Tailor-made polymers for local drug delivery: release of macromolecular model drugs from biodegradable hydrogels based on poly(ethylene oxide).

Hydrogels were synthesized from degradable and non-degradable PEO bismacromonomers. The degradability was provided by hydrolyzable segment between the main PEO chain and the methacrylate or methacrylamide groups at the both PEO chain termini. The hydrolyzable segment consisted of a monomeric alpha-hydroxy acid or a depsipeptide. The polymerization conditions and the choice of a bismacromonomer influenced the cross-linking density of the hydrogels. The release behavior of model macromolecular solutes, FITC dextran and bovine serum albumin (BSA), was studied. The small FITC-dextran 4 kDa was released rapidly from the hydrogel. The larger FITC-dextran 40 kDa and BSA were retained inside the matrix and their release rate was controlled by the degradation.