Preparation And Detection Performance Of Magnetic Noble Metal Composite Microspheres As SERS Substrate

In recent years,with the rapid development of economy,a large number of industrial wastewater,domestic sewage and agricultural wastewater are discharged into rivers.The ecological environment has been destroyed seriously;especially the pollution of water bodies.However the organic pollutants in water entered into the human food chain which makes the body function disorder and their serious harm to human health.Therefore,there are now in urgent need for a rapid and efficient method in the detection of organic pollutants.The surface enhanced Raman scattering?SERS?technique has high sensitivity,no damage and rapid access to the"fingerprint"characteristic peak of organic matter,which can realize the rapid and sensitive detection of organic molecules in water.The SERS substrate is the key to the SERS technology,the SERS substrate performance directly determines the detection effect,therefore on the design and manufacture of noble metal SERS substrate preparation has become a research hotspot.In this paper,the effect of SERS on the magnetic noble metal SERS substrate with different morphologies was studied by using the organic dye molecules as the target.For this purpose,we designed and synthesized Fe₃O₄@Ag and Fe₃O₄@Au composite microspheres with controllable surface morphology by adjusting the experimental parameters,and we analyzed the detailed properties characterization of the two kinds of SERS substrate.The preliminary results show that the two kinds of composite microspheres Fe₃O₄@Ag and Fe₃O₄@Au have high sensitivity and repeatability for R6G molecules and CV molecules,respectively.The specific study results are as follows:?1?Noble metal nanoparticles SERS substrate have high sensitivity and repeated detection performance for organic dye molecules,in order to make the SERS detection more convenient,we introduce the magnetic core into the noble metals SERS substrate,which make it easier for separation in the detection,at the same times,the ultrasonic assisted synthesis method was used to improved the particle dispersion.Based on this idea,the dispersed Fe₃O₄ particles was used as the template;then by using the ultrasonic assisted synthesis method,as well as regulating the amount of citric acid,ultrasonic time and other experimental parameters,finally the flowerlike Fe₃O₄@Ag composite microsphere was obtained.The SERS substrate prepared by this method has high sensitivity and rapid detection performance for the detection of R6G molecule.The detection limit of R6G molecule can reach 10^-12 M.?2?Based on the phenomenon of Fe₃O₄@Ag composite microspheres SERS substrate is easy to oxidize in the air,and it cannot be stored for a long time,which is not conducive to the application of SERS substrate in real life.Then we put forward the gold nanoparticles with more stable performance coated on Fe₃O₄ particles,and control the gold nanoparticles size and the surface roughness by adjusting the experimental parameters such as the pH value of the solution,reducing agent,reducing agent concentration,and then study the SERS enhancement effect.The experimental results show that this method with SERS substrate preparation has the performance of rapid detection of CV molecules,the CV molecules on the molecular detection limit can reach 10^-9 M,which can meet the trace detection needs,and this kinds of noble metal SERS substrate can be preserved for a long time,which is convenient for the application of SERS substrate in the future industrial production.