Rapid synthesis and characterization of ultra-thin shell Au@SiO_2 nanorods with tunable SPR for shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS)

摘要

The recently reported shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is considered as the next generation of advanced spectroscopy for its surface and molecular generality. With the aim to utilize the virtues of shell-isolated strategy and advance the SHINERS technique, we introduce a silane-based rapid synthesis method of silica-coating Au nanorods (Au@SiO_2 NRs) with manoeuvrable ultra-thin shell and tunable SPR. The results demonstrate that the SPR of Au NRs could be optimized to obtain large Raman enhancement using either 633 nm or 785 nm laser. Differing from previously reported Au@SiO_2 NRs synthesis method, we can tune the silica shell thickness within several nanometers to maximize the Raman signal while effectively eliminating the exterior interference. And this advanced synthesis method has also significantly reduced the silica-coating time from one day to ca. 1 h. This method as a new development of SHINERS technique has successfully got enhanced signal in solution Raman tests of malachite green, giving a great potential to be extended to in-situ measurement for daily life detection.