engleski

Mucoadhesive chitosan-coated liposomes : the influence of chitosan type on liposomal characteristics

Lecithin liposomes, empty or containing verapamil, made of lecithin were prepared by the modified ethanol injection method. Three different tzpes of chitosans with variable molecular weight and degrees of deacetylation were used, namely Seacure 113, Seacure 210 and Seacure 311. Chitosan coating was carried out by mixing the liposomal suspencion with the chitosan solution followed by incubation. The size of liposomes was measured before and after polymer coating by an image analysis technique. Uncoated empty liposomes were in the size range between 300-350 nm (mean diameter). After the coating with different type of chitosans, the size increased up to 430 nm, especially liposomes coated with high molecular weight chitosan (Seacure 311). Mean diameter of liposomes with verapamil was in the size range between 400-500 nm (prior to coating), whereas the size after the coating was between 500-700 nm, regardless of chitosan type. All chitosan-coated liposomes were of spherical shape and no morphological differences between uncoated and coated liposomes were observed. Liposomes with verapamil, originally entrapping 19% of the drug taken in the preparation and coated in the presence of unentrapped drug, contained between 35% to 50% of the drug. The highest entrapment was determined for liposomes coated with medium molecular weight chitosan (Seacure 210). By the right choice of chitosan type, it is possible to influence the characteristics of liposomes, such as liposomal size and increase the actual trapping efficiencies. One can conclude that chitosan is stabilizing original liposomal structure and protecting entrapped drug.

liposomes; chitosan

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