Europium-grafted copper nanoclusters: a sensitive fluorescence visualization strategy for tetracycline detection in food

A visualization platform for sensitive detection of tetracycline (TC) based on europium-grafted copper nanocluster (Cu NCs-Cit-Eu) nanoprobe was constructed. Upon introducing TC, TC chelated with Eu 3 + through the β-diketone structure, the red fluorescence emission at 617 nm of Eu 3+ was significantly enhanced. The blue fluorescence intensity of CuNCs at 445 nm remained stable. The ratio of two fluorescence intensities (I 617 /I 445 ) was used as the detection signal. The ratio showed a good linear relationship with the concentration of TC in the range of 0–50 μM, and the detection limit (LOD) was 4.74 nM (2.14 μg/kg). Meanwhile, the luminescence color of the detection system changed from blue to red exposed to 365 nm UV lamp. TC concentration could be preliminarily judged only by observing the color change with the naked eye, which provided great convenience for point-of-care testing (POCT). In addition, this nanoprobe was successfully used for the detection of TC in pork, eggs, milk, and honey samples, with satisfactory results. Therefore, the nanoprobe had the advantages of simple preparation, fast response and good selectivity, and showed satisfactory results in actual sample analysis, indicating that it had excellent application prospects in the fields of environmental monitoring and food safety. • Cu NCs-Cit-Eu nanoprobe for high sensitivity TC detection was developed. • The fluorescence color of the detection system changed from blue to red. • The nanoprobe was suitable for the detection of TC in pork, eggs, milk and honey.