Penetration effect of the kINPen plasma jet investigated with a 3D agar-entrapped bacteria model

Abstract

Elucidation of the penetration effect of cold atmospheric plasma on human tissues is essential for achieving a better comprehension of its diverse biomedical applications. The aim of this work was to investigate the penetration effect of the kINPen plasma jet, one of the most extensively studied plasma sources, using a novel 3D agar-entrapped bacteria model. In this study, 2.0 % agar was used as the main skeleton of the 3D model to simulate human skin tissue. Then, the feasibility and validity of evaluating the kINPen’s tissue penetration effect based on this 3D model system were explored. Our results showed that the bacteria colonies could grow uniformly within the 2 % agar skeleton. The kINPen exhibited a dose-dependent inhibitory effect on bacterial growth in the 3D model (P < 0.05). Further experiments revealed that the penetration effect of the kINPen is closely related to the long-lived active species (e.g., H2O2) produced by the plasma jet. By performing direct and indirect treatments, we found that possible components other than long-lived reactive species, such as short-lived reactive species, electric fields, UV light and electrons, play a non-negligible role in agar-entrapped bacteria inactivation. In comparison to the potassium iodide-starch model, the 3D agar-entrapped bacteria model can more objectively and sensitively reflect the penetration effect of the kINPen. Finally, the 3D agar-entrapped bacteria model is expected to be an effective assessment tool for evaluating biologically relevant penetration effect of cold atmospheric plasma.