Spherical and Flower-Shaped Gold Nanoparticles Characterization by Scattering Correlation Spectroscopy

Abstract

The aim of this study is to compare the optical scattering properties of different gold nanoparticles (GNPs), with different shapes (spherical, GNSs, and flower-shaped, GNFs), sizes (20, 30, and 50 nm), and surface chemistries (with and without PEG). These scattering properties give geometrical characterization of hydrodynamic sizes of GNPs by using the scattering correlation spectroscopy. Afterward, a multiparametric comparative study of the scattering efficiency is presented depending on various parameters such as GNPs geometry, excitation wavelength (532 and 633 nm) and powers (from 5 to 100 μW). As predicted by Mie theory, we demonstrate that the increase in GNSs size leads to an increase of the scattered intensity, proportional to the excitation power. The scattered signal is the highest when the excitation wavelength is closer to the localized surface plasmon resonance. In the case of GNFs, the measured scattered signal is around 1000 times stronger than that for GNSs of the same size and concentration. For GNFs, a scattering coefficient at the plasmon resonance of around 2 × 10 −13 m 2 was calculated, which is comparable to the scattering coefficient of a GNS with a diameter of 300 nm. Due to their strong scattering properties, GNFs appear as a good alternative to GNSs of the same size for cell imaging.

Shape and Size Effect on Photothermal Heat Elevation of Gold Nanoparticles: Absorption Coefficient Experimental Measurement of Spherical and Urchin-Shaped Gold Nanoparticles

“…Moreover, this factor is higher for smaller GNUs which suggests that in this case the smaller GNUs are more efficient heaters because of their sharp branches. These results also demonstrate that branched nanoparticles lead to an enhancement of optical properties as already reported in refs − and demonstrated by the authors. , …”

Scattering Correlation Spectroscopy and Raman Spectroscopy of Thiophenol on Gold Nanoparticles: Comparative Study between Nanospheres and Nanourchins

“…The theory of SCS was described in our previous work. 37 This method relies on scattered intensity fluctuations within a confocal volume to determine the hydrodynamic radius of GNPs. 23,38,39 The correlation curve is mathematically represented by the equation…”

“…SCS experiments were performed on a home-built instrument based on an inverted microscope previously described by the authors . The system is based on an excitation wavelength set at 633 nm (He–Ne laser, Thorlabs) with an excitation power of 10 μW to avoid any optical trapping effect .…”

Size, Shape, and Wavelength Effect on Photothermal Heat Elevation of Gold Nanoparticles: Absorption Coefficient Experimental Measurement

“…[13,[40][41][42][43][44] Complex-shaped nanoparticles as GNU and GNR compared to the spherical ones can have a high oscillation due to their sharp tips called also "hot spots." [45][46][47][48][49][50] The resonant oscillation at the LSPR wavelength leads to an energy dissipation and hence, an increase of the nanoparticles temperature. As gold has a high thermal conductivity, the temperature at the nanoparticles surface is immediately transferred to the surrounding medium.…”