Synthesis and characterization of pH-sensitive glycopolymers for oral drug delivery systems

pH-sensitive hydrogels are suitable candidates for oral delivery of therapeutic peptides and proteins. due to their ability to respond to environmental pH changes, New pH-sensitive glycopolymers have been developed by free-radical photopolymerization of rnethacrylic acid and 2-methacryloxyethyl glucoside. using tetra(ethylene glycol) dimethacrylate as a cross-linking agent. To determine the suitability of these hydrogels as carriers for oral drug delivery devices, their swelling behavior was investigated as a function of the pH and copolymer compositions. and various structural parameters such as the number-average molecular weight between cross-links, V, the mesh size., and the cross-linking density, rho(X), were calculated. The transition between the swollen and the collapsed states of these hydrogels was at a pH of 5. The swelling ratios of the hydrogels increased at pH values above 5. The mesh sizes of the hydrogels were between IS and 35 A in the collapsed state (at pH 2.2) and between 70 and 111 Angstrom in the swollen state (at pH 7.0). Finally, as the cross-linking ratio of the copolymer increased, the swelling ratio of the hydrogels decreased at both pH 2.2 and 7.0.