Intelligent detection of tetracycline by a rare earth multicolor fluorescent probe based on guanosine-5′-monophosphate

Long-term discharge of tetracycline (TC) in the environment exerts selective pressure on the bacteria, increasing resistance in sensitive bacteria and posing a serious threat to public health. Therefore, it is crucial to develop real-time detection of tetracycline. In this study, we reported a novel rare-earth fluorescent nanosensor FITC-GMP-Eu, based on the formation of guanosine-5′-monophosphate disodium salt (GMP) and fluorescein isothiocyanate (FITC), which enabled the real-time identification of tetracycline in the environment. When there was no TC in the environmental sample, the FITC-GMP-Eu nanosensor exhibited the green fluorescence of FITC due to the fluorescence quenching effect of water molecules on Eu 3+ . When the environmental samples contained TC, the red fluorescence of Eu 3+ could be sensitized due to the diketone structure in the tetracycline molecule, which enabled the naked-eye visualized identification of TC. The nanosensor had high sensitivity (detection limit of 19 nM) and a wide detection range (0–30 μM) for TC. At the same time, the sensor was characterized by high visualization and anti-interference ability due to the strong fluorescence of both FITC and Eu complexes. In order to improve the practicality of the detection, this study also prepared a paper-based and sodium alginate gelated fluorescence detection platform with low background fluorescence. Combined with the common color analysis and RGB extraction procedures in mobile phones, real-time and on-site identification of TC on the surface of various fruit samples can be achieved.