The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform

F. Fièvet - One of the best experts on this subject based on the ideXlab platform.

  • Design of ZnO nanostructured films: Characterization and ecotoxicological studies
    Thin Solid Films, 2011
    Co-Authors: Roberta Brayner, Claude Yéprémian, Alain Coute, Clémence Sicard, Hanen Ben Sassi, Zyed Beji, F. Fièvet
    Abstract:

    Abstract The potential ecotoxicological impact of ZnO nanostructured films was investigated using common Anabaena flos-aquae , Calothrix pulvinata cyanobacteria and Euglena gracilis euglenoid microalgae. The pre-formed ZnO nanoparticles were synthesized in di(ethylene glycol) medium by forced hydrolysis of ionic Zn 2+ salts. Particle size and shape were controlled by addition of protective agents such as tri- n -octylphosphine oxide and Polyoxyethylene Stearyl Ether. ZnO nanostructured films were directly prepared by spray deposition of pre-formed polyol-based ZnO nanoparticles (ZnO, ZnO-TOPO and ZnO-Brij-76) at 250 °C heated glass substrate. Another sample was prepared from zinc acetate in di(ethylene glycol) diluted in ethanol medium without nanoparticles (ZnO-SOL). In this case, ZnO nanostructured film was formed directly on the glass substrate at the same temperature. Water contact angle on ZnO-based films showed that nanostructured ZnO films containing ZnO nanoparticles prepared without protective agent or with tri- n -octylphosphine oxide present a hydrophobic character while the ones containing nanoparticles prepared using Polyoxyethylene Stearyl Ether or the control sample are hydrophilic. Here we showed that (i) the use of protective agents, (ii) the surface properties of the films and (iii) the nature of the biological system can strongly influence the ecotoxicological studies. Epifluorescence microscopy analyses and Live/Dead tests showed that all films are toxic for Euglena gracilis . In the case of Anabaena flos-aquae and Calothrix pulvinata , tri- n -octylphosphine oxide and Polyoxyethylene Stearyl Ether molecules can prevent ZnO nanoparticle toxicity.

  • ZnO Nanoparticles: Synthesis, Characterization, and Ecotoxicological Studies
    Langmuir, 2010
    Co-Authors: Roberta Brayner, Si Amar Dahoumane, Claude Yéprémian, Chakib Djediat, Alain Coute, Michael Meyer, F. Fièvet
    Abstract:

    The potential ecotoxicity of nanosized zinc oxide (ZnO), synthesized by the polyol process, was investigated using common Anabaena flos-aquae cyanobacteria and Euglena gracilis euglenoid microalgae. The photosynthetic activities of these microorganisms, after addition of ZnO nanoparticles, varied with the presence of protective agents such as tri-n-octylphosphine oxide (TOPO) and Polyoxyethylene Stearyl Ether (Brij-76) used to control particle size and shape during the synthesis. In the case of Anabaena flos-aquae, the photosynthetic activity, after addition of ZnO, ZnO-TOPO, and ZnO-Brij-76, decreased progressively due to stress induced by the presence of the nanoparticles in the culture medium. After contact with ZnO-TOPO nanoparticles, this decrease was followed by cell death. On the other hand, after 10 days, a progressive increase of the photosynthetic activity was observed after contact with ZnO and ZnO-Brij-76 nanoparticles. In the case of Euglena gracilis, cell death was observed after contact wit...

  • ZnO nanoparticles: Synthesis, characterization, and ecotoxicological studies
    Langmuir, 2010
    Co-Authors: Roberta Brayner, Si Amar Dahoumane, Claude Yéprémian, Chakib Djediat, Alain Coute, Michael Meyer, F. Fièvet
    Abstract:

    The potential ecotoxicity of nanosized zinc oxide (ZnO), synthesized by the polyol process, was investigated using common Anabaena flos-aquae cyanobacteria and Euglena gracilis euglenoid microalgae. The photosynthetic activities of these microorganisms, after addition of ZnO nanoparticles, varied with the presence of protective agents such as tri-n-octylphosphine oxide (TOPO) and Polyoxyethylene Stearyl Ether (Brij-76) used to control particle size and shape during the synthesis. In the case of Anabaena flos-aquae , the photosynthetic activity, after addition of ZnO, ZnO-TOPO, and ZnO-Brij-76, decreased progressively due to stress induced by the presence of the nanoparticles in the culture medium. After contact with ZnO-TOPO nanoparticles, this decrease was followed by cell death. On the other hand, after 10 days, a progressive increase of the photosynthetic activity was observed after contact with ZnO and ZnO-Brij-76 nanoparticles. In the case of Euglena gracilis , cell death was observed after contact with all nanoparticles. Transmission electron microscopy (TEM) analyses of ultrathin sections of microorganisms showed that polysaccharides produced by Anabaena flos-aquae avoid particle internalization after contact with ZnO and ZnO-Brij-76 nanoparticles. On the other hand, nanoparticle internalization was observed after contact with all nanoparticles in the presence of Euglena gracilis and also with ZnO-TOPO nanoparticles after contact with Anabaena flos-aquae .

  • Toxicological Impact Studies Based on Escherichia coli Bacteria in Ultrafine ZnO Nanoparticles Colloidal Medium
    Nano Letters, 2006
    Co-Authors: Roberta Brayner, Roselyne Ferrari-iliou, Nicolas Brivois, Shakib Djediat, Marc F. Benedetti, F. Fièvet
    Abstract:

    We report here preliminary studies of biocidal 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. T...

Hsiao Ming Chang - One of the best experts on this subject based on the ideXlab platform.

  • Oxyethylene chain length affects the physicochemical properties of sugar-based anionic surfactants with phosphates groups
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015
    Co-Authors: Li Huei Lin, Yu Ching Lai, Keng-ming Chen, Hsiao Ming Chang
    Abstract:

    In this study we prepared a series of novel sugar based anionic-Polyoxyethylene Stearyl Ether surfactants through reactions of propylene glycol dextrin with oxirane-containing Polyoxyethylene Stearyl Ethers and phosphorus oxychloride. These surfactants, which contain Polyoxyethylene chains and sodium phosphonate groups as hydrophilic moieties, exhibited surface activities superior to those of traditional surfactants containing only one nonpolar or hydrophobic moiety and one polar head unit. The critical micelle concentration (cmc), surface excess concentration at the surface (Γcmc) and standard free energy of micellization per mole (δGm°) of these surfactants decreased upon increasing the length of their Polyoxyethylene chain. In addition, we used UV-vis spectroscopy to study the interactions of dyes with these sugar based anionic surfactants in solution, the results shows that the interaction of the dye and surfactant molecules and the type of dye-surfactant aggregate formed will depend upon chemical structure of dye and surfactant.

Roberta Brayner - One of the best experts on this subject based on the ideXlab platform.

  • Design of ZnO nanostructured films: Characterization and ecotoxicological studies
    Thin Solid Films, 2011
    Co-Authors: Roberta Brayner, Claude Yéprémian, Alain Coute, Clémence Sicard, Hanen Ben Sassi, Zyed Beji, F. Fièvet
    Abstract:

    Abstract The potential ecotoxicological impact of ZnO nanostructured films was investigated using common Anabaena flos-aquae , Calothrix pulvinata cyanobacteria and Euglena gracilis euglenoid microalgae. The pre-formed ZnO nanoparticles were synthesized in di(ethylene glycol) medium by forced hydrolysis of ionic Zn 2+ salts. Particle size and shape were controlled by addition of protective agents such as tri- n -octylphosphine oxide and Polyoxyethylene Stearyl Ether. ZnO nanostructured films were directly prepared by spray deposition of pre-formed polyol-based ZnO nanoparticles (ZnO, ZnO-TOPO and ZnO-Brij-76) at 250 °C heated glass substrate. Another sample was prepared from zinc acetate in di(ethylene glycol) diluted in ethanol medium without nanoparticles (ZnO-SOL). In this case, ZnO nanostructured film was formed directly on the glass substrate at the same temperature. Water contact angle on ZnO-based films showed that nanostructured ZnO films containing ZnO nanoparticles prepared without protective agent or with tri- n -octylphosphine oxide present a hydrophobic character while the ones containing nanoparticles prepared using Polyoxyethylene Stearyl Ether or the control sample are hydrophilic. Here we showed that (i) the use of protective agents, (ii) the surface properties of the films and (iii) the nature of the biological system can strongly influence the ecotoxicological studies. Epifluorescence microscopy analyses and Live/Dead tests showed that all films are toxic for Euglena gracilis . In the case of Anabaena flos-aquae and Calothrix pulvinata , tri- n -octylphosphine oxide and Polyoxyethylene Stearyl Ether molecules can prevent ZnO nanoparticle toxicity.

  • ZnO Nanoparticles: Synthesis, Characterization, and Ecotoxicological Studies
    Langmuir, 2010
    Co-Authors: Roberta Brayner, Si Amar Dahoumane, Claude Yéprémian, Chakib Djediat, Alain Coute, Michael Meyer, F. Fièvet
    Abstract:

    The potential ecotoxicity of nanosized zinc oxide (ZnO), synthesized by the polyol process, was investigated using common Anabaena flos-aquae cyanobacteria and Euglena gracilis euglenoid microalgae. The photosynthetic activities of these microorganisms, after addition of ZnO nanoparticles, varied with the presence of protective agents such as tri-n-octylphosphine oxide (TOPO) and Polyoxyethylene Stearyl Ether (Brij-76) used to control particle size and shape during the synthesis. In the case of Anabaena flos-aquae, the photosynthetic activity, after addition of ZnO, ZnO-TOPO, and ZnO-Brij-76, decreased progressively due to stress induced by the presence of the nanoparticles in the culture medium. After contact with ZnO-TOPO nanoparticles, this decrease was followed by cell death. On the other hand, after 10 days, a progressive increase of the photosynthetic activity was observed after contact with ZnO and ZnO-Brij-76 nanoparticles. In the case of Euglena gracilis, cell death was observed after contact wit...

  • ZnO nanoparticles: Synthesis, characterization, and ecotoxicological studies
    Langmuir, 2010
    Co-Authors: Roberta Brayner, Si Amar Dahoumane, Claude Yéprémian, Chakib Djediat, Alain Coute, Michael Meyer, F. Fièvet
    Abstract:

    The potential ecotoxicity of nanosized zinc oxide (ZnO), synthesized by the polyol process, was investigated using common Anabaena flos-aquae cyanobacteria and Euglena gracilis euglenoid microalgae. The photosynthetic activities of these microorganisms, after addition of ZnO nanoparticles, varied with the presence of protective agents such as tri-n-octylphosphine oxide (TOPO) and Polyoxyethylene Stearyl Ether (Brij-76) used to control particle size and shape during the synthesis. In the case of Anabaena flos-aquae , the photosynthetic activity, after addition of ZnO, ZnO-TOPO, and ZnO-Brij-76, decreased progressively due to stress induced by the presence of the nanoparticles in the culture medium. After contact with ZnO-TOPO nanoparticles, this decrease was followed by cell death. On the other hand, after 10 days, a progressive increase of the photosynthetic activity was observed after contact with ZnO and ZnO-Brij-76 nanoparticles. In the case of Euglena gracilis , cell death was observed after contact with all nanoparticles. Transmission electron microscopy (TEM) analyses of ultrathin sections of microorganisms showed that polysaccharides produced by Anabaena flos-aquae avoid particle internalization after contact with ZnO and ZnO-Brij-76 nanoparticles. On the other hand, nanoparticle internalization was observed after contact with all nanoparticles in the presence of Euglena gracilis and also with ZnO-TOPO nanoparticles after contact with Anabaena flos-aquae .

  • Toxicological Impact Studies Based on Escherichia coli Bacteria in Ultrafine ZnO Nanoparticles Colloidal Medium
    Nano Letters, 2006
    Co-Authors: Roberta Brayner, Roselyne Ferrari-iliou, Nicolas Brivois, Shakib Djediat, Marc F. Benedetti, F. Fièvet
    Abstract:

    We report here preliminary studies of biocidal 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. T...

Li Huei Lin - One of the best experts on this subject based on the ideXlab platform.

  • Oxyethylene chain length affects the physicochemical properties of sugar-based anionic surfactants with phosphates groups
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015
    Co-Authors: Li Huei Lin, Yu Ching Lai, Keng-ming Chen, Hsiao Ming Chang
    Abstract:

    In this study we prepared a series of novel sugar based anionic-Polyoxyethylene Stearyl Ether surfactants through reactions of propylene glycol dextrin with oxirane-containing Polyoxyethylene Stearyl Ethers and phosphorus oxychloride. These surfactants, which contain Polyoxyethylene chains and sodium phosphonate groups as hydrophilic moieties, exhibited surface activities superior to those of traditional surfactants containing only one nonpolar or hydrophobic moiety and one polar head unit. The critical micelle concentration (cmc), surface excess concentration at the surface (Γcmc) and standard free energy of micellization per mole (δGm°) of these surfactants decreased upon increasing the length of their Polyoxyethylene chain. In addition, we used UV-vis spectroscopy to study the interactions of dyes with these sugar based anionic surfactants in solution, the results shows that the interaction of the dye and surfactant molecules and the type of dye-surfactant aggregate formed will depend upon chemical structure of dye and surfactant.

Keng-ming Chen - One of the best experts on this subject based on the ideXlab platform.

  • Oxyethylene chain length affects the physicochemical properties of sugar-based anionic surfactants with phosphates groups
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015
    Co-Authors: Li Huei Lin, Yu Ching Lai, Keng-ming Chen, Hsiao Ming Chang
    Abstract:

    In this study we prepared a series of novel sugar based anionic-Polyoxyethylene Stearyl Ether surfactants through reactions of propylene glycol dextrin with oxirane-containing Polyoxyethylene Stearyl Ethers and phosphorus oxychloride. These surfactants, which contain Polyoxyethylene chains and sodium phosphonate groups as hydrophilic moieties, exhibited surface activities superior to those of traditional surfactants containing only one nonpolar or hydrophobic moiety and one polar head unit. The critical micelle concentration (cmc), surface excess concentration at the surface (Γcmc) and standard free energy of micellization per mole (δGm°) of these surfactants decreased upon increasing the length of their Polyoxyethylene chain. In addition, we used UV-vis spectroscopy to study the interactions of dyes with these sugar based anionic surfactants in solution, the results shows that the interaction of the dye and surfactant molecules and the type of dye-surfactant aggregate formed will depend upon chemical structure of dye and surfactant.

  • Oxypropylene chain length affects the physicochemical properties of ortho ester-based gemini surfactants
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013
    Co-Authors: Yu-wun Ye, Keng-ming Chen
    Abstract:

    Abstract In this study, we synthesized ortho ester-based surfactants, with oxypropylene chain lengths from 1 to 3000, from a short-chain ortho ester, propylene glycol, and Polyoxyethylene Stearyl Ether. We subsequently reacted these ortho ester surfactants with propylene glycol as a spacer to yield gemini surfactants. We characterized the surface activities of each of these gemini surfactants in terms of its critical micelle concentration (CMC), surface excess concentration (ΓCMC), surface area demand per molecule (ACMC), surface tension at the CMC (γCMC), and standard free energy of micellization per mole of monomer unit (ΔGm). Increasing the oxypropylene chain length had a significant influence on the surface activity. Overall, these ortho ester-based gemini surfactants possess excellent surface properties, providing low contact angles and emulsion stability.