Single-Particle Study: Refractive Index Sensitivity of Localized Surface Plasmon Resonance Inflection Points in Mesoporous Silica-Coated Gold Nanorods

Abstract

Gold nanorods coated with a mesoporous silica shell (AuNRs@mSiO2, core@shell) have been in the employment for various bioapplications, including drug delivery and photothermal cancer therapy. Nevertheless, limited studies have been conducted on AuNRs@mSiO2 for their biosensing applications that use a refractive index (RI)-based localized surface plasmon resonance (LSPR). In this study, the LSPR detection sensitivity of individual AuNRs@mSiO2 with two distinctive core sizes, but the same aspect ratio of 3, was presented at LSPR inflection points (IFs) according to RI variations of the surrounding environment. The RI sensitivity at the homogeneous LSPR IF located on the low-energy side was higher than the wavelength shifts in the conventional LSPR maximum peak. Moreover, single AuNRs@mSiO2 having a smaller core size exhibited better RI sensitivity at the IFs of LSPR. Thus, we presented a better understanding of the RI-based detection sensitivity in single AuNRs@mSiO2 at LSPR IFs for developing LSPR biosensors.