Carbon Dots and Eu3+ Hybrid-Based Ratiometric Fluorescent Probe for Oxytetracycline Detection

Overuse of oxytetracycline (OTC) in livestock farming can cause environmental water pollution, risking human health. It is essential to exploit efficient, fast, and sensitive measures to sense OTC in environmental water samples. In this study, a ratiometric fluorescence probe consisted of blue-fluorescent carbon dots (CDs) and Eu3+ was constructed to detect OTC sensitively and selectively. Upon the addition of OTC, bright red fluorescence was generated due to the aggregation of Eu3+, and the intensity of blue fluorescence of CDs reduced because of the inner filter effect between OTC and CDs. Under 365 nm UV light irradiation, the increasing of OTC concentration from 0 to 10 μM resulted a transformation of probe solution fluorescence color from blue to pick. This CDs–Eu3+ hybrid probe also performed a high selectivity for OTC with minimal interference containing various antibiotics, cations, and amino acids. Importantly, the probe demonstrated a low detection limit of 9.6 nM and a satisfactory recovery efficiency for OTC detection in river and tap water.