have found that single-walled carbon nanotubes (SWCNT) can kill bacteria, such as E coli, by severely damaging their cell walls.
Using E coli as test cells, the researchers incubated cultures of the bacteria in the presence of the nanotubes for up to an hour. They found that the microbes were killed outright, but only when in direct contact with aggregates of the SWCNTs touching the bacteria.
‘We began the study out of concerns for the possible toxicity of nanotubes in aquatic environments and their presence in the food chain,’ said Menachem Elimelech, professor and chair of chemical and environmental engineering at Yale. ‘While nanotubes have great promise for medical and commercial applications there is little understanding of how they interact with humans and the environment.’
According to Elimelech, the bacteria were killed by the long, thin nanotubes puncturing the cells to cause cellular damage. The researchers had ruled out metal toxicity as a source of the cell damage because the SWCNTs were rigorously synthesised and purified in the laboratory.
‘We're now studying the toxicity of multi-walled carbon nanotubes and our preliminary results show that they are less toxic than SWCNTs,’ said Elimelech. ‘We are also looking at the effects of SWCNTs on a wide range of bacterial strains to better understand the mechanism of cellular damage.’
Elimelech also said that the SWCNTs could be used to create antimicrobial materials and surface coatings to improve hygiene, while their toxicity could be managed by embedding them to prevent their draining into the environment.