Synthesis and photophysical properties of POSS-cored multiporphyrin arrays as singlet oxygen generator

摘要

Photodynamic therapy (PDT) is a noninvasive cancer treatment based on the activation of a photosensitizer (PS) upon light irradiation for the generation of reactive oxygen species such as singlet oxygen (~1O_2) to destroy the tumors. Porphyrin, a tetrapyrrolic pigment with an 18_(TT)-electron conjugated system, is a promising candidate for PDT because of its high quantum yield of singlet oxygen generation. However, most conventional porphyrin-based photosensitizes readily aggregate in aqueous media due to strong tt-tt interactions among porphyrin molecules, resulting in the suppression of ~1O_2 generation by self-quenching. To overcome this problem, we have synthesized hydrophilic porphyrin building blocks with tri(ethylene glycol) dendron, which finally incorporated into the anchor molecules such as polyhedral oligomericsilsesquioxanes (POSS), to give water-soluble multiporphyrin arrays. Multiporphyrin arrays have some photophysical advantages such as large light absorption and high stability of excited state via intramolecular energy migration for high therapeutic efficacy. Herein, we report the synthesis of POSS-cored multiporphyrin array and its photodynamic activity including the ability of singlet oxygen generation and photocytotoxicity in tumor cells.