In-situ Measurement Of Molecular Events And Quantitative Properties Of Liquid Interface Enhanced Raman Spectroscopy

In recent years,with the development of nanomaterial,SERS technology has matured and is widely used in various fields,especially in the fields of biology,chemistry and food.Among them,liquid surface enhanced Raman spectroscopy(SERS)has attracted widespread attention.Liquid SERS is a self-healing,highly sensitive,and highly reproducible baseless SERS platform.Therefore,the article focuses on the following work around liquid SERS:In Chapter 2,the effect of ligand and nanoparticle concentration on the self-assembly of the 3D plasma array at the liquid interface is investigated.Experiments show that PVP,citrate and other common ligands can promote the self-assembly of nanoparticles,while CTAB-coated nanoparticles cannot self-assemble.The high concentration of nanoparticles breaks up the assembled oil droplets into smaller droplets and reduces the repeatability of SERS detection.By studying the self-assembly mechanism and conditions of nanoparticles,it provides a certain reference for the assembly and application of SERS at the liquid interface.It is expected to control the creation of nanomaterials with unique optical,magnetic and electronic properties for self-assembly,opening up new Technical approach.Internal standard(IS)is widely used in SERS quantitative analysis due to its high reliability.However,it has not been determined which IS has the best effect on improving the accuracy of SERS analysis.In this article,we compared three internal standards,which are organic solvent internal standards,molecules embedded inside the core-shell nanoparticles and molecules modified on the surface of the nanoparticles.Experiments have shown that the three different ISs have no absolute advantages or disadvantages,depending on the phase in which the analyte is dissolved.This provides a better choice for ensuring the accuracy of quantitative detection of analytes under different dissolution conditions,and is further used for Raman imaging and molecular quantification.A thorough understanding of the plasmon photocatalytic reaction caused by the surface plasmon resonance(SPR)effect caused by surface enhanced Raman scattering is necessary.However,due to the complexity and uncontrollability,the research on the liquid-liquid interface plasma photocatalytic reaction is rarely involved.In this paper,gold nanoparticles(Au nanoparticles,Au NPs)and silver nanowires(Ag nanowires,Ag NWs)co-assembled 3D plasma liquid spheres are placed in a cuvette to form a liquidliquid interface to study p-nitrothiophenol(4-NTP)reduction reaction.The study found that in the presence of halide ions and protons,the halide ions provide hot electrons through the oxidation half reaction to drive the conversion of 4-NTP to 4-ATP without the use of traditional catalysts.In addition,the obvious etching of silver in the photocatalytic reaction significantly enhanced the reporter signal.The type and concentration of halogen ions play a vital role in the reduction reaction and coordinate with the enhancement caused by silver etching.