Lipid Coating on Polyelectrolyte Surface Modified Colloidal Particles and Polyelectrolyte Capsules

Abstract

Dipalmitoyldiphosphatidic acid (DPPA), dipalmitoyldiphosphatidylcholine (DPPC), and sphingosine were adsorbed onto polyelectrolyte coated colloids and capsules forming composite lipidpolyelectrolyte layers. The stepwise coating was performed either by adsorption of preformed vesicles onto the capsule surface or by a solvent exchange protocol. The lipid assembly was monitored by ζ-potential measurements. Single particle light scattering, flow cytometry, and fluorescence studies of Fo ¨rster energy transfer have been used to quantify the lipid coating. Confocal microscopy images of capsules coated with fluorescent lipids demonstrated a homogeneous coverage of the capsule surface. Differential scanning calorimetry shows a phase transition temperature characteristic for lipid layer structures. It was concluded that the adsorbed DPPA form bilayers while DPPC may form multilayers. It was further shown that on top of the lipid layers further polyelectrolyte layers could be assembled. The permeability of 6-carboxyfluorescein (6-CF) through the composite layer structure was studied by means of confocal laser scanning microscopy. The permeation time through the composite layer was of the order of 10 1 -10 2 min, while in the absence of lipids 6-CF equilibrated faster than the time resolution of the technique.

Lipid layers on polyelectrolyte multilayer supports

“…Furthermore, lipid layers can be formed on polyelectrolyte multilayer coated colloidal particles. [25][26][27] This brings a considerable advantage over the use of flat macroscopic surfaces because powerful particle-based experimental techniques such as flow cytometry (FACS) can be applied.…”

Preparation of IL-loaded microreactors based on polyelectrolyte microcapsules

“…Various compounds such as drugs [43][44][45], cells [46,47], enzymes [48][49][50], proteins [51], DNA [52] and even organic solvents [53] Alternatively, crosslinkable microcapsules were prepared by LbL deposition of 4 bilayers of (PAH/PSS) then 2 bilayers of (PAH/PAA) onto…”

Confocal Laser Scanning Microscope: A Very Useful Tool in Multilayer 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][8][9][10][11][12][13][14][15][16][17][18][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.…”

“…It was possible to change the permeability by pH, salt concentration and temperature for a limited number of systems. [8][9][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.…”