Proteins as Initiators of Controlled Radical Polymerization: Grafting-from via ATRP and RAFT

Many recent developments in polymer chemistry have advanced the synthesis of materials in which synthetic polymers are immobilized to biological (macro)molecules to enhance the solubility, stability, activity, or therapeutic utility of the biological entity. In particular, the versatility and robust nature of controlled radical polymerization (CRP) has enabled access to a diverse family of new polymer bioconjugates. While nitroxide-mediated, atom transfer radical (ATRP), and reversible addition-fragmentation chain transfer (RAFT) polymerizations have all proven useful for the preparation of well-defined end-functional polymers capable of being efficiently conjugated to biological molecules, ATRP and RAFT have proven especially proficient for the synthesis of conjugates by direct polymerization of vinyl monomers from biological components functionalized to contain a group capable of initiating chain growth. This Viewpoint highlights several recent advances that have relied on grafting-from by CRP, with particular attention devoted to a recent report that seeks to facilitate the process of grafting-from proteins via ATRP under biologically relevant conditions.