Nanoscale X-ray Imaging of Bacteria

Better ability to see nanoscale structures in cells could yield important insights for evolutionary biology and biotechnology. In the case of the bacterium Deinococcus radiourans, for example, it could help to settle questions about whether – or how – the structure of this organism's DNA-bearing nucleoid region accounts for its hardiness against ionizing radiation.

The very short wavelength of X-ray radiation allows various modes of microscopy that can reach the nanometer resolution. One of the main hurdles to high-resolution X-ray microscopy is the difficulty of producing high-quality X-ray lenses. To overcome these difficulties, so-called "lensless" microscopy methods have emerged in the last decade. One technique has shown promise for ultra-high resolution imaging of materials and life science samples.

This imaging technique, called ptychography, was first introduced in the 1970s for electron diffraction. It consists in measuring full far-field diffraction patterns as a small illumination is scanned on a sample. Its use in electron microscopy is still limited. A critical step in the development of ptychography was published one year ago. The super-resolution capability of the imaging method was demonstrated with a gold test structure.

Now a research group has gone a step further and produced the first images of biological cells with the same technique. These results show that lensless X-ray imaging, in particular ptychography, can be used to obtain accurate maps of the electron density forming a biological sample. This type of quantitative measurement is extremely difficult with most other high-resolution techniques currently available. The next aim is three-dimensional imaging of biological samples.

COMPAMED.de; Source: Technische Universitaet Muenchen