Study On Preparation And Sensing Application Of Gold-silver Core-shell Nanomaterials

Noble metal nanomaterials,especially gold nanomaterials and silver nanomaterials,have attracted wide attention due to their tunable local surface plasmon resonance?LSPR?optical properties.Compared with single-component nanomaterials,bimetallic core-shell nanoparticles have more superior physical and chemical properties by changing the thickness,type,and density of the shell?such as magnetism,optics,electricity,mechanics,thermals,etc.?.And the synergistic effect of the two metals increases the surface plasmon resonance intensity of the nanoparticles.Gold nanoparticles?Au NPs?have good stability,silver nanoparticles?Ag NPs?have a high extinction coefficient,a large calibration curve slope,and high sensitivity.Based on the good properties of the two metals,gold-silver core-shell nanoparticles?Au@Ag core-shell NPs?were prepared.The plasmon resonance absorption peak can be changed by changing the thickness of the shell layer,and it has excellent surface-enhanced Raman performance,which can be widely used in research fields such as biosensing.In this paper,gold-silver core-shell nanoparticles are used as optical probes for colorimetric-Raman sensing detection of glucose and biothiols?GSH?:?1?Au@Ag core-shell nanoparticles?Au@Ag core-shell NPs?were prepared by two successive reductions using the seed growth method.Because hydrogen peroxide?H₂O₂?is oxidative,the shell Ag⁰ in Au@Ag core-shell NPs is oxidized into Ag⁺.In the presence of biothiol?glutathione?,the oxidative corrosion caused by H₂O₂ is slowed,which makes the absorption peak of silver decline slowly.The thickness change of the silver shell layer will cause the shift of the material's plasmon resonance absorption peak position,which result in the change in the absorption intensity,the change in the solution color and the surface-enhanced Raman scattering intensity?SERS?.Based on the anti-etching performance of glutathione,the colorimetric-SERS method was used to further sensitively detect glutathione.?2?Based on the prepared Au@Ag core-shell NPs,a colorimetric-SERS sensor was constructed to detect glucose in human serum.Under the catalyzing of glucose oxidase,glucose generates gluconic acid and H₂O₂.H₂O₂ etches and dissolves the silver shell,which reduces the local surface plasmon resonance intensity and SERS intensity of Au@Ag core-shell NPs,and the color of the solution also can be observed by naked eyes without the need for any color developer and other precision instruments.The detection limits of the colorimetric-SERS detection method are 300nM and 20 nM,respectively.And the method is also successfully used to detect the glucose content in human serum,which is expected to be widely used in practice life and medicine.