Synthesis and Controlled Cargo Release of Novel Photoresponsive Polysiloxane-Based Single-Chain Nanoparticles

Herein, a novel, highly branched and photoresponsive polysiloxane is synthesized and studied. The polymer is photoconstructed into a single-chain nanoparticle loaded with Nile Red and Metformin. Through the photoreversible [2+2] mechanism of the polymer's pendant coumarin moieties, the nanoparticles are de-crosslinked, and their cargo molecules released. A study of the kinetics of release is undertaken in different solvents, providing insight into the relationship between the cargo's molecular structure and that of the polymer chain. On the whole, this report's study introduces new controlled release and cationic ring-opening polymerization concepts while providing the first example of a single-chain polymer nanoparticle based on a photoresponsive polysiloxane.