Ratiometric fluorescent probe based on amino-functionalized MOF for on-site glyphosate detection via smartphone-integrated hydrogel platform

Considering the hazards of glyphosate and the limitations of current detection methods, a method for rapid detection of glyphosate is designated. Herein, a novel sensing platform based on the immobilization of ratiometric fluorescent probe NH 2 -MIL-101(Fe)@[Ru(bpy) 3 ] 2+ (briefly as MOF@Ru) into agarose hydrogel was fabricated for the rapid and selective detection of glyphosate. Firstly, MOF@Ru with an octahedral morphology was synthesized, and the chemical structure composition was further characterized by X-ray diffraction (XRD), fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS). After that, the ratiometric fluorescence probe was assembled, and the optimized conditions were investigated. Under the optimal detection conditions, the ratiometric fluorescent probe enabled rapid detection (within <2 s), demonstrating a linear response within the concentration range of 0–100 μM (R 2  = 0.9934), and the detection limit was determined to be 0.63 μM. In the spiked recovery experiments with food samples, the recovery rates ranged from 98.90 % to 112.52 %, with a relative standard deviation of less than 6.86 %. Moreover, the fabricated ratiometric fluorescent probe was immobilized into agarose hydrogel, forming a portable test kit, which was compatible with smartphone RGB analysis. The R/B ratio exhibited a concentration-dependent behavior (R 2  = 0.9980), enabling the on-site detection with a detection limit of 0.78 μM, suggesting the potential for the rapid and on-site detection of glyphosate.