Atomic Imaging

Linking atomic structure to function is the key to understanding molecular interactions of any kind. The Atomic Imaging theme is aimed at developing techniques to better determine the atomic structure of proteins. There are three key technologies we are using and refining – (a) 4th generation X-ray Free Electron Laser (XFEL)-based femtosecond nanocrystallography, (b) 3rd generation micro-focussed Synchrotron-based crystallography, and (c) cryogenic Transmission Electron Microscopy (cryo-TEM).

Using these techniques and theoretical modelling of relevant beam-sample interactions, we focus on three specific outcomes:

  1. Obtaining structural information on challenging proteins using small crystals in femtosecond nanocrystallography or electron microscopy
  2. Determining protein structures and insights into function from single molecule X-ray crystallography and/or electron microscopy experiments
  3. Obtaining accurate dynamic insights or ‘Molecular movies’ that allow us to visualise how proteins change in shape dynamically during biological function

Reseach Highlights

Fresnel coherent diffractive imaging tomography of whole cells in capillaries. New Journal of Physics, Sep 2014

Centre CIs Brian Abbey and Keith Nugent and Partner Investigator Andrew Peele were part of a team of researchers who developed a new X-ray imaging technique to image whole cells in capillaries in three dimensions. Led by Drs Mac Luu and Grant van Riessen from La Trobe University, a node of the Imaging CoE, the researchers used this high resolution cellular imaging technique to image a red blood cell infected with a malaria parasite.

The experiments were conducted at the Advanced Photon Source in Chicago. Funding for the trip was provided by the International Synchrotron Access Program supported by the Australian Government and managed by the Australian Synchrotron, a partner organisation of the Centre.

Authors: MB Luu, GA van Riessen, B Abbey, MWM Jones, NW Phillips, K Elgass, MD Junker, DJ Vine, I McNulty, G Cadenazzi, C Millet, L Tilley, KA Nugent, AG Peele

Exploring the frontiers of nano-imaging

Metallic nanoparticles are among the smallest particles in existence – measuring 1-100 nanometres, where each nanometre is a millionth of a millimetre. Associate Professor Hans Elmlund from Monash University, and collaborators in the US and South Korea, have developed a novel technique to study the 3D structure of platinum nanoparticles at a level of detail never seen before.

Despite their miniscule size, metallic nanoparticles have huge potential in nanotechnology and are heavily used in biomedical sciences and engineering. In a new paper published in Science, Elmlund and colleagues at Princeton, Berkeley, Harvard, Ulsan National Institute of Science and Technology and Amore-Pacific Corp. R&D Center demonstrate their powerful method: 3D Structure Identification of Nanoparticles by Graphene Liquid Cell EM (SINGLE). The ingenious technique combines three components: a graphene liquid cell, which is a one carbon-atom thick bag able to hold liquid that remains visible under an electron microscope; an extremely sensitive direct electron detector that captures movies of nanoparticles spinning in solution; and PRIME, a 3D modelling approach that enables the creation of 3D computer models of individual nanoparticles from such movies.

The crystalline arrangements of atoms in nanoparticles are variable, and until now, their highly complex and unpredictable structures have remained a mystery. Using their newly described method, the international collaborators were able to extract detailed information on the formation of platinum nanoparticles. Interestingly, instead of the anticipated cubical or highly symmetrical arrangement, they discovered that the particles are in fact made up of asymmetrical multi-domain structures.

The researchers chose to work with platinum nanocrystals due to their excellent catalytic capabilities, the atomic arrangement on the surface and at the core influences particles’ effectiveness in such reactions. Detailing the structure of platinum nanoparticles therefore has significant implications for their future applications in catalysis.

Since nanoparticles are exploited for such a vast range of applications – diagnostic imaging, renewable energy storage and targeted drug delivery, for example – the researchers’ innovative, hybrid method to reconstruct the particles’ 3D atomic structure and understand the intricacies of their formation will play an important role in the development of new technologies and materials.

For Elmlund and his colleagues, the next steps will involve investigating the formation and evolution of nanoparticles, and characterising the transitions they go through to reach their final form. “It is important for us to understand this so that we can design new materials, for example, to build better or more efficient solar cells, or make better and more economical use of fossil fuels,” says Elmlund.

Theme Leaders:

Keith Nugent, Brian Abbey, Harry Quiney

Collaborators:

Henry Chapman, Ilme Schlicting, Carl Caleman, Garth Williams