Cerium-doped carbon dots as superoxide dismutase-mimetic nanozymes for mitigating oxidative damage in aged soybean seeds

Cerium-doped carbon dots (Ce-CDs) were prepared via a facile one-pot hydrothermal method. • Ce-CDs demonstrated potent SOD-like activity and total antioxidant capacity. • Ce-CDs can act as an effective nanozyme for mitigating oxidative damage in seeds. Developing stable and cost-effective nanozymes as alternatives to natural superoxide dismutase (SOD) remains a significant challenge. Herein, we report the rational design and one-pot hydrothermal synthesis of cerium-doped carbon dots (Ce-CDs) as highly efficient SOD-mimetic nanozymes. The as-prepared Ce-CDs were monodisperse spherical nanoparticles (average diameter: 2.26 nm) possessing abundant surface functional groups and a high quantum yield of 46%. XPS analysis confirmed a characteristic Ce 3 + /Ce 4+ mixed-valence state, where the predominance of active Ce 3+ species (71.8%) facilitated a potent redox cycle for O 2 •- scavenging, analogous to the catalytic center of native SOD. EPR spin-trapping experiments further confirmed that Ce-CDs effectively scavenge O 2 •- , providing direct evidence for the proposed redox cycle mechanism. The Ce-CDs exhibited robust SOD-like activity and total antioxidant capacity, as evidenced by NBT and ABTS assays, maintaining high stability over varying pH and ionic strengths. When integrated into biological systems, these nanozymes effectively rejuvenate aged soybean seeds by scavenging 58.23% of O 2 •- and regulating endogenous ROS homeostasis. This work not only provides a high-performance fluorescent nanozyme with a well-defined catalytic mechanism but also demonstrates its potential for mitigating oxidative damage in seed preservation. Download: Download high-res image (157KB) Download: Download full-size image