Characterization and drug release behavior of chip-like amphiphilic chitosan–silica hybrid hydrogel for electrically modulated release of ethosuximide: an in vitro study

The hydrogel response under environmental induction often decreases with time because of the mechanical weakness of polymeric hydrogels. Therefore, to reinforce the conventional hydrogels with improved responsiveness and service performance to an external stimulus, a hybrid hydrogel consisting of an amphiphilic chitosan and inorganic silica with a minimal concentration of organic cross-linker was made in order to ascertain the biocompatibility of resulting hydrogels and improve stimulus-induced responsiveness. The hybrid hydrogels generally illustrated a rapid drug (ethosuximide, ESM) release profile over a time period of less than 60 minutes. However, after assembling the hybrid hydrogels into a chip-like device, the sandwiched hybrid showed, under a number of applied DC voltages, a variety of release profiles from a burst-like to slow-elution pattern. A release mechanism was proposed and can be successfully explained as a result of combined effects of electrophoretic and electroosmotic operations. Kinetic analysis indicated that the ESM released from the chip-like device is essentially a shuttle between the swelling-controlled pattern and the diffusion-controlled mechanism, depending on the chemical compositions that were used to prepare the hybrid hydrogels under a given DC electrical field. The hybrid hydrogel chip-like device designed in this work has experimentally proved its technical potential as an electrically responsive drug delivery system to meet various biomedical demands.