pH responsive chitosan and hyaluronic acid layer by layer film for drug delivery applications

Environmentally responsive polymer films have received much attention, but the stability of such films and the sensitivity of the response still have to be improved. The preparation of responsive films for low pH changes still faces challenges. In this study, catechol groups were used to functionalize chitosan and hyaluronic acid for mussel-inspired, catechol based adhesion. The modified chitosan and the modified hyaluronic acid were deposited in a layer-by-layer manner. The chemical properties of the compounds and surface properties of the coatings were characterized by UV, IR, scanning electron microscopy and water contact angles. The assembly and stability of the film were investigated in situ using quartz crystal microbalance (QCM-D). The film had improved stability compared to the native polymers and it showed reversible pH-dependent swelling and shrinkage. The film was loaded with a drug and placed in PBS solutions of different pH for several days, and the amount of drug released by the drug-loaded film was different under different pH environments. This provides ideas for the intelligent application in materials science and biology, and has broad prospects in drug delivery systems and tissue engineering.