Effects of template molecules on the molecular permeability of molecularly imprinted polysaccharide composite films

pH-responsive materials comprising natural polysaccharides have attracted attention due to their high biocompatibility and biodegradability, and are potentially useful as biomaterials. In particular, polysaccharide film materials can be used as drug carriers, wound dressings, and separation materials. We have succeeded in the fabrication of polysaccharide composite films from polyion complexes of anionic polysaccharides and chitosan. These films showed molecular permeability and the permeation behavior can be controlled by applying a molecular imprinting approach while using a cationic molecule as the template. However, the details of the effects of template molecules have not been clarified. In this study, to investigate the effects of the characteristics of the template molecules on the molecular permeability of the film, molecularly imprinted polysaccharide composite films were prepared by using template molecules with different sizes and charge valences. The molecular permeation behaviors of the resulting films were then evaluated under different pH conditions. It was found that differences in template molecules affected the swelling ratio and surface charge of the films. Moreover, the permeation behavior was largely affected by the surface charge of the film, while the size of the template molecule had little effect. Based on the results, the mechanism for the molecular permeation is discussed. These results will contribute to the application of polysaccharide composite films as pH-responsive materials.