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<p>Photodynamic therapy (PDT) is fundamentally limited by inefficient conversion of photoexcited energy into reactive oxygen species (ROS), especially in hypoxic pathological tissues. Photogenerated radical-ion pairs (PS⁺•/PS⁻•) from photosensitizer could overcome this limitation by broadening photoredox diversity for hypoxia-tolerant ROS production. However, conventional substrate-dependent mechanism typically generates only one radical species, limiting both photoredox diversity and overall ROS production. Here we demonstrate a substrate-free mechanism via noncovalent homodimer fission for efficient generation of PS⁺•/PS⁻• pairs from water-soluble DB-Py, unlocking multipath photoredox for hypoxia-tolerant PDT. Spectroscopic studies and calculations provide experimental evidence for homodimer formation via noncovalent interactions between a photoexcited triplet-state and a ground-state molecule, followed by fission into abundant PS⁺•/PS⁻• pairs. The resulting PS⁺• oxidizes water to generate O<sub>2</sub> in situ, which is subsequently reduced by PS⁻• to produce •OH and O<sub>2</sub>⁻•, thereby establishing a self‑oxygen‑supplying ROS generation cycle. Consequently, DB-Py achieves 4.9‑fold higher •OH and 2.7‑fold higher O<sub>2</sub>⁻• compared to commercial Rose Bengal, resulting in 7.9-fold enhanced antibacterial efficacy and 2.2-fold accelerated wound epithelialization. This work establishes a substrate-free radical generation mechanism with broad implications for the development of photodynamic, photocatalytic, and photoredox systems.</p>

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Substrate-free generation of photosensitizer radical-ion pairs enables multipath photoredox for hypoxia-tolerant photodynamic therapy

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月24日

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  • Weiyun Yao,
  • Linfang Yang,
  • Ruizhe Chen,
  • Siwei Yao,
  • Haolin Zhang,
  • Mingxuan Jia,
  • Yonghui Pan,
  • Ruida Bai,
  • Zhongzheng Yu,
  • Quli Fan,
  • Wei Huang,
  • Wenbo Hu

摘要

Photodynamic therapy (PDT) is fundamentally limited by inefficient conversion of photoexcited energy into reactive oxygen species (ROS), especially in hypoxic pathological tissues. Photogenerated radical-ion pairs (PS⁺•/PS⁻•) from photosensitizer could overcome this limitation by broadening photoredox diversity for hypoxia-tolerant ROS production. However, conventional substrate-dependent mechanism typically generates only one radical species, limiting both photoredox diversity and overall ROS production. Here we demonstrate a substrate-free mechanism via noncovalent homodimer fission for efficient generation of PS⁺•/PS⁻• pairs from water-soluble DB-Py, unlocking multipath photoredox for hypoxia-tolerant PDT. Spectroscopic studies and calculations provide experimental evidence for homodimer formation via noncovalent interactions between a photoexcited triplet-state and a ground-state molecule, followed by fission into abundant PS⁺•/PS⁻• pairs. The resulting PS⁺• oxidizes water to generate O2 in situ, which is subsequently reduced by PS⁻• to produce •OH and O2⁻•, thereby establishing a self‑oxygen‑supplying ROS generation cycle. Consequently, DB-Py achieves 4.9‑fold higher •OH and 2.7‑fold higher O2⁻• compared to commercial Rose Bengal, resulting in 7.9-fold enhanced antibacterial efficacy and 2.2-fold accelerated wound epithelialization. This work establishes a substrate-free radical generation mechanism with broad implications for the development of photodynamic, photocatalytic, and photoredox systems.