Open AccessFluorescein-Based Type I Supramolecular Photosensitizer via Induction of Charge Separation by Self-Assembly
Author(s) -
Hajime Shigemitsu,
Kei Ohkubo,
Kazuhide Sato,
Asuka Bunno,
Tadashi Mori,
Yasuko Osakada,
Mamoru Fujitsuka,
Toshiyuki Kida
Publication year - 2022
Publication title -
jacs au
Language(s) - English
Resource type - Journals
ISSN - 2691-3704
DOI - 10.1021/jacsau.2c00243
Subject(s) - photosensitizer , singlet oxygen , supramolecular chemistry , photodynamic therapy , photochemistry , chemistry , electron transfer , fluorescein , fluorescence , oxygen , organic chemistry , molecule , optics , physics
Photosensitizers (PSs) are critical substances with considerable potential for use in non-invasive photomedicine. Type I PSs, which generate reactive radical species by electron transfer from the excited state induced via photoirradiation, attracted much attention because of their suitability for photodynamic therapy (PDT) irrespective of the oxygen concentration. However, most organic PSs are type II, which activates only oxygen, generating singlet oxygen ( 1 O 2 ) via energy transfer from the triplet state. Here, we proposed a strategy to form type I supramolecular PSs (SPSs) utilizing the charge-separated state induced by self-assembly. This was demonstrated using a supramolecular assembly of fluorescein, which is a type II PS in the monomeric state; however, it changes to a type I SPS via self-assembly. The switching mechanism from type II to I via self-assembly was clarified using photophysical and electrochemical analyses, with the type I SPS exhibiting significant PDT effects on cancer cells. This study provides a promising approach for the development of type I PSs based on supramolecular assemblies.