Fig 4. Nature, concentrations and toxicity of the species produced in PAL.

A: Detection by cyclic voltammetry at a platinized microelectrode of hydrogen peroxide and nitrites produced in PBS after 1 min to 15 min of He plasma treatment. B: He-N₂ treatment. C: Model experiment mimicking PAL. 1: control bacteria incubated for 2 hours in PBS. 2: E. coli exposed to He plasma for 10 min and 2 hr storage and % of surviving cells evaluated by the CFU method. 3: Bacteria exposed to PAL (PBS treated for 10 min, He plasma) for 2 hours for 2 hours at 4°C. 4: Bacteria exposed to a mix (2.3 mM Hydrogen peroxide and 0.5 mM nitrite) for 10 min or 5: for 2 hours for 2 hours at 4°C and % of surviving cells was evaluated by the CFU method. The values are means ± SEM of 3 separate experiments (** p<0.05) vs control).