Gold nanoparticles (GNPs) are claimed as outstanding biomedical tools for cancer diagnostics and photo-thermal therapy, but without enough evidence on their potentially adverse immunological effects. Using a model of human dendritic cells (DCs), we showed that 10 nm- and 50 nm-sized GNPs (GNP10 and GNP50, respectively) were internalized predominantly via dynamin-dependent mechanisms, and they both impaired LPS-induced maturation and allostimulatory capacity of DCs, although the effect of GNP10 was more prominent. However, GNP10 inhibited LPS-induced production of IL-12p70 by DCs, and potentiated their Th2 polarization capacity, while GNP50 promoted Th17 polarization. Such effects of GNP10 correlated with a stronger inhibition of LPS-induced changes in Ca2+ oscillations, their higher number per DC, and more frequent extraendosomal localization, as judged by live-cell imaging, proton, and electron microscopy, respectively. Even when released from heat-killed necrotic HEp-2 cells, GNP10 inhibited the necrotic tumor cell-induced maturation and functions of DCs, potentiated their Th2/Th17 polarization capacity, and thus, impaired the DCs% capacity to induce T cell-mediated anti-tumor cytotoxicity in vitro. Therefore, GNP10 could potentially induce more adverse DC-mediated immunological effects, compared to GNP50.
COBISS.SI-ID: 27671847
Forced convection heat transfer from a heated circular cylinder to incompressible water-based nanofluids in the steady cross-flow regime has been investigated numerically. The momentum and thermal energy differential equations have been solved by the standard finite volume method on the non-uniform Cartesian grid. Accurate numerical results are presented in the form of the local and mean Nusselt number and the heat transfer enhancement. The results indicate clearly that the heat transfer characteristics are affected by the base-fluid Reynolds number, volume fraction and the thermo-physical properties of nanoparticles. Although those nanofluids reduce the mean Nusselt number values, they enhance the heat transfer rate.
COBISS.SI-ID: 18016790
The aim of this work was to study the cytotoxicity of different fractions of gold nanoparticles prepared by ultrasonic spray pyrolysis from gold scrap. The target cells were rat thymocytes, as a type of nonproliferating cells, and L929 mouse fibroblasts, as a type of continuous proliferating cells. Fractions1 and 2, composed of pure gold nanoparticles, as determined by scanning electron microscopy with a combination of energy dispersive X-ray analysis, were nontoxic for thymocytes, but reduced moderately the proliferative activity of L929 cells. The inhibitory effect of fraction 2, containing particles smaller in size than fraction 1, was stronger. Fraction 3, composed of Au and up to 3% Cu was noncytotoxic for thymocytes, but was cytotoxic for L929 cells. Fraction 4, composed of Au and Ag nanoparticles, and fraction 5, composed of Au together with Cu, Ni, Zn, Fe, and In were cytotoxic for both thymocytes and L929 cells. These results suggest that USP enables the synthesis of pure gold nanoparticles with controlled size, even from gold scrap. However, microstructural analyses and biocompatibility testing are necessary for their proper selection from more cytotoxic gold nanoparticles, contaminated with other elements of gold alloys.
COBISS.SI-ID: 14359830
We prepared 5 different fractions of nanoparticles from the gold scrap, by using a new technology, Ultrasonic Spray Pirolysis (USP). The aim of this study was to characterize the microstructure and cytotoxicity of the nanoparticles along with their immunomodulatory properties, using Concanavaline A (ConA)-treated rat splenocytes as a model of activated immune cells. Fractions 1 and 2, composed of pure gold nanoparticles, although non-cytotoxic, reduced cellular proliferation. Fraction 2, containing particles smaller in size and lesser agglomerated than fraction 1, up- and down-regulated the production of IL-2 and IL-10, respectively, by activated splenocytes. Fraction 3, containing nanoparticles composed of Au and up to 3 at.% Cu, was non-cytotoxic, but reduced IL-2 production and cell proliferation. Fractions 4 and 5, contaminated with alloying elements from the gold scrap, were cytotoxic. The extent of cytotoxicity and subsequent reduction of cytokine production, as well as the mode of cell death, depended on their composition. In conclusion, we showed that USP enables the synthesis of gold nanoparticles, which could be suitable for various biological applications, and that ConA-treated splenocytes represent a reliable model for fast and accurate evaluation of the immunotoxicological profiles of these particles. However, it is necessary to improve this technology and investigate further some of the immunomodulatory mechanisms using more specific immunological tests.
COBISS.SI-ID: 15970838
The present work deals with the laminar natural convection in a square cavity with differentially heated side walls subjected to constant temperatures and filled with homogenous 0,4 wt. % aqueous solution of carboxymethyl cellulose (CMC) based Au, Al2O3, Cu and TiO2 nanofluids obeying the Power law rheological model. The governing differential equations have been solved by the standard finite volume method and the hydrodynamic and thermal fields are coupled together using the Boussinesq approximation. The main objective of this study is to investigate the influence of the nanoparticles f volume fraction (0 % =( fi =( 10 %) on the heat transfer characteristics of CMC based nanofluids over a wide range of nanofluid Rayleigh number (10[sub]3 =( Ranf =( 10[sub]6). Accurate numerical results are presented in the form of dimensionless temperature and velocity variations, isotherms, mean Nusselt number and heat transfer enhancement. The results indicate clearly that the heat and momentum transfer characteristics are affected only by the nanofluid Rayleigh number, while the type of nanoparticles (i.e. thermo-phyisical properties) and their volume fraction have effect only on the heat transfer enhancement.
COBISS.SI-ID: 16722966