Ultrasound is a promising technique for treating cancer. Unlike laser light, used in photodynamic cancer therapy, ultrasound waves can reach deep into tissue—up to 12 cm—to treat deep tumors without damaging healthy cells. A team of researchers reporting in the journal Angewandte Chemie International Edition have now developed a sonodynamic cancer immunotherapy based on semiconducting polymer nanoparticles joined to immunomodulators that can be activated by ultrasound.