A ratiometric fluorescent sensor based on Eu3 + -β-diketone functionalized covalent organic framework hybrid material-loaded in electrospun polyvinylidene fluoride film for ultra-sensitive and rapid detection of glyphosate

The extensive application of glyphosate (Gly) presents significant environmental and health risks, underscoring the necessity for advanced sensors to monitor Gly levels. In this study, a novel ratiometric fluorescent sensor (Eu-TTA@COOH-COF) was developed by coordinating Eu³ ⁺ ions with carboxylated covalent organic frameworks (COOH-COF) and grafting 2-thenoyltrifluoroacetone (TTA) ligand to enhance Eu³ ⁺ sensitization. Gly detection relied on its energy competition with the COF, which quenched the characteristic red emission of Eu³ ⁺ (613 nm), and electron transfer to the COOH-COF matrix amplifying the intrinsic blue fluorescence emission (435 nm) of the COF. This dual-signal response enabled precise Gly quantification with a detection limit of 0.049 μM. In addition, a hydrophobic electrospun film (Eu-TTA@COOH-COF@PVDF) with excellent luminescent property was prepared by encapsulating the Eu-TTA@COOH-COF fluorescent probe within a polyvinylidene fluoride (PVDF) matrix. Gly exposure triggered a concentration-dependent fluorescence shift from red to blue, which can be quantified using an RGB recognition applet in smartphones. This thin-film sensing device provides valuable insights for developing intelligent portable sensing platforms to enable on-site detection of pesticide residues.