Shape influence on the ultrafast plasmonic properties of gold nanoparticles

Abstract

The aim of shape-controlled colloidal synthesis of gold (Au) is to produce Au nanoparticles (NPs) with fine control of shapes, sizes, and dispersities. We show how transient absorption spectroscopy (TAS) can be used to rapidly and accurately quantify the vast ensemble of shapes of Au NPs in solution within minutes, including the synthesized nanorods, decahedra, and nanospheres. Colloidal solutions containing Au NPs were measured in TAS and their localized surface plasmon resonance (LSPR) modes were classified according to the shape, wavelength and number of peaks. Then their excited-state relaxation dynamics were used to ascertain their electron-phonon (e-ph) coupling time constant and frequency of optomechanical modes. TAS can quickly show that an Au nanosphere sample contains a tiny fraction of Au nanorods, whereas steady-state absorbance is totally blind to the presence of nanorods. Additionally, the TAS experiments indicate that the characteristic e-ph coupling time constants in Au nanorods depend on the NPs dimensions at high excitation intensity (> 6 µJ/cm2) which can help identify if there are any elongated Au NPs in Au spheres samples. Finally, optomechanical oscillations formed by NPs breathing modes were observed, providing information related to the average size and monodispersity of Au nanospheres and nanorods.

H‐Glass Supported Hybrid Gold Nano‐Islands for Visible‐Light‐Driven Hydrogen Evolution

“…It may be noted that MNPs with a hot electron lifetime (τ) higher than ≈1.5 ps are preferred for photocatalysis. [ 53 ]…”

“…It may be noted that MNPs with a hot electron lifetime (𝜏) higher than ≈1.5 ps are preferred for photocatalysis. [53] To assess the STH efficiency of the H-Au system, online gas chromatography (Figure S28, Supporting Information) was employed. Figure 7a shows the rate of H 2 evolution under exposure to simulated solar light (AAA class solar simulator 1 Sun, 1000 mW cm −2 ) for durations up to 3 h. The absorption spectrum for H-Au glass (Figure 1d) spans from 480 to 700 nm, with a peak centered at 536 nm, attributed to particle size distribution.…”

Spider minor ampullate silk protein nanoparticles: an effective protein delivery system capable of enhancing systemic immune responses

“… 38 , 39 , 40 The shape of NPs also affects their biodistribution and uptake efficiency by APCs. 41 For example, spherical gold NPs were effectively taken up by APCs compared with rod‐shaped counterparts. The MiSp‐based NM‐NPs are with a size of ∼200 nm and a spherical morphology (Figure 1 ), after loaded with protein, the Lyso‐NM‐NPs can increase to approximately 500 nm in diameter with maintaining the spherical morphology (Figure 2B ).…”

“…[38][39][40] The shape of NPs also affects their biodistribution and uptake efficiency by APCs. 41 For example, spherical gold NPs were effectively taken up by APCs compared with rod-shaped F I G U R E 9 Spider-silk based nanoparticles as a suitable carrier for protein antigen induce a robust immune and cellular responses by subcutaneous immunization. These nanoparticles, based on MiSp, significantly enhance antigen-specific immune responses, through mechanisms involving antigen-depot effects at the injection site, efficient uptake by dendritic cells as well as internalization by lymph nodes, promoting maturation and cross-presentation.…”

Recent Development of Photoresponsive Liposomes Based on Organic Photosensitizers, Au Nanoparticles, and Azobenzene Derivatives for Nanomedicine

“…The oscillation frequency is closely related to the electron density, the effective mass of electrons, and the shape and size of the surface charge distribution . Therefore, in order to accumulate enough heat to realize the photothermal effect, particles with complex geometric features are usually prepared, which can change the shape of the charge distribution and enhance the local electron density while obtaining a larger specific surface area, which is because the electron density on the surface of Au nanoparticles is proportional to the surface curvature. , High-frequency vibration makes the local temperature rise, thus affecting the surrounding structure or material properties . In other words, Au nanoparticles provide an adjustment strategy for the release control of liposomes through the photothermal effect.…”