A novel Nitrogen-Doped Water-Soluble carbon dot for highly selective Recognition of Mg2+ by chelation conjugation enhancement effect (CCE) and its application in Synergistically enhanced photodynamic antibacterial

Magnesium (Mg 2+ ) is crucial for various biological processes, making real-time Mg 2+ monitoring essential for health. Traditional organic fluorescent sensors face challenges such as complex synthesis and poor water solubility, limiting their application. In contrast, nitrogen-doped carbon dots (N-CDs) offer a promising alternative due to their simple synthesis, stability, and biocompatibility. This study presents water-soluble N-CDs synthesized via a hydrothermal method, which show high selectivity for Mg 2+ detection through a chelation-conjugation enhancement (CCE) effect. The nitrogen doping also enhances photosensitivity, enabling the generation of reactive oxygen species (ROS) for photodynamic therapy. Notably, Mg 2+ -chelated N-CDs exhibit superior photodynamic antibacterial activity. Theoretical and experimental analyses reveal that the CCE significantly improves electron transfer, leading to enhanced photosensitizing properties. This work offers a novel and efficient strategy for dual-functional Mg 2+ detection and photodynamic therapy.