Browsing by Subject "MICROSCOPY"

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Now showing items 21-22 of 22
  • Duyvesteyn, Helen M. E.; Ginn, Helen M.; Pietila, Maija K.; Wagner, Armin; Hattne, Johan; Grimes, Jonathan M.; Hirvonen, Elina; Evans, Gwyndaf; Parsy, Marie-Laure; Sauter, Nicholas K.; Brewster, Aaron S.; Huiskonen, Juha T.; Stuart, David I.; Sutton, Geoff; Bamford, Dennis H. (2018)
    Viruses are a significant threat to both human health and the economy, and there is an urgent need for novel anti-viral drugs and vaccines. High-resolution viral structures inform our understanding of the virosphere, and inspire novel therapies. Here we present a method of obtaining such structural information that avoids potentially disruptive handling, by collecting diffraction data from intact infected cells. We identify a suitable combination of cell type and virus to accumulate particles in the cells, establish a suitable time point where most cells contain virus condensates and use electron microscopy to demonstrate that these are ordered crystalline arrays of empty capsids. We then use an X-ray free electron laser to provide extremely bright illumination of sub-micron intracellular condensates of bacteriophage phiX174 inside living Escherichia coli at room temperature. We have been able to collect low resolution diffraction data. Despite the limited resolution and completeness of these initial data, due to a far from optimal experimental setup, we have used novel methodology to determine a putative space group, unit cell dimensions, particle packing and likely maturation state of the particles.
  • Nolvi, Anton; Laidmae, Ivo; Maconi, Göran; Heinämäki, Jyrki; Haeggström, Edward; Kassamakov, Ivan (SPIE - the international society for optics and photonics, 2018)
    Proceedings of SPIE
    Recently, 3D label-free super-resolution profilers based on microsphere-assisted scanning white light interferometry were introduced having vertical resolution of few angstroms (angstrom) and a lateral resolution approaching 100 nm. However, the use of a single microsphere to generate the photonic nanojet (PNJ) limits their field of view. We overcome this limitation by using polymer microfibers to generate the PNJ. This increases the field of view by order of magnitude in comparison to the previously developed solutions while still resolving sub 100 nm features laterally and keeping the vertical resolution in 1 nm range. To validate the capabilities of our system we used a recordable Blu-ray disc as a sample. It features a grooved surface topology with heights in the range of 20 nm and with distinguishable sub 100 nm lateral features that are unresolvable by diffraction limited optics. We achieved agreement between all three measurement devices across lateral and vertical dimensions. The field of view of our instrument was 110 mu m by 2 mu m and the imaging time was a couple of seconds.