Preparation Hybrid Substrate And Surface Enhanced Raman Spectroscopy Used To Detection Thiram And Melamine

Thiram (bis-(dimethyldithio-carbamoyl)disulfide),a dithiocarbamate fungicide, isone of the most largely used worldwide in agriculture as a fungicide and animalrepellent. Moreover, the toxicity induced by exposure to thiram can lead to seriousskin and eye illnesses, as well as damage to the liver due to the carbon disulfiderelease from thiram. It’s very urgent to develop simple, rapid, ultrasensitive analyticaltechniques for the on-site analysis of trace pesticide residues to improveenvironmental and agricultural safety. Melamine (1,3,5-triazine-2,4,6-triamine) is animportant organic chemical material for producing melamine resins,which are usuallyused in glues, adhesives, and plastics.However, it was recently added to milk andvarious dairy products illegally due to its low cost and high nitrogen content, whichcan lead to incorrectly high readings for the apparent protein content whenconventional standard tests are performed. It has been reported that these high levelsof melamine in milk killed thousands of pets and caused renal function failure andeven death in infants.Objective:Surface-enhanced Raman spectroscopy (SERS)applied in trace detection withhigh sensitivity, due to its simple preparation of sample, rapid, therefore has beenwidely applied in trace detection. Raman enhancement spectrum has good SERSactive substrate and therefore preparation used high sensitivity of SERS substrate inour focus. In our experiment,we preparation the SERS substrate and application itdetect thiram and melamine.Materials and method：The Au substrate was prepared by deposition gold film on the si substrate,whichhas a rough surface.The Au substrate was dealing with the amination as linker withsilver sol, forming hybrid substrate. R6G as a probe molecule, compare the Raman intensity of R6G onAu substrate and the hybrid substrate. It is anticipated that theGO/AgNPs fabricated by the self-assembly method can be used as SERS substrates,with AgNPs supplying strong SERS activity and graphene oxide concentrating thetarget molecules we report a novel probe composed of GO and Ag NPs coated incapillary for enhanced Raman signal readout. The Ag NPs/GO hybridnano-composite structure was used as the SERS-active substrate to detect melamine.Results:R6G on hybrid substrate have stronger Raman intensity than it on the Ausubstrate. And use the hybrid substrate detect thiram, the detection limit10-9mol/L.Ag NPs/GO coated in capillary as SERS substrate, PATP on Ag NPs/GOsubstrate as probe molecules.And use the Ag NPs/GO substrate detect melamine,thedetection limit10-9mol/L.Conclusion:This paper mainly introduces the phenomenon of surface enhanced Ramanscattering (SERS), mechanism, and applications on different substrate.First，we report a structure composed of Ag NPs on Au film over nanospherefor enhanced Raman signal readout. Ag nanoparticles can be immobilized on Aufilm over nanosphere using aminosilane linkers. This is based on the fact thataliphatic amines can act as reductants and stabilizers simultaneously when preparingAg nanoparticles by thermal activation. The Ag NPs on Au film over nanospherestructure was used as the SERS-active substrate to detect rhodamine6G (R6G). Inthis work we investigate the Raman enhancement behaviors of silver nanoparticles(Ag NPs) with AuFON for the identification and detection of pesticide residues thatcaused intense public concerns by directly threatening human/animal’s health due totheir residues in agricultural products. Moreover, the as fabricated SERS substratecan be used to enhance the Raman signals of thiram, showing a detection limit aslow as0.24ppb, which is much lower than the maximal residue limit (MRL) of7ppm in fruit prescribed by the U.S. Environmental Protection Agency (EPA).Second, PATP was used as a probe molecule to evaluate the SERS performanceof the AgNPs/GO as SERS substrate. The experimental data indicated that thisnewly developed probe can enhance Raman signals overtly, in comparison withthose obtained by direct measurement using Ag NPs coated in capillary. Overall, theSERS technique based on the self-assembled sandwich nanostructure shows potential as a complementary method for the sensitive and rapid detection ofdithiocarbamate chemicals. Finally, the detection of trace amounts of melamine onthe AgNPs/GO SERS substrate was achieved.With high sensitivity of SERS substrate, used Raman markers (R6G, PATP)determine the SERS effect, to explore its role in the field of pesticide detection andfood safety, used for comprehensive evaluation of the preparation of SERS substrateand the enhancement effect of thiram and melamine will provide a scientific basisfor practical application.