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Chitosan/Alginate Dialdehyde Multilayer Films with Modulated pH‐Responsiveness and Swelling

Oxidation of alginate is a promising method that creates aldehyde groups, which can form stable cross-links with amine groups on chitosan. In this work, it is shown that a systematic variation in the oxidation degree of alginate dialdehyde allows for effective tuning of the swelling capacity of chitosan/alginate dialdehyde multilayer films. Besides, it is demonstrated that the pH-responsiveness of the multilayer films can be regulated by the choice of pH at which the layer-by-layer assembly is conducted. The combination of these two parameters allows designing polysaccharide multilayer films with tunable degree of swelling and stimuli-responsiveness. Multilayer films of chitosan and alginate dialdehyde demonstrate reversible swelling/shrinkage in response to variations in pH, due to the formation of chemical cross-links during the layer-by-layer assembly. The pH-responsiveness and swelling capacity are tunable by the pH at which the multilayer is fabricated, as well as the degree of oxidation of alginate dialdehyde.