Improved refractive index sensitivity of localized surface plasmon resonance inflection points in amalgamated gold nanorods with mesoporous silica shell

Abstract

Mesoporous silica coated gold nanorods (AuNRs@mSiO2) are very promising as multifunctional localized surface plasmon resonance (LSPR) sensors. Here, we described the refractive index (RI) sensitivities of single AuNRs@mSiO2 before and after mercury (Hg) amalgamation without their structural deformation. The amalgamated AuNRs@mSiO2 showed significant improvement in the RI sensitivity than the AuNRs@mSiO2 before the Hg amalgamation with the respect to RI changes of local environments. LSPR scattering inflection points (IFs) were then investigated to determine the LSPR sensing performance of single AuNRs@mSiO2 before and after Hg amalgamation. The RI sensitivity at the LSPR IF in the low-energy side was higher than the wavelength shifts in the conventional LSPR maximum peak. Furthermore, the amalgamated AuNRs@mSiO2 exhibited better RI sensitivity at the LSPR IFs than non-amalgamated AuNRs@mSiO2. Thus, we provide a deeper understanding of how Hg amalgamation affects RI sensitivity in single AuNRs@mSiO2.