In the weeks following the September 11th attacks, a series
of letters containing anthrax spores arrived at media outlets and the offices
of US Senators Tom Daschle and Patrick Leahy. The acts of bioterrorism gripped
the nation in confusion, anger, and fear. Scores were hospitalized and five people
died. It was a senseless tragedy. But, it could have been much worse.
“Ten grams of anthrax spores could wipe out all of
Washington, DC, and the surrounding area,” says Lori Groven, (BS ChE, MS ChE,
PhD Nanoscience and Nanoengineering). “Biological weapons are scary for
everybody, because it takes so little to do so much damage,” she adds. The
minimum lethal dose for anthrax is estimated to be 5-10,000 spores, and one gram
of anthrax contains well over a trillion spores.
Groven is a research scientist and assistant professor in
the chemical and biological engineering department at Mines. She and her team
are part way through a five-year half-million-dollar grant from the Defense
Threat Reduction Agency. The research has led to new materials and methods for
combating bioterrorism.
One challenge Groven and her team have faced is the
instability of the chemicals currently used to neutralize biological weapons.
These compounds, or biocides, are made up mostly of a fuel and oxidizer
(iodate) powder. They have a very short shelf life. “This stuff doesn’t age
very well," says Groven. “If you put it out on the counter, it literally
melts into a puddle.”
To overcome this problem, Groven has found a novel approach
that utilizes 3D printing. Her team is embedding the normally unstable iodates
into a mix of metal powder and melted plastics. The mixture protects the
iodates and keeps it from degrading. The material can be formed into a long
thread or rope and spooled. The resulting biocidal filament can then be run into
a 3D printer and layered into any shape needed.
“It’s a game changer, no one is doing this in the research
community,” she says. “We can now take a spool of this biocide, it’s stable and
protected, and print anything we want.”
The 3D-printed biocide is flammable, and when it burns it
gives off a gaseous form of iodine that can potentially neutralize a biological
agent such as anthrax. Because it can be manufactured in any form, the biocidal
material can be made to fit inside munitions, like bunker busting bombs, that
are used to penetrate and destroy stashes of biological weapons stored deep
underground.
Groven says the material may also be useful in combating an
act of bioterrorism. Take for example, an anthrax attack on a subway. One
possible scenario Groven’s team envisions is a 3D-printed drone, made from
biocidal material, that is flown into a subway car and ignited. The resulting
cloud of iodine gas would neutralize the anthrax and make the area safe.
The team is still in the testing phase and several questions
remain unanswered, including the amount of printed biocide needed to neutralize
a given amount of anthrax and the right mixtures needed to ensure proper rates
of combustion. So far, the results are very promising.
In her lab on a warm spring afternoon, Fidel Ruz-Nuglo, PhD
candidate, and Nicholas Ritchie, a sophomore in industrial engineering and an
expert on 3D printing, ignite a small strand of biocidal filament inside a
ventilation hood. There is a pop and a quick flash of light followed by a small
purple cloud of smoke.
“That’s the iodine,” Groven says.
Groven and her team have published several papers on this
work. But she says documenting this research is just the first step; more
challenges are ahead. “It’s very difficult to turn something you develop with
your students in a laboratory into a product that is actually manufactured and
used.” For Groven, success in the lab isn’t enough. There is too much at stake
when it comes to a possible biological attack. She is now in the process of
patenting this work though Mines’ Office of Research and Economic Development.
“Let’s develop something that can actually be implemented and help keep the
public safe,” she says.