Chiral plasmonic sensing: From the perspective of light-matter interaction.

Molecular chirality is represented as broken mirror symmetry in the structural orientation of constituent atoms and plays a pivotal role at every scale of nature. Since the discovery of the chiroptic property of chiral molecules, the characterization of molecular chirality is important in the fields of biology, physics, and chemistry. Over the centuries, the field of optical chiral sensing was based on chiral light-matter interactions between chiral molecules and polarized light.

Strain and crystallographic identification of the helically concaved gap surfaces of chiral nanoparticles.

Identifying the three-dimensional (3D) crystal plane and strain-field distributions of nanocrystals is essential for optical, catalytic, and electronic applications. However, it remains a challenge to image concave surfaces of nanoparticles. Here, we develop a methodology for visualizing the 3D information of chiral gold nanoparticles ≈ 200 nm in size with concave gap structures by Bragg coherent X-ray diffraction imaging.

Enantioselective sensing by collective circular dichroism.

Quantitative determination and in situ monitoring of molecular chirality at extremely low concentrations is still challenging with simple optics because of the molecular-scale mismatch with the incident light wavelength. Advances in spectroscopy and nanophotonics have successfully lowered the detection limit in enantioselective sensing, as it can bring the microscopic chiral characteristics of molecules into the macroscopic scale or squeeze the chiral light into the subwavelength scale. Conventional nanophotonic approaches depend mainly on the optical helicity density by localized resonances within an individual structure, such as localized surface plasmon resonances (LSPRs) or dielectric Mie resonances.

Morphological Evolution Trajectory of Multifaceted Palladium Nanoparticles.

Precise control over the morphology and facets of Pd nanomaterials has great importance in catalytic and sensing applications. In this study, we synthesized Pd nanoparticles with multiple types of low-Miller-index-faceted morphologies by systematically defining the synthesis conditions of the seed-mediated colloidal preparation method. We discovered the morphological evolution of Pd nanoparticles by following the trajectory of the surface Miller indices, which were determined by the cooperative effects of cetyltrimethylammonium bromide and ascorbic acid.

Circularly polarized light-sensitive, hot electron transistor with chiral plasmonic nanoparticles.

The quantitative detection of circularly polarized light (CPL) is necessary in next-generation optical communication carrying high-density information and in phase-controlled displays exhibiting volumetric imaging. In the current technology, multiple pixels of different wavelengths and polarizers are required, inevitably resulting in high loss and low detection efficiency. Here, we demonstrate a highly efficient CPL-detecting transistor composed of chiral plasmonic nanoparticles with a high Khun's dissymmetry (g-factor) of 0.

Tyrosyltyrosylcysteine-Directed Synthesis of Chiral Cobalt Oxide Nanoparticles and Peptide Conformation Analysis.

Chiral inorganic nanomaterials have revealed opportunities in various fields owing to their strong light-matter interactions. In particular, chiral metal oxide nanomaterials that can control light and biochemical reactions have been highlighted due to their catalytic activity and biocompatibility. In this study, we present the synthesis of chiral cobalt oxide nanoparticles with a -factor of 0.

A Single Chiral Nanoparticle Induced Valley Polarization Enhancement.

Valley polarization is among the most critical attributes of atomically thin materials. However, increasing contrast from monolayer transition metal dichalcogenides (TMDs) has so far been challenging. In this work, a large degree of circular polarization up to 45% from a monolayer WS is achieved at room temperature by using a single chiral plasmonic nanoparticle.

γ-Glutamylcysteine- and Cysteinylglycine-Directed Growth of Chiral Gold Nanoparticles and their Crystallographic Analysis.

Chiral optical metamaterials with delicate structures are in high demand in various fields because of their strong light-matter interactions. Recently, a scalable strategy for the synthesis of chiral plasmonic nanoparticles (NPs) using amino acids and peptides has been reported. Reported herein, 3D chiral gold NPs were synthesized using dipeptide γ-Glu-Cys and Cys-Gly and analyzed crystallographically.

Uniform Chiral Gap Synthesis for High Dissymmetry Factor in Single Plasmonic Gold Nanoparticle.

Synthesis of chiral plasmonic materials has been highlighted for the last decades with their optical properties and versatile potential applications. Recently reported aqueous-based amino acid- and peptide-directed synthesis of chiral plasmonic gold nanoparticles with 432 point-group symmetry shows exceptionally high chiroptic response within 100 nm scales. Despite its already excellent chiroptic response, a single-nanoparticle dark field scattering study revealed that full chiroptic potential of chiral gold nanoparticle is limited with its overall synthetic uniformity.

Chiral Surface and Geometry of Metal Nanocrystals.

Chirality is a basic property of nature and has great importance in photonics, biochemistry, medicine, and catalysis. This importance has led to the emergence of the chiral inorganic nanostructure field in the last two decades, providing opportunities to control the chirality of light and biochemical reactions. While the facile production of 3D nanostructures has remained a major challenge, recent advances in nanocrystal synthesis have provided a new pathway for efficient control of chirality at the nanoscale by transferring molecular chirality to the geometry of nanocrystals.