Solid-phase engineered red-emissive carbon dots for multi-scenario uranyl ion tracking and on-demand pH-triggered...

The extensive utilization of nuclear energy exacerbated both the occurrence of accidental leakage incidents and the dispersion of uranium contamination, rendering the development of innovative analytical methods tailored for rapid on-site detection and long-term tracking of uranium increasingly critical. Herein, we report a solid-phase engineered strategy to synthesize red fluorescent carbon dots (NR-CDs) derived from neutral red dye. The NR-CDs exhibit enhanced optical stability, biocompatibility, and multi-mode detection capabilities for UO₂²⁺ via absorption and fluorescent responses. The detection system achieves remarkable sensitivity with limits of detection of 20 nM (absorption) and 10 nM (fluorescence), surpassing the EPA's safety threshold (30 ppb). A scanometric analysis mode utilizing grayscale change further enables rapid and high-throughput UO₂²⁺ detection in real water and food samples. The NR-CDs also enable the visual tracking of UO₂²⁺ in living cells and zebrafish, highlighting their versatility for environmental monitoring and biomedical imaging applications. Moreover, NR-CDs demonstrate pH-activated antibacterial efficacy against both Gram-positive/negative bacteria through a proton-enhanced bactericidal mechanism, achieving an intelligent closed-loop system with environment-sensing and precision bactericidal. This study expands the design principles and synthesis strategies of multifunctional CDs, establishing a scalable and sustainable platform to address critical challenges in environmental monitoring and public health.