Assembly of a MnO₂ Nanosheets-Based Hydrogel for Regulating Oxidative Stress and Treating Atopic Dermatitis

Manganese dioxide (MnO2) nanosheets with a well-defined 2D structure can serve as catalase (CAT) and superoxide dismutase (SOD) mimics and hold a high potential in regulating the oxidative stress of atopic dermatitis (AD). However, facile, time-saving, and scalable synthesis of high-activity MnO2 nanosheets is still challenging. Here, we report a one-step oxidative synthesis strategy of MnO2 nanosheets and explore its potential as CAT and SOD mimics to exert antioxidant functions. After further gelatinization by integrating MnO2 nanosheets into a poly(ethylene glycol)diacrylate (PEGDA) polymer (PGM hydrogel), the obtained PGM hydrogel, characterized by well-designed cross-linking density and moisture retention, retains high antioxidation and cytoprotection ability. In AD-bearing mouse models, the PGM hydrogel facilitates the recovery of the impaired mice skin, reducing the severity score, scratching numbers, epidermal thickness, and immune factors, including mast cells, IgE antibodies, and inflammatory cytokines IL-4 and IL-10. Such a simple and reliable approach paves the way for the scale synthesis of MnO2 nanosheets and its practical application as antioxidative and immunoregulation agents for AD therapy.