Preparation Of Pesticide Biosensor Based On SERS And Research On Pesticide Multi-residue Analysis Method

In recent years,environmental pollution and public health safety issues caused by the large-scale use of pesticides and multiple pesticide residues have attracted widespread attention,which is essential for the development of rapid pesticide multiple residue detection methods.Surface-enhanced Raman scattering(SERS)is a method of using incident excitation light source to illuminate the surface of rough metal(such as silver,copper,gold,etc.).The medium adsorbed on the surface of the metal material will produce an enhanced Raman scattering effect.In this way,molecular structure information that is difficult to obtain by conventional Raman spectroscopy can be obtained.SERS overcomes the shortcomings of low sensitivity of conventional Raman spectroscopy and has the advantages of high sensitivity,good selectivity,and fast response speed.It has become an emerging analysis technology.In recent years,the related research of the SERS has promoted its application in various fields,including the research of Raman response substrate materals,the research of the SERS combined with biosensors or immunosensor in analysis and detection,and the research on practical applications combined with various methods,and so on.In this paper,by constructing SERS sensing systems with different structures,the Raman response intensity changes of core-shell precious metal nanoparticles in SERS beacon molecules were explored,and combined with immunoassay analysis methods and biosensor analysis methods,the following two pesticide multi-residue analyses were constructed:1.Chlorothalonil(CHL),imidacloprid(IMI)and oxyfluorfen(OXY)are often used in combination to increase crop yield.However,these three pesticides are highly toxic to aquatic organisms and cannot easily degrade in nature.In this work,a surface-enhanced Raman scattering-based lateral flow assay(SERS-LFA)test strip was prepared by combining antibodies with SERS nanotags,and then competitive immune binding was used to simultaneously detect the three pesticides.Moreover,the two-way binding effect of ss DNA-streptavidin on Ag^4-NTP@Au NPs and Ag^4-NTP@Au NPs with antibodies was used to further amplify the detection signal.Under the optimal conditions,the SERS-LFA test strips had high sensitivity,low LOD,short detection time,high specificity and low cost.Furthermore,the detection range also met international detection standards.By the detection of the SERS signal on the test line of the paper strip,accurate quantitative analysis was realized.The practical application of the proposed system was demonstrated by simultaneous detection of CHL,IMI and OXY in environmental and food samples with satisfactory results.2.The detection of multiple pesticides in food and environment is of great importance for human health and safety.In this study,under the stabilizing effect of Tween-20,Au@Ag nanoparticles(NPs)with good SERS signal response was synthesized as the base material for Raman response.Then,using Ag@Au NPs and the DNA backbone structure embedded with aptamers corresponding to three pesticides to construct Au@Ag NPs tetrahedron(Nano-tetrahedron)for simultaneous detection of three pesticides.In the presence of three pesticides,the embedded aptamers in the Nano-tetrahedron would identified them respectively.Then DNA skeleton was deformed.Ag@Au NPs in the Nano-tetrahedron approached to each other,forming SERS hot spots and increasing the intensity of the Raman signal,further realizing the detection of pesticides'concentration.The biosensor constructed from the SERS substrate with higher sensitivity and lower detection limit(profenofos:0.0021 ng/m L;acetamiprid:0.0046 ng/m L;carbendazim:0.0061 ng/m L).The practicability of this proposed method was verified by adding the recovery rate detection,and the accuracy of the method was examined by the analysis of the HPLC-MS method.The proposed SERS biosensor could distinguish and detect three pesticides in food and environmental samples,achieving sensitive detection and low detection limits,which can be used in practical applications.