Large-scale nanoporous metal-coated silica aerogels for high SERS effect improvement

Abstract

We investigate the optical properties and surface-enhanced Raman scattering (SERS) characteristics of metal-coated silica aerogels. Silica aerogels were fabricated by easily scalable sol-gel and supercritical drying processes. Metallic nanogaps were formed on the top surface of the nanoporous silica network by controlling the thickness of the metal layer. The optimized metallic nanogap structure enabled strong confinement of light inside the gaps, which is a suitable property for SERS effect. We experimentally evaluated the SERS enhancement factor with the use of benzenethiol as a probe molecule. The enhancement factor reached 7.9 × 107 when molecules were adsorbed on the surface of the 30 nm silver-coated aerogel. We also theoretically investigated the electric field distribution dependence on the structural geometry and substrate indices. On the basis of FDTD simulations, we concluded that the electric field was highly amplified in the vicinity of the target analyte owing to a combination of the aerogel’s ultralow refractive index and the high-density metallic nanogaps. The aerogel substrate with metallic nanogaps shows great potential for use as an inexpensive, highly sensitive SERS platform to detect environmental and biological target molecules.

Dual-Enhanced Raman Scattering-Based Characterization of Stem Cell Differentiation Using Graphene-Plasmonic Hybrid Nanoarray

“…The width and gap of the Au nanoarray were found to be about 250 nm while the height was about 100 nm [Figure D]. As shown in Figure E, enhancement of the Raman signal was observed after deposition of a 10 nm thick layer of Au and started to saturate between 20 to 40 nm deposition; however, it diminished with 80 nm deposition, which could be due to the connection of the Au layer . To estimate, optimize, and better understand the amplification of Raman signals of our Au nanoarray, electromagnetic simulations were conducted.…”

“…As shown in Figure 2E, enhancement of the Raman signal was observed after deposition of a 10 nm thick layer of Au and started to saturate between 20 to 40 nm deposition; however, it diminished with 80 nm deposition, which could be due to the connection of the Au layer. 42 To estimate, optimize, and better understand the amplification of Raman signals of our Au nanoarray, electromagnetic simulations were conducted. We utilized three different incident light sources (λ: 514, 633, and 785 nm), which are representative excitation wavelengths that typically provide strong LSPR in Au nanostructures [Figure 2F].…”

Bioinspired One-Step Synthesis of Pomegranate-like Silica@Gold Nanoparticles with Surface-Enhanced Raman Scattering Activity

“…[58][59][60] TP can be detected down to 10 -8 M owing to the enhancement effects by the P-SiO2@Au NPs (Figure 8b and Figure S7). The enhancement factor (EF) is calculated using the formula 61…”

Size‐Tunable Gold Aerogels: A Durable and Misfocus‐Tolerant 3D Substrate for Multiplex SERS Detection

“…On the other hand, aerogels based on silica and alumina have been recently adopted as 3D scaffolds to load SERS-active silver NPs, producing EFs in the order of 10 7 . [17,18] However, the large fraction of inert aerogel support may limit the sensitivity. Entirely assembled from SERS-active metal NPs, self-supported noble metal aerogels (NMAs) emerged recently.…”