Water microdroplet platforms for sustainable, reagent-free viral disinfection

The repeated emergence of global pandemics has highlighted the urgent need for safe, sustainable, and effective disinfection platforms that eliminate viruses without producing toxic by-products or causing surface damage associated with conventional methods such as ultraviolet irradiation and chemical disinfectants. Here, we present water microdroplet platforms that exploit reactive oxygen species (ROS) spontaneously generated at the air-water interface of micron-sized water droplets, providing a reagent-free and cost-effective approach to viral inactivation. Bacteriophage T7 and lambda (λ), together with MS2 (a non-enveloped RNA bacteriophage) and Phi6 (an enveloped RNA bacteriophage), were selected as model viral systems to evaluate disinfection efficacy across different viral structures.

Water microdroplets with an average diameter of approximately 5 μm, generated by gas nebulization or mesh nebulizers, achieved more than 99.999% viral inactivation within 20 min. Transmission electron microscopy, protein profiling, and DNA analyses revealed that microdroplet-derived ROS disrupted viral capsid integrity and degraded nucleic acids, leading to loss of infectivity. The in situ generation of multiple ROS species was directly confirmed by mass spectrometry using a TEMPO probe and by fluorescence imaging with ROS-sensitive dyes, while scavenger assays verified the ROS-dependent nature of viral inactivation. Practical feasibility was demonstrated by treating fresh produce surfaces such as lettuce and potato, as well as porous and textile materials, resulting in more than 98% viral inactivation without chemical residues.

Together, these results demonstrate that water microdroplets provide an effective, reagent-free, and environmentally benign viral disinfection strategy with broad substrate compatibility for applications in food safety, healthcare, and textile-associated environments.