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
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