Application of cerium–nitrogen co-doped carbon quantum dots to the detection of tetracyclines residues and bioimaging

We synthesized cerium–nitrogen co-doped carbon quantum dots (Ce–N–CDs) with citric acid, ethylenediamine, and cerium nitrate via the hydrothermal method. Carbon quantum dots synthesized by changing the addition amount of ethylenediamine and cerium nitrate, heating temperature, and time exhibited good water solubility and high quantum yield (QY = 93.14%). The carbon quantum dots were characterized via transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and other characterization techniques. Results confirmed successful Ce–N–CDs formation. The Ce–N–CDs showed high detection selectivity to tetracyclines (TCs) residues. When the experimental conditions were optimized and the tetracyclines member doxycycline (DC) was selected as the representative, the fluorescence quenching efficiency of the Ce–N–CDs, exhibited a good linear relationship with DC concentration within 0.4–35 µM with a detection limit of 0.25 µM. The method was successfully applied to the determination of DC and total TCs in milk and pork. Therefore, this fluorescent probe can be used as a sensitive platform for TCs analysis. The Ce–N–CDs synthesized via the hydrothermal method had low cytotoxicity and did not affect cell viability. The possible application of the Ce–N–CDs in cell imaging was explored.