Oxidative stress is a major factor in the formation of lethal aortic aneurysm. Traditional molecular antioxidants can only act as reactants to scavenge reactive oxygen species (ROS) through stoichiometric reactions, which are consumed in the process, leading to unsustainable antioxidant effects. This study proposes a nanocatalytic antioxidation strategy for treating aortic aneurysm by constructing an antioxidative biomimetic nanocatalyst, which features a Mn-N