Physicochemical Characterization and Kinetics Study of Polymer Carriers with Vitamin C for Controlled Release Applications.

This study focuses on the selection and evaluation of a kinetic model for the release of vitamin C from different delivery systems, including microcapsules, hydrogels, and a hybrid system combining both. The microcapsules were synthesized from a 2% sodium alginate solution and with vitamin C incorporated in selected formulations. Hydrogels were obtained through photopolymerization using poly(ethylene glycol) diacrylate and polyvinyl alcohol, with and without the addition of vitamin C. The hybrid system incorporated the vitamin C-containing microcapsules within the hydrogel matrix. Physicochemical properties, such as density, porosity, and water vapor transmission rate (WVTR), were evaluated. Kinetic studies of vitamin C release were conducted under dynamic and static conditions, and the experimental data were fitted to six different kinetic models: zero-order, first-order, second-order, Higuchi, Korsmeyer-Peppas, and Hixson-Crowell. The Higuchi and Korsmeyer-Peppas models provided the best fit for most systems, indicating that the release is predominantly controlled by diffusion and, in dynamic conditions, swelling of the matrix. The hybrid system, while exhibiting slower release than the microcapsules and hydrogel alone, demonstrated more controlled and sustained release, which is advantageous for applications requiring prolonged action.