Layersome: development and optimization of stable liposomes as drug delivery system

This paper describes the development of stable drug delivery systems named layersomes. The layersomes are conventional liposomes coated with one or multiple layers of biocompatible polyelectrolytes in order to stabilise their structure. The formulation strategy is based on an alternative coating procedure of positive poly(lysine) (pLL) and negative poly(glutamic acid) (pGA) polypeptides on initially charged small unilamellar liposomes (SUVs). The size distribution and the zeta potential of the final entity depend on the number of polyelectrolyte layers and the charge of the last coating layer. Morphological studies were achieved by flux cytometry and cryo electron microscopy. Release studies of encapsulated hydrophilic 5(6)-carboxyfluorescein (5,6CF) in the presence of Triton or ethanol showed an increased membrane resistance of the layersomes compared to classical SUVs. Finally, encapsulation of piroxicam (PX) was performed with success.