Transmission electron microscopy of unstained hybrid Au nanoparticles capped with PPAA (plasma-poly-allylamine): Structure and electron irradiation effects (original) (raw)
Related papers
Micron (Oxford, England : 1993), 2015
High-resolution transmission electron microscopy is used to study interactions between thiol-capped Au clusters and amorphous C support films. The morphologies of the clusters are found to depend both on their size and on the local structure of the underlying C. When the C is amorphous, larger Au clusters are crystalline, while smaller clusters are typically disordered. When the C is graphitic, the Au particles adopt either elongated shapes that maximize their contact with the edge of the C film or planar arrays when they contain few Au atoms. We demonstrate the influence of electron beam irradiation on the structure, shape and stability of the Au clusters, as well as on the formation of holes bounded by terraces of graphitic lamellae in the underlying C.
Electron microscopy of gold nanoparticles at atomic resolution
Science, 2014
Detailed structure of a gold nanoparticle Adding only a few atoms or changing the capping ligand can dramatically change the structure of individual metal nanoparticles. Azubel et al. used aberration-corrected transmission electron microscopy to derive a three-dimensional reconstruction of water-soluble gold nanoparticles. Small-angle x-ray scattering and other techniques have also corroborated this model. They used this to determine the atomic structure, which compared favorably with density functional theory calculations, without assuming any a priori structural knowledge or the use of model fitting. Science , this issue p. 909
Journal of Materials Chemistry, 2009
Glutathione protected Au 25 quantum clusters, exhibiting characteristic fluorescence, have been uniformly coated inside and outside of b-Ala-L-Ile dipeptide nanotubes. These coated structures have been imaged using the inherent fluorescence of Au 25 . Upon exposure to an electron beam, in a transmission electron microscope, the quantum clusters gradually transform to gold nanoparticles, of the metallic size regime. The nanoparticles grow to a size of 4.5 nm and thereafter the particle size is unaffected by electron beam exposure. The nanotubes are intact and this template is shown to control the uniformity of the size of the nanoparticles grown. The quantum clusters can be loaded selectively inside the tubes using capillarity of the nanotubes. The sizes of the nanoparticles grown are tuned using electron beam exposure.
High resolution SEM imaging of gold nanoparticles in cells and tissues
Journal of microscopy, 2014
The growing demand of gold nanoparticles in medical applications increases the need for simple and efficient characterization methods of the interaction between the nanoparticles and biological systems. Due to its nanometre resolution, modern scanning electron microscopy (SEM) offers straightforward visualization of metallic nanoparticles down to a few nanometre size, almost without any special preparation step. However, visualization of biological materials in SEM requires complicated preparation procedure, which is typically finished by metal coating needed to decrease charging artefacts and quick radiation damage of biomaterials in the course of SEM imaging. The finest conductive metal coating available is usually composed of a few nanometre size clusters, which are almost identical to the metal nanoparticles employed in medical applications. Therefore, SEM monitoring of metal nanoparticles within cells and tissues is incompatible with the conventional preparation methods. In thi...
Direct Imaging of Core-shell Structure in Ag-Au Nanoparticles
Microscopy and Microanalysis, 2005
Recent experiments have demonstrated the potential applications of nanoclusters in catalysis, biology, and medicine, in addition to areas such as electronics and optics. These applications all require the creation of stable arrays of clusters that can withstand the relevant operating environment and maintain their useful properties. In the field of chemistry, gold clusters with diameters ranging from 1 to 6 nm have been shown to catalyze the oxidation of carbon monoxide with size-dependent activity, while large silver clusters catalyze the oxidation of ethylene. Many metals have catalytic properties, which raises the question of how combinations of clusters of different size and composition behave in such processes. Moreover, combinations of clusters in a single system could lead to parallel or sequential catalytic processes on a single surface and may open up a host of new cluster applications. The deposition of nanoclusters on a single surface is the subject of continuing development. Here, we demonstrate the deposition of films of different nanoclusters with selected size, composition, and density onto amorphous carbon films.
Structural and morphological peculiarities of hybrid Au/ nanodiamond engineered nanostructures
Nanostructured Au nano-platelets have been synthesized from an Au(III) complex by growth process triggered by nanodiamond (ND). An electroless synthetic route has been used to obtain 2D Au/ND architectures, where individual nanodiamond particles are intimately embedded into face-centered cubic Au platelets. The combined use of high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED), was able to reveal the unusual organization of these hybrid nanoparticles, ascertaining the existence of preferential crystallographic orientations for both nanocrystalline species and highlighting their mutual locations. Detailed information on the sample microstructure have been gathered by fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) of HR-TEM images, allowing us to figure out the role of Au defects, able to anchor ND crystallites and to provide specific sites for heteroepitaxial Au growth. Aggregates constituted by coupled ND and Au, represent interesting systems conjugating the best optoelectronics and plasmonics properties of the two different materials. In order to promote realistically the applications of such outstanding Au/ND materials, the cooperative mechanisms at the basis of material synthesis and their influence on the details of the hybrid nanostructures have to be deeply understood. Nowadays, hybrid nanocrystalline particles, at the basis of many advanced materials for frontier applications in several technological fields ranging from optoelectronics to nanocatalysis and to biomedicine, receive an increasing attention owing to their outstanding properties 1,2. In this context, a key point is represented by the design of hybrid nanostructures and of their production routes. To this purpose, the definition of production protocols, able to control the growth process and innovative crystallization pathways is a primary issue. In fact, in the case of metal/nonmetal hybrid structures, which can be synthesized by both epitaxial 3 and non-epitaxial routes 4–6 , outstanding properties are often related to the coupling of different nano-crystals since a suitable microstructure could induce a synergic behavior able to enhance the intrinsic chemical-physical properties of each constituent. However, being the properties strongly related to the microstructure, an essential requirement for the production of nano-hybrids with enhanced properties is to master the synthetic route in order to control the modulation of the whole structure, mainly as far as uniformity of size, shape, composition, and structure of interfaces are concerned. Several studies have been recently dedicated to the atomic scale characterization of noble metal/Carbon nano-materials. In fact, these hybrid systems are indeed very promising for application in nanophotonics/nanoelec-tronics as well as in nanomedicine/nano-biochemistry 7–16. Moreover, a synergic approach can offer interesting solutions to technological problems related to optical labeling, imaging, molecular loading and biosensing.