Media-Responsive Swelling and Material Release Properties of Polysaccharide Composite Films

Abstract

Free-standing, water-insoluble thin films made of polyion complexes of natural polysaccharides, for example, chondroitin sulfate and chitosan, are successfully obtained by utilizing hot press techniques. These films exhibit sufficient mechanical properties to be used as structural materials in the dry state. On the other hand, the films swell to some extent and soften in water, but are not dissolved out, although they are made of water-soluble polysaccharides. The degree of swelling is controllable depending on the species and pH of the media, in addition to the polysaccharide species. When small dye molecules are used as model drugs, dye-loaded films are obtained using both pre- and post-loading methods. These dye-loaded films release the dye molecules when immersed in aqueous media. The kinetics of the dye release is affected by the species and pH of the solutions, which indicate that it is correlated with the swelling behavior of the films. These results support that the free-standing polysaccharide composite films have promise to be used as biocompatible film materials such as plasters or wound dressings having media-responsive drug release abilities.