Investigation of Physicochemical Properties of Plasma Activated Water and its Bactericidal Efficacy

Presently, the world is using different types of disinfectants for various applications such as disinfecting instrument surfaces in the medical field, sanitizers in airplanes, wash-rooms, etc. These disinfectants carry various harmful chemicals that harm our ecosystem. Hence in search of more eco-friendly disinfectants, our research leads us to explore plasma activated water (PAW). PAW can be produced with the help of plasma interaction with water. This interaction changes the physicochemical properties of water and makes it reactive to kill pathogens. PAW can be used for a wide variety of applications such as food preservation, fast germination, sterilization agents, etc. In the present work, PAW has been formed using non-thermal plasma and different gas or gas mixture as plasma forming gas. Its physicochemical properties have been studied to identify pH value, oxidation reduction potential, and chemical species formed after plasma interaction with a water surface. Further, the study has been carried out to determine the disinfectant ability of PAW for two types of pathogens named Staphylococcus aureus and Pseudomonas aeruginosa. Different bactericidal methods have been adopted to confirm the results. SEM, fluorescence microscopy, and release of nucleic acids and proteins from raptured cell membrane of pathogens clearly show bactericidal efficacy of PAW. The important finding of the present work is the effective killing of pathogens by PAW in a short span of interaction time (≤ 10 s). The PAW has a strong possibility of using it as a disinfectant to kill a wide variety of pathogens and micro-organisms.