Assessment of Immunological Responses to Water Electrospray: A Novel Non-Chemical Biocide for Safe Disinfection

Water electrospray is small charged droplets generated by a laboratory-designed prototype module. Extensive investigations have explored its physical properties and identified a potential non-chemical biocide against air-borne pathogens. However, since humans can inhale water electrospray particles through breath, humans' safety and potential toxicity warrant investigation. Hence, to offer insights into the effect of water electrospray on humans, we analyzed the immunopathological response to water electrospray using a nasal challenge mouse model. For this, we accessed the fundamental immune responses following the water electrospray intranasal challenge by comparing its effect with sodium hypochlorite, a biocidal agent with known toxicity. Our results indicate that water electrospray did not induce pathological immune reactions: challenged mice did not exhibit body weight loss and increased inflammatory cytokine production. Furthermore, histopathological analysis revealed that water electrospray did not damage the lung tissue, whereas sodium hypochlorite–treated mice showed significant lung tissue damage with signs of neutrophils and eosinophils infiltration. Finally, transcriptomic analysis on lung tissue confirmed the absence of pathological immune response in water electrospray-treated mice compared with sodium hypochlorite–treated mice. Together, we provide evidence that water electrospray is a safe technology for its use in disinfecting air-borne pathogens with little or no effect on immune system activation at the preclinical level. The treatment groups were categorized into distilled water, water electrospray, and sodium hypochlorite, with three mice assigned to each group. A total of five intra-nasal treatments were administered to each group. Subsequently, the lung tissues of the respective mice were obtained, and RNA was isolated for analysis.