SERS Study Of Magnetic Hybrid Nanoparticles And Several Long-chain Thiol Molecules' Self-assembled Monolayers

Surface-enhanced Raman scattering?SERS?as a means of molecular and substrate information detection,shows high selectivity and high sensitivity.The enhancement is generally attributed to two main types of mechanisms:electromagnetic mechanism and charge-transfers mechanism.Both of the mechanisms must take the role of the substrate into account,and the coin-metal nanosol is a traditional substrate of SERS.With the continuous development of technology,many different substrates have also been proposed,and composite magnetic nano-material,because of its good biocompatibility and other characters,and proneness to form a"hot spot”,while used as substrate it can provide better SERS activity,so it's widely used.In this paper,Fe₃O₄@SiO₂@Au/Ag magnetic nanoparticle was made with poly dimethyl diallyl ammonium?PDDA?and 3-aminopropypyltrimethoxysilane?APTMS?respectively.The optimal magnetic nanoparticles were selected and their SERS activities were investigated and were applied to the detection of some proteins.The paper also studied the adsorption of long-chain thoil molecules such as 1-hexanethiol?HT?,1-octanethiol?OT?,1-decanethiol?DT?and 1-dodecanethoil?DDT?on the surface of silver substrate and the assembly process.The research mainly goes as follow:?1?Study on the SERS Spectra of Composite Magnetic Nanoparticles Constructed Hots potsIn this paper,Fe₃O₄ nanoparticles were prepared as solvothermal method,and Fe₃O₄@SiO₂@Au/Ag magnetic composite nanoparticles were prepared with PDDA and APTMS,respectively.The composite materials were characterized by transmission electron microscope?TEM?,ultraviolet and visible spectrometry?UV-vis?and hysteresis loops,which show that Au or Ag nanoparticles are successfullyattached to the surface of modified Fe₃O₄ nanoparticles.With additional magnetic field,the composite materials have pretty good magnetic response behavior,so its magneto-optic properties can be used to change the aggregation of the composite materials by external magnetic field,and improve the SERS activity of the substrate.Use probe molecules PATP and 4-MBA,we focused on the SERS activity of the composites investigating while studying the properties of the composite substrates.The results showed that the substrates enjoyed good SERS sensitivity,and the Fe₃O₄@SiO₂@Au magnetic composite made from PDDA and Fe₃O₄@SiO₂nanoparticles have stronger SERS activity.Then the substrates were applied to the detection of protein molecules HRP,lysozyme and Atto 610 labeled proteins,and the detection ran fairly well.?2?SERS Study on SERS Spectra of Several Long-chain Thiol Molecules' Self-assembled MonolayersThe structure of HT,OT,DT and DDT adsorbed on the surface of silver nanoparticles was studied with SERS spectroscopy,and the effects of concentration to the adsorption process were investigated.In this experiment,the analysis of tetras and the gauche vibration peaks of the SERS spectra revealed that,when adsorbed for 6hours,the monolayer films formed by these long-chain thiol molecules enjoyed higher ordering at higher concentrations,as the concentration decreasing,the ordering gradually reduced.It also showed that,in these four molecules,with the chain went longer,the adsorption of molecules on the surface of silver nanoparticles got less and less,and the adsorption capacity of HT with 6 C was the highest due to the suitable chain length.The study on the kinetics of HT,OT,DT and DDT films has laid a good foundation for the preparation of monolayer films and shows obvious significance in the future applications on devices,anticorrosion and biology.