Anisotropic Gold Nanoparticles: Preparation, Properties, and Applications

Abstract

Anisotropic metal nanoparticles with a catalog of promising anisotropic electronic, optical, and chemical properties have been regarded as enabling building blocks in the bottom-up fabrication of functional materials and devices. Specifically, anisotropic gold nanoparticles are currently emerging as fascinating materials due to their unique shape-, size-, and surface-dependent properties. In this chapter, we present the synthesis, properties and applications of different one-, twoand three-dimensional anisotropic gold nanoparticles (AuNPs). The most widely adopted top-down and bottom-up synthesis approaches have been discussed in addition to some of the recently introduced new methods for the fabrication of differently shaped anisotropic AuNPs. The optical property, photothermal effect, surface enhanced Raman scattering, fluorescence enhancement and quenching, surface modification, toxicology, and supramolecular organizations of anisotropic AuNPs have been highlighted. Various practical and potential applications of anisotropic AuNPs in catalysis, sensing, photothermal therapy, drug and gene delivery, and biological and biomedical areas are briefly outlined.

Liquid crystal-templated chiral nanomaterials: from chiral plasmonics to circularly polarized luminescence

“…Chiral plasmonic nanomaterials with giant localized surface plasmon resonance (LSPR) have received increasingly significant attention for their emerging potential applications in diverse fields, such as negativerefractive-index materials, ultrasensitive biosensing, enantioselective analysis, and advanced light-polarization filters [130][131][132][133][134][135][136][137][138] . Compared to conventional top-down fabrication strategy [139][140][141][142] , the bottom-up self-assembly approach based on chiral soft templates allows for arbitrary and more tailorable structural geometries, thus enabling the development of highly complex chiral plasmonic nanomaterials with engineerable and dynamic chiroptical responses 41 .…”

Photoprogrammable Mesogenic Soft Helical Architectures: A Promising Avenue toward Future Chiro‐Optics

“…On the other hand, metal nanoparticles such as gold nanoparticles normally generate surface plasma polariton resonance upon stimulation with light, producing a photothermal effect, heating the LC helical system, and finally resulting in modulation of the chiro‐optical properties. The peak wavelength of the absorption band of a metal nanoparticle is approximately related to the size of the particles, which can be empirically expressed as λ max = 95 R + 420, [ 49 ] where R is the aspect ratio of the nanoparticle and λ max is the peak wavelength of the absorption band, which indicates that λ max shifts to longer wavelengths only if R is increased. For instance, the peak wavelength of the absorption band can be shifted to 715 nm when the aspect ratio reaches ≈3.1 (i.e., nanorods), ensuring that the absorption band overlaps the NIR band.…”

Soft Materials Driven by Photothermal Effect and Their Applications

“…A useful photothermal agent is required to exhibit strong absorption of light and efficient transduction of light into heat. Gold nanoparticles (GNPs), gold nanorods (GNRs), carbon nanotubes (CNTs), graphene, and iron oxide nanoparticles have been employed as photothermal agents due to their high photothermal conversion efficiency . Similarly, conjugated polymers and dye molecules have also been utilized as photothermal agents.…”