Nanoscale Lipid/Polymer Hybrid Vesicles: Effects of Triblock Copolymer Composition and Hydrophilic Weight Fraction

Hybrid vesicles resulting from combined self-assembly of polymers and lipids have gained interest in recent years as drug delivery systems, biosensors, and model systems for structural scaffolds as artificial organelles. So far, in the literature, more attention has been given to study how the discrepancy of chemical compositions and hydrophobic segment sizes between polymers and lipids affect the vesicle’s nature. In this study, we focused on how the hydrophilic blocks impact the vesicle’s morphology. Therefore, we developed hybrid lipid/polymer vesicle systems with lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and amphiphilic triblock copolymers composed of poly(ethylene glycol)–poly(dimethylsiloxane)–poly(ethylene glycol) (PEG–PDMS–PEG). Three types of hybrid vesicle systems were investigated in a systematic manner by changing the hydrophilic block length and the polymer–lipid composition. From the data obtained from cryo-transmission electron microscopy (cryo-TEM) and small-angle neutron scattering, we observed that the hydrophilic mass fraction of an amphiphilic polymer can affect the membrane thickness, size polydispersity, and lamellarity of polymer/lipid hybrid vesicles.