Sandia's work demonstrated to the FBI that the form of bacillus anthracis contained in those letters was not a weaponized form, a form of the bacteria prepared to disperse more readily. The possibility of a weaponized form was of great concern to investigators, says Joseph Michael, the principal investigator for the project. This information was crucial in ruling out state-sponsored terrorism.
When bacillus anthracis spores are weaponized, the spores are coated with silica nanoparticles that look almost like lint under the microscope. The "lint" makes the particles "bouncier" and less likely to clump and fall to the ground. That makes the spores more respirable and able to do more damage, says Michael. Weaponization of the spores would be an indicator of state sponsored terrorism.
"Initially, scanning electron microscopy [SEM] conducted at another laboratory, showed high silicon and oxygen signals that led them to conclude that the spores were a weaponized form, says Kotula. "The possible misinterpretation of the SEM results arose because microanalysis in the SEM is not a surface-sensitive tool," says Kotula. "Because a spore body can be 1.5 to 2 microns wide by 1 micron long, a SEM cannot localize the elemental signal from whole spore bodies."
Using more sensitive transmission electron microscopy (TEM), Kotula and Michael's research indicated that the silica in the spore samples was not added artificially, but was incorporated as a natural part of the spore formation process. "The spores we examined," Kotula says, "lacked that fuzzy outer coating that would indicate that they'd been weaponized."
Sandia's work was the first to actually link the spore material in the New York Post, the Daschle and the Leahy letters. The elemental signatures and the locations of these signatures, while not indicating intentional weaponization, did show that the spores were indistinguishable and therefore likely came from the same source. That conclusion was corroborated a few years later by the DNA studies.
The materials characterization lab serves as a materials analysis resource for a diverse collection of projects. The lab plays an important role in stockpile surveillance, supporting Sandia's nuclear weapons mission.
Michael was recently released from his nondisclosure agreement and flown to Washington, D.C., to participate in press conferences at FBI Headquarters along with several members of research teams who'd been asked to examine other aspects of the anthrax case.
The FBI was pleased with Sandia's work, says Michael. ###
Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin company, for the U.S. Department of Energy's National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
For high-res images or video, contact Sandia news media contact: Stephanie Holinka, slholin@sandia.gov, (505) 284-9227
Contact: Stephanie Holinka slholin@sandia.gov 505-284-9227 DOE/Sandia National Laboratories
Tags: Nano or Nanotechnology and Nanotech
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