Aptamer Mediated TbMOF@Au Catalytic Nanogold Reaction-SERS/RRS/Abs Assay For The Determination Of Malathion

Indiscriminate use of pesticides has been shown to be prone to pesticide residues that do not degrade in produce or food within a short period of time and can pose a serious health risk.Malathion（MAL）,a highly toxic organophosphorus insecticide（OPs）,has been widely used for rice pest control and has carcinogenic,teratogenic and mutagenic effects on infants and fetuses.Therefore,it is important to develop a sensitive,accurate and efficient detection method for environmental analysis.Metal organic framework（MOF）is a hot research topic in the field of chemical analysis in recent years.It not only has the rigidity of inorganic materials and the ductility of organic materials,but also has various functions such as adjustable porosity,large specific surface area,good thermal stability and multiple metal sites,and it can be combined with metal nanoparticles to form MOF complexes.Metal nanoparticles have received a lot of attention from researchers due to their high chemical activity and specificity,but they are prone to agglomeration due to their small size,large specific surface area and high surface energy.Using MOF as the substrate,the functional nanomaterials are attached to the MOF surface by post-treatment modification method,which can not only effectively prevent the agglomeration of metal nanoparticles,but also improve the problems such as poor chemical stability of MOF.In this paper,Terbium metal-organic framework（Tb MOF）nanomaterials were prepared by microwave method with homophthalic acid as ligand in an energy-efficient manner.The Tb MOF-loaded Au catalyst（Tb MOF@Au₁）was rapidly prepared by using HAu Cl₄ as the precursor and Na BH₄ as the reductant.The Tb MOF-loaded Ag catalyst（Tb MOF@Ag）was also prepared by using Ag NO₃ as the precursor and Na BH₄ as the reducing agent.Loading Au/Ag nanoparticles on the surface of Tb MOF can enhance the dispersion of Au/Ag nanoparticles,thus modulating the surface electronic structure of MOF and increasing its active sites to achieve improved catalytic activity of MOF.The catalytic effects of Tb MOF,Au NPs,Ag NPs,Tb MOF@Au and Tb MOF@Ag on the HAu Cl₄-Cysteine（Cys）nanoreaction were also investigated,respectively.It was found that Tb MOF@Au₁ had the strongest catalytic activity.The Au NPs generated from this reaction had a strong resonance Rayleigh scattering（RRS）and ultraviolet absorption（Abs）peak at 370 nm and 550 nm,respectively.When VB4r was added as a molecular probe,the Au NPs had a strong surface enhanced Raman scattering（SERS）effect at 1616 cm^-1.When malathion aptamer(Apt _MAL)was added,the interaction of hydrogen bonding,hydrophobic interactions,and intermolecular forces led to Apt _MAL blocking the surface-active site of Tb MOF@Au₁,thus inhibiting the catalytic effect of Tb MOF@Au₁ and leading to a decrease in the SERS/RRS/Abs signal value of the system.When MAL was added to the system,MAL would specifically bind to Apt _MAL to form a stable complex structure,releasing Tb MOF@Au₁,thus restoring its catalytic activity,and making the system’s SERS/RRS/Abs signal value recovered.Accordingly,a new simple and sensitive method for the detection of Tb MOF@Au₁ catalytic amplifying Apt SERS/RRS/Abs trimodal analysis of MAL was established.The linear determination range of MAL was 0.5-20 ng/m L,and the detection limit was 0.21 ng/m L.The high selectivity of this method under complicated conditions was investigated by related interference experiments.At the same time,this method was applied to the determination of MAL in fruits,with the recovery rate of 92.6-106.6%and the precision of 2.72-8.16%.