Epimedium-Derived Multi-Antioxidant Carbon Dots Nanozymes for Mitigating Drought Stress of Ginseng Seedlings

Drought stress induces oxidative damage that severely impairs the growth and development of ginseng seedlings. Although conventional antioxidants present a theoretical approach for mitigating such oxidative damage, their practical application is constrained by their inadequate stability. Herein, we developed multifunctional antioxidant carbon dots (CDs) synthesized from the medicinal herb Epimedium via a one-step hydrothermal method. The biomass-derived CDs exhibited efficient cascade nanozyme activities for mimicking both superoxide dismutase and catalase to achieve effective scavenging of multiple reactive oxygen species (ROS). Under drought stress, application of CDs to ginseng seedlings significantly mitigated oxidative damage through the modulation of the antioxidant enzyme system and improved osmotic regulation. Simultaneously, it could enhance photosynthetic efficiency and mitigate growth suppression caused by drought. Transcriptomic analysis revealed that CDs alleviated drought stress by triggering transcriptional reprogramming that activated genes related to antioxidant defense, photosynthetic efficiency, and stress signaling. Additionally, the CDs exhibited excellent biocompatibility and environmental safety. This work provides a novel and environmentally friendly strategy to enhance drought tolerance in medicinal plants.