Search results for "Self assembled"

Statistical Characterization of Self-Assembled Colloidal Crystals by Single-Step Vertical Deposition

2014

Abstract We have statistically characterized the self-assembly of multi-layer polystyrene colloidal crystals, using the technique of vertical deposition, with parameters chosen to produce thick layers of self-assembled crystals in one deposition step. The size distribution of domains produced with this technique was seen to follow a log-normal distribution, hinting that aggregation or fragmentation phenomena play a role. In addition, using a lithographically directed self-assembly method, we have shown that the size of multi-layer, continuous crack-free domains in lithographically defined areas can be many times larger than in the surrounding areas. In a single deposition step, we have prod…

Carbohydrate-Mediated Biomolecular Recognition and Gating of Synthetic Ion Channels

2013

Nanochannel-based biosensing devices have been proposed for selective detection of protein analyte molecules. However, the design and miniaturization of reusable channel-based biosensors is still a challenge in nanoscience and biotechnology. We present here a reusable nanofluidic biosensor based on reversible lectin-carbohydrate interactions. The nanochannels are fabricated in heavy ion tracked polymer membranes. The channel walls are functionalized with p-aminophenyl alpha-D-mannopyranoside (APMP) monolayers through carbodiimide coupling chemistry. The chemical (mannopyranoside) groups on the inner channel walls serve as binding sites and interact with specific protein molecules. The bindi…

Protein diffusion through charged nanopores with different radii at low ionic strength

2014

[EN] The diffusion of two similar molecular weight proteins, bovine serum albumin (BSA) and bovine haemoglobin (BHb), through nanoporous charged membranes with a wide range of pore radii is studied at low ionic strength. The effects of the solution pH and the membrane pore diameter on the pore permeability allow quantifying the electrostatic interaction between the chargedpore and the protein. Because of the large screening Debye length, both surface and bulk diffusion occur simultaneously. By increasing the pore diameter, the permeability tends to the bulk self-diffusion coefficient for each protein. By decreasing the pore diameter, the charges on the pore surface electrostatically hinder …

Self-assembled dimers with supramolecular chirality

2003

The possibilities to form dimeric capsules with supramolecular chirality from tetraurea calix[4]arenes composed of two different phenolic urea units are discussed in general and demonstrated experimentally for various selected examples.

Charge transfer interactions in self-assembled single walled carbon nanotubes/Dawson–Wells polyoxometalate hybrids

2014

We demonstrate the success in self-assembling pyrene-modified Dawson–Wells-type polyoxometalates (POMs) with single walled carbon nanotubes (SWCNTs) by means of π–π interactions. In this context, the immobilization of POMs onto SWCNTs is corroborated by aberration-corrected high-resolution electron microscopy, thermogravimetric analysis, and Raman spectroscopy. From steady-state and time-resolved photophysical techniques we derived evidence for mutual interactions between SWCNTs and POMs in the excited states. The latter are the inception to a charge transfer from the SWCNTs to the POMs. Our results corroborate the suitability of POM–SWCNTs assemblies for photoactive molecular devices.

Optical Properties of Self-Assembled GaxIn1-xAs/InP Quantum Wires

2002

Temperature dependent photoluminescence studies have been carried out on several samples containing self-assembled Ga x In 1-x As/InP quantum wires. A red-shift of the emission wavelength is observed when increasing the Ga content in the alloy, but the overall optical quality decreases. In the case of x = 0.15, the photoluminescence is not sensible to temperature and the emission band is conserved until room temperature is reached, which could be explained if the nanostructures are considered to be almost amorphous.

Encapsulation of Xenon by a Self-Assembled Fe4L6 Metallosupramolecular Cage

2015

We report (129)Xe NMR experiments showing that a Fe4L6 metallosupramolecular cage can encapsulate xenon in water with a binding constant of 16 M(-1). The observations pave the way for exploiting metallosupramolecular cages as economical means to extract rare gases as well as (129)Xe NMR-based bio-, pH, and temperature sensors. Xe in the Fe4L6 cage has an unusual chemical shift downfield from free Xe in water. The exchange rate between the encapsulated and free Xe was determined to be about 10 Hz, potentially allowing signal amplification via chemical exchange saturation transfer. Computational treatment showed that dynamical effects of Xe motion as well as relativistic effects have signific…

Inside Cover: A Self-Assembled M8L6 Cubic Cage that Selectively Encapsulates Large Aromatic Guests (Angew. Chem. Int. Ed. 15/2011)

2011

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…

White Phosphorus Is Air-Stable Within a Self-Assembled Tetrahedral Capsule

2009

Molecular Fire Quencher Cage-shaped molecular assemblies can regulate the reactivity of smaller molecules trapped within them. Mal et al. (p. 1697 ) extend this approach to enable the protection of elemental white phosphorus (P 4 ), a substance that rapidly ignites on contact with oxygen. The tetrahedral cages self-assemble in aqueous solution through coordination of six ligands to four iron ions, and efficiently capture phosphorus from a suspension. The water-soluble host-guest constructs were stable in air for at least 4 months, but released intact P 4 rapidly on displacement by added benzene.