Development of Greener Multi-Responsive Chitosan Biornaterials Doped with Biocompatible Ammonium Ionic Liquids

There is a current interest in the development of new stimuliresponsive materials using biodegradable and biocompatible molecules, mainly if biomedical applications are envisaged. In this work, chitosan (a cationic polyelectrolyte obtained from renewable resources) and two ammonium-based ionic liquids (ILs), namely, choline chloride ([Ch][CI]) and choline dihydrogen phosphate aCh][DHP]), were used to develop biocompatible and biodegradable materials that can be used as improved electrical and pH-sensitive drug delivery systems. The influence of each IL and of residual acetic acid on the properties of chitosan-based films was evaluated. Results showed that the employed ILs can affect the water vapor sorption capacities, water vapor transmission rates, elastic moduli, and impedances/conductivities of chitosan films. Acidic pH conditions significantly enhanced the conductivity and the actuation capacity of the films, and this effect was more pronounced for films loaded with [Ch][DHP]. The potential use of these films as tunable and stimuli-responsive drug delivery systems was also studied for chitosan films loaded with [Ch][DHP] and sodium phosphate dexamethasone (DXA). The amount of DXA released from films doped with [Ch] [DHP] was always lower than for films without IL, independent of the pH of the release medium. Therefore, choline-based ILs can be used as additives to tune drug release profiles of ionic drugs from chitosan-based materials. Furthermore, the simultaneous effect of ILs on the conductivities/impedances of films will allow the development of biocompatible and biodegradable drug delivery responsive systems for several biomedical/pharmaceutical applications such as iontophoretic devices.