Monosaccharide-Responsive Release of Insulin from Polymersomes of Polyboroxole Block Copolymers at Neutral pH

We synthesized a boroxole-containing styrenic monomer that can be polymerized by the reversible addition?fragmentation and chain transfer (RAFT) method. Poly(styreneboroxole) (PBOx) and its block copolymers with a poly(ethylene glycol) (PEG) as a hydrophilic block displayed binding to monosaccharides in phosphate buffer at neutral pH, as quantified by Wang’s competitive binding experiments. By virtue of a controlled radical polymerization, we were able to adjust the degree of polymerization of the PBOx block to yield sugar-responsive block copolymers that self-assembled into a variety of nanostructures including spherical and cylindrical micelles and polymer vesicles (polymersomes). Polymersomes of these block copolymers exhibited monosaccharide-responsive disassembly in a neutral-pH medium. We demonstrated the possibility of using these polymersomes as sugar-responsive delivery vehicles for insulin in neutral phosphate buffer (pH 7.4). Encapsulated insulin could be released from the polymersomes only in the presence of sugars under physiologically relevant pH conditions.

Journal of the American Chemical Society, 2012, 134, 4030-4033
Hyunkyu Kim, Young Ji Kang, Sebyung Kang, Kyoung Taek Kim

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