Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Algorithms, gold and holographic references boost biomolecule diffraction


X-ray single particle imaging (SPI) is a technique where the very bright pulses produced by X-ray Free Electron Lasers are used to image single particles like biomolecules. Now research group leader Dr. Kartik Ayyer from the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg has conceived a new method to image much smaller biomolecules at a finer resolution than has been possible until now. His work has been published in Optica.

When a laser beam is ‘shot’ at a particle (a molecule or a crystal) during SPI, each object produces a diffraction pattern, which helps scientists to understand the structure and behavior of that material.

Simulated diffraction pattern from a test object holographically interfering with a 2D lattice.

© Kartik Ayyer

Researchers collect a large number of diffraction patterns of randomly rotated versions of these particles and then computationally combine the information into a 3D structure.

Dr. Ayyer adds certain materials to the particle being exposed to the laser – either gold nanoparticles or 2D crystals. These additional substances produce a so-called holographic reference, an additional diffraction which – paradoxically – improves the diffraction pattern from the material being investigated.

Holographic references are one way to significantly improve the efficiency of SPI experiments. A holographic reference is something that is in close proximity to the target particle and whose diffraction "interferes" with that of the particle.

This interference has a benefit of improving the signal-to-noise ratio (SNR) but more importantly, it increases the overall signal significantly. This alleviates the big issues of particle detection and background tolerance which plague the technique, especially for smaller objects.

However, the key problem with such references is that the composite object (target particle plus reference) is usually highly heterogeneous. This means that one cannot combine multiple diffraction patterns into a good 3D structure. So while the idea of holography has been around since at least the 1940s (Dennis Gabor received the Nobel Prize in 1971 for the method), and has been proposed in the SPI context since the mid-2000s, nobody has been able to use it to obtain high resolutions 3D structures yet.

Dr. Ayyer, who leads the Computational Nanoscale Imaging group at the MPSD, has developed a new algorithm to reconstruct the structure of the target particle from these composite diffraction patterns by simultaneously solving for the relative positions, size etc. of the reference.

He also proposes two experimental configurations where such references could be utilized. The first is to attach a gold nanoparticle to the target object and image the particles in an aerosolized state.

The experimental methods, both for aerosol X-ray imaging and the attachment process, have developed rapidly over the last few years. The second configuration uses a 2D crystal as a reference. The signal is now concentrated in crystallographic peaks, which is a significant advantage from an SNR perspective, but the relative position and orientation of the target particle with respect to the unit cell of the crystal need to be determined for each pattern.

“These methods should enable us to extend the SPI technique to not just large viruses and protein complexes, but to significantly smaller particles which make up the majority of biologically interesting molecules," says Dr. Ayyer. "Exactly how much smaller requires further simulations which we are currently setting up.”

Wissenschaftliche Ansprechpartner:

Dr. Kartik Ayyer, Computational Nanoscale Imaging group:
Jenny Witt, Communications and PR, MPSD:


Weitere Informationen:

Jenny Witt | Max-Planck-Institut für Struktur und Dynamik der Materie

More articles from Information Technology:

nachricht Color barcode becomes ISO standard
14.07.2020 | Fraunhofer-Institut für Sichere Informationstechnologie SIT

nachricht Virtual reality can assist with the evaluation of future transport concepts
13.07.2020 | Fraunhofer-Institut für Arbeitswirtschaft und Organisation IAO

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron cryo-microscopy: Using inexpensive technology to produce high-resolution images

Biochemists at Martin Luther University Halle-Wittenberg (MLU) have used a standard electron cryo-microscope to achieve surprisingly good images that are on par with those taken by far more sophisticated equipment. They have succeeded in determining the structure of ferritin almost at the atomic level. Their results were published in the journal "PLOS ONE".

Electron cryo-microscopy has become increasingly important in recent years, especially in shedding light on protein structures. The developers of the new...

Im Focus: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Latest News

Shedding light on the brown color of algae

14.07.2020 | Life Sciences

Color barcode becomes ISO standard

14.07.2020 | Information Technology

New substance library to accelerate the search for active compounds

14.07.2020 | Life Sciences

Science & Research
Overview of more VideoLinks >>>