Tailorable Plasmonic Circular Dichroism Properties of Helical Nanoparticle Superstructures

Abstract

We utilize a peptide-based methodology to prepare a diverse collection of double-helical gold nanoparticle superstructures having controllable handedness and structural metrics. These materials exhibit well-defined circular dichroism signatures at visible wavelengths owing to the collective dipole–dipole interactions between the nanoparticles. We couple theory and experiment to show how tuning the metrics and structure of the helices results in predictable and tailorable chirooptical properties. Finally, we experimentally and theoretically demonstrate that the intensity, position, and nature of the chirooptical activity can be carefully adjusted via silver overgrowth. These studies illustrate the utility of peptide-based nanoparticle assembly platforms for designing and preparing complex plasmonic materials with tailorable optical properties.

Nanoparticle Superlattices: The Roles of Soft Ligands

“…Attaching biomolecules such as DNA,11, 46, 47, 135 proteins136, 137, 138, 139, 140 and antibodies141, 142 to nanoparticle surfaces offer a unique specific route to control their assembly. Such assemblies are attractive because they can be programmed into complex structures, such as chiral architectures 141.…”

Au Nanorod Helical Superstructures with Designed Chirality

“…A large collection of chiral plasmonic 'molecules' including gold nanoparticle (AuNP) dimers, 12,13 tetramers 14 , pyramids, 15,16 and gold nanorod (AuNR) dimers 17,18 , have been reported using DNA or protein guided self-assembly. Recently, chiral plasmonic superstructures such as AuNP helices [19][20][21][22][23] were introduced based on peptide, DNA origami or supramolecular nanofiber templates. Besides, by adsorbing AuNRs on twisted fibers or incorporating AuNRs into cellulose nanocrystal films, chiroptical activities were also found from these resulted nanocomposites.…”

Hidden Chirality in Superficially Racemic Patchy Silver Films

“…In fact, the CD of the CW and CCW films is comparable to some chiral metamaterials, such as twisted photonic crosses and planar gammadions, 6,25 and is significantly stronger than many recent self-assembled and solution-based structures, such as gold nanoparticle helices assembled using DNA or peptide scaffolding and chiral core−shell nanoparticles consisting of gold nanorods coated with a chiral silica shell. 10,26,27 To visualize how the different domains of the polycrystalline monolayer template contribute to the bulk CD response, the films were examined using a microscope and circular polarized light. Figure 2c shows a representative color micrograph of a CW film under 40× magnification and illuminated using right circular polarized light (RCP), while Figure 2d shows a micrograph of the same region of the film illuminated using left circular polarized light (LCP).…”