The toxic effects of single wall carbon nanotubes on e. coli and a spore-forming bacillus species

The toxicity effects of single wall carbon nanotubes (SWCNTs) on Escherichia coli (E. coli) and Bacillus atropaheus (Ba) were here investigated. As-received and chemically purified nanotubes were exposed to the aforementioned cells and representative samples of the interacting complexes were inoculated in an agar plates for colony-growth quantification. It was observed that the higher the concentrations of nanotube the higher the degree of toxicity on the cells. It was also observed, that the as-received nanotubes induced more toxicity on the microorganisms, than the purified nanotubes. Also, it was shown that whereas the E. coli is more susceptible to the toxic effects of nanotubes, especially to raw CNTs, the Bacillus spores were typically more resistance. Cell viability count through a fluorescent stain procedure was also performed on the E.coli, and it was observed that the longer the interacting times between the microorganisms and the nanotubes, the larger the number of apoptotic cells. It seems that the presence of the nickel catalyst in the "asreceived" nanotubes is an important source of toxicity for the bacteria. Further purification process of the nanotubes, effectively removed the metal catalyst reducing their toxic properties. The current research program will strengthen the basis for tailoring the toxic properties of carbon nanotubes based antimicrobial applications.