Metal Doping Enabling Defective CoMo‐Layered Double Hydroxide Nanosheets as Highly Efficient Photosensitizers for NIR‐II Photodynamic Cancer Therapy

Abstract Photodynamic therapy (PDT) is attracting widespread attention as a promising strategy for tumor treatment. However, the efficacy of PDT is severely limited by the insufficient tissue penetration depth of the light source and low reactive oxygen species (ROS) generation efficiency. Herein, the metal doping strategy is reported to construct a series of defect‐rich M‐doped amorphous CoMo‐layered double hydroxide (a‐M‐CoMo‐LDH, M = Mn, Cu, Al, Ni, Mg, Zn) photosensitizers (PSs) for NIR‐II PDT. Especially, M‐doped CoMo‐LDH nanosheets are synthesized through a simple hydrothermal method and then etched by acid treatment to prepare defect‐rich a‐M‐CoMo‐LDH nanosheets. Under NIR‐II 1270 nm laser irradiation, the defect‐rich a‐Zn‐CoMo‐LDH nanosheets exhibit the optimal PDT performance compared with other a‐M‐CoMo‐LDH nanosheets, and also possess much higher ROS production activity (3.9 times) than that of the pristine a‐CoMo‐LDH, with a singlet oxygen quantum yield up to 1.86, which is the highest among all the reported PSs. After polyethylene glycol (PEG) modification, the a‐Zn‐CoMo‐LDH‐PEG nanosheets can function as an effective inorganic PS for PDT, effectively inducing cell apoptosis in vitro and eradicating tumors in vivo. Notably, transcriptome sequencing analysis and further molecular validation highlight the critical role of the apoptotic/p53/AMPK/oxidative phosphorylation signaling pathways in a‐Zn‐CoMo‐LDH‐PEG‐induced cancer cell apoptosis.