Research On Pesticide Residue Detection Technology Based On Self-powered SERS Substrate

Pesticide residues on fruits and vegetables pose a serious threat to public health.The rapid and sensitive detection of pesticide residues in fruits and vegetables is the key to supervise the safe use of pesticides.As a high-sensitivity rapid detection technology,surface-enhanced Raman technology can provide fingerprint information related to molecular structure.It is very promising to provide a suitable solution for the rapid detection of fruit and vegetable pesticide residues.However,the current surface-enhanced Raman technology still has low sensitivity.This paper proposes and studies the use of self-powered electric field enhanced surface enhanced Raman spectroscopy?E-SERS?intensity to achieve rapid and sensitive detection of pesticide residues in fruits and vegetables.The key to self-powered E-SERS is to examine the preparation of the substrate.The substrate is divided into a self-powered part that can transform the deformation of the material into an electric field,and a noble metal structure with nanostructure characteristics that can enhance Raman spectroscopy through electromagnetic field resonance.The specific preparation method is to first modify GO with PEI,and then combine the modified rGO-PEI with PVDF-hfp to prepare a PVDF-hfp/rGO-PEI flexible composite porous piezoelectric film.Then using PVDF-hfp/rGO-PEI flexible piezoelectric composite porous film as the base material,using silver nitrate and hydrazine hydrate as raw materials,a layer of Ag nanoparticles is uniformly formed on the surface through the redox reaction to form a"Self-energizing substrate"for SERS to enhance the electric field.The effects of the amount and ratio of silver nitrate and hydrazine hydrate on the SERS performance of self-powered substrate were studied.When silver nitrate and hydrazine hydrate were obtained in a ratio of 1:5,where silver nitrate was 0.1 mol/L and hydrazine hydrate was 0.5 mol/L,the best conditions for preparing self-powered substrate were obtained.Secondly,using density functional theory and UB3LYP/6-311G basis set to optimize the spatial structure of 13 common pesticides and calculate the theoretical Raman spectrum.The theoretical Raman spectrum was compared with the actual measured Raman spectrum,and the corresponding Raman characteristic peaks of 14pesticides were assigned in the range of 200³500 cm^-1,and the interference of spectral peaks from the self-powered substrate was excluded.The results showed that each pesticide had multiple independent Raman peaks after excluding the peaks from the self-powered substrate.And,the SERS enhancement effect of pesticides with or without self-powered substrates was evaluated.It is found that the self-powered substrate does not generate electricity and has a good Raman detection effect,and the three prominent functions of pesticide Raman detection in the case of self-powered substrate power generation compared to no power generation:?1?reducing the background noise of the Raman spectrum,making the spectrum more clear and sharp;?2?more difficult to obtain characteristic peaks,characteristics The number of peaks increases;?3?For the case that no characteristic peaks may appear without generating electricity,some characteristic peaks will be displayed after power generation,which changes from scratch.And the enhancement of Raman characteristic peak by self-powered substrate mainly concentrated in the area of 500cm^-11500cm^-1.As well as Raman tests on a variety of mixed pesticides,it was found that the self-powered substrate can effectively distinguish different pesticide characteristic peaks.Furthermore,taking Apple as a research object,the self-powered substrate was used to perform Raman test on mixed pesticides in apple stock solution or extract solution.The self-powered substrate was able to effectively identify the characteristic peaks of pesticides,and provided a new method for rapid detection of pesticide residues in fruits and vegetables.