Approach to Peptide Decorated Micelles via RAFT Polymerization

Pyridyldisulfide (PDS) functionalized telechelic polymers of oligo(ethyleneglycol) acrylate (PEG-A) and their amphipbilic triblock copolymers with styrene (St) were synthesized directly by reversible addition-fragmentation chain transfer (RAFT) polymerization using a new bifunctional RAFT agent, S,S-bis[alpha,alpha'-dimethyl-alpha '' -(2-pyridyl disulfide) ethyl acetatel trithiocarbonate (BDPET). The homopolymerization of PEG-A was found to be well controlled using BDPET (PDI < 1.2). The ABA triblock copolymers poly(PEG-A)-b-poly(St)-b-poly(PEG-A) with narrow molecular weight distribution (PDI < 1.25) were synthesized using poly(PEG-A) as a macro-RAFT agent. UV-vis spectroscopic analysis revealed that 85 mol % of poly(PEG-A) and 78 mol % of poly(PEG-A)-b-poly(St)-b-poly(PEG-A) retained PDS end group functionality. Micelles were observed to form from poly(PEG-A)-b-poly(St)-b-poly(PEG-A). The presence of PDS groups within the micelle corona was evidenced by UV-vis spectroscopy and fluorescence spectroscopy. The PDS groups within the corona were then used to functionalize the micelles with a thiol group bearing model peptide, reduced glutathione, and a thiol modified fluorophore, rhodamine B, under mild reaction conditions. UV-vis and fluorescence spectrocopies revealed that approximately 80% PDS groups from the amphiphilic copolymer were tethered within the micelle coronas and accessible to glutathione and fluorophore attachment. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 899-912, 2009