pH-sensitive sodium alginate hydrogels for riboflavin controlled release.

Sodium alginate (SA) grafted with polyglycidyl methacrylate hydrogels (PGMA-g-SA) was prepared as pH sensitive drug delivery matrices for riboflavin (RF). The hydrogel copolymer matrices were compared with calcium alginate (CA) beads for swelling, degradation, entrapment efficiency and in vitro release of RF. The structure, surface morphology of the CA beads and the prepared hydrogels as well as the chemical stability of the encapsulated drug were characterized by FT-IR and SEM, respectively. The results demonstrate that the optimal formulation was achieved with PGMA-g-SA proportion of (0.75 mol/1 g) and loaded RF 0.03 g. It has been observed that the in vitro release study of RF from this formulation was superior to the other ones and was able to maintain the release for ∼3 and 4 days for the simulated intestinal fluid (SIF) and simulated gastric fluid (SGF), respectively. In general, it has been shown that, GMA grafted onto SA enhanced drug entrapment efficiency, decreased swelling and degradation behaviors of the carrier. In addition, it slowed and controlled the release of RF from the PGMA-g-SA hydrogel compared with pure SA beads crosslinked with Ca2+ ions alone, which thereby provides a facile and effective method to improve the drug delivery systems.