Hydrohybic Modification Of Sodium Alginate And Its Application In Drug-Release

Heptylamine was covalently coupled with alginate by means of carbodiimide -mediated activtion chemistry to provide the hydrophobic derivative for subsequent use in drug release. The composition and structure of product was characterized by IR, 1H-NMR and atomic absorption. The result of fluorescence analysis shows that S-3 forms self-aggregates in 0.15mol/L aqueous NaCL solution and its critical aggregation concentration is 0.7g/L.The S-3 self-aggregates are able to encapsulate hydrophobic compound like pyrene. The new heptylamine-alginate conjugate was used for immobilization of BSA by physical entrapment in the presence of calcium chloride. In addition, the encapsulation rate and the release behavior in deionized water and Tris-HCl buffer solution (pH7.2) were investigated. As compared to unmodified alginate beads, modified sodium alginate has relative higher encapsulation rate and better release behavior.The graft copolymers sodium alginate-graft-polybutyl methacrylate were synthesized by two steps: (i)synthesis of amino-end functionalized polybutyl methacrylate macromonomer by radical polymerization of butyl methacrylate with 2-amino- ethanethiol hydrochloride as chain transfer agent; (ii) alginate were hydrophobically modified by coupling of polybutyl methacrylate onto it. The composition and structure of the product were characterized by IR, 1HNMR and TG. The result of fluorescence analysis showed that the modified alginate has increased their hydrophobicity. The new PBMA-g-SA conjugate was used for immobilization of BSA in the presence of calcium chloride. In addition, the release behavior in deionized water and Tris-HCl buffer solution (pH7.2) were investigated. Comparing to unmodified alginate, the modified sodium alginate has relative prolonger release behavior.Sodium alginate (SA) was graft-copolymerized with butyl methacrylate in the mixed solution of ethanol and water with KPS as the initiator. Graft copolymers with both a high grafting efficiency (60%) and a high percentage of grafting were obtained, which indicated that the KPS was an efficient initiator for this grafting. The grafting parameter, including grafting efficiency was evaluated comparatively. The dependence of these parameters on temperature and time, monomer concentration, initiator concentration, and SA backbone concentration was also investigated. Proof of grafting was obtained from gravimetric analysis and IR spectra. A tentative mechanism involving a two-step, single-electrontransfer process of KPS is proposed to explain the generation of radicals and the initiation of grafting. Some basic properties of the grafted copolymer were studied by instrumental analyses, including thermogravimetry and scanning electron microscopy.