Conjugated‐Polymer‐Based Photodynamic Therapy

Abstract

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.

Immunotherapy: cancer immunotherapy and its combination with nanomaterials and other therapies

“…It has been clinically applied in tumor treatment with minimal damage to healthy tissues during local treatment. 195 But tumor recurrence and metastasis have restricted the use of PDT in the therapy of solid tumors and advanced cancers. 196 Advanced nanomedicines have recently been designed to enhance the effectiveness of PDT.…”

Crystallization-Driven Self-Assembly toward Uniform Nanofibers Containing a Donor–Acceptor Core with Near-Infrared Absorption/Emission, Photodynamic, and Photothermal Activities: A Small Variation on the Structure of Donor–Acceptor Segment Matters

“…Different from π-conjugated homopolymers and homo-oligomers, π-conjugated copolymers and co-oligomers containing both D and A (D = electron-rich donor and A = electron-deficient acceptor) units can exhibit more intriguing electrical/optical properties, such as near-infrared (NIR) absorption/emission, photothermal (PT), and photodynamic (PD) activities, due to enhanced electron push–pull effect and intra/intermolecular charge-transfer interaction of D–A structure. − Given the merits of non-invasivity, spatial selectivity, improved tissue penetration depth, limited drug resistance of NIR-guided photodynamic and photothermal therapies, − and appealing advantages of longer circulation time in vivo, less renal clearance, more efficient cellular uptake, stronger capacity in going across blood–brain barrier of fiber-like nanostructures over spherical counterparts, − and D–A fiber-like micelles with NIR absorption/emission, PT, and PD activities exhibit promising applications in nanomedicine . Thus, the extension of living CDSA to BCPs containing diverse D–A blocks becomes more attractive.…”

Suitable Isolation Side Chains: A Simple Strategy for Simultaneously Improving the Phototherapy Efficacy and Biodegradation Capacities of Conjugated Polymer Nanoparticles

“…As a controllable, spatiotemporally precise, and non-invasive treatment approach, phototherapy has attracted a great deal of attention in the ablation of cancer cells, microorganisms, etc. − Photodynamic therapy (PDT) and photothermal therapy (PTT) are two typical modalities of phototherapy. Under proper light irradiation, the PDT agent, usually termed the photosensitizer (PS), can produce reactive oxygen species (ROS), such as singlet oxygen ( 1 O 2 ), superoxide anion radical (O 2 ·– ), etc., with strong oxidizing properties, − while the PTT agent can produce heat. − Both ROS and high temperature could be utilized to induce cancer cell ablation for tumor therapy.…”

“…As a controllable, spatiotemporally precise, and non-invasive treatment approach, phototherapy has attracted a great deal of attention in the ablation of cancer cells, microorganisms, etc. − Photodynamic therapy (PDT) and photothermal therapy (PTT) are two typical modalities of phototherapy. Under proper light irradiation, the PDT agent, usually termed the photosensitizer (PS), can produce reactive oxygen species (ROS), such as singlet oxygen ( 1 O 2 ), superoxide anion radical (O 2 ·– ), etc., with strong oxidizing properties, − while the PTT agent can produce heat. − Both ROS and high temperature could be utilized to induce cancer cell ablation for tumor therapy. It has been confirmed that the combination of PDT and PTT can realize much better treatment efficacy and decrease the risk of recurrence, as compared to PDT or PTT alone. − The “1 + 1 > 2” superadditive therapeutic effects have also been observed in certain materials, , because the PDT and PTT processes can be mutually reinforcing.…”