Simple Route to Functional Cyclized/Knotted PManEMA-co-IMs: One-Pot RAFT/Hydroxyl–Isocyanate Reaction

This work reports on a simple route to the synthesis of cyclized/knotted poly(2-(α-d-mannosoxy)ethyl methacry-late/2-isocyanatoethyl methacrylate)s (PManEMA-co-IMs) by the one-pot reaction, i.e., reversible addition–fragmentation chain transfer polymerization (RAFT) and coupling of –OH groups and –NCO groups. A mechanism for this one-pot method was proposed based on boundary effects. The as-obtained PManEMA-co-IMs were characterized through nuclear magnetic resonance, dynamic light scattering, multidetector size exclusion chromatography (MDSEC), elemental analysis, and Fourier transform infrared (FT-IR) spectroscopy. Based on the results of elemental analysis and conversion of monomers, calculation equations for the degree of branching and cyclization (BC), degree of branching (DB), and degree of cyclization (DC) were given. The BC, DB, and DC are all proportional to the monomer ratio of isocyanatoethyl methacrylate. The highest ratio of the ring could reach 53.6%, confirming that PManEMA-co-IMs are of the cyclized/knotted architecture. Moreover, the PManEMA-co-IMs were degraded by NaBH₄, generating PManEMA-co-IM-SH which could be reversibly converted to PManEMA-co-IM-SS with the help of H₂O₂ and glutathione (GSH). Finally, PManEMA-co-IM-SS was used to load DOX obtaining GSH-response DOX@PManEMA-co-IM-SS release system. DOX@PManEMA-co-IM-SS exhibited a specific inhibitory effect on Hella cells.