Preparation and characterization of antibacterial magnetic-/pH-sensitive alginate/Ag/Fe3O4 hydrogel beads for controlled drug release.

This work reports the synthesis of novel antibacterial magnetic-/pH-sensitive hydrogel beads based on ionotropic-gelation of alginate biopolymer. Using pomegranate peels extract, green-Ag nanoparticles were synthesized inside a mixture of alginate and Fe3O4, via in situ method. The alginate beads were investigated by VSM, TEM, XRD, and FE-SEM techniques. The introducing Ag and Fe3O4 nanoparticles in hydrogel beads caused a reduction in the swelling capacity of hydrogel beads. Besides, a pH-dependent swelling behavior was observed for hydrogel beads with a maximum swelling capacity at pH = 7.4. Diclofenac sodium (DS) as a model drug was loaded in hydrogel beads and its release showed a pH-dependent behavior. Drug release studies exhibited significant behaviors on the subject of physiological simulated pHs with a high release rate at pH = 7.4. The alginate beads have shown a prolonged and successive controlled drug release nearly 83% at pH = 7.4 and time 200 min. In addition to the pH, the release of DS from magnetic beads was affected by the external-magnetic-fields. Also, the Ag-incorporated alginate beads showed strong antibacterial activity against S. aureus and E. coli. These results indicated that the hydrogel beads have potentially applicable in drug delivery systems.