A Magnetically Responsive Selenium‐Doped CeO 2 Nanozyme for On‐Demand Reactive Oxygen Species Modulation and Enhanced Tissue Regeneration

ABSTRACT Precise control of reactive oxygen species (ROS) is indispensable during tissue repairing. Inorganic nanozymes such as cerium dioxide (CeO 2 ) have emerged as potent ROS modulators, however, their fixed catalytic activity prevents on‐demand adaptation to the rapidly changing immune microenvironment. Here, we reported a magnetically responsive dynamic antioxidant system that autonomously tunes its ROS‐scavenging capacity on demand. Selenium (Se) doping was first exploited to engineer high‐density oxygen vacancies (Vo) in the CeO 2 lattice, enabling the nanozyme intrinsic antioxidant activity enhancement. Its catalytic efficiency could be further amplified under a static magnetic field (SMF). In vitro analysis revealed that Se‐CeO 2 under SMF significantly promoted the polarization of macrophages toward the pro‐regenerative M2 phenotype. The as‐prepared Se‐CeO 2 was subsequently loaded into a sodium alginate–hyaluronic acid hydrogel (SCSH‐Gel), witnessed to protect chondrocytes and fibroblasts from oxidative stress in vitro. Followed in vivo tests found SMF and Se‐CeO 2 synergistically accelerate neocartilage formation in a cartilage defect model and promoted re‐epithelialization in a full‐thickness skin‐wound model. Collectively, our results demonstrated that Se doping coupled with magnetic actuation enables inorganic nanozymes to dynamically modulate ROS homeostasis, offering a versatile strategy for precisely programming the microenvironment to facilitate tissue regeneration.