Thermal and Reactive Oxygen Species Dual-Responsive OEGylated Polysulfides with Oxidation-Tunable Lower Critical Solution Temperatures.

In this work, two monomethoxy oligo(ethylene glycol) (OEG)-substituted episulfides are prepared and a series of polysulfides are synthesized with subsequent ring-opening polymerization. The OEGylated polysulfides exhibit thermal and reactive oxygen species (ROS) dual-responsive behavior. Their lower critical solution temperatures (LCSTs) are close to human body temperature and depend on the degree of polymerization and OEG length. Notably, the LCST of the polysulfide increases linearly with the oxidation degree by H2 O2 , showing a highly tunable change regulated by the ratio between hydrophobic sulfide and hydrophilic sulfoxide/sulfone in the backbone. Further, the OEGylated polysulfide can act as a ROS scavenger to protect red blood cells (RBCs) from oxidative damage in an RBCs aging model in vitro. This work paves a facile way to synthesize LCST-tunable polysulfides, which hold great promise in biological applications.