One-, Two-, and Three-Dimensional Superstructures of Gold Nanorods Induced by Dimercaptosuccinic Acid

Abstract

A method is described for assembling gold nanorods into one-, two-, and three-dimensional superstructures. The addition of dimercaptosuccinic acid (DMSA) into the nanorod solution was found to induce self-assembly of the latter to one-dimensional "tapelike", two-dimensional "sheetlike" and three-dimensional "superlattice-like" structures depending on the DMSA concentration. The assembly was found to follow a smectic structure, where the nanorod long axes are parallel to each other. The rods are spaced 8.5 +/- 0.3 nm apart in the resulting structures, which extend over several micrometers in length. Organizations perpendicular to the grid were also found. The nanorod tapes were found to bend, and they form circular assemblies as well. The assembly and morphology of the nanorod structures were characterized by transmission electron microscopy and UV-vis spectroscopy. The effect of the DMSA concentration as well as the pH of the medium was also studied. On the basis of several control experiments utilizing similar molecules, charge neutralization of the nanorods by the carboxylic group of DMSA was found to be the principal reason for such an assembly, while the mercapto groups render additional stability to its structure. A mechanistic model of the assembly is proposed. This type of assembly would plausibly function as a plasmonic waveguide in potential nanodevices.

Gold Nanorods: From Synthesis and Properties to Biological and Biomedical Applications

“…14C). Such assemblies via charge interaction were also demonstrated by Orendorff et al [249] using adipic acid, by Jain et al [97] using citrate molecules, and by Sreeprasad et al [250] using dimercaptosuccinic acid. In a different way, Gole and Murphy [251] coated gold nanorods with the poly(acrylic acid) (PAA) polymer leaving a layer of free carboxylic acids for the binding of biotin-PEO-amine (where PEO is polyethylene oxide) through EDC-catalyzed carboxidine reaction.…”

“…However, the generally used PEG 5000 molecules have a hydrodynamic length of 10 nm. [321] This is longer than that of the CTAB bilayer (4 nm, [250] ) and the brush conformation of the polymer could form a crosslinked layer outside of the undisplaced REVIEW www.advmat.de CTAB molecules. This shears the potential nonspecific protein adsorption of the positively charged CTAB capping molecules.…”

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

“…[ 13 ] Sreeprasad et al utilized the charge neutralization of CTAB-capped GNRs by dimercaptosuccinic acid and EDTA, ultimately leading to the formation of one-, two-, and three-dimensional superstructures of GNRs. [ 14 ] Two-and three-dimensional arrays of hydrophobic GNRs by solvent evaporation on a substrate were also reported by Mitamura and co-workers. [ 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.…”

Unconventional Assembly of Bimetallic Au–Ni Janus Nanoparticles on Chemically Modified Silica Spheres

“…p-Toluenesulfonic acid, oleic acid (OA), vanillin, HAuCl 4 ·4H 2 O, Fe-(acac) 3 , and Ni(NO 3 ) 2 ·6H 2 O were obtain from the Chemical Reagent Co. of Shanghai (Shanghai, China). Chloroform and other solvents were analytical grade from Beijing Chemical Factory (China) and were used without further purification.…”