Polyurethane based thin hydrogels for sustained protein delivery

The development of materials that allow the sustained release of therapeutic proteins is the key feature for improving their pharmacokinetics, bioavailability, and dose reduction. In this context, hydrogels are attracting interest, but their design to provide a sustained release profile is still a challenge. Usually, a large mass of polymer is required to prolong the release of the therapeutic agent, involving hydrogels with high thicknesses, which limits their use in some applications. Here, the synthesis of thin thermoresponsive and functionalized hydrogels (tHGs) for sustained protein release is reported to tackle this problem. tHGs were obtained by photo-crosslinking of linear thermoresponsive polyurethanes (PU) based on polyethilenglycol and a functional diol (methyldiethanolamine) that contribute to tertiary amine functionality. These biocompatible tHGs conserved the thermosensitive property of PU, exhibiting a reversible volume change between the swollen and the collapsed state, as a function of temperature. tHGs were able to load the model protein ovalbumin homogenously in their matrix, and sustainably release it during 25 days with a tuneable profile, by changing the PU composition. Finally, this proposal, which combined a very thin delivery film with a sustained protein release, could be a good candidate for its application in ocular therapy.