Effects of cold atmospheric plasma treatment on 24-h and on 72-h in situ biofilms formed on 288 microstructured titanium slices.

In each treatment subgroup 18 independent biofilm covered slices were analyzed by four different investigation methods (144 slices for 24 hours biofilms and 144 slices for 72 hours biofilms). Experimental treatment sequences I–III (no air/water spray, air/water spray, air/water spray plus additional irradiation), subgroups a–c with different intensities of plasma irradiation (no plasma, 3 W, 5 W). Bacterial biofilms were analyzed by contact culture (Rodac), fluorescence microscopy (live/dead staining), scanning electron microscopy (SEM) and analysis of the total protein amounts (bicinchoninic acid protein assay). Fluorescence microscopy was evaluated for three different parameters (total fuorescence intensity, area without fluorescence and ratio of red (dead) versus green (vital) fluorescence.*statistically significant differences of total protein amounts in comparison to no treatment biofilm control (U-test: p