Hockeypuck-Micellen aus Oligo(p-benzamid)-b-PEG-Stab-Knäuel-Blockcopolymeren

Learning from Nature: β-Sheet-Mimicking Copolymers Get Organized

The solution structures formed by coil-coil copolymers arise from the selective solvation of one of the two blocks and have been well described. In most cases in such relatively simple synthetic structures there are no specific attractive forces that can aid the aggregation process. Nature, however, provides plenty of inspiring polymeric architectures that are shaped and ordered hierarchically by noncovalent forces. The high level of structural definition displayed by proteins, for example, is unmatched by synthetic polymers. An emerging area of interest in polymer science tries to combine the best of both worlds, the natural and the synthetic, by conjugating synthetic polymers and beta-sheet-forming peptides. Understanding the supramolecular organization of the block copolymers driven exclusively by the intermolecular attractive forces of the peptide sequence is of particular interest. Not only do these peptide-polymer hybrid structures present an interesting new class of materials, they can also provide important insights into self-organization processes prevalent in nature.

Towards automated diffraction tomography: part I--data acquisition

The ultimate aim of electron diffraction data collection for structure analysis is to sample the reciprocal space as accurately as possible to obtain a high-quality data set for crystal structure determination. Besides a more precise lattice parameter determination, fine sampling is expected to deliver superior data on reflection intensities, which is crucial for subsequent structure analysis. Traditionally, three-dimensional (3D) diffraction data are collected by manually tilting a crystal around a selected crystallographic axis and recording a set of diffraction patterns (a tilt series) at various crystallographic zones. In a second step, diffraction data from these zones are combined into a 3D data set and analyzed to yield the desired structure information. Data collection can also be performed automatically, with the recent advances in tomography acquisition providing a suitable basis. An experimental software module has been developed for the Tecnai microscope for such an automated diffraction pattern collection while tilting around the goniometer axis. The module combines STEM imaging with diffraction pattern acquisition in nanodiffraction mode. It allows automated recording of diffraction tilt series from nanoparticles with a size down to 5nm.