Lanthanide coordination polymer nanoparticles as a ratiometric fluorescence sensor for real-time and visual detection of tetracycline by a smartphone and test paper based on the analyte-triggered antenna effect and inner filter effect

Lanthanide coordination polymer nanoparticles (LML-Eu 3+ -GMP CPNPs) were fabricated as a ratiometric fluorescence sensor for real-time and visual assays of tetracycline (TC). The LML-Eu 3+ -GMP CPNPs were prepared by spontaneous self-assembly of Eu 3+ , luminol (LML) and guanosine 5′-monophosphate (GMP) at room temperature , which only emitted blue fluorescence dominated by LML, and no red characteristic fluorescence of Eu 3+ was observed. In the presence of TC, TC can trigger the antenna effect (AE) and inner filter effect (IFE), the blue fluorescence of LML-Eu 3+ -GMP CPNPs is quenched by TC via IFE, and the red characteristic fluorescence of Eu 3+ can be turned on through AE. When sodium citrate (Cit) is added to the sensing system, it can further enhance the red fluorescence of Eu 3+ . The dual-ligand CPNP sensor has a rapid fluorescence response, noticeable fluorescence color change, good selectivity , and high sensitivity with a detection limit of 3.4 nM. It was successfully applied to detect TC in honey, milk, lake water and tap water . Meanwhile, the portable smartphone and test paper were applied to develop POCT devices for real-time and visual detection of TC, which could offer a promising application for real-time and semiquantitative assays of TC.