Testing and Evaluation of Nanoparticle Efficacy on E. Coli, and Bacillus Anthracis Spores

Fast, effective, antimicrobial and antisporicidal methods against biological warfare agents, which include the spores from Bacillus anthracis, are urgently required in the biological warfare agent neutralization arena. Metal nanoparticles, which have been previously shown to have antimicrobial effects against vegetative microbes, show great promise in having likewise efficacy against the more resistant spores. In this study, the suitability of commercial and developmental dry-powder nanoparticles against Escherichia coli, and Bacillus anthracis spores was evaluated. Testing included various metal oxides and metals in nanopowder form, dispersed in water. Nanoparticles with average particle sizes equal to or less than 25nm composed of silver, as well as silver in combination with iron, and nickel, were found to have significant reduction of E. coli and B. anthracis bacteria and spores, in some cases in excess of an 8-log reduction in bacterial count. The dispersed dry powders were shown to efficiently kill vegetative bacterial species. In addition to the specific composition of the nanoparticle, the testing demonstrated that the particle size is a critical parameter for efficacy. Based on these tests, such materials may have application as countermeasures to biowarfare agents.