• biodegradable;
  • chitosan;
  • drug delivery systems;
  • swelling


Novel pH-dependent chitosan/poly(ethylene glycol) (PEG) membranes were developed for oral drug delivery. The preparation of these membranes involved a solution-mediating process with glucose addition at different pHs. Fourier transform infrared/attenuated total reflectance showed that the Schiff-base reaction was favored at high pHs and high glucose concentrations. X-ray diffraction analysis showed a continuous increase in the glucose addition transformed the chitosan/PEG samples into amorphous polymers. The equilibrium swelling measurements showed that the swelling ratio of the solution-mediated membranes decreased as the glucose concentration increased, and this was demonstrated by degree-of-mediation analysis. The glucose-mediated membranes had different degrees of mediation, which depended on the pH and glucose concentration. The in vitro release profiles of theophylline-loaded, pH 6 treated, glucose-mediated membranes showed that the theophylline release decreased as the glucose concentration increased. Also, the release behavior of the theophylline from the glucose-mediated membranes varied with the pH of the release medium, the glucose concentration, and the final pH of the glucose-mediated chitosan/PEG gels. Chitosan/PEG membranes prepared by a basic glucose-mediated process could lead to successful applications in localized drug delivery to the intestine. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1083–1094, 2005