Heterogeneous‐Structure‐Based AuNBs@TiO₂ Nano‐Photosensitizers for Computed Tomography Imaging Guided NIR‐II Photodynamic Therapy and Cancer Metastatic Prevention

Abstract Photodynamic therapy (PDT) is a minimally invasive cancer treatment that, despite its significant attention, faces limitations in penetration depth, which restrict its effectiveness. Herein, it is found that gold nanobipyramid (AuNBs) coated with TiO₂ can form a core–shell heterogeneous structure (AuNBs@TiO₂) with strong absorption at second near infrared (NIR‐II) region. A substantial quantity of reactive oxygen species (ROS), including singlet oxygen (¹O₂), superoxide anion radicals, and hydroxyl radicals, can be rapidly generated when subjecting the AuNBs@TiO₂ aqueous suspension to 1064 nm laser irradiation. The quantum yield for sensitization of ¹O₂ by AuNBs@TiO₂ is 0.36 at 1064 nm light excitation. In addition, the Au element as high‐Z atoms in the nanosystem can improve the ability of computed tomographic (CT) imaging. As compared to commercial iohexol, the AuNBs@TiO₂ nanoparticle exhibits significantly better CT imaging effect, which can be used to guide PDT. In addition, the nano‐photosensitizer shows a remarkable therapeutic effect against established solid tumors and prevents tumor metastasis and potentiates immune checkpoint blockade therapy. More importantly, here the great potentials of AuNBs@TiO₂ are highlighted as a theranostic platform for CT‐guided cancer photodynamic immunotherapy.