A pH-sensitive, stimuli-responsive, superabsorbent, smart hydrogel from psyllium ( Plantago ovata ) for intelligent drug delivery.

Herein, we report a polysaccharide-based hydrogel isolated from psyllium husk (a well-known dietary fiber) and evaluated for its swelling properties in deionized water (DW) at different physiological pH values, i.e. , 1.2, 6.8 and 7.4. Swelling of psyllium hydrogel (PSH) in DW under the influence of temperature and at different concentrations of NaCl and KCl solutions was also examined. A pH-dependent swelling pattern of PSH was observed following the order DW > pH 7.4 > pH 6.8 > pH 1.2. Stimuli-responsive swelling and deswelling (on-off switching) behavior of PSH was observed in DW and ethanol, DW and normal saline, at pH 7.4 and pH 1.2 environments, respectively. Similar swelling behavior and on-off switching attribute of PSH-containing tablets indicated the unaltered nature of PSH even after compression. Scanning electron micrographs of swollen and then freeze-dried PSH via transverse and longitudinal cross-sections revealed hollow channels with an average pore size of 6 ± 2 μm. Furthermore, PSH concentration-dependent sustained release of theophylline from tablet formulation was witnessed for >15 h following the non-Fickian diffusion mechanism. Subacute toxicity studies revealed the non-toxic nature of PSH. Therefore, dietary fiber-based material, i.e. , PSH could be a valuable pharmaceutical excipient for intelligent and targeted drug delivery.