Rapid Detection Of Melamine Based On Surface-enhanced Raman Spectroscopy And Supramolecular Action

Melamine belongs to the low toxic substance.But when ingested in gastric juice,it automatically generates the melamine cyanuric acid which body cannot dissolve out,causing kidney stones and lack of protein which even threaten life.It acts as protein in dairy products or through a variety of ways to enter the water environment,absorbed by the fish.This may not only affect the product quality,but also cause lacking of protein,if in infant food.Surface-enhanced Raman spectroscopy（SERS）technique is a simple,fast and ultra sensitive detection methods,combined with supramolecular interaction,can further reduce the detection limit of Melamine.In this thesis,the Raman substrate preparation of gold nanoparticles and gold magnetic nanoparticles were discussed.The indirectly detection of melamine is achieved by substrate modification combining with the super molecular hydrogen bonding interaction.The primary aspects are as the following :The synthesis of gold nanoparticles was optimized.Gold nanoparticles of various sizes were prepared and characterized based on Frens method.In this chapter,32 nm size was regarded as the optimal diameter of Au nanoparticles due to the strongest SERS effect,and choose it as the foundation for later Raman substrate synthesis.The detection of Melamine uses Au/AOA gold nanoparticles as SERS substrate.32 nm Au nanoparticles were conjugated with 5-Aminoorotic Acid and the Raman probe was synthetized.The most suitable volume ratio of Au/AOA and RBIC/AOA was set for 150 μL:150 μL.The logarithmic intensity of the spectral peak of RBIC was found to be proportional to the concentration of melamine with a limit of detection of 2 μg/m L in water and 3 μg/m L in milk.The detection of Melamine uses Fe₃O₄/Au/AOA gold nanoparticles as SERS substrate.Using Fe₃O₄ nanoparticles as a magnetic core,the gold nanoparticles were assembled on the surface of Fe₃O₄ nanoparticles,formed with core-shell structure of Fe₃O₄/SiO₂/Au gold magnetic nanoparticles.The logarithmic intensity of the spectralpeak of RBIC was found to be proportional to the concentration of melamine with a limit of detection of 1 μg/m L in water,2 μg/m L in milk and 2.5 μg/m L in squid.