Organic redox-initiated polymerization process for the fabrication of hydrogels for colon-specific drug delivery.

Organic-redox initiated polymerization technique based on the co-initiators system comprising benzoyl peroxide and N-phenyldiethanolamine was used at ambient temperature to fabricate pH-responsive hydrogels. The effects of changes in the concentration of the co-initiators system, the ratio in which the co-initiators combined, the type of the polymerization solvent, the pH of the hydrating medium, the concentration of the cross-linking agent based on azo-bond and the pH-sensitive cross-linking agent on the properties of the hydrogels were investigated. Increasing the concentration of the co-initiators system, decreasing the concentration of the two types of cross-linking agents, and replacing DMSO by ethanol as the polymerization solvent resulted in hydrogels with increased equilibrium swelling ratio and increased molecular weight between cross-links at pH 7.