Application of air ions for bacterial de-colonization in air filters contaminated by aerosolized bacteria

We aerosolized the Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis) bacteria and collected them on membrane filters. Then we generated air ions by applying a high voltage to a carbon fiber tip and applied them to the contaminated filters. The antibacterial efficiency was not significantly affected by the bacteria being Gram-positive or Gram-negative, however, negative ions showed a lower antibacterial efficiency than positive ions to both E. coli and S. epidermidis, even though the concentration of negative air ions was much higher than that of positive air ions. With a field emission scanning electron microscope (FE-SEM) images and fluorescence microscopy images using a LIVE/DEAD BacLight Bacterial Viability Kit, electrostatic disruption of the bacteria was found to be the dominant antibacterial effect.

Research Highlights
► This study examined the effects of air ions generated by a carbon fiber ionizer on the inactivation of bioaerosols.
► When the ion exposure time and the ion generation concentration were increased, the antibacterial efficiency increased.
► The bioaerosols carried a significant number of negative electrical charges.
► Negative ions showed lower antibacterial efficiency than positive ions to both E. coli and S. epidermidis, even though the concentration of negative air ions was much higher than that of positive air ions.