Credit: © 2007 ACS

Many toxicology studies of nanomaterials focus on human cells and animals. Now, however, a new study by researchers at Yale University in the US shows that single-walled carbon nanotubes (SWNTs) can interact with microbes and kill them.

Menachem Elimelech and colleagues1 made highly pure SWNTs and allowed the bacteria E. coli to swim in a solution containing the nanotubes before measuring their survival using fluorescence-based assays. A 60-minute incubation killed a substantial portion of the bacterial cells in a dose-independent manner and those that attached onto the surface of the SWNTs almost always died. It is suggested that direct contact between the cells and nanotubes is necessary to kill the bacteria. When E. coli was allowed to flow through an SWNT-coated filter, 80% of the cells that accumulated on the top of the filter did not survive.

Scanning electron microscopy images revealed that the E. coli cells had damaged membranes, suggesting that intracellular material is discharged and results in death of the bacteria. This study shows that pristine SWNTs can kill bacteria through direct physical contact and may be useful for making antimicrobial materials in the future.