Plasma jet's shielding gas impact on bacterial inactivation

Abstract

One of the most desired aims in plasma medicine is to inactivate prokaryotic cells and leave eukaryotic cells unharmed or even stimulate proliferation to promote wound healing. The method of choice is to precisely control the plasma component composition. Here the authors investigate the inactivation of bacteria (Escherichia coli) by a plasma jet treatment. The reactive species composition created by the plasma in liquids is tuned by the use of a shielding gas device to achieve a reactive nitrogen species dominated condition or a reactive oxygen species dominated condition. A strong correlation between composition of the reactive components and the inactivation of the bacteria is observed. The authors compare the results to earlier investigations on eukaryotic cells and show that it is possible to find a plasma composition where bacterial inactivation is strongest and adverse effects on eukaryotic cells are minimized.

Non‐Thermal Plasma in Contact with Water: The Origin of Species

“…This suggests that not just the amount, but also the selectivity of radical generation can be controlled by different plasma conditions, such as plasma feed gas humidity and oxygen content (see Figure S12 in the Supporting Information). Such an ability to tune the nature of the reactive species in the liquid sample presents great potential for possible cold plasma applications …”

“…Such an ability to tune the nature of the reactive speciesi n the liquid sample presents great potential for possible cold plasma applications. [48] Ozone and 1 O 2 are readily availablei no xygen-rich plasma systems. [34,49,50] These species may lead to the formation of other reactive species, for example, ·OH and O 2 · À radicals, by post-exposure reactions in the liquid sample.…”

Helium plasma jet interactions with water in well plates

“…Dynamics and environmental factors that modify the plasma–liquid interaction may produce a change in PAM chemical properties (through transport of gas‐phase species and their solvation) and eventually its biomedical effect. Studies have been performed on the influence of environmental parameters, such as the consequences of shielding gases on plasma jets or the effect of touching and nontouching plasma jets with liquid . Apart from the chemical composition of the gas and liquid, other environmental parameters including plasma jet geometry, liquid container topology, and its material properties can affect the dynamics of gas flow and the transport of species to the liquid layer.…”

How to produce an NOx- instead of Ox-based chemistry with a cold atmospheric plasma jet

“…However, the amount and composition of this RONS cocktail can vary significantly, e.g., from a nitrogen oxides (NO x )‐dominated plasma chemistry to an O x (atomic oxygen, O, singlet oxygen, , ozone, O 3 )‐dominated chemistry . However, very different CAP source concepts were proven to be effective, e.g., for their antibacterial properties . Also commercially available plasma sources that are certified as medical products and applied for the treatment of chronic wounds and pathogen‐based diseases are based on different concepts and produce very different reactive species outputs: The kinpen MED (neoplas tools GmbH, Germany) is an argon‐operated jet operated at a frequency of 1 MHz and is very similar to the kinpen Sci studied in this work (however, the kinpen MED is operated in a burst mode at a frequency of 2.5 kHz with 50% duty cycle) and produces an O/O 3 ‐dominated plasma chemistry .…”

“…It has previously been shown that by changing the shielding gas composition, the reactive species output of the jet can be significantly influenced . The setup has been used in further studies, focusing on RONS in plasma‐treated liquids as well as in biological investigations, which revealed that both the antimicrobial effectiveness as well as the cytotoxicity, genomic, and proteomic response depend on the composition of the shielding gas . Additionally, a control of the RONS composition can be achieved by using molecular feed gas admixtures: In ref .…”