"For anthrax to be effective, it has to be made into a fine powder that can easily enter the lungs when inhaled," said Ya-Ping Sun of Clemson University. "That is what makes it lethal. What we have done is come up with an agent that clings to the anthrax spores to make their inhalation into the lungs more difficult."

Ya-Ping Sun and colleagues originally used carbon nanotubes as "unique one-dimensional semiflexible scaffolds for displaying carbohydrates … to bind and aggregate pathogenic cells such as E. coli O157:H7." E. coli can cause severe food poisoning.

At a presentation given by Sun, Stephen Lee of the US Army Research Office asked about the use of the materials for aggregating anthrax spores, and the team decided to investigate further.

The researchers attached monosaccharides – either derivatized mannose or galactose – to single-walled carbon nanotubes. These attached to carbohydrates expressed on the surface of anthrax spores, including rhamnose, 3-O-methyl rhamnose and galactosamine. The process was aided by the presence of divalent calcium cations and the resulting aggregates were visible to the naked eye.

The aggregation process reduced the percentage of anthrax colony forming units by up to 97.7%.

Treatment with polystyrene nanospheres attached to the same sugars did not cause the anthrax spores to aggregate, despite the nanospheres being able to adhere to E. coli strains.

"The nanotubes are unique in displaying the carbohydrate molecules to make such [anthrax] binding and aggregation possible," said Sun. The scientists believe the process requires a specific arrangement of carbohydrates for the interaction with the spore surface, which the nanotube is able to provide.

"We see potential applications in the development of countermeasure technologies that may not be specific/selective, but are adequate for minimizing the inhalation infection risks," said Sun. "We also see potential uses in rapid screening of white powdery materials for the possible presence of anthrax spores."

Now Sun says the team needs to validate the same approach for the more lethal Ames strain spores. "We would also like to explore the technology aspects to move towards the potential applications," he added.

The researchers reported their work in Journal of the American Chemical Society.