Controlled Heterogeneous Nucleation for Synthesis of Uniform Mesoporous Silica-Coated Gold Nanorods with Tailorable Rotational Diffusion and 1 nm-Scale Size Tunability

Abstract

We demonstrate a strategy for the synthesis of discrete and uniform gold nanorod (GNR)@mesoporous silica (mSiO2) core–shell nanoparticles (NPs) with finely tuned shell thickness by significantly suppressing the formation of undesired core-free NPs. We could control the thickness of the mSiO2 shell with high precision, close to 1 nm, and hence the rotational diffusion mode of NPs by simply controlling the silica precursor injection times. The growth of the mSiO2 shell on the GNR seeds and the formation of core-free mSiO2 NPs could be explained by two models based on the modified LaMer’s theory. Between these two, we found the most suitable one for the synthesis of GNR@mSiO2 NPs with a precisely controlled shell thickness and negligible core-free NPs as the synthesis mostly occurs via heterogeneous nucleation on GNR seeds. As our results are very simple and highly reproducible, we expect this work to provide profound insights into the synthesis of a variety of heterogeneous nanostructures.

Gold Nanorods for LSPR Biosensing: Synthesis, Coating by Silica, and Bioanalytical Applications

“…Another less obvious parameter that is commonly used to modulate the thickness of the silica coating is the concentration of CTAB. Indeed, several authors observed that increasing the concentration of CTAB in solution results, for the same amount of added TEOS in thinner silica shell (Abadeer et al [ 82 ]: From 26 to 11 nm (see Figure 9 B); Yoon et al [ 83 ]: From 30 to 13 nm).…”

“…As a consequence, the position of the l-LSPR band also allows silica shell growth monitoring. Indeed, a red shift in its position has been observed in several studies and correlated to the thickness of silica shell up to a certain value [ 83 ]. Figure 13 C illustrates the l-LSPR shift upon successive additions of TEOS resulting in silica shell thicknesses ranging from 8 to 20 nm.…”

“…( B ) Position of l-LSPR band maximum λ max as a function of AuNRs AR, Simulation results using the DDA (Discrete Dipole Approximation) method (black circles) [ 14 ] and experimental data from the works of Al-Sayed et al (open circles) [ 104 ], Pérez-Juste et al (diamonds and squares) [ 105 ] and Brioude et al (crosses) [ 14 ]. ( C ) l-LSPR band shift with increasing silica shell thickness adapted from ref [ 83 ].…”

From a precursor to an etchant: spontaneous inversion of the role of Au(iii) chloride for one-pot synthesis of smooth and spherical gold nanoparticles

“…S2b †). 36,37 When 110 mL of AA was used, we found that the size of the secondary AuNPs slowly decreased, while the spherical shape was retained as the reaction progressed. Thus, by extracting samples in a timely sequence from the same batch, we were able to obtain smooth AuNPs with 1 nm-scale size tunability (Fig.…”

High-throughput in-focus differential interference contrast imaging of three-dimensional orientations of single gold nanorods coated with a mesoporous silica shell

“…Elliptical and spherical AuNRs@mSiO 2 particles were fabricated by a slightly modied literature protocol, 19,20 and were structurally characterized by TEM and SEM. Fig.…”