On the Origin of the Plasmonic Properties of Gold Nanoparticles

Abstract

Gold nanoparticles (AuNPs) are widely used as biological imaging agents, colorimetric sensors, surface‐enhanced Raman spectroscopy (SERS) substrates, photothermal anti‐cancer agents, visible wavelength photocatalysts, and photovoltaic materials. These applications are based on the plasmonic properties of AuNPs. Therefore, a fundamental understanding of the origin of the plasmonic behavior of AuNPs allows us to control the properties of AuNPs and widen their applications. In this review, we discuss the origin of the color, SERS, and hot‐carrier generation of AuNPs. We start with the free‐electron Drude model and the dielectric constant of AuNPs, which defines the material properties. We then explain the mechanism that determines the colors of bulk and nanosized gold, enhancement of the electric fields outside the AuNPs, and generation of hot carriers during the decay of plasmons.

Influence of mercury amalgamation on three‐dimensional orientation of single gold nanorods coated with mesoporous silica shell

“…Recently, dark‐field (DF) microscopy and spectroscopy were utilized to better understand Au–Hg amalgam formation and spectral variations in single gold nanorods (AuNRs) upon Hg amalgamation 4–8 . After the Hg amalgamation of AuNRs, they exhibited a remarkable shape change and became spherical, accompanied by a drastic blue shift in the LSPR peak 4,6 .…”

“…3 Recently, dark-field (DF) microscopy and spectroscopy were utilized to better understand Au-Hg amalgam formation and spectral variations in single gold nanorods (AuNRs) upon Hg amalgamation. [4][5][6][7][8] After the Hg amalgamation of AuNRs, they exhibited a remarkable shape change and became spherical, accompanied by a drastic blue shift in the LSPR peak. 4,6 Despite the previous studies on Hg amalgamation process, 4,5,9 the structural and spectral changes of AuNRs following Hg amalgamation have not been fully understood.…”

Conjugation strategies of DNA to gold nanoparticles

“…Furthermore, the localized surface plasmon peak of AuNPs depends on its ligand adsorption or binding. Therefore, the plasmonic properties of AuNPs are versatile and useful in designing optical biosensors 27 . Third, AuNPs have good biocompatibility and low toxicity.…”

“…Therefore, the plasmonic properties of AuNPs are versatile and useful in designing optical biosensors. 27 Third, AuNPs have good biocompatibility and low toxicity. Finally, there are well-established bioconjugation chemistries available with AuNPs.…”

Observation of reactions in single molecules/nanoparticles using light microscopy

“…DF microscopy for the observation of scattering changes using plasmon coupling LSPR λ max shifting can be induced by changes in the ambient refractive index and plasmon coupling. 59,60 When the two plasmonic nanoparticles are close, plasmon coupling occurs, and the scattering spectrum shifts depending on their distance. 61 Bissell et al employed plasmonic coupling between neighboring plasmonic metal NPs as optical probes for reversible molecular rulers to overcome the limitations of organic rulers, such as Föster resonance energy transfer (FRET) (Figure 4d).…”