| Objective:In the past few years,there have been frequent incidents of illegally adding plasticizers and pesticide residues.The toxic substances in these foods can enter the human body directly or indirectly,posing a great threat to human life and health.The shortcomings of the classic detection methods for toxic substances in food,such as time-consuming,insufficient detection limits,large sample size,etc.,make these methods difficult to apply to rapid detection of food on site.Compared with these classical methods,Surface Enhanced Raman Scattering Spectroscopy（SERS）has the advantages of simple operation,simple pre-treatment,no damage to samples,high sensitivity,and detection on site.These advantages make SERS widely used in trace In terms of substance detection.In this experiment,a core-shell nanostructure with gold nanorods multimers as the core was used as the SERS substrate,which improved the stability of the substrate and had high SERS sensitivity.And sensitive and rapid detection of several toxic substances has been achieved.Method:Firstly,the polymerization of Au NRs was induced to form Au NRs multimers by ethanol,L-cysteine and sodium citrate,and the TEOS were added to form a mesoporous silicon shell to form a core-shell structure nanoparticles,and then the core-shell nanostructure was used as the SERS substrate,and crystal violet was used as a Raman probe to investigate the sensitivity and repeatability of the substrate.Finally,several different toxic substances such as malachite green（MG）,thiabenzimidazole（TBZ）,and butyl benzyl phthalate（BBP）were selected as the test objects,and the SERS detection of toxic substances were treated based on the core-shell nanostructures,and the results were analyzed.Result:1.After synthesizing Au NRs by seed synthesis method,Au NRs are induced to polymerize into polymers and form mesoporous silicon shells..First,using crystal violet as a Raman probe to investigate its SERS performance.The results of sensitivity inspections of crystal violet at different concentrations show that the substrate can detect a crystal violet solution with a concentration of 10-8mol/L,then the crystal violet solution with a concentration of 10-6 mol/L was selected to investigate its repeatability.The results showed that the relative standard deviation of 40 tests of the crystal violet solution on this substrate was 8.53%,which indicates that the substrate has high sensitivity and good repeatability,to meet the needs of SERS detection of subsequent poisons.2.After eliminating the influence of solvents and substrates on the detection structure by blank control,SERS detection was performed on three different kinds of poisons using the core-shell nanostructure as the substrate.The experimental results show that the substrate is highly sensitive in the SERS detection of these poisons,and the characteristic peaks of the analytes in the obtained SERS spectrum are clearly visible.The detection limits of MG,TBZ,and BBP can reach 5×10-9mol/L,10-11mol/L,10-8mol/L respectively.Then by adding BBP to a liquor and testing it by SERS,and performing SERS detection,the results show that the characteristic peaks of BBP in the SERS spectrum obtained under the interference of liquor are still clearly visible.It shows that the multi-core-mesoporous silicon shell nanostructures have great application prospects in the detection of poisons.Conclusion:In this experiment,a core-shell nanostructure was prepared in two steps,which overcomes the shortcomings of poor stability of Au NRs.By observing its morphological characteristics,the material has a uniform morphology.The results of investigations by Raman probes show that the core-shell nanomaterials have high sensitivity and good repeatability as SERS substrates.Finally,the results of SERS detection on several toxic substances also show that the substrate has high sensitivity and good repeatability. |
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