The advances and technical improvements of X-ray imaging techniques, taking advantage of X-ray focussing optics and high intensity synchrotron sources, nowadays allow for the use of X-rays to probe the cellular nanoscale. Importantly, X-rays permit thick samples to be imaged without sectioning or slicing. In this work, two macromolecules, namely keratin intermediate filament (IF) proteins and DNA, both essential components of cells, were studied by X-ray techniques. Keratin IF proteins make up an integral part of the cytoskeleton of epithelial cells and form a dense intracellular network of bundles. This network is built from monomers in a hierarchical fashion. Thus, the keratin structure formation spans a large range of length scales from a few nanometres (monomers) to micrometres (networks). Here, keratin was studied at three different scales: i) filaments, ii) bundles and iii) networks. Solution small-angle X-ray scattering revealed distinct structural and organisational characteristics of these highly charged polyelectrolyte filaments, such as increasing radius with increasing salt concentration and spatial accumulation of ions depending on the salt concentration. The results are quantified by employing advanced modelling of keratin IFs by a core cylinder fl anked with Gaussian chains. Scanning micro- diffraction was used to study keratin at the bundle scale. Very different morphologies of keratin bundles were observed at different salt conditions. At the network scale, new imaging approaches and analyses were applied to the study of whole cells. Ptychography and scanning X-ray nano-diffraction imaging were performed on the same cells, allowing for high resolution in real and reciprocal space, thereby revealing the internal structure of these networks. By using a fitting routine based on simulations of IFs packed on a hexagonal lattice, the radius of each fi lament and distance between fi laments were retrieved. In mammalian cells, each nucleus contains 2 nm-thick DNA double helices with a total length of about 2 m. The DNA strands are packed in a highly hierarchical manner into individual chromosomes. DNA was studied in intact cells by visible light microscopy and scanning X-ray nano-diffraction, unveiling the compaction und decompaction of DNA during the cell cycle. Thus, we obtained information on the aggregation state of the nuclear DNA at a real space resolution on the order of few hundreds nm. To exploit to the reciprocal space information, individual diffraction patterns were analysed according to a generalised Porod’s law at a resolution down to 10 nm. We were able to distinguish nucleoli, heterochromatin and euchromatin in the nuclei and follow the compaction and decompaction during the cell division cycle.

In this work, two macromolecules, both essential components of cells (keratin protein and DNA nucleic acid) were studied by X-ray techniques. I described the implementation and use of different methods to investigate these biopolymers at the nanoscale: solution SAXS, ptychography and scanning X-ray diffraction. Keratin proteins belong to the cytoskeleton of epithelial cells forming a dense network. This network is built from monomers in a stepwise fashion. First, two monomers assemble to form a parallel heterodimer (about 2~nm diameter). Second, tetramers (4 to 5~nm diameter) are formed by ...

In this work, two macromolecules, both essential components of cells (keratin protein and DNA nucleic acid) were studied by X-ray techniques. I described the implementation and use of different methods to investigate these biopolymers at the nanoscale: solution SAXS, ptychography and scanning X-ray diffraction. Keratin proteins belong to the cytoskeleton of epithelial cells forming a dense network. This network is built from monomers in a stepwise fashion. First, two monomers assemble to form a parallel heterodimer (about 2~nm diameter). Second, tetramers (4 to 5~nm diameter) are formed by ...

This open access book, edited and authored by a team of world-leading researchers, provides a broad overview of advanced photonic methods for nanoscale visualization, as well as describing a range of fascinating in-depth studies. Introductory chapters cover the most relevant physics and basic methods that young researchers need to master in order to work effectively in the field of nanoscale photonic imaging, from physical first principles, to instrumentation, to mathematical foundations of imaging and data analysis. Subsequent chapters demonstrate how these cutting edge methods are applied to a variety of systems, including complex fluids and biomolecular systems, for visualizing their structure and dynamics, in space and on timescales extending over many orders of magnitude down to the femtosecond range. Progress in nanoscale photonic imaging in Göttingen has been the sum total of more than a decade of work by a wide range of scientists and mathematicians across disciplines, working together in a vibrant collaboration of a kind rarely matched. This volume presents the highlights of their research achievements and serves as a record of the unique and remarkable constellation of contributors, as well as looking ahead at the future prospects in this field. It will serve not only as a useful reference for experienced researchers but also as a valuable point of entry for newcomers.

X-rays provide an ideal probe for studying structures at the nano-scale and are routinely employed for investigating the structure and the composition of biological systems, making use of the variety of different techniques. By raster scanning the sample with a small beam, structural information obtained from individual scattering patterns in reciprocal space can be combined with positional information in real space. In this work, scanning X-ray diffraction using a nano-focused beam was applied to samples of biological cells in order to probe the structure of cytoskeletal bundles and networks of keratin intermediate filaments. Cellular samples were prepared using different methods, starting from well-established freeze-dried samples and going on to fixed-hydrated and finally living cells. In this context, the development of X-ray compatible microfluidic devices allowing for measurements on living cellular samples was an important aspect. Comparing the scattering signal from freeze-dried, fixed-hydrated and living cells, differences between the sample types at length scales of several tens of nanometers were determined. The successful application to hydrated and living cells further demonstrates the potential for structural analysis at hardly accessible length scales in native samples. Published: 2014

This work furthers the overall understanding of a 3w-measurement, by considering previously unexamined macroscopic influence factors within measurement by Finite Element simulations (FES). Moreover, new measuring configurations are developed to determine (an)isotropic thermal conductivities of nanoscale samples. Since no analytic solutions are available for these configurations, a new evaluation methodology is presented to determine emergent thermal conductivities by FES and Neural Networks.

An up-to-date overview of the different x-ray based methods in the hot fields of nanoscience and nanotechnology, including methods for imaging nanomaterials, as well as for probing the electronic structure of nanostructured materials in order to investigate their different properties. Written by authors at one of the world's top facilities working with these methods, this monograph presents and discusses techniques and applications in the fields of x-ray scattering, spectroscopy and microscope imaging. The resulting systematic collection of these advanced tools will benefit graduate students, postdocs as well as professional researchers.