The Effect of Plasma Activated Water on Acanthamoeba castellanii

Cold Plasma is an emerging non-thermal, chemical-free, environmentally friendly disinfection technology. Plasma-activated water has received considerable attention from researchers in recent years. Despite extensive studies on the antibacterial effects of plasma-activated water, its anti-eukaryotic effects have not been identified. In humans, Acanthamoeba causes granulomatous encephalitis, skin ulcers, and Acanthamoeba keratitis. Considering the health importance of Acanthamoeba, this study investigated the anti-amoeba effect of plasma-activated water on trophozoites and cysts of Acanthamoeba castellanii.

In this study, plasma-activated water prepared by the cold atmospheric plasma method.Physicochemical properties of produced water were evaluated by measuring pH, hydrogen peroxide, nitrite, and nitrate. To assess the effect of plasma-activated water on A. castellanii, trophozoites and cysts were exposed to plasma-activated water for 0.5, 1, 2, 3, 4, and 5 hours. Three replicates were examined each time. At the mentioned times, cell viability was calculated by trypan-blue staining and counting on a hemocytometer, and the results were statistically analyzed.

Based on the physicochemical results, the mean pH of plasma-activated water in this study was about 3.4, and the amount of hydrogen peroxide, nitrate, and nitrite were 102, 737, and 36.94 μM, respectively. The present study showed that plasma-activated water killed A. castellanii trophozoites after three hours of exposure and A. castellanii cysts after four hours of exposure. On the other hand, some trophozoites gradually became cysts after exposure to plasma-activated water. These cysts became more resistant to plasma-activated water and inactivated after five hours of exposure.

In this study, for the first time, the effect of plasma-activated water on A. castellanii was investigated. The results of the present study showed that plasma-activated water is able to inactivate A. castellanii trophozoites and cysts. Therefore, plasma-activated water can be used to disinfect and inactivate A. castellanii.