Three-Dimensional Self-Assembling of Gold Nanorods with Controlled Macroscopic Shape and Local Smectic B Order

Abstract

We describe a method of controlled evaporation on a textured substrate for self-assembling and shaping gold-nanorod-based materials. Tridimensional wall features are formed over areas as large as several square millimeters. Furthermore, analyses by small-angle X-ray scattering and scanning electron microscopy techniques demonstrate that colloids are locally ordered as a smectic B phase. Such crystallization is in fact possible because we could finely adjust the nanoparticle charge, knowledge that additionally enables tuning the lattice parameters. In the future, the type of ordered self-assemblies of gold nanorods we have prepared could be used for amplifying optical signals.

Peptidic Ligands to Control the Three‐Dimensional Self‐Assembly of Quantum Rods in Aqueous Media

“…As expected, we also noticed an electrophoretic mobility increasing with the TCCPAC/TCCPAM ratio. Similar results have previously been observed for QDs coated with PEGylated peptidic ligands and for GNRs coated with PEGylated alkyl thiolate ligands . In a second set of experiments, we introduced TCPAC, a peptide similar to TCCPAC although it does not include the alkyl chain (see Figure S7a).…”

“…In view to integrate nanorods into devices, we explored a controlled drying method yielding well‐defined patterns of auto‐organized superstructures . More precisely, an aqueous suspension of TCCPAC‐QRs was first confined between a flat substrate and a PDMS stamp before water was allowed to evaporate freely (see Figure a,b).…”

“…Previously, we have described an original strategy for shaping self‐assemblies of gold nanorods (GNRs) by slow drying of the corresponding aqueous solution between a smooth substrate and a topologically micropatterned mold. Walls displaying a smectic B packing were then obtained, organized on a regular lattice over several square millimeters . Moreover, the spacing between particles could be varied by adjusting their surface charge and thus their interaction potential.…”

“…Furthermore, for the sake of clarity our approach is here demonstrated by focusing on a single peptide, although various molecular structures have revealed themselves functional during our research. The crucial role of the coating for successful 3D self‐assembly has motivated the utilization of a large set of techniques to understand binding events at the nanoparticle surface during the ligand exchange process . More precisely, fluorescence, infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopies enabled us to show that the hydrophobic phosphorylated molecules serving for the QR capping, the octadecyl phosphonic acid (ODPA), the hexyl phosphonic acid (HPA), as well as the tri‐octyl phosphine oxide (TOPO) and the tri‐octyl phosphine (TOP), can be completely replaced by peptides.…”

Large Area Self‐Assembly of Nematic Liquid‐Crystal‐Functionalized Gold Nanorods

“…[ 15 ] One of the fi rst examples using softmatter templates was the self-assembly of GNRs into 1D and 2D structures using DNA as template. [ 16 ] More recently, three-dimensional superstructures of (1-mercaptoundec-11-yl)-hexa(ethylene glycol)-capped GNRs having a local smectic B order have been described by Hamon et al [ 17 ] They employed a novel drying method in which GNRs crystallization was carried out between smooth surfaces and a topographically patterned stamp.…”