Synthesis And Performances Of Au@mSiO₂ Core-shell Structure Derivatives

Gold nanomaterials have been widely developed and applied in the fields of catalysis,drug delivery,gene therapy,biosensing and fluorescence imaging due to its unique physical and chemical properties.Gold nanomaterials exhibits the advantages in terms of biocompatibility,good dispersion and size controllability,futhermore in surface enhanced Raman scattering and fluorescence because of its local surface plasmon resonance produced by local electromagnetic field enhancement effects.Mesoporous silica nanomaterials are easy to prepare.Mesoporous silica not only has a variety of surface modification groups,but also has the characteristics of large specific surface area,low toxicity,good biocompatibility and biodegradability.Now they have been widely used in drug delivery and biomedicine.The Au@mSiO₂ core-shell structure that combines the two has better performance and more extensive applications.In this thesis,the Au@mSiO₂core-shell structure is further optimized and assembled,and its preparation methods and related properties are explored.We used a simple one-pot method to synthesize Au@mSiO₂ yolk-shell structure,Au-M@mSiO₂（M=Pd,Pt,Ru,Rh,Ir,Os）core-shell structure and Au@mSiO₂@MOFs sandwich structure.The morphology,composition and crystal structure of the prepared nanoparticles were characterized,and their properties in catalysis,surface-enhanced Raman scattering and enhanced fluorescence were studied.The main research contents of this paper are as follows:（1）The Au@mSiO₂ core-shell structure was synthesized by the"one-pot one-step"method.Afterwards,Au@mSiO₂ was etched by the method of organosilane-assisted etching to construct yolk-shell nanoparticles with gold as the core and silica as the shell.In addition,Au@mSiO₂ yolk shell structure as a catalyst for p-nitrophenol and Raman substrate of p-mercaptoaniline surface enhancement showed a stronger effect than the core-shell structure.（2）Under alkaline conditions,the precursors of chloroauric acid and platinum metals were reduced by formaldehyde,and Au-M（M=Pd,Pt,Ru,Rh,Ir,Os）bimetal structure and Au-M@mSiO₂ core-shell structure were successfully synthesized in a one-pot system.It can be known that Au-M@mSiO₂ has successfully completed the coating by physical characterizations.We explored the effect of Au-M on electrocatalytic ethanol oxidation,and the results showed that Au-Pd has the best catalytic effect.（3）Based on the"one-pot one-step"method synthesis of Au@mSiO₂ core-shell structure,the Au@mSiO₂@ZIF-8 sandwich structure was finally synthesized through the selection of different MOFs and the test of different reaction conditions.The dye agent Rhodamine 6G was loaded on the structure for fluorescence test,and the results showed that Au@mSiO₂@ZIF-8 had fluorescence quenching effect on Rhodamine 6G.