Development of an azo-based photosensitizer activated under mild hypoxia for photodynamic therapy

Wen Piao, Kenjiro Hanaoka, Tomotsumi Fujisawa, Satoshi Takeuchi, Toru Komatsu, Tasuku Ueno, Takuya Terai, Tahei Tahara, Tetsuo Nagano, Yasuteru Urano

Research output: Contribution to journalArticlepeer-review

181 Citations (Scopus)


Photodynamic therapy (PDT) utilizes photoirradiation in the presence of photosensitizers to ablate cancer cells via generation of singlet oxygen (1O2), but it is important to minimize concomitant injury to normal tissues. One approach for achieving this is to use activatable photosensitizers that can generate 1O2 only under specific conditions. Here, we report a novel photosensitizer that is selectively activated under hypoxia, a common condition in solid tumors. We found that introducing an azo moiety into the conjugated system of a seleno-rosamine dye effectively hinders the intersystem crossing process that leads to 1O2 generation. We show that the azo group is reductively cleaved in cells under hypoxia, enabling production of 1O2 to occur. In PDT in vitro, cells under mild hypoxia, within the range typically found in solid tumors (up to about 5% O2), were selectively ablated, leaving adjacent normoxic cells intact. This simple and practical azobased strategy should be widely applicable to design a range of activatable photosensitizers.

Original languageEnglish
Pages (from-to)13713-13719
Number of pages7
JournalJournal of the American Chemical Society
Issue number39
Publication statusPublished - 2017 Oct 4
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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