Terahertz multispectral imaging for the analysis of gold nanoparticles’ size and the number of unit cells in comparison with other techniques

Abstract

In this work, we investigate the use of a Terahertz multispectral reconstructive imaging technique to measure the size of individual gold nanoparticles and accordingly the number of unit cells in a given gold nanoparticle. The gold nanoparticles were synthesized by the Frens-Turkevich citrate method and characterized by UV-Vis absorption spectroscopy, Dynamic light Scattering, and Transmission Electron Microscopy as well as by terahertz 3D image analysis. The size of the gold nanoparticles as determined by the Terahertz reconstructive imaging was 18.5 nm which was comparable to the size obtained by the other aforementioned measurement techniques with the exception of Dynamic light scattering which actually measures the hydrodynamic diameter. Using the size of the gold nanoparticles determined by terahertz reconstructive imaging, the number of unit cells in the gold nanoparticle was computed to be 48,825. The results demonstrate that Terahertz multispectral reconstructive imaging is a powerful nondestructive, non-contact technique for the size analysis of gold nanoparticles.

N-Heterocyclic Carbene Gold Complexes in a Photocatalytic CO2 Reduction Reaction

“…Only two of the lowest TON value catalysts ( 4 Cl and 1 OH 1 BF4 ) show a moderate DLS signal between 2 nm and 800 nm sizes (Figure ). A small signal is observed near 1 nm for 1 NTf2 and 1 OH 1 BF4 as well, although we note this is near the detection limit of the instrument, and assuming a spherical nanoparticle would only correspond to approximately 8 Au atoms if the entire particle was Au atoms face-centered-cubic-packed with a unit cell volume of 0.0679 nm 3 . Notably, the Au atom count of a particle would likely be smaller than this since DLS actually measures the hydrodynamic radius .…”

“…A small signal is observed near 1 nm for 1 NTf2 and 1 OH 1 BF4 as well, although we note this is near the detection limit of the instrument, and assuming a spherical nanoparticle would only correspond to approximately 8 Au atoms if the entire particle was Au atoms face-centered-cubic-packed with a unit cell volume of 0.0679 nm 3 . Notably, the Au atom count of a particle would likely be smaller than this since DLS actually measures the hydrodynamic radius . Combined, these three tests for heterogeneity suggest the catalysts may be functioning as molecular systems since the highest performing catalysts do not show evidence of forming heterogeneous species across three common heterogeneity tests.…”

Gold Nanoparticles Functionalized with Angiogenin for Wound Care Application

“…Hence, the molar concentration of AuNP dispersion was calculated according to Equation (3): ε = Ad γ , where ε (M −1 cm −1 ) is the extinction coefficient, d is the core diameter of the nanoparticles previously calculated, and γ = 3.30, A = 4.7 × 10 4 M −1 cm −1 for d ≤ 85 nm, γ = 1.47, A = 1.6 × 10 8 M −1 cm −1 for d > 85 nm [ 59 ]. In order to calculate the NP number per mL, considering the spherical shape of the nanoparticle and a uniform face centered cubic (fcc) structure of the nanoclusters, with the length parameter of unit cell of L = 0.408 nm [ 38 , 60 ], the unit cell volume value ( V cell = L 3 = 0.0679 nm 3 ) was calculated to obtain the volume of a particle, , given by Equation (4): …”

Effect of Surface Modifications on Cellular Uptake of Gold Nanorods in Human Primary Cells and Established Cell Lines

“…The mean size of the gold nanorods used in this study was about 70 nm in length and 10 nm in width. From the density of gold (19.32 g/cm 3 ) or the size of the crystal lattice (0.4078 nm for four gold atoms), 61 the number of gold atoms in one gold nanorod can be calculated to be 3.47 × 10 5 . The amount of internalized gold nanorods was shown as “μg of gold per 10 5 cells” and “number of gold nanorods in one cell”.…”