World’s most powerful X-ray takes a ‘sledgehammer’ to molecules
MELBOURNE SATURDAY 9 SEPTEMBER, 2016: An international team of over 20 researchers, led by the Imaging CoE, has inadvertently discovered how to create a new type of crystal using light ten billion times brighter than the sun. And, their findings reverse what has been accepted thinking in crystallography for more than 100 years.
The discovery, led by CIs Brian Abbey, La Trobe University and Harry Quiney, the University of Melbourne, was published in the journal Science Advances in September.
The team exposed a sample of crystals, known as Buckminsterfullerene or Buckyballs, to intense light emitted from the world’s first hard X-ray free electron laser (XFEL), based at Stanford University in the United States.
Light from the XFEL is around one billion times brighter than light generated by any other X-ray equipment — light from the Australian Synchrotron pales in comparison. The other big difference: X-ray sources deliver their energy much slower than the XFEL does and all previous observations found X-rays melt or destroy crystals randomly. So, scientists assumed that XFELs would do the same.
However, the results from XFEL experiments on Buckyballs, was not at all expected. When the XFEL intensity was cranked up, past a critical point, the electrons in the Buckyballs spontaneously re-arranged their positions, changing the shape of the molecules completely.
Imaging CoE CI and senior author, Brian Abbey said that every molecule in the crystal changed from being shaped like a soccer ball to being shaped like a rugby ball at the same time.
“This effect produces completely different images at the detector. It also altered the sample’s optical and physical properties,” he said. “It was like smashing a walnut with a sledgehammer, but instead of destroying it and shattering it into a million pieces, we instead found an almond inside!” Brian said.
“Currently, crystallography is the tool used by biologists and immunologists to probe the inner workings of proteins and molecules — the machines of life. Being able to see these structures in new ways will help us to understand interactions in the human body and may open new avenues for drug development,” Brian said.
Harry Quiney said the results were not expected at all and the team was stunned: “This is the first time that we have seen X-ray light effectively create a new type of crystal phase.
“Though it only remains stable for a tiny fraction of a second, we observed that the sample’s physical, optical and chemical characteristics changed dramatically, from its original form,” Harry said.
“This change means that when we use XFELs for crystallography experiments we will have to change the way interpret the data. The results give the 100-year-old science of crystallography a new, exciting direction,” Brian said.
As well as being an Imaging CoE CI, Brian Abbey is an Australian Research Council (ARC) Future Fellow, based at the La Trobe Institute for Molecular Sciences (LIMS). His research was undertaken with Professor Keith Nugent, also based at La Trobe University as well as scientists from the University Melbourne University, Imperial College London, the CSIRO, the Australian Synchrotron, Swinburne Institute of Technology, the University of Oxford, Brookhaven National Laboratory, the Stanford Linear Accelerator (SLAC), the BioXFEL Science and Technology Centre, Uppsala University and the Florey Institute of Neuroscience and Mental Health.