Release behavior of high molecular weight solutes from poly(ethylene glycol)-based degradable networks

Water-soluble PEG-based macromers containing oligomeric blocks of a hydrolyzable alpha-hydroxy acid were synthesized and photopolymerized to form degradable hydrogels to control the release of high molecular weight, hydrophilic solutes. First, network mesh size and volume swelling ratio during the degradation process were characterized to understand fundamentally the effect of hydrogel degradation kinetics and subsequent changes in network structure on solute release. Second, the release behavior was examined and related to the swelling and structural properties of the hydrogels; experimental results show that solute transport can be diffusion controlled or degradation controlled depending on the relative size of the hydrogel mesh size to the solute. Finally, the ability to tailor the release from multilaminated biodegradable hydrogels to obtain an approximate zero-order release profile was studied theoretically.