Autofluorescence-Guided Removal of Bacterial Biofilms From Tissues Using Cold Atmospheric Pressure Plasma (CAP)

Cold atmospheric pressure plasma (CAP) has the potential to completely remove biofilms from surfaces. The goal of this study is to employ the autofluorescence nature of bacterial biofilms to guide the removal of these biofilms using a CAP scalpel. Pseudomonas fluorescens biofilms, which produce a green fluorescence under 405-nm UV light, were grown on 12 chicken samples. The tissue model (chicken tissue) is placed on a motorized $X$ – $Y$ stage with the plasma discharge device directly above the sample. Fluorescent-guided CAP treatment of biofilm regions was carried out using a 1.37-lpm Ar/H2O plasma device with $39.5\times 54\,\,{\mathrm{ mm}}^{2}$ dimension and a $1\times 0.6\,\,{\mathrm{ mm}}^{2}$ plasma discharge outlet with discharge speed was 1 mm/s and sample distance of 4 mm. The discharge voltage and current were 3.24 kV and 1.2 mA, respectively. Results based on analysis of the fluorescent images show that 97% biofilm removal; colony-forming unit analysis confirms that up to 99.98% of the bacteria are now absent from the tissue’s surface. This is the first instance of two new applications: 1) using CAP to remove bacterial biofilms from soft tissues and 2) employing CAP in an image-guided procedure.