Iron Metal Organic Framework Catalytic Amplification-SERS/RRS Aptamer Determination Of Glyphosate

Metal-organic frameworks（MOFs）are a kind of three-dimensional pore structure that has developed rapidly in the past two decades.Generally,metal ions are used as connection points,and organic ligands are supported to form coordination polymers that extend in 3D space,as well as outside of zeolites and carbon nanotubes is a kind of important new porous material,which are widely used in catalysis,energy storage and separation.Iron metal organic frameworks（FeMOFs）are widely used in catalysis due to their excellent water solubility,high specific surface area,and abundant reactive sites.However,it is rarely used for nanocatalytic amplification-surface enhanced Raman scattering（SERS）quantitative analysis.Therefore,this paper aims to develop a universal method for the detection and analysis of trace substances based on aptamer-regulated FeMOF catalytic activity.A SERS/RRS dual-mode sensor was designed to identify trace glyphosate,Co²⁺,Pb²⁺,As³⁺and other target analytes by using FeMOF catalytic amplification of H₂O₂-TMB molecular reaction and adaptor specific recognition of glyphosate,Co²⁺,Pb²⁺,As³⁺and other target analytes.The details are as follows:1.The preparation and characterization of FeMOFIn this chapter,Fe/Co/Cu/Ni-MOFs were successfully prepared by room temperature stirring method using trimesic acid as ligand and different metal ions(Fe³⁺,Co²⁺,Cu²⁺,Ni²⁺)as connection points.The method does not require overnight reaction at high temperature and high pressure,and the method used is simple and effective.Then,we selected FeMOF with the strongest catalytic activity by the slope of Fe/Co/Cu/Ni-MOF on H₂O₂-TMB reaction as the evaluation criterion.Further considering the effect of the type of ligand on the catalytic activity of FeMOF,three MOFs were synthesized by using benzoic acid,terephthalic acid and trimesic acid as ligands.It was found that when the ligand was selected as trimesic acid,FeMOF has the best catalytic activity.Finally,we optimized the preparation conditions of FeMOF,including the effects of terephthalic acid,sodium hydroxide and ferrous sulfate heptahydrate on the catalytic performance of FeMOF.Then,the optical properties of FeMOF were studied by using Resonant Rayleigh Scattering,Ultraviolet-Visible and Infrared Spectroscopy.The structure of FeMOF was further characterized by X-ray powder diffraction（XRD）,scanning electron microscope（SEM）and laser light scattering.Finally,the optimal preparation conditions of FeMOF and the FeMOF with the best catalytic performance were obtained,which laid the foundation for the subsequent application of it to the catalytic amplification of nano-reactions.2.Iron metal-organic framework catalytic amplification SERS/RRS aptamer determination of glyphosateIn this chapter,based on the aptamer-mediated FeMOF-catalyzed H₂O₂-TMB molecular reaction,a new SERS/RRS dual-mode method for the detection of glyphosate,Co²⁺,Pb²⁺,As³⁺and other target analytes was established.It was found that FeMOF exhibited a strong catalytic effect on the H₂O₂-TMB reaction,and its reaction product TMB_OX could be used as a probe molecule for surface-enhanced Raman scattering（SERS）.In addition,resonance energy transfer occurred between FeMOF and TMB_OX.After adding aptamer（Apt）,Apt can encapsulate FeMOF through intermolecular interaction,thereby inhibiting its catalysis,reducing the generated TMB_OXand the RRS/SERS signals of the system.With the addition of target analytes such as glyphosate,Co²⁺,Pb²⁺,As³⁺,Apt specifically binds to the target,and FeMOF is released again to restore its catalytic ability,resulting in an increase in the generated TMB_OX,the recovery of the RRS and SERS signals of the system,and their increments are linearly related to the concentrations of target analytes such as glyphosate,Co²⁺,Pb²⁺,As³⁺,etc.Thus,the quantification of target analytes are realized.Finally,taking the detection of glyphosate as an example,the method was applied to the detection of glyphosate in domestic landfill leachate and environmental soil,the linear ranges were2.53 nmol/L-15.21μmol/L,2.11 nmol/L-4.22 nmol/L,and the detection limits were 0.85 nmol/L and 0.70 nmol/L,the results were satisfactory with the recoveries of 94.67-96.45%and 93.49-100.59%,respectively.