Synthesis and Characterization of Polyion Complex Micelles with Glycopolymer Shells for Drug Delivery Carriers

Double hydrophilic diblock copolymers (G₂₀A₁₀₀ and G₁₀₀A₉₈), composed of non-charged poly(glycosyloxyethyl methacrylate) (PGEMA, G) and cationic poly((3-acrylamidopropyl)trimethylammonium chloride), were synthesized via reversible addition-fragementation chain transfer (RAFT) radical polymerization. Likewise, diblock copolymers (G₂₀S₈₀ and G₁₀₀S₇₈), composed of PGEMA and anionic poly(2-acrylamido-2-methylpropanesulfonate) were synthesized via RAFT. The subscripts in these abbreviations indicate the degree of polymerization (DP) of each block. Polyion complex (PIC) aggregates (G₂₀A₁₀₀/G₂₀S₈₀ and G₁₀₀A₉₈/G₁₀₀S₇₈) were formed through electrostatic interactions by combining oppositely charged diblock copolymers with matched DPs for charge neutralization. The hydrodynamic radii of the G₂₀A₁₀₀/G₂₀S₈₀ and G₁₀₀A₉₈/G₁₀₀S₇₈ PIC aggregates were 77.4 and 26.2 nm, respectively, with zeta potentials close to 0 mV. The G₂₀A₁₀₀/G₂₀S₈₀ PIC micelles tend to form intermicellar aggregates, resulting in an increase in the particle size over time. In contrast, G₁₀₀A₉₈/G₁₀₀S₇₈ PIC micelles exhibited colloidal stability with a constant spherical core-shell shape, which was unaffected by time. The morphology and stability of the PIC aggregates depend upon the DP ratio of PGEMA and oppositely charged polyelectrolyte blocks. Both G₂₀A₁₀₀/G₂₀S₈₀ and G₁₀₀A₉₈/G₁₀₀S₇₈ PIC aggregates dissociated above 0.8 M NaCl due to the screening effect of NaCl.