Free Radicals Generated in Perfluorocarbon–Water (Liquid–Liquid) Interfacial Contact Electrification and Their Application in Cancer Therapy

Electron transfer during solid–liquid contact electrification has been demonstrated to produce reactive oxygen species (ROS) such as hydroxyl radicals (^•OH) and superoxide anion radicals (^•O₂^–). Here, we show that such a process also occurs in liquid–liquid contact electrification. By preparing perfluorocarbon nanoemulsions to construct a perfluorocarbon–water “liquid–liquid” interface, we confirmed that electrons were transferred from water to perfluorocarbon in ultrasonication-induced high-frequency liquid–liquid contact to produce ^•OH and ^•O₂^–. The produced ROS could be applied to ablate tumors by triggering large-scale immunogenic cell death in tumor cells, promoting dendritic cell maturation and macrophage polarization, ultimately activating T cell-mediated antitumor immune response. Importantly, the raw material for producing ^•OH is water, so the tumor therapy is not limited by the endogenous substances (O₂, H₂O₂, etc.) in the tumor microenvironment. This work provides new perspectives for elucidating the mechanism of generation of free radicals in liquid–liquid contact and provides an excellent tumor therapeutic modality.