Confocal Laser Scanning Microscope: A Very Useful Tool in Multilayer Capsules

Abstract

Liposomes are widely used as drug carriers to deliver functional compounds into the membrane. [1-3] However, the liposomes from phospholipids are not stable even in the living system. Much attention has been drawn to the mixed polyelectrolyte/lipid system and all of these methods have been commonly recognized to stabilize the mixed film and assigned lipids some new features. [4-6] In order to prepare stabilized vesicles with a defined size, an alternative strategy has been developed by employing layer-by-layer technique. PE multilayers were assembled on the colloidal particles and the colloidal particles were selectivley sacrificed by dissolution to obtain hollow multilayered PE capsules. Phospholipids are adsorbed on these capsules. By this way, giant liposomes can be obtained with a defined size, shape and such giant liposomes are very stable from months to years. [7-19] Based on our past work on the successful fabricating giant liposomes, a deeper and systematic understanding of the multilayer versatility regarding their functions and properties is clearly necessary. It was possible to change the permeability by pH, salt concentration and temperature for a limited number of systems. [8-10] In this paper, multilayered PE capsules fabricated with Layer-By-Layer (LBL) method were employed as supports and then the lipid bilayers were assembled on them, thus giant liposomes were obtained and their sizes were determined by the supports’ size. Their permeabilities will be tuned by the lipid coating and the surface enzyme catalysis reaction. The small fluorescence molecule 6-CF diffusion behavior across the capsule’s wall was studied by Confocal Laser Scanning Microscopy (CLSM), which may give information on the permeability control of “artificial cell”. All the experimental results were got at room temperature.