A smartphone-integrated ratiometric fluorescent platform based on europium (III)-functionalized metal-organic frameworks for quantitative and visual detection of tetracycline

Food safety and environmental pollution caused by tetracycline antibiotics (TCs) are of great concern for public health worldwide. To realize on-site, real-time, ultrasensitive visual detection of tetracycline is an urgent need. Herein, a ratiometric fluorescent probe has been constructed by grafting Cit-Eu3+ on the amino-silanes-modified metal–organic framework for the detection of tetracycline. Under exciting at 330 nm, the red emission at 617 nm of Eu3+ was significantly enhanced by the antenna effect upon adding tetracycline, while the intrinsic fluorescence quenching at 425 nm of the probe ascribes to the inner filter effect, resulting in a reversible signal response. Under optimum conditions, the probe exhibits a visualized fluorescence evolution from blue to red with a linear range of 0.1–60 μM, and a limit of detection as low as 24.6 nM. Furthermore, a test strip was further fabricated by dropping NH2-MIL(Al)@SiO2-Cit-Eu3+ on filter paper, which can be used for on-site of tetracycline conveniently by using a smartphone. Moreover, the proposed probe has also been successfully applied for TCs detection in spiked honey and tap water sample with satisfactory recoveries in the range from 91.21–102.97 %, demonstrating the potential real application performance. This the smart sensing platform lays a foundation for the rapid screening of TCs in food and environmental matrices.