New Aspects of the Gold Nanorod Formation Mechanism via Seed-Mediated Methods Revealed by Molecular Dynamics Simulations

Abstract

New aspects of the formation and growth mechanism of gold nanorods (AuNRs) during seed-mediated colloidal synthesis are revealed from the results of molecular dynamics simulation. The model systems consist of cetyltrimethylammonium bromide (CTAB) units adsorbed on low-index [Au(110), Au(100), and Au(111)] and high-index [Au(250)] gold surfaces. The CTAB units are adsorbed as adjacent cylindrical micelles when the relative number of adsorbed bromide ions is small. At later AuNR growth stages, the number of bromide ions increases as the [AuBr] species pass through the channels between the adsorbed micelles on the gold surface. Thus, the mature AuNRs have a high concentration of bromide ions at their surface, which appears to change the organization of the CTAB units on the particle surface from adsorbed micelles to a compact CTAB bilayer.

Ultrasmall gold nanorods: synthesis and glycocalyx-related permeability in human endothelial cells

“…In addition, our absorption spectrum and aspect ratio results agree with the maximum absorption peak wavelengths and aspect ratios reported by Nikoobakht and Feng, who obtained, for example, 700 nm for GNRs of 2.7 aspect ratio, 728 nm for GNRs of 3.4 aspect ratio, and 760 nm for GNRs of 3.9 aspect ratio. 30,48 Pegylation mitigates gNr toxicity At present, CTAB-based GNRs [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] are well known to be toxic. To address this issue, a few modifications have been incorporated into published CTAB-GNR synthesis protocols.…”

“…This work aimed to develop a nanoscale vehicle that would pass through the nanoporous endothelial GCX as it degrades and as its porosity increases. Towards this aim, we describe a new method to develop GNRs that, compared to previously published versions, [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] are ultrasmall and better suited for GCX penetration. Further unlike many developers of nanoparticle drug delivery vehicles who have not carefully considered the GCX, we investigated GCX-mediated endothelial permeability to these GNRs.…”

“…Rod-shaped nanoparticles have the advantage of long axes that have large surface areas for enhanced interaction with the ECs on blood vessel walls ( Figure 1). 21 At present, the cetyltrimethylammonium bromide (CTAB)-based GNR synthesis protocols [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] produce GNRs with diameters that are too big for GCX-mediated permeability across the vessel wall. One common approach to GNR synthesis is the CTABmediated seed growth method used by Nikoobakht's and other research groups.…”

“…One common approach to GNR synthesis is the CTABmediated seed growth method used by Nikoobakht's and other research groups. [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] This method utilizes CTAB solution and chloroauric acid (HAuCl 4 ). Combining these chemicals creates an Au(III)-CTAB complex, due to formation of an ion pair between the negatively charged AuCl 4 and the positive head groups of the CTAB micelles.…”

Metal Nanoparticles‐Enhanced Biosensors: Synthesis, Design and Applications in Fluorescence Enhancement and Surface‐enhanced Raman Scattering

“…The edge length of the Au nanocubes could be tuned by varying the amount of Au seeds. Bromide ions were found to be favourably adsorbed on the {100} facet, [25] playing an important role as a shape-driven agent to form the Au nanocubes. As shown in Figure 1b, a higher amount of Br À ions resulted in the formation of Au nanocubes with sharper edges and corners.…”