Researchers demonstrate nanoscale X-ray imaging of bacterial cells

Dec 07, 2009
Researchers demonstrate nanoscale X-ray imaging of bacterial cells
Technische Universitaet Muenchen biophysicists (left to right) Dr. Pierre Thibault, Prof. Dr. Franz Pfeiffer, and Martin Dierolf are co-authors of the PNAS paper, "Quantitative biological imaging by ptychographic X-ray diffraction microscopy." They collaborated with colleagues at the University of Goettingen and the Swiss Light Source. Credit: Andreas Battenberg, Technische Universitaet Muenchen.

An ultra-high-resolution imaging technique using X-ray diffraction is a step closer to fulfilling its promise as a window on nanometer-scale structures in biological samples. In the Proceedings of the National Academy of Sciences, researchers report progress in applying an approach to "lensless" X-ray microscopy that they introduced one year ago.

They have produced the first images, using this technique, of biological cells - specifically the intriguing polyextremophile Deinococcus radiourans. Better ability to see in cells could yield important insights for and biotechnology. In the case of D. 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. Having demonstrated the resolution, reliability, and reproducibility of their technique, the researchers are now working to extend it to three-dimensional imaging of biological cells.

X-ray imaging is best known for its medical applications, such as traditional radiographs and CT scans. Yet the use of X-rays goes far beyond routine imaging. In particular, 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. A technique developed by researchers now in the biomedical physics group at Technische Universitaet Muenchen (TUM) has shown great 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. While its use in electron microscopy is still limited, ptychography has gained tremendous popularity in the X-ray imaging community in the last few years, thanks to the development by Franz Pfeiffer, now chair of the biomedical physics group at TUM, and his team. A critical step in the development of ptychography was published by the team one year ago in Science. The super-resolution capability of the imaging method was successfully demonstrated with a gold test structure.

Now a collaboration of the Pfeiffer group (Technische Universitaet Muenchen, Germany), together with researchers at University of Goettingen and at the Swiss Light Source (Villigen, Switzerland), has gone a step further and produced the first images of biological cells with the same technique.

These results, published in the , 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. Moreover, biological samples are very fragile and nearly transparent to X-rays, making this type of accurate measurement even more challenging.

The Pfeiffer group is now moving beyond this success and looking into ways of improving the technique further. In particular, the team is aiming at the next milestone: three-dimensional imaging of biological samples.

More information:

K. Giewekemeyer, P. Thibault, S. Kalbfleisch, A. Beerlink, C. M. Kewish, M. Dierolf, F. Pfeiffer, T. Salditt, Quantitative biological imaging by ptychographic microscopy, PNAS Early Edition, Proceedings of the National Academy of Sciences of the USA, Dec. 7-11, 2009.

P. Thibault, M. Dierolf, A. Menzel, O. Bunk, C. David, F. Pfeiffer, High-resolution scanning x-ray diffraction , Science 321, 379 - 381 (2008).

Source: Technische Universitaet Muenchen

Explore further: Lightweight membrane can significantly reduce in-flight aircraft noise

Related Stories

Scientists take the sharpest image ever made with light

Aug 29, 2008

( -- A team of scientists from the Technische Universit├Ąt Dresden (Germany) and the ESRF in Grenoble (France) has produced the image of an object at the highest resolution ever achieved with X-ray ...

Microscope Sees with Nanoscale Resolution

Jan 28, 2008

Researchers have recently built an x-ray microscope that has a pixel resolution of just 15 nanometers, allowing scientists to study the properties of materials at the molecular scale and beyond.

Recommended for you

Thinner capsules yield faster implosions

14 hours ago

In National Ignition Facility (NIF) inertial confinement fusion (ICF) experiments, the fusion fuel implodes at a high speed in reaction to the rapid ablation, or blow-off, of the outer layers of the target ...

Direct visualization of magnetoelectric domains

16 hours ago

A novel microscopy technique called magnetoelectric force microscopy (MeFM) was developed to detect the local cross-coupling between magnetic and electric dipoles. Combined experimental observation and theoretical ...

Upside down and inside out

17 hours ago

Researchers have captured the first 3D video of a living algal embryo turning itself inside out, from a sphere to a mushroom shape and back again. The results could help unravel the mechanical processes at ...

Heat makes electrons spin in magnetic superconductors

Apr 24, 2015

Physicists have shown how heat can be exploited for controlling magnetic properties of matter. The finding helps in the development of more efficient mass memories. The result was published yesterday in Physical Review Le ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.