Low-dose three-dimensional hard x-ray imaging of bacterial cells
1 Institut für Röntgenphysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
2 HASYLAB at DESY, Notkestr. 85, 22607 Hamburg, Germany
Optical Nanoscopy 2012, 1:10 doi:10.1186/2192-2853-1-10Published: 30 November 2012
We have imaged the three-dimensional density distribution of unstained and unsliced, freeze-dried cells of the gram-positive bacterium Deinococcus radiodurans by tomographic x-ray propagation microscopy, i.e. projection tomography with phase contrast formation by free space propagation. The work extends previous x-ray imaging of biological cells in the simple in-line holography geometry to full three-dimensional reconstruction, based on a fast iterative phase reconstruction algorithm which circumvents the usual twin-image problem. The sample is illuminated by the highly curved wave fronts emitted from a virtual quasi-point source with 10 nm cross section, realized by two crossed x-ray waveguides. The experimental scheme allows for a particularly dose efficient determination of the 3D density distribution in the cellular structure.