OPTICAL RESONANCES OF A PLASMA NATURE IN TWO-LAYER NANOSPHEROIDS

The process of light scattering by two-layer spheroids consisting of a dielectric core and a silver shell, which depends on the length of an incident wave and particle geometry, is considered. One optical resonance is observed when the foci of the nuclear surfaces and the shell coincide, while when this condition is violated, additional resonances appear. Namely, in the absorption and scattering bands, resonances were found, including previously unknown ones, the position and intensity of which depended on the shell thickness, the shape of the spheroid and its core. To substantiate the reliability of the results obtained, the convergence of the calculations was analyzed depending on the number of harmonics which were taken into consideration in the calculations.

Roles of ROS and cell cycle arrest in the genotoxicity induced by gold nanorod core/silver shell nanostructure

To understand the genotoxicity induced in the liver by silver nanoparticles (AgNPs) and silver ions, an engineered gold nanorod core/silver shell nanostructure (Au@Ag NR) and humanized hepatocyte HepaRG cells were used in this study. The involvement of oxidative stress and cell cycle arrest in the DNA and chromosome damage induced by 0.4–20 µg mL−1 Au@Ag NR were investigated by comet assay, γ-H2AX assay and micronucleus test. Further, the distribution of Au@Ag NR was analyzed. Our results demonstrated that both Ag+ and Au@Ag NR led to DNA cleavage and chromosome damage (clastogenicity) in HepaRG cells and that the Au@Ag NR retained in the nucleus may further release Ag+, aggravating the damages, which are mainly caused by cell cycle arrest and ROS formation. The results reveal the correlation between the intracellular accumulation, Ag+ ion release and the potential genotoxicity of AgNPs.

Extinction Cross-Section Modeling of Metallic Nanoparticles

Localized surface plasmons (LSPs) are a potentially valuable property for the practical use of small size metallic particles. Exploiting the LSPs in metallic nanoparticle (NP)-based solar cells was shown to increase the efficiency of solar panels. A large extinction cross section of NPs allows for high scattering of light at the surface of the panel, which reduces the panel thickness, allowing for small size and low-cost solar cells. In this paper, the extinction cross-section of spherical nanoparticles is studied and simulated numerically. Surface plasmons were first modeled using the Drude’s model then the scattering and absorption cross-sections were derived. Commercial3D simulation software was used to model the near field distribution of the three NP structures. A spherical nanoparticle made of silver was modeled first and the field distribution inside the sphere was presented. The extinction cross-section was also calculated. Two other structures were also presented; a silica NP was first coated with silver shell then a silver NP was coated with silica shell. These structures were studied to estimate the effects of the surroundings on the extinction cross-section. The results show that the silica NP coated with a silver shell provides a high extinction cross-section and can be considered as a good choice for the LSPs-based solar cells.

Roles of ROS and Cell Cycle Arrest in the Genotoxicity Induced by Gold Nanorod Core/silver Shell Nanostructure

To understand the genotoxicity induced in the liver by silver nanoparticles (AgNPs) and silver ions, an engineered gold nanorod core/silver shell nanostructure (Au@Ag NR) and humanized hepatocyte HepaRG cells were used in this study. The involvement of oxidative stress and cell cycle arrest in the DNA and chromosome damage induced by 0.4 - 20 µg.mL-1 Au@Ag NR were investigated by comet assay, γ-H2AX assay, and micronucleus test. Further, the distribution of Au@Ag NR was analyzed. Our results demonstrated that both Ag+ and Au@Ag NR led to DNA cleavage and chromosome damage (clastogenicity) in HepaRG cells, and that the Au@Ag NR retained in the nucleus may further release Ag+, aggravating the damages, which are mainly caused by cell cycle arrest and ROS formation. The results reveal the correlation between the intracellular accumulation, Ag+ ion release as well as the potential genotoxicity of AgNPs.

Core–shell nanoparticles suppress metastasis and modify the tumour-supportive activity of cancer-associated fibroblasts

Background Although accumulating evidence suggests that the crosstalk between malignant cells and cancer-associated fibroblasts (CAFs) actively contributes to tumour growth and metastatic dissemination, therapeutic strategies targeting tumour stroma are still not common in the clinical practice. Metal-based nanomaterials have been shown to exert excellent cytotoxic and anti-cancerous activities, however, their effects on the reactive stroma have never been investigated in details. Thus, using feasible in vitro and in vivo systems to model tumour microenvironment, we tested whether the presence of gold, silver or gold-core silver-shell nanoparticles exerts anti-tumour and metastasis suppressing activities by influencing the tumour-supporting activity of stromal fibroblasts. Results We found that the presence of gold-core silver-shell hybrid nanomaterials in the tumour microenvironment attenuated the tumour cell-promoting behaviour of CAFs, and this phenomenon led to a prominent attenuation of metastatic dissemination in vivo as well. Mechanistically, transcriptome analysis on tumour-promoting CAFs revealed that silver-based nanomaterials trigger expressional changes in genes related to cancer invasion and tumour metastasis. Conclusions Here we report that metal nanoparticles can influence the cancer-promoting activity of tumour stroma by affecting the gene expressional and secretory profiles of stromal fibroblasts and thereby altering their intrinsic crosstalk with malignant cells. This potential of metal nanomaterials should be exploited in multimodal treatment approaches and translated into improved therapeutic outcomes.

In Vivo Metabolic Response upon Exposure to Gold Nanorod Core/Silver Shell Nanostructures: Modulation of Inflammation and Upregulation of Dopamine

With the increasing applications of silver nanoparticles (Ag NPs), the concerns of widespread human exposure as well as subsequent health risks have been continuously growing. The acute and chronic toxicities of Ag NPs in cellular tests and animal tests have been widely investigated. Accumulating evidence shows that Ag NPs can induce inflammation, yet the overall mechanism is incomplete. Herein, using gold nanorod core/silver shell nanostructures (Au@Ag NRs) as a model system, we studied the influence on mice liver and lungs from the viewpoint of metabolism. In agreement with previous studies, Au@Ag NRs’ intravenous exposure caused inflammatory reaction, accompanying with metabolic alterations, including energy metabolism, membrane/choline metabolism, redox metabolism, and purine metabolism, the disturbances of which contribute to inflammation. At the same time, dopamine metabolism in liver was also changed. This is the first time to observe the production of dopamine in non-neural tissue after treatment with Ag NPs. As the upregulation of dopamine resists inflammation, it indicates the activation of antioxidant defense systems against oxidative stress induced by Au@Ag NRs. In the end, our findings deepened the understanding of molecular mechanisms of Ag NPs-induced inflammation and provide assistance in the rational design of their biomedical applications.