GSH-triggered release of sulfur dioxide gas to regulate redox balance for enhanced photodynamic therapy.

Herein, a promising strategy is explored to regulate redox balance in tumor cells by simultaneously consuming GSH and releasing SO2 gas for enhanced photodynamic therapy. The photosensitizer is loaded with a carrier that releases SO2 gas in response to GSH overexpressed in the cell. SO2 was found not only to induce cell apoptosis but also increase the intercellular ROS level. Meanwhile, the loaded-photosensitizers could also generate ROS with light irradiation, resulting in apoptosis or necrosis of cells.