Abstract

Porphyrin is the most common photosensitizer for photodynamic therapy (PDT) where its interaction with light and oxygen generates cytotoxic singlet oxygen species. We recently discovered a unique porphyrin nanostructure, called porphysome, which converts the singlet oxygen generating PDT mechanism of porphyrin molecules to a completely thermal mechanism for efficient photothermal therapy (PTT). This nanostructure-driven PDT to PTT conversion is based on the extremely high porphyrin packing density (>80,000/particle) in porphysome that induces super light absorption and super-quenching of photodynamic activity. Here we explored a reverse process by using receptor-mediated endocytosis to facilitate the disruption of the nanostructure inside cells, thus rapidly switching the PTT mechanism of porphysome to the PDT effect of porphyrin molecules. Therefore, we are closing the loop between PDT and PTT by tailoring the nanostructure-dependent activation mechanism.

© 2014 Optical Society of America