RESEÑAS SOBRE "NANOTECHNOLOGY VOL1, Nº2"
Bueno, con un pelín de retraso, pero aquí os paso una selección de artículos del nº2 del Nanotechnology. Lo tengo en mi despacho por si alguien quiere hojearlo todo.
REVIEW ARTICLE: Inorganic nanotubes and fullerene-like nanoparticles
Although graphite, with its anisotropic two-dimensional lattice, is the stable form of carbon under ambient conditions, on nanometre length scales it forms zero- and one-dimensional structures, namely fullerenes and nanotubes, respectively. This virtue is not limited to carbon and, in recent years, fullerene-like structures and nanotubes have been made from numerous compounds with layered two-dimensional structures. Furthermore, crystalline and polycrystalline nanotubes of pure elements and compounds with quasi-isotropic (three-dimensional) unit cells have also been synthesized, usually by making use of solid templates. These findings open up vast opportunities for the synthesis and study of new kinds of nanostructures with properties that may differ significantly from the corresponding bulk materials.
Parallel patterning of nanoparticles via electrodynamic focusing of charged aerosols
The development of nanodevices that exploit the unique properties of nanoparticles will require high-speed methods for patterning surfaces with nanoparticles over large areas and
with high resolution. Moreover, the technique will need to work with both conducting and non-conducting surfaces. It is reported an ion-induced parallel-focusing approach that
satisfies all requirements. Charged monodisperse aerosol nanoparticles are deposited onto a surface patterned with a photoresist while ions of the same polarity are introduced into
the deposition chamber in the presence of an applied electric field. The ions accumulate on the photoresist, modifying the applied field to produce nanoscopic electrostatic lenses that
focus the nanoparticles onto the exposed parts of the surface. The technique could produce high resolution patterns at high speed on both conducting (p-type silicon) and non-conducting (silica) surfaces.
Mechanochemistry: targeted delivery of single molecules
The use of scanning probe microscopy-based techniques to manipulate single molecules1 and deliver them in a precisely controlled manner to a specific target represents a significant
nanotechnological challenge. The ultimate physical limit in the design and fabrication of organic surfaces can be reached using this approach. Here we show that the atomic force microscope (AFM), which has been used extensively to investigate the stretching of individual molecules, can deliver and immobilize single molecules, one at a time, on a surface. Reactive polymer molecules, attached at one end to an AFM tip, are brought into contact with a modified silicon
substrate to which they become linked by a chemical reaction. When the AFM tip is pulled away from the surface, the resulting mechanical force causes the weakest bond — the one between the tip and polymer — to break. This process transfers the polymer molecule to the substrate where it can be modified by further chemical reactions.
Metal-enhanced fluorescence of colloidal nanocrystals with nanoscale control (Ayy!)
Engineering the spectral properties of fluorophores, such as the enhancement of luminescence intensity, can be achieved through coupling with surface plasmons in metallic nanostructures. This process, referred to as metal-enhanced fluorescence, offers promise for a range of applications, including LEDs, sensor technology, microarrays and single-molecule studies. It becomes even more appealing when applied to colloidal semiconductor nanocrystals, which exhibit size-dependent optical properties, have high photochemical stability, and are characterized by broad excitation spectra and narrow emission bands. Other approaches have relied upon the coupling of fluorophores (typically organic dyes) to random distributions of metallic nanoparticles or nanoscale roughness in metallic films. A highly reproducible
fabrication of ordered arrays of gold nanostructures coupled to CdSe/ZnS nanocrystals dispersed in a polymer blend has been developed. A precise control and a high spatial selectivity of the fluorescence enhancement process is demonstrated.
REVIEW ARTICLE: Inorganic nanotubes and fullerene-like nanoparticles
Although graphite, with its anisotropic two-dimensional lattice, is the stable form of carbon under ambient conditions, on nanometre length scales it forms zero- and one-dimensional structures, namely fullerenes and nanotubes, respectively. This virtue is not limited to carbon and, in recent years, fullerene-like structures and nanotubes have been made from numerous compounds with layered two-dimensional structures. Furthermore, crystalline and polycrystalline nanotubes of pure elements and compounds with quasi-isotropic (three-dimensional) unit cells have also been synthesized, usually by making use of solid templates. These findings open up vast opportunities for the synthesis and study of new kinds of nanostructures with properties that may differ significantly from the corresponding bulk materials.
Parallel patterning of nanoparticles via electrodynamic focusing of charged aerosols
The development of nanodevices that exploit the unique properties of nanoparticles will require high-speed methods for patterning surfaces with nanoparticles over large areas and
with high resolution. Moreover, the technique will need to work with both conducting and non-conducting surfaces. It is reported an ion-induced parallel-focusing approach that
satisfies all requirements. Charged monodisperse aerosol nanoparticles are deposited onto a surface patterned with a photoresist while ions of the same polarity are introduced into
the deposition chamber in the presence of an applied electric field. The ions accumulate on the photoresist, modifying the applied field to produce nanoscopic electrostatic lenses that
focus the nanoparticles onto the exposed parts of the surface. The technique could produce high resolution patterns at high speed on both conducting (p-type silicon) and non-conducting (silica) surfaces.
Mechanochemistry: targeted delivery of single molecules
The use of scanning probe microscopy-based techniques to manipulate single molecules1 and deliver them in a precisely controlled manner to a specific target represents a significant
nanotechnological challenge. The ultimate physical limit in the design and fabrication of organic surfaces can be reached using this approach. Here we show that the atomic force microscope (AFM), which has been used extensively to investigate the stretching of individual molecules, can deliver and immobilize single molecules, one at a time, on a surface. Reactive polymer molecules, attached at one end to an AFM tip, are brought into contact with a modified silicon
substrate to which they become linked by a chemical reaction. When the AFM tip is pulled away from the surface, the resulting mechanical force causes the weakest bond — the one between the tip and polymer — to break. This process transfers the polymer molecule to the substrate where it can be modified by further chemical reactions.
Metal-enhanced fluorescence of colloidal nanocrystals with nanoscale control (Ayy!)
Engineering the spectral properties of fluorophores, such as the enhancement of luminescence intensity, can be achieved through coupling with surface plasmons in metallic nanostructures. This process, referred to as metal-enhanced fluorescence, offers promise for a range of applications, including LEDs, sensor technology, microarrays and single-molecule studies. It becomes even more appealing when applied to colloidal semiconductor nanocrystals, which exhibit size-dependent optical properties, have high photochemical stability, and are characterized by broad excitation spectra and narrow emission bands. Other approaches have relied upon the coupling of fluorophores (typically organic dyes) to random distributions of metallic nanoparticles or nanoscale roughness in metallic films. A highly reproducible
fabrication of ordered arrays of gold nanostructures coupled to CdSe/ZnS nanocrystals dispersed in a polymer blend has been developed. A precise control and a high spatial selectivity of the fluorescence enhancement process is demonstrated.
posted by JUAN at
12:01 a. m.
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