Dye Sensitized Lanthanide‐Triplet Cascade Energy Transfer for Near‐Infrared Therapy

Abstract Near‐infrared light sensitized reactive oxygen species generation holds significant potential for photocatalysis, organic synthesis, and photodynamic therapy. Conventional approaches, however, often require complex NIR photosensitizer design or rely on inefficient upconversion‐based energy transfer processes to overcome the limited tissue penetration depth of visible light for common photosensitizers. Herein, a straightforward and efficient strategy is presented for NIR‐sensitized ROS production through a rationally designed triplet energy transfer cascade. This approach employs Yb 3 ⁺‐doped lanthanide nanoparticles (YbNPs) as an energy transducer to couple a strong NIR‐absorbing dye (IR806) with a commonly used photosensitizer (chlorin e6, Ce6). Under NIR irradiation, IR806 is populated to singlet excited states, undergoes intersystem crossing, and subsequently sensitizes the Ce6 triplet state via a dye sensitized lanthanide‐triplet (DSLT) energy transfer pathway (IR806 → Yb 3 ⁺ → Ce6), without populating the higher‐lying excited singlet state of Ce6. The activated Ce6 triplet state then efficiently generates ROS through energy transfer to molecular oxygen. This facile and highly efficient NIR‐sensitized ROS generation platform effectively suppressed tumor growth in vivo, demonstrating its promise as a novel nanomedicine paradigm. The strategy exhibits considerable potential for driving photocatalytic organic transformations and biological medicine.