pH-Responsive Hydroxypropyl Cellulose-Based Membranes for Controlled Mass Transport and Drug Release.

The swelling-regulated transport properties of modified and cross-linked HPC-based hydrogel formulations containing NaCMC and citric acid were studied as stimuli-responsive polymeric membranes under various conditions, including deionized water. Physiological conditions were simulated by evaluating various pH conditions (1.2, 6.8, and 7.4). The pseudo-second-order kinetic model best described the swelling process, suggesting that both solvent uptake capacity and polymer network relaxation contribute to the extent of swelling. The swelling behavior of the hydrogel formulations was significantly influenced by salt concentration. The modified HPC hydrogel system exhibited stimuli-responsive swelling-switching behavior under saline, water/ethanol, and acidic/basic environments, demonstrating reversible swelling-deswelling cycles. Maximum swelling was observed in water at pH 7.4. In contrast, abrupt deswelling in an ethanol solution at pH 1.2 reduced hydrogel swelling and water uptake. The effect of temperature on the swelling behavior of the hydrogel and its thermo-responsive swelling behavior was also evaluated. Drug release behavior suggested diffusion-mediated release through the swelling hydrogel matrix. These findings suggest that the modified HPC-based hydrogel system may be useful for pH-responsive oral drug delivery applications.