Au Nanorod Helical Superstructures with Designed Chirality

Abstract

A great challenge for nanotechnology is to controllably organize anisotropic nanomaterials into well-defined three-dimensional superstructures with customized properties. Here we successfully constructed anisotropic Au nanorod (AuNR) helical superstructures (helices) with tailored chirality in a programmable manner. By designing the 'X' pattern of the arrangement of DNA capturing strands (15nt) on both sides of a two-dimensional DNA origami template, AuNRs functionalized with the complementary DNA sequences were positioned on the origami and were assembled into AuNR helices with the origami intercalated between neighboring AuNRs. Left-handed (LH) and right-handed (RH) AuNR helices were conveniently accomplished by solely tuning the mirrored-symmetric 'X' patterns of capturing strands on the origami. The inter-rod distance was precisely defined as 14 nm and inter-rod angle as 45°, thus a full helix contains 9 AuNRs with its length up to about 220 nm. By changing the AuNR/origami molar ratio in the assembly system, the average number of AuNR in the helices was tuned from 2 to 4 and 9. Intense chiroptical activities arose from the longest AuNR helices with a maximum anisotropy factor of ∼0.02, which is highly comparable to the reported macroscopic AuNR assemblies. We expect that our strategy of origami templated assembly of anisotropic chiral superstructures would inspire the bottom-up fabrication of optically active nanostructures and shed light on a variety of applications, such as chiral fluids, chiral signal amplification, and fluorescence combined chiral spectroscopy.

Chiral plasmonics

“…Lan et al . ( 64 ) used DNA nanosheets to create stacks of rotated gold nanorods. The individual sheets were dressed with capture strands on both sides, forming an “X” shape, as shown in Fig.…”

Fabrication of a Spherical Superstructure of Carbon Nanorods

“…[1][2][3][4] Highly organized building blocks of metals, [5,6] semiconductors, [7,8] hybrid metal-organic materials, [9][10][11] and transition-metal dichalcogenides [12] have been fabricated by using various methods. From the aspect of synthesis, self-assembly of simple building blocks into 3D, highly ordered superstructure with novel properties has attracted great interest in the fields of optics, catalysis, and energy storage.…”

“…[19,20] However, the self-assemblies of 1D carbon nanomaterials into 3D ordered spherical superstructures are considerably challenging owing to the reduced accessible contact areas between the building blocks and core templates. [1][2][3][4] Highly organized building blocks of metals, [5,6] semiconductors, [7,8] hybrid metal-organic materials, [9][10][11] and transition-metal dichalcogenides [12] have been fabricated by using various methods. [24] The use of MOF as a template or precursor to synthesize carbon nanostructure is an efficient approach to produce carbon materials with controlled morphology and Hierarchical superstructures in nano/microsize have attracted great attention owing to their wide potential applications.…”

Tuning the structural asymmetries of three-dimensional gold nanorod assemblies

“…28 As demonstrated in Fig. Due to the same mesomeric effect, trimer2 also displayed a lower CD intensity in comparison with dimer2.…”