Albumin-Conjugated pH/Thermo Responsive Poly(amino urethane) Multiblock Copolymer as an Injectable Hydrogel for Protein Delivery

Albumin-conjugated pH and thermo responsive poly(amino urethane) multiblock copolymers are synthesized. The aqueous solution of the conjugate exhibits pH/temperature dependent sol-gel phase transitions that can be tuned by changing solution concentration and albumin composition. The gel window well covers the physiological condition allowing the flowing liquid to readily form the solid gel under the back of the Sprangue-Dawley (SD) rats. The release profile of lysozyme, as a model protein, shows that the conjugate hydrogel is able to effectively reduce the burst effect, in vivo, and maintain the sustained release of lysozyme over 4 and 2 weeks in the in vitro and in vivo experiments, respectively. Such conjugate hydrogel can be considered as a potential candidate for long-term delivery of proteins.