Templated Growth of Surface Enhanced Raman Scattering-Active Branched Gold Nanoparticles within Radial Mesoporous Silica Shells

Abstract

Noble metal nanoparticles are widely used as probes or substrates for surface enhanced Raman scattering (SERS), due to their characteristic plasmon resonances in the visible and near-IR spectral ranges. Aiming at obtaining a versatile system with high SERS performance, we developed the synthesis of quasi-monodisperse, nonaggregated gold nanoparticles protected by radial mesoporous silica shells. The radial mesoporous channels were used as templates for the growth of gold tips branching out from the cores, thereby improving the plasmonic performance of the particles while favoring the localization of analyte molecules at high electric field regions: close to the tips, inside the pores. The method, which additionally provides control over tip length, was successfully applied to gold nanoparticles with various shapes, leading to materials with highly efficient SERS performance. The obtained nanoparticles are stable in ethanol and water upon thermal consolidation and can be safely stored as a powder.

Electron Tomography: A Unique Tool Solving Intricate Hollow Nanostructures

“…[9] Compared to hollow nanoparticles with an empty inner space, core-/yolk-shell nanoparticles are fabricated with inner space fully or partially occupied. [101] Upon the growth of short nanowires on gold cores, these detailed nanostructures are precisely determined by 3D analysis, favorably using HAADF-STEM tomography. ET technique has been well applied to distinguish nanostructures in core-shell nanoparticles.…”

“…ET technique has been well applied to distinguish nanostructures in core-shell nanoparticles. [101][102][103][104] A representative example would be the hybrid particle of Au@mesoSiO 2 , in which the core can be clearly distinguished due to their obvious contrast compared to amorphous silica. [101] Upon the growth of short nanowires on gold cores, these detailed nanostructures are precisely determined by 3D analysis, favorably using HAADF-STEM tomography.…”

“…[101][102][103][104] A representative example would be the hybrid particle of Au@mesoSiO 2 , in which the core can be clearly distinguished due to their obvious contrast compared to amorphous silica. [101] Upon the growth of short nanowires on gold cores, these detailed nanostructures are precisely determined by 3D analysis, favorably using HAADF-STEM tomography. Recently, Yue et al [104] developed core-shell materials with triple layers of Fe 3 O 4 @resorcinol-formaldehyde@ mesoSiO 2 , for which the tomographic analysis provides clear identification of each shell as well as detailed features, such as ordered mesopores.…”

Combination of HAADF‐STEM and ADF‐STEM Tomography for Core–Shell Hybrid Materials

“…Cetyltrimethylammonium bromide was used as surfactant and tetraethoxysilane as the silica source. [ 27 ] Characterization and Instrumentation : Samples for TEM were prepared by casting drops of ethanol suspension containing the PTW Au@mSiO 2 nanoparticles on a quantifoil carbon TEM grid. The grid was placed in a model 2020 Fischione Instruments tomography holder.…”

Toward plasmonic monitoring of surface effects on bacterial quorum-sensing

“…Alternatively, mesoporous silica shells can also be grown over individual plasmonic nanoparticles of different shapes and sizes [70]. These particles allow the diffusion of small molecules such as quorum sensing signals into the pores of the silica matrix to interact with the surface of the plasmonic particles within, allowing SERS detection of analytes.…”