Analysis of Operating Conditions Influencing the Morphology and In vitro Behaviour of Chitosan Coated Liposomes

Among nanoparticle-based drug delivery formulations, lecithin/chitosan liposomes are promising candidates because of their biocompatibility, biodegradability and bioadhesion properties. Lecithin is a mixture of highly biocompatible phospholipids, while chitosan represents one of the most used polymers in pharmaceutical formulations. Their combination results in positively charged complexes that are able to sustain a specific, prolonged and controlled release. Scarce reproducibility and batch-to-batch variation in lecithin/chitosan liposome synthesis, as well as difficult scale-up to industrial production, is a major challenge for their utilization. Here we present a strictly controlled procedure, based on ethanol diffusion in water, which yields to a precise and reproducible self-organization of lecithin and chitosan molecules. We analysed the size, surface charge and stability of chitosan coated liposomes at different lecithin/chitosan ratios. We found that increasing the lecithin/chitosan ratio both mean particle size and surface charge were progressively reduced. A good stability was observed for all formulations, though interactions occurred in the presence of low amount of surface-adsorbed chitosan liposome vesicle. Chitosan coated liposomes interact with A549 and Caco-2 cells inducing low toxic effects only with prolonged incubation times. In conclusion, the proposed procedure provides good reproducibility in the formation of non-toxic and highly stable formulations of chitosan coated liposomes as drug delivery systems.