Dandelion-Derived Carbon Dots with pH-Responsive Charge and Dual ROS Regulation for Anti-Infection and Accelerated Wound Repair

Bacterial infections associated with biofilm formation hinder wound healing via enhanced antibiotic resistance and impaired tissue repair. Herein, we fabricated dandelion herb-derived carbon dots (DH-CDs) through a green solvothermal-extraction method, developing a biocompatible antimicrobial agent with synergistic wound healing potential. Physicochemical characterization showed that DH-CDs are quasi-spherical (4.87 nm), partially graphitized nanoparticles with abundant surface functional groups and pH-responsive charge-switching capability. In vitro studies demonstrated that DH-CDs exhibit broad-spectrum antibacterial activity against S. aureus and E. coli, with minimum inhibitory concentrations (MICs) of 62.5 μg/mL at pH 7.4 and 31.25 μg/mL at pH 5.5. The antibacterial effect is mediated by a multimodal mechanism involving electrostatically driven bacterial membrane disruption, energy metabolism inhibition, intracellular reactive oxygen species (ROS) generation, and antioxidant enzyme inactivation. Moreover, DH-CDs achieve complete disruption of mature S. aureus biofilms at 300 μg/mL. Notably, DH-CDs possess excellent biocompatibility, with a 10% hemolysis concentration (HC10) exceeding 4000 μg/mL and over 95% viability of NIH 3T3 fibroblasts at 2000 μg/mL. A unique dual ROS-modulating capability was identified that DH-CDs generate excessive ROS to eradicate bacteria while scavenging deleterious ROS in mammalian cells, thereby preserving redox homeostasis. In vivo evaluations in a murine S. aureus-infected full-thickness wound model demonstrated that DH-CDs significantly accelerate wound closure by promoting re-epithelialization, granulation tissue maturation, collagen deposition, and hair follicle regeneration, outperforming a commercial wound healing spray. Collectively, DH-CDs integrate green synthesis, pH-responsive antibacterial/antibiofilm activity, dual ROS regulation, and biocompatibility, representing a promising translational candidate for bacteria-infected wounds and a paradigm for multifunctional biomass-derived nanomaterials.