Plasmonic Circular Dichroism of Gold Nanoparticle Based Nanostructures

Abstract

IntroductionChirality refers to the certain handedness in geometry with a mirror image that cannot coincide with itself. [1] Mirror images with opposite chirality are enantiomers, and can be divided into left-and right-handedness, respectively. Two enantiomers can interact differently with left-(LCP) and right-circularly With great advances in wet chemical synthesis of nanoparticles (NPs), plasmonic NPs with various sizes and morphologies are easily available nowadays and demonstrate great potentials in optical, electronic, and biomedical applications. Plasmonic circular dichroism (CD), relating to circular dichroism responses at localized surface plasmon resonance of metal nanostructures, has emerged as a research direction of plasmonics with promising prospects in enantioselective catalysis, chiral separation, and ultrasensitive detections. Herein, plasmonic CD responses of gold nanoparticle based nanostructures are summarized. Two kinds of plasmonic CD phenomena are investigated: structural CD and induced CD. Structural CD is the response from chiral assemblies composed of plasmonic NPs with strong dipole-dipole interactions. Induced CD is the response of nonchiral plasmonic NPs with chiral molecules attached at surface. The weak CD is the result of Coulomb interaction between chiral molecules and plasmonic NPs. Efforts on how to achieve strong CD signals for these two configurations by using chiral molecules and Au nanoparticles are reported. The fabrication of chiral nanostructures, tuning and amplification of CD responses, CD-based biosensors, chiral catalysis, and future perspectives are presented. The importance of the shape anisotropy of gold nanorods in the generation and amplification of CD signals is especially highlighted.

Chiral detection by induced surface-enhanced Raman optical activity

“…S5, ESI †). Although plasmonic CD is sometimes observable in colloids, 57,58 in our case addition of a small amount of the chiral compound did not produce it.…”

In Situ Spectroscopic Probes for Structures and Processes at the Surface of Noble Metallic Nanoparticles

“…For example, circular dichroism (CD) spectroscope is a powerful method for analyzing the chiral structure of biomolecules during their interaction with metal NPs. [180,181] It measures the absorption of circularly polarized light by chiral molecules/structures. The difference in the absorption obtained with left-hand and right-hand circular polarization lasers can reflect the chirality of biomolecules enhanced by the surface plasmon of the NPs, or from the assembled structure of NP S with chiral molecules.…”

“…The difference in the absorption obtained with left-hand and right-hand circular polarization lasers can reflect the chirality of biomolecules enhanced by the surface plasmon of the NPs, or from the assembled structure of NP S with chiral molecules. [181] Recently, Visheratina et al [182] combined luminescence and CD spectral methods for the determination of hybrid nanostructures based on chlorin e6 and ZnS:Mn quantum dots (QDs). The formation show size scaling expected from the geometric increase of the conical volume available to the alkane chain on a curved surface.…”

Atomistic investigation of hybrid plasmonic systems

“…Thus, the performed TD-DFTB simulations appear as an encouraging starting point to be further investigated with the future perspectives to reduce the computational costs and to study larger systems of interest for experimental groups. In fact, several recent experimental works [42][43][44][45] focused on how to tune the plasmon-exciton coupling in hybrid systems. To fulfil this objective, the fundamental requirement is the ability to precisely manipulate light on the nanometer scale.…”