Inactivation of Bacillus anthracis Spores by Single-Walled Carbon Nanotubes Coupled with Oxidizing Antimicrobial Chemicals

In this study, we investigated the sporicidal effects of single-walled carbon nanotubes (SWCNTs) and SWCNTs combined with oxidizing antimicrobial chemicals, H2O2 and NaOCl, on B. anthracis spores. The results indicated that treatment with SWCNTs alone exhibited little sporicidal effect on B. anthracis spores, while treatment with H2O2 or NaOCl alone showed moderate sporicidal effect. The combination treatment with SWCNTs (100 mu g/mL) and H2O2 (1.5%) or NaOCl (0.25%) exhibited much stronger sporicidal effect on the spores, compared to treatment with H2O2 or NaOCl alone at the same concentrations, doubling the log reduction of viable spore number (similar to 3.3 log vs similar to 1.6 log). Such enhanced sporicidal efficiency was due to the synergistic effect contributed by the two individual antimicrobial mechanisms of SWCNTs and the oxidizing antimicrobial chemicals. The ordered sequential treatment with SWCNTs and H2O2 or NaOCl revealed that SWCNTs played the key role in making the spores more permeable/susceptible to chemicals. This study demonstrated the potential of combination treatment with SWCNTs and oxidizing antimicrobial agents in developing highly effective sporicidal agents/methods.