There
is a current interest in the development of new stimuli-responsive
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][Cl])
and choline dihydrogen phosphate ([Ch][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.