Coassembly of Charged Copolymer Amphiphiles Featuring pH-Regulated Antifouling Properties

Understanding the formation of highly ordered structures through self-assembly is crucial for developing various biologically relevant systems. A significant expansion in the development of self-assembly chemistry features stable coassembly formation using a mixture of two oppositely charged polymers. This study provides insightful findings on the coassembly of hydrophobic coumarin-integrated cationic (P1-P3) and anionic (P1'-P3') copolymers toward the formation of vesicles in aqueous medium at pH 7.4, with a hydrodynamic diameter (D_h) of 160 ± 10 nm and electrically neutral zwitterionic surfaces, confirmed by dynamic light scattering. Upon varying the solution pH, an intriguing charge switchable behavior (+ve → 0 → -ve) and a drastic morphological transition to spherical aggregates of the vesicles were noticed. At pH 7.4, these coassembled vesicles possess a neutral surface charge, empowering them to resist nonspecific protein (pepsin and lysozyme) adsorption via electrostatic repulsion, as evidenced by size evolution and protein binding measurements. Additionally, the bilayer membrane allows for the encapsulation of hydrophilic and hydrophobic guest molecules and their sustained release in the presence of 10 mM esterase; thus, this study demonstrates potential applications of coassembly to serve as a drug delivery vehicle.