Two-Photon Carbon Quantum Dots for Detection of Chlortetracycline in Foods

Antibiotics are emerging contaminants in the environment, and their monitoring is important for food safety and human health. Herein, we synthesized a two-photon carbon quantum dots (TP-CQDs) nanoprobe using a simple and green hydrothermal approach and applied it as a chemosensor to detect chlortetracycline (CTC). CTC quenches the intrinsic fluorescence of TP-CQDs, providing a linear response within the 0.5 to 60 μM range and yielding a limit of detection of only 25 nM. Besides excellent stability and good optical properties, we found that TP-CQDs are selective to CTC as structurally similar antibiotics, along with cations, anions, and amino acids, had no significant influence on fluorescence emission. Finally, we successfully applied this sensing platform to quantify CTC in milk, fish, and eggs.