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
Microalloying of pure gold, which has the highest biocompatibility but relatively low yield strength and poor wear resistance, might improve its applicability as adornments and biomedical implants. The objective of this study was to analyse the microstructure and biocompatibility of gold-lanthanum (Au-0.5 wt% La) microstrips as a potential biomaterial in dentistry or medicine. We found that microalloying of Au with La produced very fine nanosized grains homogeneously dispersed through the entire volume of the rapidly solidified (RS) alloys. This initiates the formation of Au6La phase which increases strength and hardness of the alloy significantly. By RS, large reduction of grains and microsegregation increases the strength of the alloy additionally. Our results suggest that Au-La microstrips, although non-cytotoxic for L929 cells, rat thymocytes, rat peritoneal macrophages (PMØ) and human peripheral blood mononuclear cells (PBMNCs), can activate immune cells. Namely, RS Au-La microstrips stimulated the production of nitric oxide (NO) by PMØ. Using a model of phytohemaglutinine (PHA)-stimulated human PBMNCs, we found that RS Au-La strips increased the proliferation of these cells and stimulated the production of Th1, Th17 cytokines, and immunoregulatory cytokine IL-10. Our results suggest that RS Au-La microstrips are biocompatible, but they can modulate the immune response. Therefore, their use as potential implants should be considered carefully.
COBISS.SI-ID: 18017302
The aim of this work was to determine the effect of boron on the solidification and processes taking place during heat treatment of an Al-Mn-Be-based alloy. Several phases formed upon slow cooling of the investigated alloy Al89Mn2Be2B7: BeB12, AlBeB, T-Al15Mn3Be2, Al6Mn and aluminium solid solution (Alss). An icosahedral quasicrystalline phase (IQC) was formed during rapid solidification by melt spinning; partly dissolving Be and B, while the remaining Be and B precipitated as a ternary compound AlBeB. The primary IQC persisted within the microstructure up to 400 °C, whilst at temperatures above 450 °C the initial microstructure started to transform quickly into AlBeB, Al6Mn and Alss, which appeared to be the stable phases below the alloy's solidus temperature. The hardness remained almost unchanged up to 400 °C, whilst at temperatures above 450 °C it dropped abruptly
COBISS.SI-ID: 18035478
In this research, the structure changes along the depth of gradient layers of titanium substrate, after etching with NaOH and subsequent thermal treatment at various temperatures between 300 and 800 °C, were investigated by XRD, FTIR and AES. Particularly, the changes of Ti substrate after etching with NaOH, subsequent ionic exchange of Na+ with Ca2+ ions and thermal treatment at 700 °C were analysed. Due to this approach, it was possible to get insight into the chemical changes and changes of Ti oxidation states and consequent phase analysis, along the depth of the titanium oxide coatings. In addition, Secondary Electron Imaging (SEI) showed very interesting nanotopology of all samples. Particularly interesting topology, consisting of very thin nano-designed walls between mutually interconnected pores, was observed for the sample in which Na+ were replaced with Ca2+ ions. This structure might be suitable for deposition of hydroxyapatite by biomimetic or plasma methods and as an appropriate scaffold for cell adhesion and proliferation.
COBISS.SI-ID: 17537814
A combination of internal oxidation (IO) and equal channel angular pressing (ECAP) was used to explore the possibility of uniting the mechanisms of dispersion and deformation strengthening to improve the properties of a Cu-Al alloy with 0.4 % Al. The IO of Cu-Al billets served in the first step of the experiment as a means for dispersion, strengthening the mantle of the billets with a fine dispersion of nanosized oxide particles. The experimental procedure continued with deformation strengthening performed by ECAP, which allowed an intense plastic strain through simple shear. Material flow in a partly internally oxidized Cu-0.4 % Al billet and in a homogenous reference sample made of modelling mass was also studied to analyse, on the macroscale, the influence of the internal oxidation zone (IOZ) on the material flow behaviour during the ECAP process. The analysis was performed with the aim of revealing the uniformity of the strain distribution and to obtain information about the deformation strengthening across the volume of the billet. We found that the oxide particles have a minor influence on the material flow on the macroscopic scale during the ECAP process. However, the degree of deformation strengthening in the IOZ was much lower than in the unoxidized core region. The combination of IO and ECAP allows us to produce a Cu composite composed of a hardened oxidized mantle region with good electrical and thermal conductivity and a high- hardened core region. This combination represents a new technological route for the production of high-hardness Cu composites, which could also be used at higher temperatures.
COBISS.SI-ID: 17823510