The effects of the nature of the sterol on the properties and stability of niosome bilayer vesicles

Abstract

Niosome vesicles as potential nanocarriers for drug delivery systems have been in development since the mid-1980s. These vesicles form by self-assembly of cholesterol and nonionic surfactants in an aqueous phase. The aim of the present molecular dynamics (MD) simulation study is to determine how changes in the sterol side chain and ring affect the structure and stability of sorbitan monostearate (Span60) niosome bilayers. Five sterols are examined: cholesterol (CHL), β-sitosterol (BST), ergosterol (ERG), stigmasterol (STS), and lanosterol (LST). Different sets of simulations were performed by varying the number of molecules (30, 40, and 50 % sterol concentration). The interactions between Span60 and the different sterols are found to be strongly dependent on the sterol’s side chain and head group. BST is found to markedly reduce the effectiveness of the sterol on the ordering of the bilayers, a result that persists over the whole range of concentrations examined in this work.