Leila Samia Smiri

Size-dependent magnetic properties of CoFe2O4 nanoparticles prepared in polyol.

Highly crystalline CoFe(2)O(4) nanoparticles with different diameters ranging from 2.4 to 6.1 nm have been synthesized by forced hydrolysis in polyol. The size can be controlled through adjusting the nominal water/metal molar ratio. X-ray diffraction, transmission electron microscopy, x-ray absorption spectroscopy and (57)Fe Mössbauer spectrometry were employed to investigate the structure and the microstructure of the particles produced. Magnetic measurements performed on these particles show that they are superparamagnetic with a size-dependent blocking temperature. At 5 K, high saturation magnetization (~85 emu g(-1)) approaching that of the bulk was found for the larger particles, whereas a very large coercivity (14.5 kOe) is observed for the 3.5 nm sized particles.

Age modulates Fe3O4 nanoparticles liver toxicity: dose-dependent decrease in mitochondrial respiratory chain complexes activities and coupling in middle-aged as compared to young rats.

We examined the effects of iron oxide nanoparticles (IONPs) on mitochondrial respiratory chain complexes activities and mitochondrial coupling in young (3 months) and middle-aged (18 months) rat liver, organ largely involved in body iron detoxification. Isolated liver mitochondria were extracted using differential centrifugations. Maximal oxidative capacities (V max, complexes I, III, and IV activities), V succ (complexes II, III, and IV activities), and V tmpd, (complex IV activity), together with mitochondrial coupling (V max/V 0) were determined in controls conditions and after exposure to 250, 300, and 350 μg/ml Fe3O4 in young and middle-aged rats. In young liver mitochondria, exposure to IONPs did not alter mitochondrial function. In contrast, IONPs dose-dependently impaired all complexes of the mitochondrial respiratory chain in middle-aged rat liver: V max (from 30 ± 1.6 to 17.9 ± 1.5; P < 0.001), V succ (from 33.9 ± 1.7 to 24.3 ± 1.0; P < 0.01), V tmpd (from 43.0 ± 1.6 to 26.3 ± 2.2 µmol O2/min/g protein; P < 0.001) using Fe3O4 350 µg/ml. Mitochondrial coupling also decreased. Interestingly, 350 μg/ml Fe3O4 in the form of Fe3+ solution did not impair liver mitochondrial function in middle-aged rats. Thus, IONPs showed a specific toxicity in middle-aged rats suggesting caution when using it in old age.

Crystal structure of NaRbB4O5(OH)4·4H2O: comparison with other tetraborate hydrates

The crystal structure and the thermal behavior of a new tetraborate, NaRbB4O5(OH)4·4H2O, are presented. It crystallizes in the monoclinic system, space group P21/c with unit cell dimensions a=8.1138(5) A, b=11.471(1) A, c=12.8233(9) A, β=91.91(4)°, V=1192.8(1) A3; Z=4. The structure was determined from 3474 unique reflections and refined until R=0.045 and Rw=0.12. It is composed of isolated [B4O5(OH)4]2− polyanions separated by free water molecules and Na,Rb cations. A structural relationship is found between NaRbB4O5(OH)4·4H2O and Cs2B4O5(OH)4·3H2O. It is related to the following replacements at caesium sites: Cs(1)+→Na++H2O and Cs(2)+→Rb+. The dehydration of NaRbB4O5(OH)4·4H2O occurs in two close steps. The resulting amorphous phase undergoes a recrystallization to give two successive metastable phases before melting. Upon cooling, a new form of NaRbB4O7 appears.

Investigation of mixed divalent cation phosphates: synthesis and X-ray powder structure determination of CdBa2(P2O7)(HPO4)

Hydrothermal synthesis, characterization by X-ray diffraction, IR absorption, TGA and ab-initio crystal structure determination are reported for a new phosphate CdBa2(P2O7)(HPO4). It crystallizes in a monoclinic cell (space group Im, No. 8, Z=2) with a=11.9022(1) A, b=5.5530(1) A, c=7.3401(1) A, β=90.091(1)°. The X-ray powder diffraction pattern was fitted by the Rietveld method technique with reliability RBragg=0.037. Hydrogen atoms could not be located. The crystal structure of CdBa2(P2O7)(HPO4) is built up from P2O7 diphosphate groups sharing four oxygen atoms with two CdO6 trigonal prisms. Each CdO6 trigonal prism shares one edge with the HPO4 unit. Such an arrangement builds up isolated infinite chains CdP3O11 running along the b axis. Ba2+ ions are inserted between these chains in the (b,c) plane.

Size tuned polyol-made Zn0.9M0.1Fe2O4 (M = Mn, Co, Ni) ferrite nanoparticles as potential heating agents for magnetic hyperthermia: from synthesis control to toxicity survey

Zn-rich substituted Zn0.9M0.1Fe2O4 (M?=?Mn, Co, Ni) ferrite nanoparticles (NPs) of about 5 and 10 nm were produced by the so-called polyol method. They were engineered for hyperthermia therapy based on their magnetic and morphological properties. Indeed, because of their comparatively low Curie temperature and reasonable magnetization, these probes may turn into useful self-regulated heating agents under suitable conditions. For such a purpose, the structure, the microstructure, the magnetic and magnetocalorimetric properties of the produced NPs as well as their in vitro cytotoxicity were investigated. Our results demonstrate that the magnetic properties of these magnetically diluted spinel ferrite particles can be largely modified by just changing their size. They also show that the about 10 nm sized manganese-based ones exhibit the highest heating power under a 700 kHz ac magnetic field and the lowest cytotoxicity on Immortalized human umbilical vascular endothelial cells (HUVEC).

Facile synthesis of highly thermally stable TiO2 photocatalysts

A new and facile method of synthesizing high-temperature stable titanium dioxide (TiO2) nanoparticles (NPs) is presented in this work. This novel approach allows the production of titanium dioxide nanoparticles owing to a modified solvothermal process that makes use of titanium(IV) butoxide as a titanium precursor and Dimethyl Sulfoxide (DMSO) as a solvent. The structure and morphology of the TiO2 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX) and high-resolution transmission electron microscopy (HRTEM). Based on FTIR and TDA/TGA measurements, a proposed mechanism for the formation of TiO2 NPs in DMSO (without adding any other reagents) is discussed in this contribution. Optical absorption measurements showed that the TiO2 nanoparticles exhibited a UV significant absorption peak clearly blue-shifted with respect to that of bulk TiO2. The results showed that monodisperse quasi-spherical TiO2 nanoparticles (with an average size of 11 nm) consisting of a pure anatase phase were formed. The titanium dioxide nanoparticles showed a high photocatalytic performance in the degradation of diuron pesticide (C9H10Cl2N2O) under illumination by UV light. The high crystalline quality, together with the easy synthesis process, makes TiO2 nanoparticles a promising candidate for many applications, such as optoelectronics and water photolysis for hydrogen production.

Facile Synthesis of Cu Doped Au–ZnS Photocatalyst

In this work, we report on the synthesis of of Cu-doped Au–ZnS nanoparticles (Au–Zn1−xCuxS; where x = 0.00, 0.1 and 1%) using a one-pot chemical method that makes use of 1,3-propanediol as a solvent, a reducting agent and a stabilizing layer. The structure and morphology of the as prepared nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray spectrometry (EDX). Optical extinction measurements showed that the Cu-doped Au–ZnS nanoparticles exhibit a localized surface plasmon resonance (SPR) clearly red-shifted with respect to that of bare Au nanoparticles (AuNPs). In addition, it was found that the optical band gaps of Cu-doped ZnS nanocrystals blue-shifted (i.e., the band gap widening) to shorter wavelength compared to pure ZnS nanocrystals. Photocatalytic activities of Cu-doped Au–ZnS nanocomposites were evaluated by the degradation of 4-Nitrophenol under illumination by solar light. Enhanced performances compared either to undoped Au–ZnS nanocomposites were observed. The effect of various parameters was investigated on the photocatalytic activities of Cu-doped Au–ZnS nanocomposites.

Alkyl phosphonic acid-based ligands as tools for converting hydrophobic iron nanoparticles into water soluble iron–iron oxide core–shell nanoparticles

Phosphonic acid derivatives are suitable compounds for controlling the surface properties of materials and nanomaterials. Here, we present for the first time the use of alkyl phosphonic acid ligands to transfer into water zero-valent iron nanoparticles (FeNP) synthesized by an organometallic approach. The transfer takes place with the formation of an oxide layer at the surface of the iron nanoparticles, beneficial for the coordination of the alkyl phosphonic acid ligands. The nanoparticles are highly soluble in water and present a core–shell structure, with a monocrystalline body-centered cubic iron core of ca. 10 nm in size surrounded by a spinel oxide shell of ca. 2 nm thickness. These hydrophilic nanoparticles display excellent structural stability, magnetization still reaching 70% of that of bulk iron, and a transversal relaxivity r2 of 335 mM−1 s−1 which give them high potential for biomedical applications.

Gold Octahedra nanoparticles (Au_ 0.03 and Au_ 0.045 ): Synthesis and impact on marine clams Ruditapes decussatus

The increased use of gold nanoparticles (AuNPs) in several applications has led to a rise in concerns about their potential toxicity to aquatic organisms. In addition, toxicity of nanoparticles to aquatic organisms is related to their physical and chemical properties. In the present study, we synthesize two forms of gold octahedra nanoparticles (Au_0.03 and Au_0.045) in 1.3-propandiol with polyvinyl-pyrrolidone K30 (PVPK30) as capping agent using polyol process. Shape, size and optical properties of the particles could be tuned by changing the molar ratio of PVP K30 to metal salts. The anisotropy in nanoparticles shape shows strong localized surface plasmon resonance (SPR) in the near infrared region of the electromagnetic spectrum. Environmental impact of Oct-AuNPs was determined in the marine bivalve, Ruditapes decussatus exposed to different concentrations of Au_0.03 and Au_0.045. The dynamic light scattering showed the stability and resistance of Au_0.03 and Au_0.045 in the natural seawater. No significant modification in vg-like proteins, MDA level and enzymatic activities were observed in treated clams with Au_0.03 even at high concentration. In contrast, Au_0.045 induced superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST) activities, in a concentration dependent manner indicating defense against oxidative stress. Enhanced lipid peroxidation represented by malondialdehyde content confirmed oxidative stress of Au_0.045 at high concentration. These results highlight the importance of the physical form of nanomaterials on their interactions with marine organisms and provide a useful guideline for future use of Oct-AuNPs. In addition, Vitellogenin is shown not to be an appropriate biomarker for Oct-AuNPs contamination even at high concentration. We further show that Oct-AuNPs exhibit an important antioxidant response without inducing estrogenic disruption.

Investigation of mechanical properties of developed antimicrobial PPsuture/Ag nanocomposite

In order to prevent surgical complications due to microbial infections, we have developed polypropylene suture grafted with silver nanoparticles (PPsuture/Ag nanocomposite) by a simple immersion procedure. Physical and mechanical properties of developed suture are investigated. Suture surface characteristics are examined by scanning electron microscopy (SEM) imaging and atomic force microscopy (AFM). Silver content on suture surface was determined by Inductively coupled plasma atomic emission spectroscopy (ICP-AES). The mechanical properties of developed antibacterial PP suture/Ag were studied. We note that proposed silver coating method has not affected mechanical performances of suture. Antimicrobial performances of PP suture/Ag nanocomposites against S. aureus and E. coli colonies were also investigated.