Figure 1: Cell number of recovered HaCaT cells (a) 24 h after treatment with surface DBD/air (red line; ) or DBD/argon (blue line; ) plasma for 20 s to 300 s and induction of apoptosis (b) after DBD/air treatment ( h after plasma treatment, ○ = 24 h after plasma treatment; ). Apoptosis was analysed by flow cytometry using Annexin V-FITC and PI (early apoptotoc cells = Annexin V+PI−). Untreated cells served as controls (see time 0). Results are given as mean ± SEM. , , (-test), (Mann-Whitney test) versus control cells; , (-test); (Mann-Whitney test).