Enhanced population of excited single state strategy: Irradiation and ultrasound dual-response and host tumor-driven nano-sensitizers construction in triple synergistic therapy

Phototheranostics is an emerging field in synergistic antitumor therapy in which irradiation and sensitizers are combined to produce reactive oxygen species (ROS), bio-images, and high temperatures. All of these are arrived from the energy of sensitizers, which located in excited single state (S₁). Undeniably, the decentralization of the S₁ population indirectly decreases the effect of each individual treatment. In this study, a strategy was proposed for enhancing the S₁ population, and a sensitizer with mitochondrial targeting property, 1,4-indolyl iodinated pyrrolo[3,2-b]pyrrole derivative (2I-TPIS), was assembled into adenosine triphosphate (ATP)-responsive nanoparticles (DPA-2I NPs) to achieve dual responses to irradiation and ultrasonication (US) for application to photo-sonodynamic therapy (PSDT). Compared with monotherapies, 2I-TPIS generated more ROS in PSDT, inducing mitochondrial autophagy and apoptosis, which in turn triggered immunogenic cell death (ICD). Subsequently, DPA-2I NPs were constructed and self-assembled with the chemotherapeutic agents DPA-Cd and 2I-TPIS to achieve a triple synergistic strategy involving chemotherapy (CT) and PSDT. DPA-2I NPs exhibited absolute sensitization, intra-tumoral overexpression of ATP, and disassembly. Importantly, the biosafety and potent antitumor efficiency of the DPA-2I NP-based “PSDT + CT” therapy were revealed using a 4T1 tumor model. The study results provide insights into the design of sensitizers possessing a sufficient S₁ population and a highly efficient tumor ablation capacity derived from molecular structural modulation, further enabling triple synergistic antitumor therapies, and expanding the clinical application of sensitizers.