Synthesis of hydrazine-functionalized Polyrotaxane and formation of adaptable sliding hydrogels

This work details the synthesis and characterization of Polyrotaxane-Hydrazine (PR-Hyd) , a polyethylene glycol-based polymer utilized in the formation of Adaptable Sliding Hydrogels (ASG) . ASG is a viscoelastic 3D cell culture system with reversible hydrazone bonds that can be leveraged to present cells with tunable stress relaxation and mechanical plasticity. ASG builds upon our lab’s previously reported Sliding Hydrogel (SG) platform which is formed via irreversible covalent crosslinking between norbornene functionalized Polyrotaxane (PR-NB) and a dithiol crosslinker. To generate PR-Hyd, we adapted and optimized the synthesis protocol for PR-NB and used proton NMR to quantify polymer functionality and reduce batch-to-batch variability. In addition, this work outlines our protocol for facile ASG scaffold formation using aldehyde functionalized polyethylene glycol macromers for crosslinking. Taken together, these methods enable reproducible synthesis of PR-Hyd and the fabrication of reversibly crosslinked ASG scaffolds that can be leveraged as a 3D cell niche for applications including regenerative medicine and in vitro disease modeling. • Synthesis method for Polyrotaxane-Hydrazine, a polyethylene glycol-based polymer precursor designed for forming Adaptable Sliding Hydrogels (ASG) • Characterization of polymer functionality via proton NMR • Reproducible fabrication of ASG hydrogels