This presentation will describe our recent work in the area of polymer-protein conjugates, protein-loaded polymersomes, and new strategies for polymerization in the presence of sensitive biological macromolecules. Biofriendly, aqueous controlled radical polymerization (CRP) conditions are a prerequisite for preparing homopolymer- and block copolymer-protein bioconjugates, and recent advances in this area have allowed access to new conjugates that involve polymers with complex macromolecular architectures, many of which offer considerable promise for in vivo applications. We have employed both the grafting-to and grafting-from strategies to access these materials. Grafting-to was accomplished by conjugation of RAFT-generated polymers by copper(I)-catalyzed azide-alkyne cycloaddition, thiol-ene Michael addition, or amidation of activated esters. Each conjugation method was highly efficient and led to polymer-protein conjugates in good yield. While the first two methods allowed site-specific functionalization of thiols in cysteine residues in either bovine serum albumin (BSA) or ovalbumin, the latter approach targeted free amine groups contained in either lysine residues or the amine terminus of lysozyme or osteoprotegerin. Conjugation of RAFT polymers to proteins was also accomplished by first immobilizing the R-group of a RAFT agent to a protein and subsequently conducting the polymerization of a vinyl monomer in the presence of the protein macro-chain transfer agent. These grafting-from polymerizations can be initiated by conventional thermal initiation, irradiation of a conventional photoinitiator, or via direct photolysis of thiocarbonylthio compounds. Moreover, polymerization-induced self-assembly (PISA) in the presence of proteins has been shown to be an excellent strategy for incorporating proteins within vesicles.

Polymer-protein conjugates and protein-loaded polymersomes

256th National Meeting (2018)

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