Preparation Of Novel SERS Substrate And Its Application In Environmental And Food Analysis

In recent years,with the environmental pollution and food safety and other issues have aroused more and more attention,Surface-enhanced Raman scattering(SERS)is increasingly used in food detection,detection of single-molecule species,environmental monitoring,bioanalytical detection and so on,and plays a more and more important role in the field of analysis.However,it is still difficult and important to construct a new,stable and homogeneous SERS substrate material,which can be achieved on the analyte of simple,rapid and sensitive analysis and detection.In the first chapter,we mainly introduce Raman scattering and SERS discovery and its principle.On the other hand,we also introduce the application of SERS in analytical science and its future development.In the second chapter,we mainly report a SERS analysis method based on the composite structure of graphene/noble metal nanomaterials for PAHs contaminants in the environment.This novel nanocomposite structure can be used as a substrate material for SERS activity.The nanomaterials have a large number of Raman active sites and special structural properties of graphene,which can greatly enhance the Raman signal of the analyte.These characteristics make the composite structure have good sensitivity,stability and repeatability in realizing SERS detection of PAHs pollutants,and can be used as an ideal SERS substrate material.The substrate can be used for the analysis and detection of PAHs in seawater.The detection limit can reach 0.03ppm,Far below the US environmental protection department requirements of the maximum limit of 7ppm.This composite structure can be used for enrichment detection of PAHs pollutants in water environment,which provides a sensitive,portable,fast,stable and recyclable analytical detection method for on-site contaminant analysis and detection.Composite structure and analytical detection methods have potential application value.In the third chapter,we report a method for the selective detection of nitrite based on the mixture of 1,8-diaminonaphthalene-modified spherical gold nanoparticles and p-mercaptoaniline-modified gold nanorods.Under acidic conditions,mercaptoaniline forms diazonium salts in the presence of 1,8-diaminonaphthalene,and gold azoes and globular gold nanoparticles are connected at both ends of the azo molecule.Forming a satellite structure,this structure has a large number of active sites,the azo molecular Raman signal has greatly enhanced.The reaction has anti-interference and selectivity,and can realize the SERS detection of nitrite.Azo molecules with absorbance,can also use ultraviolet spectrophotometer technology to achieve the detection of nitrite.1,8-diaminonaphthalene has fluorescence,but the resulting azo molecules are not fluorescent,but also can use fluorescent spectrophotometer technology to achieve the detection of nitrite.By this method,not only can use ultraviolet spectrophotometer and fluorescence spectrophotometer technology to detect nitrite,but also can use the SERS technology to achieve nitrite fast,simple and sensitive analysis and detection.