Versatile Hyperbranched Poly(β-Hydrazide Ester) Macromers as Injectable Antioxidative Hydrogels.

Synthetic reactive oxygen species (ROS)-responsive biomaterials have emerged as a useful platform for regulating critical aspects of ROS-induced pathologies and can improve such hostile microenvironments. Here, we report a series of new hyperbranched poly(β-hydrazide ester) macromers (HB-PBHEs) with disulfide moieties synthesized via an "A2+B4" Michael addition approach. The three-dimensional structure of HB-PBHEs with multi-acrylate end groups endows the macromers with rapid gelation capabilities to form (1) injectable hydrogels via crosslinking with thiolated hyaluronic acid, and (2) robust UV-crosslinked hydrogels. The disulfide containing macromers and hydrogels exhibit H2O2-responsive degradation compared to the counterparts synthesized by a dihydrazide monomer without disulfide moieties. The cell viability under a high ROS environment can be well-maintained under the protection of the disulfide containing hydrogel.