Effect of surfactants on the formation and characterization of a new type of colloidal drug delivery system: Nanostructured lipid carriers

Nanostructured lipid carriers (NLC) consisted of solid lipid and liquid lipid are a new type of colloidal drug delivery system, which offer the advantage of improved drug loading capacity and release properties. Surfactants play important roles in the formation and characterization of NLC. In order to investigate the influence of surfactants on properties of NLC, four types of surfactants and their mixtures were used in the absence of model drugs thereby avoiding the interaction between surfactants and drugs. The hot high-pressure homogenization method was employed to produce NLC and the physicochemical properties of NLC, such as particle size distribution, zeta potential and DSC analysis were investigated. The results indicated that ionic surfactants such as sodium deoxycholate (SDC), showed obviously low emulsification efficiency in the preparation. However, it increased the zeta potential of nanoparticles leading to improve the physical stability of the system. Non-ionic emulsifier, especially Poloxamer 188, offered additional steric stabilization effect avoiding aggregation of the nanoparticles in the colloidal system. The formulation in the study combined four types of additives including ionic surfactant (SDC), non-ionic emulsifier (Poloxamer 188 and Tween-80), and Lecithin to obtain favorably stable NLC drug delivery system, which could stabilize for more than 1 year without phase separation at 4 °C.