Shaohuang Weng

Implant-associated infections (IAIs) represent one of the most challenging complications following orthopedic implantation. Current antibacterial strategies struggle to achieve complete pathogen eradication while maintaining sustained osteogenic activity at the implant-bone interface. Leveraging the spatial divergence in energy metabolism between prokaryotic and eukaryotic cells, we designed and synthesized guanidine-quaternary ammonium polymer-derived carbon dots (GQCDs) with confirmed structure. Under non-infected conditions, GQCDs enhance mitochondrial metabolism to promote bone regeneration. In infected microenvironments, GQCDs not only selectively target bacterial membranes and inhibit the respiratory chain to exert potent antibacterial effects, but also downregulate host inflammatory responses and restore mitochondrial function in osteoblasts, thereby creating a favorable microenvironment for bone repair. GQCDs can be stably integrated onto various clinical implant substrates via a coating process. GQCDs-coated implants possessed the dual antibacterial and osteogenic functionalities, which were validated using in vitro co-culture systems and in vivo implant infection models in rats and beagles, offering a promising strategy with encouraging translational prospects to address IAIs.

Bacterial sepsis is a life‐threatening condition marked by uncontrolled infection and immune dysregulation, in which iron metabolism critically influences pathogen proliferation and host inflammatory. Herein, we designed and synthesized functional diethylenetriaminepentaacetic acid–spermidine carbon dots (D‐CDs), which exerted dual antibacterial and immunomodulatory effects by targeting iron metabolism. D‐CDs exhibited high affinity for Fe ³⁺ , effectively chelating Fe ³⁺ to induce “iron starvation” in bacteria, leading to metabolic disruption and increased oxidative stress, as evidenced by altered expression of gene associated with iron acquisition, energy metabolism, and oxidative stress defense. Furthermore, D‐CDs displayed potent antibacterial activity against bacteria containing clinical isolated resistant strains. Concurrently, D‐CDs protected host macrophages by attenuating ferroptosis through activation of the Nrf2/HMOX1 pathway and inhibition of the NF‐κB pathway, thereby restoring redox balance and promoting polarization toward the anti‐inflammatory M2 phenotype. In the two rat models of sepsis, induced by intravenous administration of bacterial suspension and by cecal ligation and puncture, D‐CDs significantly improved survival rates, reduced systemic bacterial burden, and alleviated multi‐organ inflammatory injury. Taken together, these findings suggest that iron metabolism centered modulation as a dual‐targeting strategy possess brilliant future for treating severe bacterial infections through integrating antibacterial action with immune homeostasis.

The convenient and widespread implementation of doxycycline (DOXY) detection still requires the development of new methods to enable rapid detection across various environments. In this study, blue-emitting nitrogen-doped carbon dots (N-CDs) were successfully prepared using glutamine and anhydrous citric acid as primary materials. Correspondingly, a simple and sensitive fluorescence method for detecting DOXY was developed using N-CDs as probe. The fluorescence intensities of N-CDs were significantly quenched by variable concentrations of DOXY based on the internal filtration effect, which was verified through quantum efficiency correction experiment. Under the optimized testing conditions, the concentrations of DOXY showed a good linear relationship with fluorescence quenching efficiencies in the range of 0.1-35 μg/mL, with a detection limit (LOD) of 0.018 μg/mL, suggesting the good analytical performance. This method was successfully applied for the determination of DOXY in human plasma, dairy products and tap water samples, demonstrating satisfactory recoveries and reproducibility. The results highlight the promising potential of this approach for clinical monitoring of blood drug concentrations, detection of drug residues, and environmental sample analysis.