Fabrication Of New SERS Substrates And Its Application In The Detection Of Prohibited Additives

Surface enhanced Raman spectroscopy（SERS）technology has been widely used in surface science,material science,food safety,drug analysis due to its high sensitivity,high response characteristics and fingerprint spectral characteristics.In this thesis,the development of SERS technology at domestic and abroad and its application in the field of food and drug safety were analyzed to develop a new SERS substrate.For the purpose of expanding the detection objects,the performance of SERS substrates with different structures was studied through theoretical analysis,simulation calculation and experimental study.Meanwhile,the new SERS substrates were used to detect the banned antibiotic heavy metals and dyes in food and drugs,so as to further promote the application of SERS technology in the field of food and drug safety.Based on electromagnetic enhancement mechanism,the finite difference time domain（FDTD）method was used to simulate and calculate the electric field distribution of nanostructures with different morphology.It was concluded that Au nanobipyramids had strong electromagnetic field at their tips,which provided theoretical basis for the subsequent development of SERS base of Au nanobipyramids.Then,the theoretical spectra of chlortetracycline hydrochloride and levofloxacin,as well as the industrial dye scarlet 808,were calculated based on density functional theory（DFT）using Gaussian software,and assigned the Raman characteristic peaks of the drugs in combination with the measured spectra of the standard product,providing a theoretical basis for subsequent practical detection.The monodispersed Au nanobipyramids structure was prepared by seed growth method,combined with phase transfer and self-assembly technology,a new SERS substrate with two-dimensional hot spots was obtained.The substrate analysis enhancement factor was 7.35×10⁵.Compared with the traditional SERS base of Au nanospheres,the SERS base of Au nanobipyramids had better Raman signal enhancement effect,and could ensure the signal repeatability and time stability in the process of use.Au nanobipyramids base could be used to quickly detect aureomycin hydrochloride residue in the pretreated milk samples on site.A new Ag NPs-AAO SERS solid substrate was prepared by self-assembly technique in which Ag NPs particles were assembled into holes in AAO.SERS substrate prepared based on 41 nm Ag nanospheres had an enhancement factor of1.17?10⁶ for the analysis of 4-MBA probes.Through the limitation of AAO holes,the distribution uniformity of silver nanoparticles in the substrate is better than that in the traditional silicon substrate,and it has good signal repeatability and time stability.The LOD of Ag NPs-AAO SERS substrate for levofloxacin residue in milk was 1.88?10^-6 mol/L.Functionalized CV-Ag NPs probe was prepared by modifying CV molecule on the surface of Ag nanoparticles,which could be used to detect mercury ions in solution.SERS substrate with in-situ extraction function was prepared by modifying Ag nanospheres on the substrate of filter paper using interface self-assembly technology.By using CV-Ag NPs probe to determine the soluble mercury in cinnabar,the soluble mercury content in cinnabar of different batches is 0.624?g/g and 5.140?g/g,respectively.The minimum detection limit of scarlet 808 in cinnabar was 0.05μg/m L by Paper-Based SERS Substrate.The above results indicate that SERS technology has a certain application potential in the field of traditional Chinese medicine.