No abstract

Using temporary self-assembled scaffolds to preorganize building blocks is a potentially powerful method for the synthesis of organic nanostructures with programmed shapes. We examined the underlying phenomena governing the loading of hydrophobic monomers into lipid bilayer interior and demonstrated successful control of the amount and ratio of loaded monomers. When excess styrene derivatives or acrylates were added to the aqueous solution of unilamellar liposomes made from saturated phospholipids, most loading occurs within the first few hours. Dynamic light scattering and transmission electron microscopy revealed no evidence of aggregation caused by monomers. Bilayers appeared to have a certain capacity for accommodating monomers. The total volume of loaded monomers is independent of monomer structure. X-ray scattering showed the increase in bilayer thickness consistent with loading monomers into bilayer interior. Loading kinetics is inversely proportional to the hydrophobicity and size of monomers. Loading and extraction kinetic data suggest that crossing the polar heads region is the rate limiting step. Consideration of loading kinetics and multiple equilibria are important for achieving reproducible monomer loading. The total amount of monomers loaded into the bilayer can be controlled by the loading time or length of hydrophobic lipid tails. The ratio of loaded monomers can be varied by changing the ratio of monomers used for loading or by the time-controlled replacement of a preloaded monomer. Understanding and controlling the loading of monomers into bilayers contributes to the directed assembly of organic nanostructures.

High-quality atomically flat substrates are critical for the analysis and imaging of surface-mounted ultrathin films and nanostructures. Here we report significant improvement in the preparation of large areas of atomically smooth Au(111) substrates. A thin layer of gold on silicon is flame-annealed in air and then stripped from the template. The substrates were analyzed with X-ray diffraction and high-resolution atomic force microscopy (AFM). In contrast to the previously reported template stripped gold (TSG) substrates, flame-annealed template stripped substrates reveal no detectable pinholes. The substrate surface is atomically smooth with most grains being larger than 1 µm 2 . The entire procedure requires less than 2 h and uses readily available materials and common laboratory equipment. The resulting substrates can be stored for longer periods of time and then used immediately without need for common cleaning procedures. Evidence is provided that self-assembled monolayers on these substrates are higher quality than those prepared with previously reported gold substrates.

Nanosieb: Subnanometerdünnes organisches Material mit einheitlichen Poren entsteht durch kontrollierte Polymerisation in temporären selbstorganisierten Gerüsten. Die Porengröße wird mithilfe farbiger Größensonden bestimmt. Eine Nanokapsel ohne Poren hält gelbe, rote und blaue Proben zurück und ist daher braun; bei 0.8 nm großen Poren werden die gelben Sonden freigesetzt, und Kapseln mit 1.3 nm großen Poren halten nur die blauen Sonden zurück.