Abstract: Chitosan grafted poly(methacrylic acid)(CS-g-PMAA) was synthesized using methacrylic acid and chitosan as precursors and cerium ammonium nitrate as initiator. Products with different grafting degree were characterized by means of FTIR, 1H NMR and elemental analysis. Drug-loaded beads made from the as-prepared copolymers were fabricated by combining ionic-crosslink with chemical-crosslink using trisodium citrate and glutaraldehyde as crosslinking agent, respectively. The beads have a core-shell structure as-revealed from scanning electron microscopy. The release behaviors of model drug incorporated in the beads were monitored using UV/Vis spectrophotometer and found to be dependent on pH and NaCl content. The results show that the drug release rate is slowest for CS-g-PMAA beads with grafting fraction(Gg) of 12.21%. The total drug release fraction for the CS-g-PMAA beads is 44.18% at pH=1.8 and is less than that of CS beads, which is 65.24%. Therefore, the grafting of CS could improve the drug release behavior. In addition, CS-g-PMAA beads have higher enzymatic stability than that of CS beads.

Key words: chitosan, methacrylic acid, graft copolymer, drug release, core-shell structure