Development of a novel smart bio-composite hydrogel based on dextran, citric acid, and glucoxylan for pH-dependent drug delivery and stimuli-responsive swelling and release

The present research was aimed to design a benign bio-composite hydrogel based on dextran and glucoxylan (a polysaccharide isolated from chia seed, i.e., CSH) using citric acid (CA) as a cross-linking agent for developing a pH-dependent drug delivery system (DDS). The glucoxylan suspension was heated with the aqueous solution of CA and dextran at 80°C for 24 h. High swelling capacity of Dextran-CA-CSH (powder and tablet) was observed in distilled water (DW) and buffer solutions of pH 6.8 and 7.4, while negligible swelling was witnessed at pH 1.2. The swelling capacity of Dextran-CA-CSH (powder and tablet) in aqueous solutions of NaCl and KCl was decreased with increasing concentration. Comparatively, the swelling capacity of Dextran-CA-CSH (powder and tablet) in aqueous solution of NaCl was greater than in aqueous solution of KCl. The swelling-deswelling (on/off switching) properties of Dextran-CA-CSH (powder and tablet) versus different stimuli such as pH 7.4 and pH 1.2, DW and normal saline, and DW and ethanol revealed its stimuli-responsive nature. The release of diclofenac sodium (DFS) from the tablet formulation of Dextran-CA-CSH was pH dependent and followed the first-order kinetic model as well as a non-Fickian diffusion mechanism. Hence, these preliminary studies confirmed the pH-responsive nature of the Dextran-CA-CSH composite and its usefulness for targeted drug delivery at the pH of the distal parts of the gastrointestinal tract.