Phosphorus-Nitrogen Co-doped Carbon Dots for Fluorescence Detection of Tigecycline: Mechanistic Exploration.

Carbon dots (CDs) have been broadly employed in many fields due to their excellent fluorescence property, especially in pharmaceutical analysis. Herein, we developed a simple and rapid method to prepare the phosphorus-nitrogen (P, N) co-doped carbon dots via a 3-minute 50-second microwave-assisted synthesis, using N-butyldiethanolamine as the carbon source with phosphoric acid accelerating the CDs formation reaction. The prepared CDs (termed CD1) were characterized by TEM, FT-IR, XPS, XRD and fluorescence spectroscopy. P, N co-doped CDs exhibited notable water solubility, a quantum yield of 19.7% and good photobleaching resistance. Taking advantage of their superior fluorescence, these CDs served as a bright-blue probe for tigecycline detection through fluorescence quenching. The sensor displayed excellent selectivity and anti-interference ability against common coexisting drugs (e.g., voriconazole, ceftazidime, amikacin). Under optimized conditions, a wide linear range (1-936 µM) between F0/F and Tigecycline concentration was established, with a correlation coefficient (R) of 0.984, and the detection limit (LOD) was calculated to be 1.10 µM. Furthermore, we clarified the fluorescence quenching mechanism of CD1 toward tigecycline, which was attributed to the internal filtration effect (IFE). Thus, this work demonstrated a novel P, N co-doped CD-based sensing strategy for rapid tigecycline monitoring.