Search results for "NANOSTRUCTURE"
showing 10 items of 792 documents
Orientation of Polymer Functionalized Nanorods in Thin Films
2010
A directed self assembly of anisotropic nanostructures offers a possibility to provide unique functional materials, which are e.g., important in optoelectronic devices. We use the liquid crystalline behavior of polymer functionalized TiO2 and ZnO nanorods to apply methods well known for low molecular liquid crystals to achieve oriented thin films. Convective forces in the meniscus on a structured substrate obtain thin layers of oriented nanoparticles with a ordering parameter of S = 0.7. As another method we present the orientation of polystyrene covered ZnO nanorods under an applied electric field. The method offers a perpendicular alignment of the rods to the surface.
Dielectrophoresis as a tool for nanoscale DNA manipulation
2005
The use of the dielectrophoresis as a tool for DNA manipulation is demonstrated experimentally, using both unmodified 48,500 base pairs long bacteriophage lambda dsDNA (λ-DNA), ∼16 μm in length and 414 base pairs long thiol modified natural dsDNA (avDNA), ∼140 nm in length. We show that both the dsDNA types used, are effectively directed between the planar gold electrodes by the positive dielectrophoresis while applying an AC voltage at frequencies between 500 kHz and 1 MHz. With high concentrations of dsDNA in buffer the attached dsDNA molecules are shown to form bundles or clumps (both λ-DNA and avDNA). Furthermore, we demonstrate the attaching of a single avDNA molecule to an electrode v…
Racemic and Optically Pure Heptahelicene-2-carboxylic Acid: Its Synthesis and Self-Assembly into Nanowire-Like Aggregates
2010
Heptahelicene-2-carboxylic acid was effectively synthesised from suitably functionalised naphthalene building blocks. Methoxy-substituted 1,1'-ethyne-1,2-diylbis(2-but-3-yn-1-ylnaphthalene) was cyclised in the presence of CpCo(CO)(2)/PPh(3) to 2-methoxy-7,8,11,12-tetrahydroheptahelicene, which was converted into heptahelicen-2-yl trifluoromethanesulfonate. This reactive intermediate underwent Pd(OAc)(2)/dppp-catalysed methoxycarbonylation reaction to provide, after hydrolysis, heptahelicene-2-carboxylic acid. The racemate was resolved into enantiomers by semipreparative HPLC on a chiral column. The helicity of (+)-(P)-heptahelicene-2-carboxylic acid was assigned by correlating its CD spectr…
Hydrogen peroxide sensing with horseradish peroxidase-modified polymer single conical nanochannels.
2011
Inspired from the funtioning and responsiveness of biological ion channels, researchers attempt to develop biosensing systems based on polymer and solid-state nanochannels. The applicability of these nanochannels for detection/sensing of any foreign analyte in the surrounding environment depends critically on the surface characteristics of the inner walls. Attaching recognition sites to the channel walls leads to the preparation of sensors targeted at a specific molecule. There are many nanochannel platforms for the detection of DNA and proteins, but only a few are capable of detecting small molecules. Here, we describe a nanochannel platform for the detection of hydrogen peroxide, H(2)O(2)…
Trapping and Immobilization of DNA Molecules Between Nanoelectrodes
2011
DNA is one of the most promising molecules for nanoscale bottom-up fabrication. For both scientific studies and fabrication of devices, it is desirable to be able to manipulate DNA molecules, or self--assembled DNA constructions, at the single unit level. Efficient methods are needed for precisely attaching the single unit to the external measurement setup or the device structure. So far, this has often been too cumbersome to achieve, and consequently most of the scientific studies are based on a statistical analysis or measurements done for a sample containing numerous molecules in liquid or in a dry state. Here, we explain a method for trapping and attaching nanoscale double-stranded DNA …
Self-Assembled DNA-Based Structures for Nanoelectronics
2023
Recent developments in structural DNA nanotechnology have made com-plex and spatially exactly controlled self-assembled DNA nanoarchitectureswidely accessible. The available methods enable large variety of differ-ent possible shapes combined with the possibility of using DNA structuresas templates for high-resolution patterning of nano-objects, thus openingup various opportunities for diverse nanotechnological applications. TheseDNA motifs possess enormous possibilities to be exploited in realization ofmolecular scale sensors and electronic devices, and thus, could enable fur-ther miniaturization of electronics. However, there are arguably two mainissues on making use of DNA-based electroni…
From Single Molecules to Nanoscopically Structured Functional Materials
2006
AbstractThe synthesis of MS2 (M = Mo, W) onion-like nanoparticles by means of a high temperature MOCVD process starting from W(CO)6 and elemental sulfur is reported. The reaction can also be carried out in two steps where the intermediate amorphous WS2 nanoparticles formed through the high temperature reaction of tungsten and sulfur in the initial phase of the reaction are isolated and converted in a separate annealing step to onion-type WS2 nanoparticles. Based on a study of the temperature dependence of the reaction a set of conditions could be derived where onion-like structures were formed in a one-step reaction. Onion-like structures obtained in the single-step process were filled, whe…
Assembly of iron oxide nanosheets at the air-water interface by leucine-histidine peptides
2021
The fabrication of inorganic nanomaterials is important for a wide range of disciplines. While many purely inorganic synthetic routes have enabled a manifold of nanostructures under well-controlled conditions, organisms have the ability to synthesize structures under ambient conditions. For example, magnetotactic bacteria, can synthesize tiny ‘compass needles’ of magnetite (Fe3O4). Here, we demonstrate the bio-inspired synthesis of extended, self-supporting, nanometer-thin sheets of iron oxide at the water–air interface through self-assembly using small histidine-rich peptides.
Data from: Body coloration and mechanisms of colour production in Archelosauria: the case of deirocheline turtles
2019
Animal body coloration is a complex trait resulting from the interplay of multiple mechanisms. While many studies address the functions of animal coloration, the mechanisms of colour production still remain unknown in most taxa. Here we compare reflectance spectra, cellular, ultra- and nano- structure of colour-producing elements, and pigment types in two freshwater turtles with contrasting courtship behaviour, Trachemys scripta and Pseudemys concinna. The two species differ in the distribution of pigment cell-types and in pigment diversity. We found xanthophores, melanocytes, abundant iridophores and dermal collagen fibres in stripes of both species. The yellow chin and forelimb stripes of…
Liquid structure of a choline chloride-water natural deep eutectic solvent: A molecular dynamics characterization
2021
The liquid structure of a representative of the first water-in-salt (WiS) Natural Deep Eutectic Solvents (NADES), hereinafter indicated as aquoline, a mixture of choline chloride (ChCl) and water with molar ratio 1:3.33, is ex- plored at ambient conditions. Using Molecular Dynamics (MD) simulation tools, we extract structural informa- tion at atomistic level on the nature of inter-correlations between the different moieties. Despite being a very fluid liquid, with much lower viscosity than other common ChCl-based DES, aquoline turns out to be very struc- tured. Computed X-ray and neutron weighted scattering patterns (the latter also on selectively deuterated mix- tures) highlight the existe…