X-ray modeling
February 3, 2011
Using intense X-ray pulses, scientists have devised a way to capture the first images of proteins and viruses, according to research published in the journal Nature on Thursday.
A team of researchers lead by Henry Chapman of the Center for Free-Electron Laser Science at the Deutsches Elektronen-Synchotron (DESY) in Hamburg, Germany, achieved the results at the free-electron laser at Stanford University in California.
By harnessing the free electron laser at the Linac Coherent Light Source, the research team was able to visualize a single viral particle in a single flash lasting several femtoseconds (10-15 seconds). The virus studied was the mimivirus, the largest known virus in the world, which infects amoebas.
The challenge to capturing images with an X-ray has been that the objects within the laser explode from the concentrated radiation. Each biological particle is injected into the beam of photons at a speed of 300 kilometers per hour and then, with temperatures reaching 100,000 degrees Kelvin, turn to plasma. But, before doing so, it has time to diffract 1.7 million photons, from which its image is recreated using mathematical calculations and software developed by the team of researchers.
By capturing the images of the intact virus, the researchers have made a first step into the realm of studying viruses at the nanoscale, with the goal of producing stop-motion movies of chemical changes taking place in molecules and within living cells.
"I think it will be the start of nano-cinema for us," DESY spokesman Thomas Zafoul told Deutsche Welle.
Team effort
Until now, biologists have been limited to freezing and slicing viruses, microbes or living cells in order to make images of them.
“These achievements are a culmination of many years of effort that began with prototype experiments at DESY's FLASH facility, the free-electron laser in Hamburg,” lead researcher Chapman said in a statement from DESY.
A collaborative effort, these achievements were attained through the cooperation of more than 80 researchers from 21 different institutions.
Such cooperation is part of a growing trend in the field, according to Zafoul.
"The trend is that the groups participating are growing larger and more interdisciplinary," he told Deutsche Welle, adding that he anticipated this spirit of collaboration to persist when research on this subject eventually begins at the European XFEL project, to come online in 2014.
The tunnels that will house the XFEL are currently being bored out underneath a town outside Hamburg. When complete, the XFEL is expected to begin firing off 27,000 flashes per second, and to begin active experiments some time in 2015.
Author: Stuart Tiffen
Editor: John Blau