Static and dynamic surface properties of mixed non-ionic surfactant/cholesterol monolayers as niosome shell models

Abstract

This work focuses on the study of the thermodynamic and rheological properties of mixed monolayers of non-ionic surfactants with cholesterol, which are models for the bilayer shells of niosomes. In contrast to many traditional surfactants, Spans and Tweens, due to their easy self-assembly, can, like lipids, form stable monolayers at the air-water interface, bilayer structures on solid substrates and high-quality vesicles (niosomes). Thermodynamic (surface pressure-area compression isotherms and surface compressibility modulus) and dynamic characteristics (surface dilational modulus and its elastic and viscous components) of mixed monolayers at the air-water interface were performed. The role of each component of the Span/Tween and Span/Tween/Chol mixtures and the degree of saturation of the hydrocarbon chain in realising the mechanical properties of the systems has been revealed. The high values of surface dilational viscosity allow the monolayer to be considered as a viscoelastic system with the ability to dissipate more energy than the elastic systems.