Wound-Based Bacterial Biofilm Imaging for Selective Cold Atmospheric Pressure Plasma Treatment

Bacterial biofilms on chronic wounds are a major global health concern. They delay wound healing and even cause further deterioration. They have also been shown to be highly resistant to treatment options such as the use of antibiotics and antiseptics. Cold atmospheric pressure plasmas (CAP) have the potential to remove biofilms from chronic wounds. The goal of this study is to develop an imaging technique to identify biofilm regions on a wound surface for selective treatment with a CAP jet, thereby, avoiding damage to healthy tissue. The imaging technique is carried out using Trypan Blue, a dye that selectively stains dead cells as well as bacterial biofilms. Various combinations of ambient multi-colored LED lights were explored to obtain maximum differentiation between the blue-stained biofilm regions and the substrates during image acquisition with the aid of a monochrome camera. CAP treatment of biofilm regions was carried out using a 1.37 lpm Ar/H 2 O plasma jet device with discharge voltage of 3.54 kV and discharge current of 1.2 mA. The average speed of the plasma jet over the substrate is 1 mm/s and the gap between the substrate and the discharge is 2 mm. This in vitro study was carried out on 12 glass and 10 chicken tissue substrates and imaging results were visually and statistically compared to fluorescence imaging by comparing the area of biofilm regions obtained by both methods. Also, the action of the plasma discharge was evaluated via the fluorescence images. CAP treatment of biofilm on chicken tissue has shown the ability to remove the biofilm, and these results will be presented.