Synthesis and SERS application of SiO2@Au nanoparticles

In this letter, we report a chemical route for synthesizing SiO2@Au core-shell nanoparticles. The process includes four steps: i) preparation of the silica cores, ii) grafting gold nanoparticles over SiO2 cores, iii) priming of the silica-coated gold nanoparticles with 2 and 10 nm gold colloids and finally iv) formation of complete shell. The optical extinction spectra were experimentally measured and compared to numerical calculations in order to confirm the dimensions deduced from SEM images. Finally, the potential of such core-shell nanoparticles for biosensing was probed by means of Surface Enhanced Raman Scattering measurements and revealed higher sensitivities with much lower gold quantity of such core-shell nanoparticles compared to Au nanoparticles exhibiting similar diameters.