Effect of aqueous pH and electrolyte concentration on structure, stability and flow behavior of non-ionic surfactant based solid lipid nanoparticles

The effects of pH and electrolyte concentration on the structure evolution, polymorphism, flow behavior and stability of solid lipid nanoparticles (SLNs), stabilized by the food-grade non-ionic surfactant Tween 80, were investigated. Development of a lipid crystal was governed by thermodynamically stable beta- and beta'-subunits and relative crystallinity decreased with increasing pH and electrolyte concentration. Aqueous stability and dispersibility increased with increasing pH and decreased with increasing electrolyte concentration. Flow behavior of the SLNs suspension was affected by the electrolyte concentration. However, the pH of the aqueous surfactant medium has not shown any effect on the flow behavior. From the results, it is clear that the pH and electrolyte concentration are among the potential factors which determines the stability and release properties of entrapped materials from SLNs. (C) 2013 Elsevier Ltd. All rights reserved.