Summary:
Liposomes are lipid vesicular nano-structures; consist principally of phospholipids which
spontaneously are self-assembled in an aqueous medium under specified circumstances,
to form bilayer structures which entrap the aqueous medium, where they are dispersed.
Due to their biocompatible and amphiphilic character, they have been extensively used as
targeted controlled release delivery systems of both hydrophilic and lipophilic active
ingredients.
Elastic liposomes, also called transfersomes, have been widely investigated as
transdermal drug delivery systems, surpassing the first-pass effect of the liver and
providing an alternative and noninvasive route. Transfersomes consist of phospholipids
and a surfactant which increases the elasticity of the bilayer, improving the capability to
penetrate efficiently into the deeper skin layers until systemic circulation, under the
influence of the hydration gradient, in comparison of conventional rigid liposomes.
The aim of the present study is the formation of elastic liposomes by thin film hydration
method, using different lipids and surfactants, in order to determine the effect of the
components on their physical characteristics and physical stability.
Physical properties of elastic liposomes were evaluated using dynamic light scattering
method (DLS). The particle size at the day of their preparation, was ranged between
small and large unilamellar vesicles (SUVs and LUVs), dependent on the hydrophilicity
of the surfactant used, while their PDI value was close to zero, indicating monodispersed
systems. Physical stability study involved the measure of particle size, as a quantifiable
physical property, at selected times over a 30-days period, at storage conditions: i) 4˚C,
ii) 25˚C, iii) 45˚C, suggested that refrigerated conditions promote physical stability, while
high temperatures induce aggregation. Finally according to physical stability study
primarily Tween80 based elastic liposomes were more stable in terms of aggregation, in
comparison of Span80 based transfersomes, at ambient conditions.
