One-pot synthesis of highly mechanical and redox-degradable polyurethane hydrogels based on tetra-PEG and disulfide/thiol chemistry

Highly mechanical hydrogels with stimuli degradability are promising scaffold materials for tissue engineering, due to their unique advantage of retaining mechanical strength in use, while being able to be readily removed by external stimuli after use. However, it has always been a big challenge to integrate both good mechanical properties and stimuli degradability into one single hydrogel. In this work, a series of tetra-PEG polyurethane hydrogels with tunable redox-degradability and a high compressive fracture strength has been synthesized by a one-pot method. The good mechanical properties are owed to an extremely uniform network of tetra-PEG, and the redox-degradability is realized using cystamine, which contains a highly DTT-sensitive disulfide bond. The mechanical strength of the as-prepared hydrogels reaches a megapascal range, and their complete degradation time can be flexibly adjusted from 4 to 22 days by controlling the proportion of cystamine. With the above properties, these hydrogels are believed to have potential bio-applications.