Amphiphilic urethane acrylate hydrogels: pH sensitivity and drug-releasing behaviors

Amphiphilic urethane acrylate hydrogels containing ionic groups (dimethylolpropionic acid, DMPA) were prepared with varying the molecular weight of the hydrophobic segment (polyether type, PTMG), and their swelling and drug-releasing behaviors were examined. Amphiphilic property for the hydrogels could be confirmed by observing the swelling in both water and organic solvent (benzene) readily. High pH sensitivity was observed due to the carboxylic groups incorporated into the molecular backbone of the urethane acrylate molecules. Owing to the amphiphilic property, it was possible to load hydrophilic (riboflavin selected) and hydrophobic (indomethacin selected) drugs in the network with ease. Each drug successfully released from the network of the urethane acrylate. The releasing behaviors were dependent upon the swelling ones and followed Fickian diffusion.