Anthracene-Bridged Photosensitizers for Effective and Safe Photodynamic Therapy

Photodynamic therapy (PDT) is a minimally invasive therapeutic modality. However, the residual photosensitizers (PSs) after PDT can still produce toxic singlet oxygen ( 1 O 2 ) under sunlight to damage normal tissues. The PS that can be switched off after PDT is desirable but rare. Herein, we propose a general strategy to design effective and self-degradable PSs by embedding an anthracene bridge into donor–acceptor (D–A) structures. First, the steric anthracene can regulate the orbital distribution for enhancing the 1 O 2 production capacity. More importantly, the anthracene is responsive to the self-produced 1 O 2 for self-degradation. Besides, the degradation rate can be fine-tuned by the hydrophilicity of PSs. In this way, the PSs can realize a balance between treatment and suicide to ensure PDT and post-treatment safety. This work provides new insights into the design of degradable PSs with a clear mechanism, aiming to improve the post-safety of PDT.