternation pattern. The second is a steep decrease of ion intensities after some clusters called ‘magic numbers'.     

Effects of silver nanoparticles on seed germination and seedling growth: A review

The advancement in nanotechnology, nanoparticles are reported to have applications in various fields. Their positive role in the environment, especially in plant ecosystem, is extensively studied nowadays. Among the metal nanoparticles, the silver nanoparticles (AgNPs) are receiving special attention because of their ability to increase the growth and yield in many crops. Although many studies are found that shows the toxic effects of AgNPs, the perspective of the present review is to collect the information about their positive roles in growth and yield enhancement of crops. During this overview, there are many methods of synthesizing silver AgNPs nanoparticles discussed, including chemical, bacterial-induced, fungal-derived and plant-mediated synthesis. There are numerous approaches towards the synthesis of AgNPs, including biological and chemical methods. Because of the use of reducing agents such as sodium borohydride in the synthesis of AgNPs, conventional methods have opened a path that threatens environmental sustainability. The chemical synthesis of silver colloids is the consequence of increased aggregation as storage time increases. AgNPs possess unique properties which has many applications such as antimicrobial and anticancer activities. It was concluded that cautious and sensible use of nanotechnology can warrant food security through boosting agricultural production. This review is aimed at providing an insight into the syntheses of AgNPs, its significant applications in various fields, and characterization techniques involved.     

多金属氧酸盐及其溶液自聚集行为研究进展

多金属氧酸盐(POM)是一类由过渡金属与氧原子桥连而成的阴离子簇合物,由于其特殊的分子结构及优异的物理化学性质,使其在催化、医药、材料科学、表面化学、超分子化学等领域有广泛的应用价值。 POM在稀的水溶液中能够发生自聚集,形成类似两亲分子溶液中的“有序聚集体结构”,赋予其新的结构和性质,以期开发出新型纳米器件及在催化、药物等领域得到应用。 本文介绍了POM的主要结构、性质和近年来的应用,阐述了其在溶液中自聚集行为的研究状况和新进展。