Safety evaluation of nonthermal atmospheric pressure plasma liquid treatment: Single DNA molecule-based method

• A method for safety evaluation of NTP plasma treatment of biocontaminated liquids is provided.
• Escherichia coli and λDNA in isotonic or acidic liquid are mixed and exposed to plasma.
• Single molecule measurements demonstrate the effect of NTP bacteria decontamination on extracellular dsDNA.
• There is correlation between the bacteria inactivation and the extracellular dsDNA damage.
• The NTP safety versus the decontamination effect is evaluated.

We evaluated the beneficial effect of biological decontamination versus the DNA double strand breakage for a range of plasma jet treatment durations. We confirmed the effectiveness of the experimental procedure using a mixture of Escherichia coli and λDNA in buffered solutions. We simultaneously obtained the DNA cutting rate, k, and the decimal reduction value of the viability, D, for safety evaluation of plasma treatment. The results indicate that the toxicity of injected radicals could be quantitatively evaluated by measuring the DNA cutting rate k. In addition, the evaluation could be performed fast without cell cultivation.