Olivier Spalla

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The production of nanoparticles (NPs) is increasing rapidly for applications in electronics, chemistry, and biology. This interest is due to the very small size of NPs which provides them with many interesting properties such as rapid diffusion, high specific surface areas, reactivity in liquid or gas phase, and a size close to biomacromolecules. In turn,(More)
Little is known about the production of exopolysaccharides (EPS) in cyanobacteria, and there are no genetic and physiological evidences that EPS are involved in cell protection against the frequently encountered environmental stresses caused by salt and metals. We studied four presumptive EPS production genes, sll0923, sll1581, slr1875 and sll5052, in the(More)
Preparing TiO(2) nanoparticle (NP) suspensions displaying well-defined and reproducible dispersion state is a key feature to perform relevant toxicity experiments for environmental, animal, or human concerns. Relying on the evolution of surface charge with pH, and interactions between nanoparticles in their medium, we developed an optimized dispersion(More)
Seine River water was used as a natural environmental medium to quantify the ecotoxicological impact of three types of manufactured titanium dioxide (TiO(2)) nanoparticles toward the model bacterium Escherichia coli. Under ambient light, a significant toxicity starting at 10 ppm of TiO(2) in water was observed. Presence of the anatase polymorph slightly(More)
We have studied the effect of TiO2 nanoparticles (NPs) on the model cyanobacteria Synechocystis PCC6803. We used well-characterized NPs suspensions in artificial and natural (Seine River, France) waters. We report that NPs trigger direct (cell killing) and indirect (cell sedimentation precluding the capture of light, which is crucial to photosynthesis)(More)
Atomic Force Microscopy (AFM) and in situ Small Angle X-ray Scattering (SAXS) were used to investigate the evolution of the aluminogermanate imogolite-like nanotubes concentration and morphology during their synthesis. In particular, in situ SAXS allowed quantifying the transformation of protoimogolite into nanotubes. The size distribution of the final(More)
The remarkable chemical durability of silicate glass makes it suitable for a wide range of applications. The slowdown of the aqueous glass corrosion kinetics that is frequently observed at long time is generally attributed to chemical affinity effects (saturation of the solution with respect to silica). Here, we demonstrate a new mechanism and highlight the(More)
We probe in situ by synchrotron SAXS/WAXS and UV-visible spectroscopy the nucleation and growth of gold nanoparticles. The use of a fast-mixing stopped-flow device enables the assessment of the whole particle formation process with a 200 ms time resolution. The number of particles, their size distribution, and the yield of the reaction is determined in real(More)
Gold nanorods in aqueous solution are generally surrounded by surfactants or capping agents. This is crucial for anisotropic growth during synthesis and for their final stability in solution. When CTAB is used, a bilayer has been evidenced from analytical methods even though no direct morphological characterization of the precise thickness and compactness(More)
The ecotoxicity of nanoparticles (NPs) is a growing area of research with many challenges ahead. To be relevant, laboratory experiments must be performed with well-controlled and environmentally realistic (i.e., low) exposure doses. Moreover, when focusing on the intensively manufactured titanium dioxide (TiO2) NPs, sample preparations and chemical analysis(More)