Polymer–vesicle association

Abstract

Mixed polymer-surfactant systems have been intensively investigated in the last two decades, with the main focus on surfactant micelles as the surfactant aggregate in interaction. The main types of phase behavior, driving forces and structural/rheological effects at stake are now fairly well understood. Polymer-vesicle systems, on the other hand, have received comparatively less attention from a physico-chemical perspective. In this review, our main goal has been to bridge this gap, taking a broad approach to cover a field that is in clear expansion, in view of its multiple implications for colloid and biological sciences and in applied areas. We start by a general background on amphiphile self-assembly and phase separation phenomena in mixed polymer-surfactant solutions. We then address vesicle formation, properties and stability not only in classic lipids, but also in various other surfactant systems, among which catanionic vesicles are highlighted. Traditionally, lipid and surfactant vesicles have been studied separately, with little cross-information and comparison, giving duplication of physico-chemical interpretations. This situation has changed in more recent times. We then proceed to cover more in-depth the work done on different aspects of the associative behavior between vesicles (of different composition and type of stability) and different types of polymers, including polysaccharides, proteins and DNA. Thus, phase behavior features, effects of vesicle structure and stability, and the forces/mechanisms of vesicle-macromolecule interaction are addressed. Such association may generate gels with interesting rheological properties and high potential for applications. Finally, special focus is also given to DNA, a high charge polymer, and its interactions with surfactants, and vesicles, in particular, in the context of gene transfection studies.

Polycation-Mediated Gene Delivery: The Physicochemical Aspects Governing the Process

“…135 nm). It appears then, that as DNA comes in contact with MEP, the polyanion acts as a stabilizer of the liposomes, a result that has been observed for other polymer-vesicle interactions (Antunes et al, 2009;Rodriguez-Pulido et al, 2008). Very importantly, compared to the other DNA-cationic vector formulations here studied, in particular to the DNA-chitosan system (R H up to 450 nm), the sizes depicted by the DNA-MEP complexes are considerably lower.…”

Ethanol effects on the gelation behavior of α-tocopherol acetate-encapsulated ethosomes with water-soluble polymers

“…Therefore, many investigators have explored the ethosome-improving skin delivery [11,18,29,30], and the gel agents, such as PVP-VA mixed gum rosin [1], carbomer [23,[30][31][32][33][34], hydroxypropyl methylcellulose [22], acrylic resin [35], and pluronic F127 [36], were used to gel with ethosomes for enhancing formulation viscosity. Several studies on the gelation of catanionic vesicles by watersoluble polymers have pointed out that electrostatic and hydrophobic interactions are two major factors governing the association between vesicles and polymers [37][38][39], but the effect of the solution dielectric constant on polymer configuration and thereby the formation of ethosome/polymer mixtures seem to lack systematic studies. Furthermore, the effect of the drug itself on the gelation behavior of ethosome by gelators also needs to be examined.…”

Recent Strategies in the Development of Catanionic Vesicles

“…The former include counterions, whereas in the latter, the counterions are removed, leaving the two oppositely charged amphiphilic ions 4,6 . In early studies, the phase behavior of catanionic mixtures indicated that the vesicle domains exist in the excess cationic or anionic surfactant region and the low-concentration region, whereas precipitation generally occurs under equimolar conditions 4,5,7 .…”

“…However, the phase behavior of catanionic mixtures possessing several components is complicated for analysis 18 , although simplified ternary diagrams cationic surfactant, anionic surfactant, and water have often been adopted. In addition, the vesicle domains usually exist in the excess cationic or anionic surfactant region and the low-concentration region, whereas precipitation occurs under equimolar conditions 4,5,7 . As a result, the applications of catanionic mixtures are limited.…”