Cold plasmas have multipronged attack to destroy bacteria

18 October 2013

Researchers at Ruhr-Universität (RUB)in Germany have discovered how cold plasmas destroy bacteria at both the cellular and molecular level, making them efficient disinfectants.

 Depending on their specific composition, plasmas may contain different components, for example ions, radicals or light in the ultraviolet spectrum, so-called UV photons. Until now, scientists have not understood which components of the complex mixture contribute to which extent to the antibacterial effect.

The team led by Dr Julia Bandow, Head of the Junior Research Group Microbial Antibiotic Research at the RUB, analysed the effect of UV photons and reactive particles (radicals and ozone) on both the cellular level and on the level of single biomolecules (DNA and proteins).

The plasma reactor used by the research team
The plasma reactor used by the research team
Source RUB. © Jan-Wilm Lackmann

They found that on the cellular level, the reactive particles alone were most effective: they destroyed the cell envelope. On the molecular level, both plasma components were effective. Both UV radiation and reactive particles damaged the DNA; in addition, the reactive particles inactivated proteins.

“This is too great a challenge for the repair mechanisms and the stress response systems of bacteria,” says Junior Professor Dr Julia Bandow, Head of the Junior Research Group Microbial Antibiotic Research at the RUB.

“In order to develop plasmas for specific applications, for example for treating chronic wounds or for root canal disinfection, it is important to understand how they affect cells. Thus, undesirable side effects may be avoided right from the start.” The team reports in the “Journal of the Royal Society Interface”.

Atmospheric-pressure plasmas are already being used as surgical tools, for example in nasal and intestinal polyp extraction. Their properties as disinfectants may also be of interest with regard to medical applications. “In ten years, bacteria might have developed resistance against all antibiotics that are available to us today,” says Julia Bandow. Without antibiotics, surgery would become impossible due to high infection rates.


J.-W.Lackmann, et al. Photons and particles emitted from cold atmospheric-pressure plasma inactivate bacteria and biomolecules independently and synergistically, Journal of the Royal Society  Interface, 2013. doi: 10.1098/rsif.2013.0591


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