Interfacial stability of lipid nanocapsules

In order to obtain information on the structure and the stability of lipid nanoparticles, interfacial films, made from their spreading, were studied at the air/water interface. The related results were compared with the spreading of their individual components at the same interface. The interfacial behaviour of the particles indicated a nanocapsule structure with an oily core surrounded by a surfactant layer. Unlike liposomes or high density lipoproteins (HDL), no destruction leading to the release of their core was observed during their spreading and compression. Moreover, the sampling of the nanoparticle films at the air/water interface deposited on mica plate depicted by atomic force microscopy (AFM) showed entire nanocapsules. This stability is attributed to their surface cohesion related to their surfactant shell. Indeed, a partial particle surface "erosion" occurred leading to the spread of a certain amount of less attached hydrophilic surfactant molecules without releasing the nanocapsule lipid content. This study illustrates that the Langmuir balance can be used as a tool for studying the general organisation of lipid particles. Moreover, this method may allow the determination of the release profile of some encapsulated drugs. (C) 2003 Elsevier Science B.V. All rights reserved.