Chemical Transformation of Nanorods to Nanowires: Reversible Growth and Dissolution of Anisotropic Gold Nanostructures

Abstract

This manuscript describes a reversible wet chemical process for the tip-selective one-dimensional (1D) growth and dissolution of gold nanorods (AuNRs) and gold nanowires (AuNWs). Tip-selective dissolution was achieved by oxidation of AuNRs with a Au(III)/CTAB complex, whereas the growth of AuNRs was carried out by the reduction of Au(I) ions on the AuNR surface with a mild reducing agent, ascorbic acid (AA). Both the dissolution and growth processes are highly tip selective and proceed exclusively in one dimension. A decrease in the aspect ratio (AR) of AuNRs during the dissolution resulted in a blue shift in the longitudinal plasmon band (LPB) position, and red shifts in the LPB position were achieved by increasing the AR by 1D growth of AuNRs. Both growth and dissolution processes are fully controllable and can be stopped and resumed at any given time when the desired AR and/or LPB position is achieved. In addition, the tip-selective 1D growth of AuNRs can be continued with the additional supply of Au(I)/CTAB/AA solution to produce extremely long AuNWs.

Wire‐Like Tip‐To‐Tip Linked Assemblies of CdSe‐CdS Quantum Rods Promoted on Supramolecular Nanofibers of Hybrid Organo‐ and Hydrogels

“…It can be noted in these images that QRs can appear shorter than their original length. This could be due to an out‐of‐plane orientation within the gel deposit on the TEM grid or due to some truncation or erosion occurring during the processing of the QRs into the hybrid material . However, contrasting with this interpretation, no luminescence “pollution” by CdS shell residuals is observed.…”

Recent advances in gold nanoparticles for biomedical applications: from hybrid structures to multi-functionality

“…24 For prolonged blood circulation halflife, the NPs should be within the size window of 10-150 nm. In cases where rapid renal clearance is desirable, the NPs should be smaller than 10 nm, which is the effective cut-off size of the 47 (b) single crystal nanowire, 52 (c) chiral NPs, 31,45 (d) core-shell NPs, 27 (e) Janus NPs, 23 (f) alloyed NPs, 142,174 (g) plasmonic meta-molecules, 175 (h) DNA-origami templated assemblies, 25 (i) large-scale assemblies of NPs. 99,176 Adapted by permission from the corresponding references.…”

“…50,51 Moving up along the length scale (5-100+ nm), there exist a wide variety of Au nanocrystals with different shapes (Fig. 2b), 52 ranging from the classical spheres to cubes, plates, rods, wires and stars. Anisotropic shapes with a large aspect ratio can shift the LSPR to NIR wavelength which could be beneficial for in vivo applications.…”

Noble Metal Nanostructured Materials for Chemical and Biosensing Systems

“…In this mode, the CTAB acts as both a template and coating agent, facilitating mass production of NRs and nanowires [57,58]. Khanal et al developed a reversible chemical process for tip selective one-dimensional growth and dissolution of AuNRs, which can be continued with additional supply of Au(I)/CTAB/ascorbic acid solution to produce extremely long Au nanowires [59] (Figure 3). Electrochemical method is a process of applying a certain current or voltage to a noble metal electrolyte system to cause an electrochemical reaction (anodization, electrolysis, deposition) to obtain a noble metal nanomaterial.…”

“…Length distribution (a-g), width distribution (o-u) and corresponding TEM images (h-n) during the growth and dissolution processes. Reproduced with permission from[59]. Copyright ACS Nano, 2019.…”