Modeling of Water Transport in and Release from Glucose-Sensitive Swelling-Controlled Release Systems Based on Poly(Diethylaminoethyl Methacrylate-g-Ethylene Glycol)

The glucose-sensitive behavior of glucose-sensitive, poly(diethylaminoethyl methacrylate- g -ethylene glycol) hydrogels was modeled and analyzed in the case of exposure to glucose solutions. Gel microparticles were prepared with molar ratios of 10:1 diethylaminoethyl methacrylate to poly(ethylene glycol) of molecular weights 200, 400, and 1000, using tetra(ethylene glycol) dimethacrylate as a cross-linking agent. Glucose oxidase and catalase was immobilized in the matrix during polymerization. The equilibrium and dynamic swelling properties of these hydrogels were investigated. The pH-dependent equilibrium swelling characteristics showed a sharp transition between the swollen state and the collapsed state at a pH of 7.0. Microparticles showed rapid swelling and collapse under the influence of pulsatile pH changes. The glucose-sensitive behavior of the gels due to glucose oxidase was also studied. Diffusion and relaxation models were used to predict swelling of single microparticles under different pH and glucose conditions. Swelling models were coupled with insulin diffusion models to predict release profiles. These results can be used for better design and understanding of the behavior of glucose-sensitive systems.