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3. Feminists Reshaping Gender

Author

Crossley, Alison Dahl, Nelson, Laura K., DeLamater, John, Series Editor, Risman, Barbara J., editor, Froyum, Carissa M., editor, and Scarborough, William J., editor

Published
2018
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34. Electroanalysis using macro-, micro-, and nanochemical architectures on electrode surfaces. Bulk surface modification of glassy carbon microspheres with gold nanoparticles and their electrical wiring using carbon nanotubes

Author

Dai, Xuan, Wildgoose, Gregory G., Salter, Chris, Crossley, Alison, and Compton, Richard G.

Subjects
Nanoparticles -- Electric properties, Nanoparticles -- Chemical properties, Nanotechnology -- Research, Gold compounds -- Chemical properties, Gold compounds -- Electric properties, Scanning electron microscopes -- Observations, Voltammetry, Chemistry
Abstract

Gold nanoparticles (~30-60 nm in diameter) were deposited onto the surface of glassy carbon microspheres (10-20 [micro]m) through electroless plating to produce bulk (i.e., gram) quantities of nanoparticle surface-modified microspheres. The gold nanoparticle-modified powder was then characterized by means of scanning electron microscopy and cyclic voltammetry. The voltammetric response of a macroelectrode consisting of a film of gold nanoparticle-modified glassy carbon microspheres, bound together and 'wired-up' using multiwalled carbon nanotubes (MWCNTs), was investigated. We demonstrate that by intelligently exploiting both nano- and microchemical architectures and wiring up the electroactive centers using MWCNTs in this way, we can obtain macroelectrode voltammetric behavior while only using ~1% by mass of the expensive gold material that would be required to construct the equivalent gold film macrodisk electrode. The potential utility of electrodes constructed using chemical architectures such as this was demonstrated by applying them to the analytical determination of arsenic(III) concentration. An optimized limit of detection of 2.5 ppb was obtained.

Published
2006

39. Influence of soil porewater properties on the fate and toxicity of silver nanoparticles to Caenorhabditis elegans

Author

Schultz, Carolin L., Lahive, Elma, Lawlor, Alan, Crossley, Alison, Puntes, Víctor F., Unrine, Jason M., Svendsen, Claus, Spurgeon, David J., Natural Environment Research Council (UK), European Commission, and National Science Foundation (US)

Subjects
Silver, Bioavailability, Dissolved organic matter, Nanotoxicology, Ecology and Environment
Abstract

Engineered nanoparticles (NPs) entering the environment are subject to various transformations that in turn influence how particles are presented to, and taken up by, organisms. To understand the effect of soil properties on the toxicity of nanosilver to Caenorhabditis elegans, toxicity assays were performed in porewater extracts from natural soils with varying organic matter content and pH using 3-8 nm unfunctionalized silver (Ag 3-8Unf), 52-nm polyvinylpyrrolidone (PVP)-coated Ag NPs (Ag 52PVP), and AgNO3 as ionic Ag. Effects on NP agglomeration and stability were investigated using ultraviolet-visible (UV-vis) spectroscopy and asymmetric flow field-flow fractionation (AF4); Ag+ showed greater overall toxicity than nanosilver, with little difference between the NP types. Increasing soil organic matter content significantly decreased the toxicity of Ag 3-8Unf, whereas it increased that of AgNO3 . The toxicity of all Ag treatments significantly decreased with increasing porewater pH. Dissolution of both NPs in the porewater extracts was too low to have contributed to their observed toxic effects. The UV-vis spectroscopy revealed low levels of agglomeration/aggregation independent of soil properties for Ag 3-8Unf, whereas higher organic matter as well as low pH appeared to stabilize Ag 52PVP. Overall, both soil organic matter content and pH affected NP fate as well as toxicity to C. elegans; however, there appears to be no clear connection between the measured particle characteristics and their effect., C.L. Schultz, A. Lawlor, and D.J. Spurgeon received support from the UK Natural Environment Research Council (NERC) Highlight topic on nanomaterials (NE/N006224/1). C.L. Schultz and V. Puntes were supported by the European Union 7th Framework Programme, Marie Curie Actions, Innovative Training Networks Nanotechnology: Training of Experts in Safety (ITN NanoTOES; PITN-GA-2010-264506). E. Lahive was supported by a joint NERC/US Environmental Protection Agency (USEPA) Transatlantic Initiative for Nanotechnology and the Environment (TINE) grant (NE/H013679/1, RD83457401). D.J. Spurgeon and C. Svendsen received support from National Capability funding through the UK NERC-Centre for Ecology & Hydrology (CEH) Pollution and Environmental Risk Theme and the European Union FP7 project GUIDEnano (CP-FP7 604387). J.M. Unrine was supported by the US National Science Foundation (NSF) and the USEPA under NSF Cooperative Agreement EF-0830093 and DBI-1266252, Center for the Environmental Implications of NanoTechnology (CEINT).

Published
2018
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41. Influence of soil porewater properties on the fate and toxicity of silver nanoparticles to Caenorhabditis elegans

Author

Natural Environment Research Council (UK), European Commission, National Science Foundation (US), Schultz, Carolin L., Lahive, Elma, Lawlor, Alan, Crossley, Alison, Puntes, Víctor F., Unrine, Jason M., Svendsen, Claus, Spurgeon, David J., Natural Environment Research Council (UK), European Commission, National Science Foundation (US), Schultz, Carolin L., Lahive, Elma, Lawlor, Alan, Crossley, Alison, Puntes, Víctor F., Unrine, Jason M., Svendsen, Claus, and Spurgeon, David J.

Abstract

Engineered nanoparticles (NPs) entering the environment are subject to various transformations that in turn influence how particles are presented to, and taken up by, organisms. To understand the effect of soil properties on the toxicity of nanosilver to Caenorhabditis elegans, toxicity assays were performed in porewater extracts from natural soils with varying organic matter content and pH using 3-8 nm unfunctionalized silver (Ag 3-8Unf), 52-nm polyvinylpyrrolidone (PVP)-coated Ag NPs (Ag 52PVP), and AgNO3 as ionic Ag. Effects on NP agglomeration and stability were investigated using ultraviolet-visible (UV-vis) spectroscopy and asymmetric flow field-flow fractionation (AF4); Ag+ showed greater overall toxicity than nanosilver, with little difference between the NP types. Increasing soil organic matter content significantly decreased the toxicity of Ag 3-8Unf, whereas it increased that of AgNO3 . The toxicity of all Ag treatments significantly decreased with increasing porewater pH. Dissolution of both NPs in the porewater extracts was too low to have contributed to their observed toxic effects. The UV-vis spectroscopy revealed low levels of agglomeration/aggregation independent of soil properties for Ag 3-8Unf, whereas higher organic matter as well as low pH appeared to stabilize Ag 52PVP. Overall, both soil organic matter content and pH affected NP fate as well as toxicity to C. elegans; however, there appears to be no clear connection between the measured particle characteristics and their effect.

Published
2018

50. Toxic interactions of different silver forms with freshwater green algae and cyanobacteria and their effects on mechanistic endpoints and the production of extracellular polymeric substances

Author

Taylor, Cameron, Matzke, Marianne, Kroll, Alexandra, Read, Daniel S., Svendsen, Claus, Crossley, Alison, Taylor, Cameron, Matzke, Marianne, Kroll, Alexandra, Read, Daniel S., Svendsen, Claus, and Crossley, Alison

Abstract

This study investigated the magnitude and mechanisms of toxicity that ionic silver and two silver nanoparticles (AgNPs) of differing size and stabiliser imparted on two model organisms, green algae (Chlamydomonas reinhardtii) and cyanobacteria (Synechococcus leopoliensis), and their effect on the extracellular polymeric substances (EPS) produced. Major silver losses were detected during the 72 h of exposure compared with introduced nominal concentrations. Cell viability and production of reactive oxygen species (ROS) were investigated to assess mechanisms of toxicity. All silver forms had a significant effect on viability for C. reinhardtii but only ionic silver significantly affected ROS production. For S. leopoliensis, only ionic silver affected viability. Levels of EPS produced by both species were similar between all treatments. Compositional differences were noted for C. reinhardtii with greater levels of lower molecular weight material produced in the presence of all silver forms. The results indicate that ionic silver has the greatest effect on the toxic stress endpoints. Variations between the ionic control and the two AgNP treatments are possibly due to differences in the ionic release dynamics and interactions with EPS produced by microorganisms. S. leopoliensis showing greater reduction in growth rates but lower impact on viability and ROS than C. reinhardtii is likely related to differences in relevant biological properties such as size and cell wall composition.

Published
2016

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