NOVEL ASPECTS OF THE INTERACTION BETWEEN STAPHYLOCOCCUS AUREUS BACTERIUM AND CARBON NANOTUBES
János Fent and Susan Lakatos
Department of Pathophysiology, Laboratory Institute for Health Protection, Medical Centre of Hungarian Defense Forces
H-1134, Róbert Károly krt. 44, Budapest, Hungary
Vast amount, although sometimes contradictory, literature and data are available on the biological effect of single-walled carbon nanotubes exerted on various bacterial strains. In some cases, the presence of nanoparticles results in a decrease in bacterial counts. The variability of findings can be attributed to different experimental setups. However, rotating/shaking of bacterial samples in the presence of nanotubes is part of most experimental setups in order to increase the probability of contacts between bacteria and nanotubes. According to our experience, increased rotating speed even in the absence of single-walled carbon nanotubes (SWNT) resulted in decreased bacterial counts attributable either to adhesion of the bacteria to the wall of the sample container and/or to the decrease in their viability. Interestingly enough, the extent of this effect is modified in the presence of pristine or covalently modified single-walled nanotubes. In the case of Staphylococcus aureus pristine SWNT partly, amid-and PEG-modified SWNTs completely prevents the shaking caused bacterial count decrease, while the carboxyl-modified one has no preventive effect. The extent of preventive effects correlates well with the various aggregation propensity between various SWNTs and S. aureus. The small amounts of aggregates found between S. aureus and the carboxyl-modified SWNT can be attributed to the repulsive effect between their negative charges.