Synthesis and Characterization of Chitosan-Albumin Conjugates as pH-Sensitive Biodegradable Hydrogels

A new kind of biodegradable pH-sensitive drug delivery system was developed via chitosan-albumin conjugate hydrogel. Through changing the feeding modes of reactants, two types of hydrogels(comb-type and reticular-type) were synthesized by amidation reactions between 6-O-succinoylated N-phthaloyl chitosan and albumin. The structures and morphologies of the hydrogels were characterized by SEM. And their water swelling capacity, drug loading and releasing properties at different pH values were also investigated. It was found that the comb-type of hydrogels with looser space construction had better water swelling ratio(more than 400% of its original mass) than the reticular-type of ones did(about 180% of its original mass). In vitro release experiments of Rifampicin show that the hydrogels provided the controlled release of the entrapped drug for more than 50 h. The drug release rates of both types of hydrogels under acidic condition were lower than those under neutral or basic condition. The introduction of albumin not only improved the hydrophilicity of chitosan, but also provided the possibility of the carrier system combining other biologically active materials more easily to fulfill the delivery and therapy functions.