Rational Design\nof Self-Reporting Polymersomes for\nthe Controlled Release of Sulfur Dioxide

As a new member of the gaseous regulators, sulfur dioxide\n(SO<sub>2</sub>) plays a crucial role in many biological activities.\nRecent\nstudies have shown that SO<sub>2</sub> is capable of inducing cancer\ncell apoptosis by regulating intracellular reactive oxygen species\n(ROS), allowing SO<sub>2</sub> to serve as an efficient therapeutic\nagent. Although various polymer-based platforms have presented great\npotential for the controlled release of SO<sub>2</sub>, most of the\nsystems are incapable of monitoring the intracellular generation of\nSO<sub>2</sub>. In this work we present the rational design of SO<sub>2</sub>-releasing biodegradable polymersomes, accompanied by a self-reporting\nproperty. The polymersome consists of a hydrophilic block of poly(ethylene\nglycol) (PEG) and a hydrophobic segment of poly(trimethylene carbonate)\n(PTMC)-based SO<sub>2</sub> donors. The polymersomes not only exhibit\ngood SO<sub>2</sub>-releasing performance upon treatment with glutathione\n(GSH), but can also regulate the fluorescence change of the system, offering a good platform for real-time\nmonitoring of the intracellular production of SO<sub>2</sub>. Significantly,\nthe <i>in vitro</i> and <i>in vivo</i> studies\nindicate the potential for exploitation of these polymersomes as antitumor\nagents. We expect that incorporating both the SO<sub>2</sub>-releasing\ncapacity and self-reporting feature within a polymersome system will\nprovide a unique opportunity for the development of intelligent gas\nnanovehicles.