The Synthesis Of SiO₂@Ag Composite Nanospheres And Application Based On SERS Immunochromatographic Method

Objective: The synthesis of a good dispersion and uniform particle of SiO2@Ag composite nanospheres,and can be used as surface enhanced Raman scattering(SERS)substrate;Established a rapid detection method based on immune chromatography SERS and applied to the detection of Ig G and ricin.Methods: we synthesised of 80 nm SiO2 using a modified Sto ber method,Which was used as the core,The SiO2@PEI nanospheres were synthesized through a cationic polymer polyethyleneimine(PEI)self-assembly process under sonication condition.and then the SiO2@PEI@3 nm Au nanospheres structure formated through the strongly electropositive of PEI layer that adsorpted a uniform、densed 3nm Au particles layer on the surface of SiO2@PEI nanospheres.3 nm Au as the reduction seed,adding Polyvinylpyrolidone(PVP)as dispersing agent,formaldehyde as reducing agent,The SiO2@Ag composite nanospheres were synthesized by seed growth method,which is complete,continuous,and with hot spots.The prepared 100 nm SiO2@Ag composite nanospheres were applied to the immune experiment.and established a method of immunochromatographic method based SERS to detect human Ig G,Which was mainly divided into three steps:(1)The preparation of immune SERS–Tag、characterization and optimization of conditions.(2)Preparation and assembly of immunochromatographic strip.(3)Detection of human Ig G samples.To rapid detection of ricin SERS immunochromatographic detection methods have been established.Results: The SiO2@Ag composite nanospheres were synthesized with the particle size was about 100 nm,with uniform size,good dispersion.Adding different amount of silver nitrate of silver nitrate(0 m M、0.05 m M、0.1 m M、0.2 m M、0.3 m M)to reducing Ag shell,it was observed that the degree of continuous formation of Ag shell,And then through the detection of these nanospheres on small molecule PATP(concentration of 10-6 M)Raman enhancement effect to choice the best content of silver nitrate,Which with best quality.The SiO2@Ag composite nanospheres as SERS substrate for to detect different concentrations of thiram containing thiram,the detection sensitivity was 10-9 M,which proved that the SiO2@Ag nanospheres with good SERS enhancement effect.The preparation of SERS-Tag,observed by transmission electron microscopy with well dispersed state.optimized the experimental conditions of SERS method,Sured when adding amount of 10 m M molecular Raman,the Raman enhancement effect was the strongest.when the NC membrane pore size specifications for 6 μm,The result of chromatography is the best.When the Ig G concentration of 0.8 mg/m L was best detection effect.The sensitivity of SERS immunochromatographic method to detect Ig G was for 1 ng/m L.The method of immunochromatographic method based SERS was used to rapid detection of ricin and the sensitivity is 1 ng/m L.Conclusion: The high performance SiO2@Ag composite nanospheres with good dispersion,uniform particle size and rough surface that can enhance Raman molecular signals significantly were Successfully synthesised.The composite nanospheres can be used as SERS substrates for the detection of non labeling of small molecules,and completion of the pesticide thiram detection with high sensitivity.A well dispersed immune SERS–Tag was successfully prepared,and established a method of immunochromatographic method based SERS to detect human Ig G,and the detected sensitivity of huma Ig G was 1 ng/m L.The method of immunochromatographic assaya based SERS was used to rapid detection of ricin,the detection sensitivity is 1 ng/m L.