Ultrasound‐Responsive Oxygen‐Carrying Pollen for Enhancing Chemo‐Sonodynamic Therapy of Breast Cancer

The tumor‐suppressing efficacy of either chemotherapeutics or gaseous drugs has been confirmed in treating the triple negative breast cancer (TNBC), while the efficacy of single treatment is usually dissatisfactory. Herein, a novel ultrasound responsive natural pollen delivery system is presented to simultaneously load chemotherapeutics and gaseous drugs for synergistic treatment of TNBC. The hollow structure of pollen grains carries oxygen‐enriched perfluorocarbon (PFC), and the porous spinous process structure adsorbs the chemotherapeutic drug doxorubicin (DOX) (PO/D‐PGs). Ultrasound can trigger the oxygen release from PFC and excite DOX, which is not only a chemotherapeutic but also a sonosensitizer, to realize chemo‐sonodynamic therapy. The PO/D‐PGs are demonstrated to effectively enhance oxygen concentration and increase the production of reactive oxygen species in the presence of low‐intensity ultrasound, synergistically enhancing the tumor killing ability. Thus, the synergistic therapy based on ultrasound‐facilitated PO/D‐PGs significantly enhances the antitumor effect in the mouse TNBC model. It is believed that the proposed natural pollen cross‐state microcarrier can be used as an effective strategy to enhance chemo‐sonodynamic therapy for TNBC.