Conjugated-Polymer-Based Photodynamic Therapy

Photodynamic therapy (PDT) is a promising method for cancer treatment owing to its high spatiotemporal precision and minimally invasive properties. The efficiency of reactive oxygen species (ROS) production by photosensitizers (PSs) directly affects PDT efficacy. Conjugated polymers (CPs) exhibit excellent light-harvesting capabilities and effective intra- and intermolecular energy transfer between CPs and traditional PSs by the "molecular wire effect," leading to a significant improvement in ROS generation efficiency when PSs are carefully paired with suitable CPs as energy donors. The recently proposed "polymerization-enhanced photosensitization effect" further reveals that donor-acceptor type CPs can directly function as high-performance PSs. Recently, two-photon excitation and chemiluminescence excitation technologies are employed to enhance the penetration depth, a common challenge in phototherapy of CP-based PDT systems. Furthermore, if precisely designed, CPs can endow the system with useful functions such as photothermal effects and drug-delivery capacity, which can lead to a synergistic therapy with PDT. Here, recent advances are summarized in CP-based PDT, including its underlying phenomena, mechanisms, and applications. Strategies for improving PDT performance are the focus of the discussions. In the conclusion, challenges and opportunities are discussed by considering further perspectives.