The influence of the chain length and the functional group steric accessibility of thiols on the phase transfer efficiency of gold nanoparticles from water to toluene

The papers were published with the financial support from the budget of the West Pomeranian Voivodeship.This paper describes the influence of the chain length and the functional group steric accessibility of thiols modifiers on the phase transfer process efficiency of water synthesized gold nanoparticles (AuNPs) to toluene. The following thiols were tested: 1-decanethiol, 1,1-dimethyldecanethiol, 1-dodecanethiol, 1-tetradecanethiol and 1-oktadecanethiol. Nanoparticles (NPs) synthesized in water were precisely characterized before the phase transfer process using Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The optical properties of AuNPs before and after the phase transfer were studied by the UV-Vis spectroscopy. Additionally, the particle size and size distribution before and after the phase transfer of nanoparticles were investigated using Dynamic Light Scattering (DLS). It turned out that the modification of NPs surface was not effective in the case of 1,1-dimethyldecanethiol, probably because of the difficult steric accessibility of the thiol functional group to NPs surface. Consequently, the effective phase transfer of AuNPs from water to toluene did not occur. In toluene the most stable were nanoparticles modified with 1-decanethiol, 1-dodecanethiol and 1-tetradecanethiol.This work was supported by FP7-NMP-2010-SMALL-4 program (HYMEC), project number 263073. Scientific work supported by the Polish Ministry of Science and Higher Education, funds for science in 2011–2014 allocated for the cofounded international project

T Lymphocyte-Derived Exosomes Transport MEK1/2 and ERK1/2 and Induce NOX4-Dependent Oxidative Stress in Cardiac Microvascular Endothelial Cells

Background: Activation of endothelial cells by inflammatory mediators secreted by CD4+ T lymphocytes plays a key role in the inflammatory response. Exosomes represent a specific class of signaling cues transporting a mixture of proteins, nucleic acids, and other biomolecules. So far, the impact of exosomes shed by T lymphocytes on cardiac endothelial cells remained unknown. Methods and results: Supernatants of CD4+ T cells activated with anti-CD3/CD28 beads were used to isolate exosomes by differential centrifugation. Activation of CD4+ T cells enhanced exosome production, and these exosomes (CD4-exosomes) induced oxidative stress in cardiac microvascular endothelial cells (cMVECs) without affecting their adhesive properties. Furthermore, CD4-exosome treatment aggravated the generation of mitochondrial reactive oxygen species (ROS), reduced nitric oxide (NO) levels, and enhanced the proliferation of cMVECs. These effects were reversed by adding the antioxidant apocynin. On the molecular level, CD4-exosomes increased NOX2, NOX4, ERK1/2, and MEK1/2 in cMVECs, and ERK1/2 and MEK1/2 proteins were found in CD4-exosomes. Inhibition of either MEK/ERK with U0126 or ERK with FR180204 successfully protected cMVECs from increased ROS levels and reduced NO bioavailability. Treatment with NOX1/4 inhibitor GKT136901 effectively blocked excessive ROS and superoxide production, reversed impaired NO levels, and reversed enhanced cMVEC proliferation triggered by CD4-exosomes. The siRNA-mediated silencing of Nox4 in cMVECs confirmed the key role of NOX4 in CD4-exosome-induced oxidative stress. To address the properties of exosomes under inflammatory conditions, we used the mouse model of CD4+ T cell-dependent experimental autoimmune myocarditis. In contrast to exosomes obtained from control hearts, exosomes obtained from inflamed hearts upregulated NOX2, NOX4, ERK1/2, MEK1/2, increased ROS and superoxide levels, and reduced NO bioavailability in treated cMVECs, and these changes were reversed by apocynin. Conclusion: Our results point to exosomes as a novel class of bioactive factors secreted by CD4+ T cells in immune response and represent potential important triggers of NOX4-dependent endothelial dysfunction. Neutralization of the prooxidative aspect of CD4-exosomes could open perspectives for the development of new therapeutic strategies in inflammatory cardiovascular diseases

Multifunctional protein APPL2 contributes to survival of human glioma cells

Some endocytic proteins have recently been shown to play a role in tumorigenesis. In this study, we demonstrate that APPL2, an adapter protein with known endocytic functions, is upregulated in 40% cases of glioblastoma multiforme, the most common and aggressive cancer of the central nervous system. The silencing of APPL2 expression by small interfering RNAs (siRNAs) in glioma cells markedly reduces cell survival under conditions of low growth factor availability and enhances apoptosis (measured by executor caspase activity). Long‐term depletion of APPL2 by short hairpin RNAs (shRNAs), under regular growth factor availability, suppresses the cell transformation abilities, assessed by inhibited colony formation in soft agar and by reduced xenograft tumor growth in vivo. At the molecular level, the negative effect of APPL2 knockdown on cell survival is not due to the alterations in AKT or GSK3β activities which were reported to be modulated by APPL proteins. Instead, we attribute the reduced cell survival upon APPL2 depletion to the changes in gene expression, in particular to the upregulation of apoptosis‐related genes, such as UNC5B (a proapoptotic dependence receptor) and HRK (harakiri, an activator of apoptosis, which antagonizes anti‐apoptotic function of Bcl2). In support of this notion, the loss of glioma cell survival upon APPL2 knockdown can be rescued either by an excess of netrin‐1, the prosurvival ligand of UNC5B or by simultaneous silencing of HRK. Consistently, APPL2 overexpression reduces expression of HRK and caspase activation in cells treated with apoptosis inducers, resulting in the enhancement of cell viability. This prosurvival activity of APPL2 is independent of its endosomal localization. Cumulatively, our data indicate that a high level of APPL2 protein might enhance glioblastoma growth by maintaining low expression level of genes responsible for cell death induction

Versatile Phase Transfer Method for the Efficient Surface Functionalization of Gold Nanoparticles: Towards Controlled Nanoparticle Dispersion in a Polymer Matrix

In electronic devices based on hybrid materials such as nonvolatile memory elements (NVMEs), it is essential to control precisely the dispersion of metallic nanoparticles (NPs) in an insulating polymer matrix such as polystyrene in order to control the functionality of the device. In this work the incorporation of AuNPs in polystyrene films is controlled by tuning the surface functionalization of the metallic nanoparticles via ligand exchange. Two ligands with different structures were used for functionalization: 1-decanethiol and thiol-terminated polystyrene. This paper presents a versatile method for the modification of gold nanoparticles (AuNPs) with thiol-terminated polystyrene ligands via phase transfer process. An organic colloid of AuNPs (5±1 nm diameter) is obtained by the phase transfer process (from water to toluene) that allows exchanging the ligand adsorbed on AuNPs surface (hydrophilic citrate/tannic acid to hydrophobic thiols). The stability, size distribution, and precise location of modified AuNPs in the polymer matrix are obtained from UV-Vis spectroscopy, dynamic light scattering (DLS), and electron tomography. TEM tomographic 3D imaging demonstrates that the modification of AuNPs with thiol-terminated polystyrene results in homogeneous particle distribution in the polystyrene matrix compared to 1-decanethiol modified AuNPs for which a vertical phase separation with a homogeneous layer of AuNPs located at the bottom of the polymer matrix was observed.This work was supported by FP7-NMP-2010-SMALL-4 Program (“Hybrid Organic/Inorganic Memory Elements for Integration of Electronic and Photonic Circuitry,” HYMEC), Project no. 263073. Eric Gonthier is acknowledged for technical support in the preparation of hybrid thin films. Scientific work was supported by the Polish Ministry of Science and Higher Education Funds for Science in 2011–2014 allocated for the cofunded international project

Detection Limits of DLS and UV-Vis Spectroscopy in Characterization of Polydisperse Nanoparticles Colloids

Dynamic light scattering is a method that depends on the interaction of light with particles. This method can be used for measurements of narrow particle size distributions especially in the range of 2–500 nm. Sample polydispersity can distort the results, and we could not see the real populations of particles because big particles presented in the sample can screen smaller ones. Although the theory and mathematical basics of DLS technique are already well known, little has been done to determine its limits experimentally. The size and size distribution of artificially prepared polydisperse silver nanoparticles (NPs) colloids were studied using dynamic light scattering (DLS) and ultraviolet-visible (UV-Vis) spectroscopy. Polydisperse colloids were prepared based on the mixture of chemically synthesized monodisperse colloids well characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), DLS, and UV-Vis spectroscopy. Analysis of the DLS results obtained for polydisperse colloids reveals that several percent of the volume content of bigger NPs could screen completely the presence of smaller ones. The presented results could be extremely important from nanoparticles metrology point of view and should help to understand experimental data especially for the one who works with DLS and/or UV-Vis only

Marinating and Grilling as Methods of Sensory Enhancement of Sous Vide Beef from Holstein-Friesian Bulls

An attempt was made to identify technological solutions that would improve the quality of products from the meat of Holstein-Friesian (HF) bulls, with particular emphasis on standardising the quality of the longissimus lumborum (LL) and semimembranosus (SM) muscles. Marinating (Mar) and grilling (Grill) were used in combination with the sous vide (SV) method. The effects of the type of muscle (LL or SM) and the applied treatments (SV, SVMar, and SVGrill) on the yield, colour, maximum shear force (WBSF), tenderness, juiciness, and aroma intensity of grilled and marinated meat were determined. The applied treatments had a significant influence on the meat yield (p < 0.001), WBSF (p < 0.001), tenderness (p < 0.01), and juiciness (p < 0.05) assessed in sensory evaluation. Additional treatments supported the optimisation of the aroma and taste of LL and SM and reduced the WBSF. The SVMar method optimised the beef’s tenderness, and therefore, it can be recommended for preparing meat from HF bulls for consumption

Application of DFT - Cellular Method to Alkaline Metals: Lithium

A Kuhn-Sham scheme following method of binding energy calculation for alkaline metals is proposed. The main idea of the method consists of introducing the interatomic distance dependent positive crystal field, and determining the charge density and potential term. The obtained results show good agreement between the calculated and experimental binding energies, and relatively large error in the equilibrium interatomic distance calculation