Nanomaterials A Danger or a Promise?: A Chemical and Biological Perspective

With the increased presence of nanomaterials in commercial products such as cosmetics and sunscreens, fillers in dental fillings, water filtration process, catalysis, photovoltaic cells, bio-detection, a growing public debate is emerging on toxicological and environmental effects of direct and indirect exposure to these materials. Nanomaterials: A Danger or a Promise? forms a balanced overview of the health and environmental issues of nanoscale materials.   By considering both the benefits and risks associated with nanomaterials, Nanomaterials: A Danger or a Promise? compiles a complete and detailed image of the many aspects of the interface between nanomaterials and their real-life application. The full cycle of nanomaterials life will be presented and critically assessed to consider and answer questions such as: ·         How are nanomaterials made? ·         What they are used for? ·         What is their environmental fate? ·         Can we make them better?   Including coverage of relevant aspects about the toxicity of manufactured nanomaterials, nanomaterials life cycle, exposure issues, Nanomaterials: A Danger or a Promise? provides a comprehensive overview of the actual knowledge in these fields but also presents perspectives for the future development of a safer nanoscience. This comprehensive resource is a key reference for students, researcher, manufacturers and industry professionals alike

Design of Magnetic Gelatine/Silica Nanocomposites by Nanoemulsification: Encapsulation versus in Situ Growth of Iron Oxide Colloids

International audienceThe design of magnetic nanoparticles by incorporation of iron oxide colloids within gelatine/silica hybrid nanoparticles has been performed for the first time through a nanoemulsion route using the encapsulation of pre-formed magnetite nanocrystals and the in situ precipitation of ferrous/ferric ions. The first method leads to bi-continuous hybrid nanocomposites containing a limited amount of well-dispersed magnetite colloids. In contrast, the second approach allows the formation of gelatine-silica core-shell nanostructures incorporating larger amounts of agglomerated iron oxide colloids. Both magnetic nanocomposites exhibit similar superparamagnetic behaviors. Whereas nanocomposites obtained via an in situ approach show a strong tendency to aggregate in solution, the OPEN ACCESS Nanomaterials 2014, 4 613 encapsulation route allows further surface modification of the magnetic nanocomposites, leading to quaternary gold/iron oxide/silica/gelatine nanoparticles. Hence, such a first-time rational combination of nano-emulsion, nanocrystallization and sol-gel chemistry allows the elaboration of multi-component functional nanomaterials. This constitutes a step forward in the design of more complex bio-nanoplatforms

Niobia-Supported Palladium-Manganese Materials: Synthesis and Structural Investigation

International audiencePd/niobia, Mn/niobia, and bimetallic Pd-Mn/niobia materials, which are catalysts for the total oxidation of ethanal,were prepared by anchoring molecular precursors, Pd(acac)2and/or Mn(acac)2, on niobia before calcination at 400 °C and reduction by either soft chemical routes in liquid medium (Pd-based samples) or at 600 °C in H2 (Mn/niobia sample). The structure of the obtained materials was investigated by FTIR spectroscopy of adsorbed CO, transmission electron microscopy, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure-X-ray absorption near edge spectroscopy. On Mn/niobia, Mn2+ is largely predominant, in spite of the high reduction temperature used for this sample, and it is mainly engaged in manganese niobate MnNb2O6. On Pd/niobia, nanoparticles of palladium metal (mean particle size 2.7 nm) are predominant, with a contribution of Pd2+. The surface structure of Pd-Mn/niobia is rather complex. Palladium is distributed between Pd3Mn nanoparticles and palladium clusters, and both are partially covered by oxygen atoms, whereas Mn2+ ions are engaged in MnO clusters linked to niobia

Ecotoxicological Studies of ZnO and CdS Nanoparticles on Chlorella vulgaris Photosynthetic Microorganism in Seine River Water

International audienceSeine river water was used as natural environmental medium to study the ecotoxicological impact of ZnO and CdS nanoparticles and Zn 2+ and Cd 2+ free ions using Chlorella vulgaris as a biological target. It was demonstrated by viability tests and photosynthetic activity measurements that free Zn 2+ (IC 50 = 2.7 × 10 −4 M) is less toxic than free Cd 2+ and ZnO nanoparticles (IC 50 = 1.4 × 10 −4 M). In the case of cadmium species, free Cd 2+ (IC 50 = 3.5 × 10 −5 M) was similar to CdS nanoparticles (CdS-1: IC 50 = 1.9 × 10 −5 M and CdS-2: IC 50 = 1.9 × 10 −5 M), as follows: CdS > Cd 2+ > ZnO > Zn 2+. Adenosine-5'-triphosphate (ATP) assay and superoxide dismutase (SOD) enzymatic activity confirmed these results. Transmission electron microscopy (TEM), coupled with energy-dispersive X-ray spectroscopy (EDS), confirmed the internalization of CdS-1 nanoparticles after 48 h of contact with Chlorella vulgaris at 10 −3 M. With a higher concentration of nanoparticles (10 −2 M), ZnO and CdS-2 were also localized inside cells

Design of Iron Oxide/Silica/Alginate HYbrid MAgnetic Carriers (HYMAC)

A large number of natural and synthetic polymers have already been evaluated for the design of nanomaterials incorporating magnetic nanoparticles for biomedical applications. The possibility to use hybrid (bio)-organic/inorganic nano-carriers have been much less studied. Here we describe the design of Hybrid MAgnetic Carriers (HYMAC) consisting of alginate/silica nanocomposites incorporating magnetite nanoparticles, based on a spray-drying approach. Transmission electron microscopy and X-ray energy dispersive spectrometry confirm the successful incorporation of magnetic colloids within homogeneous hybrid capsules. X-ray diffraction data suggest that surface iron ions are partially desorbed by the spray-drying process, leading to the formation of lepidocrocite and of an iron silicate phase. Magnetic measurements show that the resulting nanocomposites exhibit a superparamagnetic behaviour with a blocking temperature close to 225 K. Comparison with un-silicified capsules indicate that the mineral phase enhances the thermal stability of the polymer network and do not modify of the amount of incorporated iron oxide nanoparticles. Moreover, evaluation of nanocomposite up-take by fibroblasts indicates their possible internalization. A selective intracellular alginate degradation is observed, suggesting that these HYMAC nanomaterials may exhibit interesting properties for the design of drug delivery devices

Two-dimensional determination of dissolved iron and sulfur species in marine sediment pore-waters by thin-film based imaging. Thau lagoon (France)

International audienceA device composed of a polyacrylamide gel thin-film (18 cm high, 5 cm wide and 0.4 mm thick) and a PVC (polyvinyl chloride) film was used as a sediment probe to obtain iron and S(−II) sulfur dissolved species' distributions in sediment pore waters. A porous protective membrane was set on top of hydrogel layer. Probes were deployed in May 2003 for 24–48 h in the superficial sediment of Thau lagoon (France), in a shellfish farming area. The polyacrylamide gel layer was used as a DET (Diffusive Equilibration in Thin-films) device for 2D Fe(II) concentration determination, and as the diffusive layer of a DGT-like (Diffusive Gradients in Thin-films) device for sulfur species study. The accumulation layer of the DGT device consisted in a PVC film layer underneath the polyacrylamide layer. Iron determinations were performed by colorimetric methods with Ferrozine and imaging technique. Image acquisitions were performed with a flatbed scanner. Fe(II) concentrations were deducted from densitometry analysis of the magenta zones (ImageJ software). The calibration curve was obtained by densitometry analysis of polyacrylamide gel pieces which were equilibrated in known iron (II) concentration solutions. ΣFe distribution was performed but not quantified. Analysis of gray zones on the PVC layer provided a qualitative distribution of unidentified S(−II) dissolved compounds, related to H2S zone for which information is obtained by classical methods (peeper and colorimetric measurements). EDX (X-ray energy dispersive spectrometry) and GIXR (Grazing-Incidence X-ray Diffraction) analyses of gray zone of this PVC layer provide evidence for FeS2 catalyzed precipitation onto this film. Dissolved Fe(II) was mainly located near the sediment–water interface (SWI), showing a nonhomogeneous layer about 10 mm thick. Small Fe rich domains appeared deeper in the sediment and likely confirm newest paradigms in the field of sediment biogeochemistry. S(−II) species are detected from 3 to 4 cm below the SWI, with a heterogeneous spatial distribution showing a burrow-like structure

Toxicological Impact Studies Based on Escherichia coli Bacteria in Ultrafine ZnO Nanoparticles Colloidal Medium

International audienceWe report here preliminary studies of blocidal effects and cellular internalization of ZnO nanoparticles on Escherichia coli bacteria. ZnO nanoparticles were synthesized in di(ethylene glycol) (DEG) medium by forced hydrolysis of ionic Zn2+ salts. particle size and shape were controlled by addition of small molecules and macromolecules such as tri-n-octylphosphine oxide, sodium dodecyl sulfate, polyoxyethylene stearyl ether, and bovine serum albumin. Transmission electron microscopy (TEM) and X-ray diffraction analyses were used to characterize particle structure, size, and morphology. Bactericidal tests were performed in Luria-Bertani medium on solid agar plates and in liquid systems with different concentrations of small and macromolecules and also with ZnO nanoparticles. TEM analyses of bacteria thin sections were used to study biocidal action of ZnO materials. The results confirmed that E. coli cells after contact with DEG and ZnO were damaged showing a Gram-negative triple membrane disorganization. This behavior causes the increase of membrane permeability leading to accumulation of ZnO nanoparticles in the bacterial membrane and also cellular internalization of these nanoparticles