A novel nitrogen-doped carbon dots using chitosan and 4-hydroxycoumarin as the precursors for identification of Al3+ and tetracyclines and its applications.

Aluminum and tetracyclines (TCs) are important environmental pollutants, and the development of simple and efficient analytic techniques is of great significance. In this work, an economical nitrogen-doped carbon dots (N-CDs) from chitosan and 4-hydroxycoumarin was prepared through one-step hydrothermal process. The N-CDs with blue fluorescence emission exhibited satisfactory water solubility, stability and biocompatibility. When the addition of Al3+ or TCs, the N-CDs solution presents obvious fluorescence enhancing or quenching, Al3+ can make the fluorescence in the N-CDs-TCs system recover. The N-CDs sensor platform shows satisfactory selectivity and sensitivity in detection of Al3+, tetracycline, oxytetracycline and chlortetracycline, and their low detection limits are 0.857 μM, 120 μM, 127 μM, and 117 μM, respectively. The N-CDs sensor can be applied for the detection of trace Al3+ and TCs in real samples such as tap water and milk, moreover, possible mechanisms on the combination of N-CDs with Al3+ and TCs also were investigated by IR, UV, XPS analysis and DFT calculations. In addition, the N-CDs with good water solubility and biocompatibility can be used to observe the hatching process for medaka fish embryo and fluorescence bio-imaging to indicate that it may have good application potential in biomedical field.