New Biocompatible β-Phosphorylated Linear Nitrones Targeting Mitochondria: Protective Effect in Apoptotic Cells

The mitochondrion, an essential organelle involved in cellular respiration, energy production, and cell death, is the main cellular source of reactive oxygen species (ROS), including superoxide. Mitochondrial diseases resulting from uncontrolled/excess ROS generation are an emerging public health concern and there is current interest in specific mitochondriotropic probes to get information on in-situ ROS production. As such, nitrones vectorized by the triphenylphosphonium (TPP) cation have recently drawn attention despite reported cytotoxicity. Herein, we describe the synthesis of 13 low-toxic derivatives of N-benzylidene-1-diethoxyphosphoryl-1-methylethylamine N-oxide (PPN) alkyl chain-grafted to a pyridinium, triethylammonium or berberinium lipophilic cation. These nitrones showed in-vitro superoxide quenching activity and EPR/spin-trapping efficiency towards biologically relevant free radicals, including superoxide and hydroxyl radicals. Their mitochondrial penetration was confirmed by ³¹P NMR spectroscopy, and their anti-apoptotic properties were assessed in Schwann cells treated with hydrogen peroxide. Two pyridinium-substituted PPNs were identified as potentially better alternatives to TPP nitrones conjugates for studying mitochondrial oxidative damage.     

Multilayer films ageing under ultraviolet radiations: Complementary study by dielectric spectroscopy

The effect of ultraviolet (UV) irradiation on a multilayer film made of poly(ethylene terephthalate)/Polyamide 6/poly(ethylene terephthalate) was investigated by uniaxial tractions, UV‐visible‐NIR and Fourier transformed infra‐red‐attenuated total reflection spectroscopy, differential scanning calorimetry ( DSC), and dynamic dielectric spectroscopy (DDS). The multilayer was exposed to ultraviolet radiations (filtered at 270 nm) for 7 days, in air. The complexity of the multilayer thermograms recorded by DSC and DDS has required the study of each film constituting the multilayer to assess each the contribution of each one of them. A deterioration in mechanical properties and a decrease in UV transmission for low wavelengths are observed. These evolutions seem to result to the photo‐oxidation of the poly(ethylene terephthalate) film mainly localized at the exposed layer. This layer acts as a UV protection filter for the other layers. However, the DDS analyses show a plasticization effect of the primary mode in the Polyamide 6, which is evidence of photo‐oxidation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Characterization of thermochemical properties of Al nanoparticle and NiO nanowire composites

Thermochemical properties and microstructures of the composite of Al nanoparticles and NiO nanowires were characterized. The nanowires were synthesized using a hydrothermal method and were mixed with these nanoparticles by sonication. Electron microscopic images of these composites showed dispersed NiO nanowires decorated with Al nanoparticles. Thermal analysis suggests the influence of NiO mass ratio was insignificant with regard to the onset temperature of the observed thermite reaction, although energy release values changed dramatically with varying NiO ratios. Reaction products from the fuel-rich composites were found to include elemental Al and Ni, Al₂O₃, and AlNi. The production of the AlNi phase, confirmed by an ab initio molecular dynamics simulation, was associated with the formation of some metallic liquid spheres from the thermite reaction.     

Synthesis and performances of bio-sourced nanostructured carbon membranes elaborated by hydrothermal conversion of beer industry wastes

Hydrothermal carbonization (HTC) process of beer wastes (Almaza Brewery) yields a biochar and homogeneous carbon-based nanoparticles (NPs). The NPs have been used to prepare carbon membrane on commercial alumina support. Water filtration experiments evidenced the quasi-dense behavior of the membrane with no measurable water flux below an applied nitrogen pressure of 6 bar. Gas permeation tests were conducted and gave remarkable results, namely (1) the existence of a limit temperature of utilization of the membrane, which was below 100°C in our experimental conditions, (2) an evolution of the microstructure of the carbon membrane with the operating temperature that yielded to improved performances in gas separation, (3) the temperature-dependent gas permeance should follow a Knudsen diffusion mechanism, and (4) He permeance was increasing with the applied pressure, whereas N₂ and CO₂ permeances remained stable in the same conditions. These results yielded an enhancement of both the He/N₂ and He/CO₂ permselectivities with the applied pressure. These promising results made biomass-sourced HTC-processed carbon membranes encouraging candidates as ultralow-cost and sustainable membranes for gas separation applications.     

Engineering a pharmacologically superior form of leptin for the treatment of obesity

Leptin plays a central role in the homeostasis of body weight through its regulatory effects on appetite and energy expenditure, yet in trials as a therapeutic agent for the treatment of obesity in humans it has been disappointing. The poor clinical efficacy of leptin results from its short circulating half-life, low potency and poor solubility, necessitating large and frequent doses to obtain even modest clinical benefit. Engineered Fc-leptin immunofusins, consisting of the Fc fragment of an immunoglobulin gamma chain followed by leptin, exhibit improved pharmacological properties with very consistent and potent biological activities. Furthermore, in extending the circulating half-life of the protein in vivo from a few minutes for leptin to many hours for Fc-leptin, these proteins have the potential to reduce drastically the dosage and frequency of administration required to obtain clinical benefit. The results of this study show that the engineered leptin immunofusins described here have significantly enhanced pharmacological properties in comparison with the recombinant leptin that was used in clinical trials. As such, they could represent an important step towards a therapeutically superior form of leptin if the disappointing performance of leptin in early clinical trials was due to its poor pharmacological properties rather than any conceptual weakness in the strategy of using leptin for the treatment of obesity and its related disorders.     

The development of a silica nanoparticle-based label-free DNA biosensor

A silica nanoparticle-based DNA biosensor capable of detecting Bacillus anthracis bacteria through the use of unlabelled ss-oligonucleotides has been developed. The biosensor makes use of the optical changes that accompany a nanoparticle-immobilized cationic conjugated polymer (polythiophene) interacting with single-stranded vs. hybridized oligonucleotides, where a fluorescence signal appears only when hybridized DNA is present (i.e. only when the ss-oligonucleotide interacting with the polymer has hybridized with its complement). In order to enhance the sensitivity of the biosensor, two different nanoparticle architectures were developed and used to elucidate how the presence of neighboring fluorophores on the nanoparticle surface affects F?rster-resonant energy transfer (FRET) between the polythiophene/oligonucleotide complex (FRET donor) and the fluorophores (FRET acceptors). We demonstrate that the silica nanoparticle-based FRET platform lowers the limit of detection at least 10-fold in comparison to the polythiophene itself, and allows the detection of ～2 × 10(-12) moles of ss-oligonucleotide in a 100 μL sample with a standard fluorimeter (i.e. has a limit of detection of ～2 nM ssDNA). Such nanoparticle-based biosensor platforms are beneficial because of the robustness and stability inherent to their covalent assembly and they provide a valuable new tool that may allow for the sensitive, label-free detection (the target DNA that produces the fluorescence signal is unlabelled) without the use of polymerase chain reaction.     

Effects of the nature of the doping salt and of the thermal pre-treatment and sintering temperature on Spark Plasma Sintering of transparent alumina

A slurry of α-Al₂O₃ was doped with Mg, Zr and La nitrates or chlorides, in various amounts in the range 150-500 wt ppm and then freeze-dried to produce nanosized doped powder (∼150 nm). The powder was sintered by SPS to yield transparent polycrystalline alpha alumina. The influence of the nature of the doping element and the starting salt, the thermal treatment before sintering and the sintering temperature on the transparency of the ceramics were investigated. The transparency of the ceramics of nanosized Al₂O₃ was shown to depend mainly on the way the powder was prepared, the nature of the doping salt also had an effect. Finally, a high real inline transmittance, reaching 48.1% was achieved after optimization.     

Irreversible changes in protein conformation due to interaction with superparamagnetic iron oxide nanoparticles

The understanding of the interactions between nanomaterials and proteins is of extreme importance in medicine. In a biological fluid, proteins can adsorb and associate with nanoparticles, which can have significant impact on the biological behavior of the proteins and the nanoparticles. We report here on the interactions of iron saturated human transferrin protein with both bare and polyvinyl alcohol coated superparamagnetic iron oxide nanoparticles (SPIONs). The exposure of human transferrin to SPIONs results in the release of iron, which changes the main function of the protein, which is the transport of iron among cells. After removal of the magnetic nanoparticles, the original protein conformation is not recovered, indicating irreversible changes in transferrin conformation: from a compact to an open structure.     

Coating carbon nanotubes with a polystyrene-based polymer protects against pulmonary toxicity

Background  

carbon nanotubes (CNT) can have adverse effects on health. Therefore, minimizing the risk associated with CNT exposure is of crucial importance. The aim of this work was to evaluate if coating multi-walled CNT (MWCNT) with polymers could modify their toxicity, thus representing a useful strategy to decrease adverse health effects of CNT. We used industrially-produced MWCNT uncoated (NT1) or coated (50/50 wt%) with acid-based (NT2) or polystyrene-based (NT3) polymer, and exposed murine macrophages (RAW 264.7 cell line) or Balb/c mice by intratracheal administration. Biological experiments were performed both in vitro and in vivo, examining time- and dose-dependent effects of CNT, in terms of cytotoxicity, expression of genes and proteins related to oxidative stress, inflammation and tissue remodeling, cell and lung tissue morphology (optical and transmission electron microscopy), and bronchoalveolar lavage fluid content analysis.     

Unique hue data for colour appearance models. Part I: Loci of unique hues and hue uniformity

Psychophysical experiments were conducted to assess unique hues on a CRT display for a large sample of colour‐normal observers (n = 185). These data were then used to evaluate the most commonly used colour appearance model, CIECAM02, by transforming the CIEXYZ tristimulus values of the unique hues to the CIECAM02 colour appearance attributes, lightness, chroma and hue angle. We report two findings: (1) the hue angles derived from our unique hue data are inconsistent with the commonly used Natural Color System hues that are incorporated in the CIECAM02 model. We argue that our predicted unique hue angles (derived from our large dataset) provide a more reliable standard for colour management applications when the precise specification of these salient colours is important. (2) We test hue uniformity for CIECAM02 in all four unique hues and show significant disagreements for all hues, except for unique red which seems to be invariant under lightness changes. Our dataset is useful to improve the CIECAM02 model as it provides reliable data for benchmarking. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011