An Activatable Prodrug Nanosystem for Ultrasound-Driven Multimodal Tumor Therapy and Metastasis Inhibition

Ultrasound, featuring deep tissue penetration and noninvasiveness, offers a new opportunity to activate functional materials in a tumor-selective manner. However, very few direct ultrasound-responsive redox systems are applicable under therapeutic ultrasound (1 MHz). Herein, the investigations on nanoprodrug of DHE@PEG-SS-DSPE are reported, which exhibit glutathione-activated release of dihydroethidium (DHE) in tumor cells. DHE is stable with good biosafety and is transformed into cytotoxic ethidium to induce DNA damage under medical ultrasound irradiation, accompanied by the generation of reactive oxygen species. Further, DHE@PEG-SS-DSPE could effectively induce ferroptosis through glutathione depletion, lipid peroxide accumulation, and downregulation of glutathione peroxidase 4. In vivo studies confirmed that DHE@PEG-SS-DSPE nanoparticles effectively inhibit both the growth of solid tumors and the expression of metastasis-related proteins in mice, thus effectively inhibiting lung metastasis. This DHE-based prodrug nanosystem could lay a foundation for the design of ultrasound-driven therapeutic agents.