Injectable self-assembled microgels incorporating MnO2-decorated Mg-doped bioactive glass nanozymes for in vitro protection of nucleus pulposus cells.

Intervertebral disc degeneration (IDD) is a prevalent pathological condition characterized by an oxidative stress microenvironment that drives nucleus pulposus (NP) cell dysfunction and extracellular matrix (ECM) catabolism. While nanozyme-based antioxidant strategies have shown promise, their clinical translation remains hindered by poor local retention and insufficiently sustained catalytic activity within the degenerative disc. Here, we developed an injectable, self-healing microgel (MPMB/GO) for the co-delivery of MnO2 nanozymes and magnesium ions (Mg2+) to modulate oxidative and inflammatory stress-associated responses. In vitro studies demonstrated that MPMB/GO effectively scavenged reactive oxygen species (ROS), preserved mitochondrial membrane potential, and attenuated oxidative stress-induced NP cell apoptosis. In summary, MPMB/GO provides a nanozyme-engineered injectable microgel strategy for localized redox modulation and NP-cell protection, offering a potential material platform for future IDD intervention studies.