Endolytic, pH-Responsive HPMA-b-(L-Glu) Copolymers Synthesized via Sequential Aqueous RAFT and Ring-Opening Polymerizations
Polymers and High Performance Materials
A facile synthetic pathway for preparing block copolymers with pH-responsive L-glutamic acid segments for membrane disruption is reported. Aqueous reversible addition-fragmentation chain transfer (aRAFT) polymerization was first used to prepare biocompatible, nonimmunogenic poly[N-(2-hydroxypropyl)methacrylamide]. This macro chain transfer agent (CTA) was then converted into a macroinitiator via simultaneous aminolysis and thiol-ene Michael addition using the primary amine substituted N-(3-aminopropyl)methacrylamide. This macroinitiator was subsequently utilized in the ring-opening polymerization of the N-carboxyanhydride monomer of gamma-benzyl-L-glutamate. After deprotection, the pH-dependent coil-to-helix transformations of the resulting HPMA-b-(L-Glu) copolymers were monitored via circular dichroism spectroscopy. HPMA segments confer water solubility and biocompatibility while the L-glutamic acid repeats provide reversible coil-to-helix transitions at endosomal pH values (similar to 5-6). The endolytic properties of these novel [HPMA-b-(L-Glu)] copolymers and their potential as modular components in drug carrier constructs was demonstrated utilizing red blood cell hemolysis and fluorescein release from POPC vesicles.
(2013). Endolytic, pH-Responsive HPMA-b-(L-Glu) Copolymers Synthesized via Sequential Aqueous RAFT and Ring-Opening Polymerizations. BIOMACROMOLECULES, 14(10), 3793-3799.
Available at: http://aquila.usm.edu/fac_pubs/7875