Preparation of oxidized sodium alginate-graft-poly((2-dimethylamino) ethyl methacrylate) gel beads and in vitro controlled release behavior of BSA

Graft copolymerization of amino group-terminated poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA-NH2) onto oxidized sodium alginate (OSA) was reacted without using a catalyst. The structure of the graft was investigated by Fourier transform infrared (FT-IR) spectroscopy. The OSA-g-PDMAEMA gel beads were prepared by dropping the aqueous solution of the graft copolymer into CaCl2 aqueous solution. The effects of pH and ionic strength on the swelling behaviors of the gel beads were studied. The results indicate that the gel beads have pH and ionic strength sensitivity. Bovine serum albumin (BSA) was entrapped in the beads and the in vitro drug release profiles were established in buffer solution with pH 1.8 (HCl), pH 7.4 (KH2PO4–NaOH), and 0.9% (w/v) NaCl at 37 °C. The results showed that the oral delivery of proteins can be controlled by adjusting the graft percentage (G, %), pH and ionic strength. According to this study, the OSA-g-PDMAEMA gel beads could be suitable for the oral delivery of proteins.