Whirlwind Acoustic Vortex-Regulated Intelligent Microbots for Enhanced Uniform Drug Bioaccumulation to Boost Systemic Immunity Against Large Tumors

Engineered bacteria as intelligent microbots preferentially targeting and colonizing tumors have overcome the poor delivery efficacy of nanomedicines toward large hypoxic tumors. In this study, Escherichia coli (E.coli) filled with gas vesicles is modified with drugs-loaded liposomes via amide condensation to achieve synergistic sono-chemotherapy. In this study, to regulate intelligent microbots for high-performance tumor therapy, a whirlwind-focused acoustic vortex (FAV) is used, which has a larger focal region and stronger thermal and cavitation effects as compared to the conventional focused ultrasound (FUS). The large tumors receiving single FAV irradiation exhibited enhanced and uniform drug bioaccumulation throughout the entire tumor due to the full coverage and rapid and uniform heating characteristics of FAV irradiation. The FAV-regulated intelligent microbots caused more serious DNA double-strand breaks (DSBs), activated the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway to release immune cytokines, and induced immunogenic cell death (ICD) for innate immunity activation. The activated systemic immunity is further boosted by combining FAV-regulated sono-chemotherapy with immune checkpoint blockades to increase the infiltration of cytotoxic T cells, decrease the population of immunosuppressive cells, and finally reshape the immunosuppressive tumor microenvironment. This study provides a synergistic strategy via regulating intelligent microbots for large tumor immunotherapy.