Thirty Femtograms Detection of Iron in Mammalian Cells

Inorganic nanomaterials and particles with enhanced optical, mechanical or magnetic attributes are currently being developed for a wide range of applications. Safety issues have been formulated however concerning their potential cyto- and genotoxicity. For in vivo and in vitro experimentations, recent developments have heightened the need of simple and facile methods to measure the amount of nanoparticles taken up by cells or tissues. In this work, we present a rapid and highly sensitive method for quantifying the uptake of iron oxide nanoparticles in mammalian cells. Our approach exploits the digestion of incubated cells with concentrated hydrochloric acid reactant and a colorimetric based UV-Visible absorption technique. The technique allows the detection of iron in cells over 4 decades in masses, from 0.03 to 300 picograms per cell. Applied on particles of different surface chemistry and sizes, the protocol demonstrates that the coating is the key parameter in the nanoparticle/cell interactions. The data are corroborated by scanning and transmission electron microscopy and stress the importance of resiliently adsorbed nanoparticles at the plasma membrane.Comment: 18 pages, 6 figure

In vitro toxicity of nanoceria: effect of coating and stability in biofluids

Due to the increasing use of nanometric cerium oxide in applications, concerns about the toxicity of these particles have been raised and have resulted in a large number of investigations. We report here on the interactions between 7 nm anionically charged cerium oxide particles and living mammalian cells. By a modification of the particle coating including low-molecular weight ligands and polymers, two generic behaviors are compared: particles coated with citrate ions that precipitate in biofluids and particles coated with poly(acrylic acid) that are stable and remain nanometric. We find that nanoceria covered with both coating agents are taken up by mouse fibroblasts and localized into membrane-bound compartments. However, flow cytometry and electron microscopy reveal that as a result of their precipitation, citrate-coated particles interact more strongly with cells. At cerium concentration above 1 mM, only citrate-coated nanoceria (and not particles coated with poly(acrylic acid)) display toxicity and moderate genotoxicity. The results demonstrate that the control of the surface chemistry of the particles and its ability to prevent aggregation can affect the toxicity of nanomaterials.Comment: 33 pages 10 figures, accepted at Nanotoxicolog

Situation sanitaire de l’arganeraie de Tindouf (Algérie) : rôle des termites et champignons associés

La situation sanitaire de l’arganeraie de Tindouf (sud-ouest de l’Algérie) a été évaluée dans quatre placettes d’étude installées dans les périmètres de Touaref Bouaam et de Markala. En janvier 2013, plus de 209 sujets ont été examinés. Nos résultats ont montré un dépérissement très marqué de l’arganier dans les placettes de Oued El-Gahouene et de Oued Bouyadhine avec un indice de santé de 2,11. Cette situation critique est le résultat de l’effet conjugué de plusieurs facteurs biotiques et abiotiques, à savoir la sécheresse, la pollution, la dégradation des sols, le surpâturage, les coupes illicites de bois et les insectes ravageurs, particulièrement les termites qui véhiculent des champignons phytopathogènes. Ce dernier facteur a fait l’objet d’un examen particulier au laboratoire avec pour but l’identification des champignons responsables de la dégradation du bois de l’arganier. Ce constat invite à prendre les mesures de gestion qui s’imposent