In this paper, we propose a multi-parametric in vitro study of the cytotoxicity of gold nanoparticles (GNPs) on human endothelial cell (HUVEC). The cytotoxicity is evaluated by incubating cells with six different GNP types which have two different morphologies: spherical and flower-shaped, two sizes (∼15 and ∼50 nm diameter) and two surface chemistries (as prepared form and PEGylated form). Our results showed that by increasing the concentration of GNPs the cell viability decreases with a toxic concentration threshold of 10 pM for spherical GNPs and of 1 pM for flower-shaped GNPs. Dark field images, flow cytometry and spreading test revealed that flower-shaped GNPs have more deleterious effects on the cell mechanisms than spherical GNPs. We demonstrated that the main parameter in the evaluation of the GNPs toxicity is the GNPs roughness and that this effect is independent on the surface chemistry. We assume that this behavior is highly related to the efficiency of the GNPs internalization within the cells and that this effect is enhanced due to the specific geometry of the flower-shaped GNPs.

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.