A superporous and pH-sensitive hydrogel from <i>Salvia hispanica</i> (chia) seeds: stimuli responsiveness, on–off switching, and pharmaceutical applications

Abstract

C/NMR) spectra. Thermal analysis indicated that the CSH is a thermally stable material and decomposes in two steps. The scanning electron microscope (SEM) images of CSH witnessed the existence of microscopic channeling and a superporous nature with average pore sizes of 18 ± 11 μm (transverse cross-sections) and 23 ± 15 μm (longitudinal cross-sections). The CSH is a haemocompatible material. The CSH revealed pH and saline-responsive swelling in powder and compressed form (tablet) in the following order; distilled water (DW) > pH 7.4 > pH 6.8 > pH 1.2. Moreover, the swelling of CSH followed second-order kinetics. The swelling of CSH powder and tablets was decreased with increasing salt concentration. The pH, solvent, and saline responsive on/off switching (swelling/deswelling) results of the CSH and tablets disclosed its stimuli-responsive nature. The CSH prolonged the release of valsartan for 5 h at pH 7.4, whereas, negligible release (19.3%) was noted at pH 1.2. The valsartan release followed first-order kinetics and the non-Fickian diffusion. In conclusion, the CSH is a stimuli-responsive smart material with great potential to develop pH-sensitive and targeted DDSs.