Modulation of the biocatalytic activity and selectivity of CeO₂ nanozymes via atomic doping engineering

Artificial enzymes show prospects in biomedical applications due to their stable enzymatic catalytic activity and ease of preparation. CeO₂ nanozymes represent a versatile platform showing multiple enzyme-mimicking activities, although their biocatalytic activities and selectivity are relatively poor for biomedical use. Herein, we developed Mn- and Co-doped CeO₂ nanozymes (M/CeO₂, M = Mn or Co) via atomic engineering to achieve a significant increase in enzyme-like activity. The M/CeO₂ nanozymes exhibited outstanding peroxidase-like activity with a reaction rate about 8-10 times higher than that of CeO₂. Importantly, the Co/CeO₂ nanozyme preferred for catalase-like activity with a 4-6-fold higher catalytic rate than CeO₂, while the Mn/CeO₂ nanozyme had a predilection for improving the superoxide dismutase-like capacity. This indicated the selective modulation of enzyme-mimicking activities via atomic doping engineering. Cellular level experiments revealed the in vitro therapeutic effects of the nanozymes. Mn/CeO₂ and Co/CeO₂ selectively modulated the intracellular redox imbalance in lipopolysaccharide (LPS)- or H₂O₂-stimulated nerve cells and improved cell survival. This work provides a feasible strategy for the design of catalytically selective artificial enzymes and facilitates the widespread application of CeO₂ nanozymes in redox-related diseases.