Enhanced drug resistance suppression by serum-stable micelles from multi-arm amphiphilic block copolymers and tocopheryl polyethylene glycol 1000 succinate.

To develop a robust drug-delivery system using multi-arm amphiphilic block copolymers for enhanced efficacy in cancer therapy. Two series of amphiphilic polymer micelles, PEG-b-PCL and PEG-b-PCL/TPGS, were synthesized. Doxorubicin (DOX) loading into the micelles was achieved via solvent dialysis.

Hybrid Block Copolymer Synthesis by Merging Photoiniferter and Organocatalytic Ring-Opening Polymerizations.

Access to block copolymers from monomers that do not polymerize via a common mechanism requires initiation from a multifunctional species that allows orthogonal polymerization chemistries. We disclose a strategy to provide well-defined polyacrylamido-b-polyether block copolymers by a one-pot combination of photoiniferter polymerization and organocatalytic ring-opening polymerization (ROP) using a hydroxy-functionalized trithiocarbonate photoiniferter as the dual initiator at ambient temperature. Our results reveal good compatibility between the two polymerization systems and highlight that they can be performed in arbitrary order or simultaneously with good retention of the thiocarbonylthio functionality.

Block Copolymer Sequence Inversion through Photoiniferter Polymerization.

Block copolymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization are often restricted to a specific comonomer blocking sequence that is dictated by intermediate radical stability and relative radical leaving group abilities. Techniques that provide alternative pathways for reinitiation of thiocarbonylthio-terminated polymers could allow access to block copolymer sequences currently unobtainable through the RAFT process. We report a method for preparing "inverted" block copolymers, whereby the traditional order of monomer addition has been reversed through the use of photoiniferter-mediated radical polymerization.

Revealing the Cytotoxicity of Residues of Phosphazene Catalysts Used for the Synthesis of Poly(ethylene oxide).

We herein report a case study on the toxicity of residual catalyst in metal-free polymer. Eight-arm star-like poly(ethylene oxide)s were successfully synthesized via phosphazene-catalyzed ring-opening polymerization of ethylene oxide using sucrose as an octahydroxy initiator. The products were subjected to MTT assay using human cancer cell lines (MDA-MB-231 and A2780).