Chiral plasmonics of self-assembled nanorod dimers

Ma, Wei; Kuang, Hua; Wang, Libing; Xu, Liguang; Chang, Wei-Shun; Zhang, Huanan; Sun, Maozhong; Zhu, Yinyue; Zhao, Yuan; Liu, Liqiang; Link, Stephan; Kotov, Nicholas A.

doi:10.1038/srep01934

Cited by 200 publications

(242 citation statements)

References 33 publications

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“…However, these asymmetrically coupled plasmonic structures are often not thermodynamically favourable, and the self-assembly of such structures remains a challenge. By judicious selection of linker molecules, the bonding direction of gold nanorods can be controlled to form directional nanodimers and, as has been demonstrated recently, chiral plasmonic structures 18 . Nevertheless, all previously reported nanorod assemblies, in general, tend to aggregate and align side by side or end to end as a consequence of maximized interparticle interaction and minimized surface energy, and there is no controlled structural selection with a longitudinal symmetry-breaking phenomenon [19][20][21] .…”

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confidence: 94%

Feedback-driven self-assembly of symmetry-breaking optical metamaterials in solution

Yang

Yin

et al. 2014

Nature Nanotech

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Thermodynamically driven self-assembly offers a direct route to organize individual nanoscopic components into threedimensional structures over a large scale [1][2][3] . The most thermodynamically favourable configurations, however, may not be ideal for some applications. In plasmonics, for instance, nanophotonic constructs with non-trivial broken symmetries can display optical properties of interest, such as Fano resonance, but are usually not thermodynamically favoured 4 . Here, we present a self-assembly route with a feedback mechanism for the bottom-up synthesis of a new class of symmetry-breaking optical metamaterials. We self-assemble plasmonic nanorod dimers with a longitudinal offset that determines the degree of symmetry breaking and its electromagnetic response. The clear difference in plasmonic resonance profiles of nanorod dimers in different configurations enables high spectra selectivity. On the basis of this plasmonic signature, our self-assembly route with feedback mechanism promotes the assembly of desired metamaterial structures through selective excitation and photothermal disassembly of unwanted assemblies in solution. In this fashion, our method can selectively reconfigure and homogenize the properties of the dimer, leading to highly monodispersed aqueous metamaterials with tailored symmetries and electromagnetic responses.In the last decade, control over structural symmetries has led to novel materials properties and the prediction of potentially exciting applications. Optical metamaterials 5 , unlike conventional materials, can be designed to have negative refraction, rainbow trapping and nonlinear metal optics. However, particularly rich and exciting physics comes into play when symmetry-breaking mechanisms are introduced that have the potential to enable strong anisotropic plasmon hybridization 6 , leading to unusual phenomena including plasmon-induced transparency 7 , anti-Hermitian plasmonic antennas 8 and optical magnetism, and consequently negative-index metamaterials 9 . These intriguing properties can be used in a number of important applications, such as subwavelength imaging, optical cloaking and sensing [10][11][12] . These applications could be hindered by the fact that most structures are fabricated predominantly by top-down lithography, a technique that is inefficient for producing isotropic metamaterials in three dimensions and is often not cost-effective for large-scale fabrication. To mitigate these limitations, self-assembly approaches have recently been explored. However, they generate the most thermodynamically favourable structure, which usually results in a high degree of structural symmetry and inevitable inhomogeneity. For example, such self-assembly methods have been used to synthesize symmetric coupled plasmonic nanoclusters on a substrate 13 . Very recently, assisted by DNA or polystyrene-particle scaffolds, a circular dichroic plasmonic cluster and optical metafluid with high symmetry have also been reported 14,15

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confidence: 94%

Feedback-driven self-assembly of symmetry-breaking optical metamaterials in solution

Yang

Yin

et al. 2014

Nature Nanotech

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“…For example, a single bio-entity that binds to the DNA arms and its subsequent reactions with other chemical compounds could trigger a series of conformational changes of the plasmonic metamolecule. With a combination of single-particle dark-field microscopy and CD spectroscopy 22 , the conformation changes of the plasmonic molecule arising from single bio-entity binding could be optically detected in real time. In addition, the unprecedented level of spatial and temporal control offered by DNA nanotechnology may advance the development of smart nanomaterials for plasmonics.…”

Section: Left-handedmentioning

confidence: 99%

“…Owing to close proximity, the excited plasmons in the two AuNRs can be strongly coupled 18 . The two crossed AuNRs constitute a 3D plasmonic chiral object [19][20][21][22] , which generates a theme of handedness when interacting with left-and right-handed circularly polarized light, giving rise to strong CD. …”

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confidence: 99%

Reconfigurable 3D plasmonic metamolecules

et al. 2014

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A reconfigurable plasmonic nanosystem combines an active plasmonic structure with a regulated physical or chemical control input. There have been considerable e orts on integration of plasmonic nanostructures with active platforms using topdown techniques. The active media include phase-transition materials, graphene, liquid crystals and carrier-modulated semiconductors, which can respond to thermal 1 , electrical 2 and optical stimuli 3-5 . However, these plasmonic nanostructures are often restricted to two-dimensional substrates, showing desired optical response only along specific excitation directions. Alternatively, bottom-up techniques o er a new pathway to impart reconfigurability and functionality to passive systems. In particular, DNA has proven to be one of the most versatile and robust building blocks 6-9 for construction of complex three-dimensional architectures with high fidelity 10-14 . Here we show the creation of reconfigurable three-dimensional plasmonic metamolecules, which execute DNA-regulated conformational changes at the nanoscale. DNA serves as both a construction material to organize plasmonic nanoparticles in three dimensions, as well as fuel for driving the metamolecules to distinct conformational states. Simultaneously, the threedimensional plasmonic metamolecules can work as optical reporters, which transduce their conformational changes in situ into circular dichroism changes in the visible wavelength range.Circular dichroism (CD), that is, differential absorption of left-and right-handed circularly polarized light, of natural chiral macromolecules is highly sensitive to their three-dimensional (3D) conformations 15 . Taking a similar strategy, we create 3D reconfigurable plasmonic chiral metamolecules 4,16 , whose conformation changes are highly correlated with their pronounced and distinct CD spectral changes in the visible wavelength range. Figure 1a shows the design schematic. Two gold nanorods (AuNRs) are hosted on a reconfigurable DNA origami template 7,10 , which consists of two 14-helix bundles (80 nm × 16 nm × 8 nm) folded from a long single-stranded DNA (ssDNA) scaffold with the help of hundreds of staple strands 13 . The two origami bundles are linked together by the scaffold strand passing twice between them at one point. To ensure the mobility of the DNA bundles and avoid the formation of a Holliday junction 17 , 8 unpaired bases are introduced to each ssDNA connector (Supplementary Note 1). Twelve binding sites are extended from each origami bundle for robust assembly of one AuNR (38 nm × 10 nm) functionalized with complementary DNA (Supplementary Note 2). The surface to surface distance of the two AuNRs is roughly 25 nm. Owing to close proximity, the excited plasmons in the two AuNRs can be strongly coupled 18 . The two crossed AuNRs constitute a 3D plasmonic chiral object [19][20][21][22] , which generates a theme of handedness when interacting with left-and right-handed circularly polarized light, giving rise to strong CD. Left-handedRight-handed Two gold nanorods (...

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“…Stronger effects could be obtained in systems of achiral nanoparticles arranged in a chiral superstructure with strong interparticle interaction [13][14][15][16] . Recently, Kotov and colleagues 17 demonstrated that the chiroptical activity of a chiral particle dimer is intense enough to monitor on a single nanoparticle level. The most intuitive approach to obtain large chiroptical activity is by forming nanoparticles with an actual chiral shape such as a gammadion or a helix.…”

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confidence: 99%

Enantioselective control of lattice and shape chirality in inorganic nanostructures using chiral biomolecules

et al. 2014

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A large number of inorganic materials form crystals with chiral symmetry groups. Enantioselectively synthesizing nanostructures of such materials should lead to interesting optical activity effects. Here we report the synthesis of colloidal tellurium and selenium nanostructures using thiolated chiral biomolecules. The synthesis conditions are tuned to obtain tellurium nanostructures with chiral shapes and large optical activity. These nanostructures exhibit visible optical and chiroptical responses that shift with size and are successfully simulated by an electromagnetic model. The model shows that they behave as chiral optical resonators. The chiral tellurium nanostructures are transformed into chiral gold and silver telluride nanostructures with very large chiroptical activity, demonstrating a simple colloidal chemistry path to chiral plasmonic and semiconductor metamaterials. These materials are natural candidates for studies related to interactions of chiral (bio)molecules with chiral inorganic surfaces, with relevance to asymmetric catalysis, chiral crystallization and the evolution of homochirality in biomolecules.

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Chiral plasmonics of self-assembled nanorod dimers

Cited by 200 publications

References 33 publications

Feedback-driven self-assembly of symmetry-breaking optical metamaterials in solution

Feedback-driven self-assembly of symmetry-breaking optical metamaterials in solution

Reconfigurable 3D plasmonic metamolecules

Enantioselective control of lattice and shape chirality in inorganic nanostructures using chiral biomolecules

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