Emodin-derived red-emissive carbon dots: Light-driven ROS generation and antioxidant activities in non-illuminative...

Reactive oxygen species (ROS) play dual roles in physiological processes and disease pathogenesis, making their precise regulation crucial for therapeutic applications. Herein, we report the rational design of red-emissive carbon dots (CDs) with light-switchable pro-oxidant/antioxidant bifunctionality for precision nanomedicine. Synthesized from emodin and urea via a solvothermal method, these N-doped CDs exhibit: (1) red emission (>650 nm) with enhanced tissue penetration, (2) efficient type I/II ROS generation under light irradiation, (3) effective ROS scavenging in darkness , and superior water solubility and biocompatibility for in vivo applications. Density functional theory (DFT) calculations confirm that N-doping optimizes the spectral properties of Emo-CDs and promotes the generation of ROS. The unique graphene-like core with abundant surface functional groups enables reversible switching between oxidative and antioxidative states under dark conditions. This work establishes a new paradigm for developing intelligent theranostic agents capable of precise oxidative stress regulation, with promising applications in photodynamic and antioxidant therapy.