An NIR-II Excitable AIE Small Molecule with Multimodal Phototheranostic Features for Orthotopic Breast Cancer Treatment

One-for-all phototheranostics, referring to a single component simultaneously exhibiting multiple optical imaging and therapeutic modalities, has attracted significant attention due to its excellent performance in cancer treatment. Benefitting from the superiority in balancing the diverse competing energy dissipation pathways, aggregation-induced emission luminogens (AIEgens) are proven to be ideal templates for constructing one-for-all multimodal phototheranostic agents. However, to this knowledge, the all-round AIEgens that can be triggered by a second near-infrared (NIR-II, 1000-1700 nm) light have not been reported. Given the deep tissue penetration and high maximum permissible exposure of the NIR-II excitation light, herein, this work reports for the first time an NIR-II laser excitable AIE small molecule (named BETT-2) with multimodal phototheranostic features by taking full use of the advantage of AIEgens in single molecule-facilitated versatility as well as synchronously maximizing the molecular donor-acceptor strength and conformational distortion. As formulated into nanoparticles (NPs), the high performance of BETT-2 NPs in NIR-II light-driven fluorescence-photoacoustic-photothermal trimodal imaging-guided photodynamic-photothermal synergistic therapy of orthotopic mouse breast tumors is fully demonstrated by the systematic in vitro and in vivo evaluations. This work offers valuable insights for developing NIR-II laser activatable one-for-all phototheranostic systems.