Amphiphilic trismethylpyridylporphyrin-fullerene (C₇₀) dyad: an efficient photosensitizer under hypoxia conditions

Abstract

Amphiphilic trismethylpyridylporphyrin-C₇₀ (PC₇₀) dyad with improved photosensitization has been successfully prepared. The PC₇₀ dyad forms a liposomal nanostructure through molecular self-assembling. An increased absorption coefficient in the visible region, good biocompatibility, and high photostability were observed on the self-assembling structure. Surprisingly, in comparison with previously reported photosensitizer porphyrins, PC₇₀ exhibited an enhanced photodynamic therapy (PDT) effect under hypoxia conditions. Further investigations illustrated that PC₇₀ went through an extremely long-life triplet state (211.3 μs) under hypoxia, which enabled the exiguous oxygen to approach and interact with the activated (³P-C₇₀)* more efficiently and produce more singlet oxygen. This would overcome the problem of existing photosensitizers of low PDT efficiency in cancerous tissues under hypoxia. The excellent properties of PC₇₀ dyad make it a promising phototherapeutic agent, especially for the treatment of early- and late-stage cancers under shallow and hypoxia tissues.