Bioinspired Carbon Dots with Multi‐Enzyme Activity, Single‐Atom Catalytic, High Efficiency ROS Scavenging and Antioxidant Therapy for Rheumatoid Arthritis

Carbon dots (CDs) with enzyme-like activity have garnered significant attention due to their ability to mimic the catalytic functions of natural enzymes, making them suitable for specific biochemical reactions in biological environments. However, the development of CDs with multi-enzyme activities remains a challenge due to the inherent complexity of incorporating multiple catalytic functions into a single nanostructure. Here, the synthesis of multi-enzyme active CDs are successfully demonstrated via a hydrothermal process utilizing hemin chloride and urea as precursors. Detailed structural and theoretical investigations reveal that the CDs possess a highly graphitized π-electron system and single-atom iron centers arranged in a monodisperse, four-coordinate configuration with nitrogen atoms. This distinctive structural configuration imparts CDs with multiple enzyme-like activities, including superoxide dismutase and catalase, which contribute to the efficient scavenging of reactive oxygen species. Furthermore, encapsulating these CDs within macrophage membranes enables selective targeting of inflammatory sites and circumvention of immune clearance in a collagen-induced arthritis rat model, offering a targeted and effective antioxidant therapy for rheumatoid arthritis.