Direct synthesis of well-defined heterotelechelic polymers for bioconjugations

Direct synthesis of well-defined heterotelechelic polymers having functional groups allowing the chemoselective bioconjugations would be desirable to enhance the versatility of polymers for bioconjugations and bio-related applications. Considering this, well-defined alpha-azide, omega-dithiopyridine polymers were synthesized in one step via the reversible addition-fragmentation chain transfer (RAFT) polymerization. The telechelic functionality (i.e., mole ratio of the omega-dithiopyridine to the alpha-azide end group) of polymers was above 0.90, indicating the efficient generation of well-defined heterotelechelic polymers. The heterotelechelic functionality for chemoselective bioconjugations was tested by reacting alpha-azide, omega-dithiopyridine poly(NIPAAm) with model biomolecules, i.e., biotin/avidin, glutathione, and bovine serum albumin, via click and thiol-disulfide exchange chemistries. Near-stoichiometric conjugation with biomolecules indicated high functionality of the polymer end groups.