Laura Sigg

Eawag: Das Wasserforschungs-Institut des ETH-Bereichs | Eawag · Department of Environmental Toxicology

Nanoparticles, such as silver (Ag-NP) and zinc oxide (ZnO-NP), are increasingly used in many consumer products. These nanoparticles (NPs) will likely be exposed to the aquatic environment (rain, river, lake water) and to light (visible and UV) in the products where they are applied, or after those products are discharged. Dissolution of Ag-NP and Z...

Aerobic methane-oxidizing bacteria (MOB) substantially reduce methane fluxes from freshwater sediments to the atmosphere. Their metalloenzyme methane monooxygenase (MMO) catalyses the first oxidation step converting methane to methanol. Its most prevalent form is the copper-dependent particulate pMMO, however, some MOB are also able to express the...

Silver nanoparticles (Ag NPs) are widely used in consumer products especially because of their antimicrobial properties. However, this wide usage of Ag NPs is accompanied by their release into the environment where they will be rapidly transformed to other silver species – especially silver sulfide (Ag2S). In the present study, we synthesized Ag NP...

Understanding the ability of fish intestinal cells to act as barrier for nanoparticle (NP) uptake and effects is of significance from an environmental perspective but as well for human health,...

Background Silver nanoparticles (AgNP) are widely applied and can, upon use, be released into the aquatic environment. This raises concerns about potential impacts of AgNP on aquatic organisms. We here present a side by side comparison of the interaction of AgNP with two contrasting cell types: algal cells, using the algae Euglena gracilis as model...

Principles for determining uptake kinetics and bioconcentration factors for nanoparticles and test organisms have only been cursorily explored. Here we report the derivation of bioconcentration factors (BCFs) and the role of surface functionalization in the interactions between the nematode Plectus aquatilis and titanium dioxide nanoparticles (TiO2...

Upon contact with biota, nanoparticles can bind to proteins, which coat the nanoparticles and form a nanoparticle-protein corona. Knowledge of corona proteins is therefore important for a mechanistic understanding of how nanoparticles interact with biomolecules in cells. Here we present the first study to reveal the identity of corona proteins from...

Dieses Buch behandelt die Grundlagen der aquatischen Chemie, der Chemie wässriger Lösungen und ihrer Anwendung auf die natürlichen Gewässer und auf andere aquatische Systeme. Das Lehrbuch "Aquatische Chemie" wurde in der 5. Auflage vollständig neu bearbeitet und erscheint in der 6. Auflage mit einigen Korrekturen und Aenderungen.

While short-term exposures of vertebrate cells, such as from fish, can be performed in defined, serum-free media, long-term cultures generally require addition of growth factors and proteins, normally supplied with a serum supplement. However, proteins are known to alter nanoparticle properties by binding to nanoparticles. Therefore, in order to be...

We introduce a novel in vitro rainbow trout intestinal barrier model and demonstrate its suitability for investigating nanoparticle transport across the intestinal epithelium. Rainbow trout (Oncorhynchus mykiss) intestinal cells (RTgutGC) were grown as monolayers on permeable supports leading to a two-compartment intestinal barrier model consisting...

We investigated the evolutionary response of an ecologically important freshwater crustacean, Daphnia, to a rapidly changing toxin environment. From the 1920s until the 1960s, the use of leaded gasoline caused the aquatic concentration of Pb to increase at least 5-fold, presumably exerting rapid selective pressure on organisms for resistance. We pr...

Toxicity of carbon coated copper nanoparticles (CuNP) to the unicellular green alga Chlamydomonas reinhardtii was investigated and compared with effects of dissolved Cu2+. The CuNP with original size of 6 – 7 nm rapidly agglomerated in the medium to average particle sizes of 140 – 200 nm. Dissolved Cu from CuNP increased over 2 h to 1 – 2 % of tota...

The impact of silver nanoparticles (AgNPs) on aquatic algae has largely been studied with model species that possess a rigid cell wall. Here, we explored the interactions of AgNPs with Euglena gracilis, a green alga having no cell wall but a pellicle. The toxicity and silver uptake upon 1–2 h of exposure to various concentrations of AgNO3 and AgNPs...

Organisms have developed metal regulatory mechanisms in response to changes in the bioavailability of trace metals. Just as metal bioavailability dictates cellular uptake, intracellular metal speciation determines the availability of metals to exert biological effects. However, the missing link in understanding the relationship between metal uptake...

Dissolution of silver nanoparticles (AgNP with carbonate or citrate coating, total Ag 1-5 μM) was examined in the presence of the ligands cysteine, chloride and fulvic acids and of the oxidant hydrogen peroxide (H2O2) at low concentrations at pH 7.5. Dissolved Ag was separated from AgNP by ultrafiltration. Cysteine in the concentration range 0.2-5...

Various factors have been invoked to explain the toxicity of silver nanoparticles (AgNP) to microorganisms including particle size, the nature of stabilizing coatings as well as the amount of dissolved silver occurring in AgNP suspensions. In this study we have assessed the effects of nine differently coated AgNP (chitosan, lactate, polyvinyl pyrro...

The growing use of TiO2 nanoparticles (TiO2 NP) will inevitably result in an increased environmental release of these materials. Depending on the water chemistry, TiO2 NP entering aquatic environments are prone to agglomeration and sedimentation1, which results in increased exposure of biofilms to TiO2 NP.2 Since TiO2 NP are highly photoactive, one...

Chronic Pb exposure microcosm studies were carried out on two different periphyton communities over the course of 3 weeks to link Pb distribution to biological effects in periphyton. We show that three-week exposures of periphyton to 20.6 ± 0.4 μM PbT (330 nM Pb(2+)) did not have observable biological effects on photosynthesis, respiration, extrace...

The dissolution of some widely used nanoparticles (NPs), Ag (citrate coated), ZnO, CuO and Cu-carbon coated (Cu/C), has been studied over a period of 9 days in five different natural waters: wastewater treatment plant effluent (WWTP Du¨bendorf) and lakes Greifen, Lucerne, Grue`re and Cristallina. These waters differ in ionic strength, pH and dissol...

Metals to be considered for water quality parameters are those which may exert toxic effects on aquatic organisms and may be elevated by various sources. However, the speciation of metals is determining their bioavailability, which has so far only in few cases been considered in the definition of water quality criteria. Further development of these...

Nanoecotoxicology strives to understand the processes and mechanisms by which engineered nanoparticles (ENP) may exert toxic effects on aquatic organisms. Detailed knowledge of the chemical reactions of nanoparticles in the media and of their interactions with organisms is required to understand these effects. The processes of agglomeration of nano...

Streams are potential receiving compartments for engineered nanoparticles (NP). In streams, NP may remain dispersed or settle to the benthic compartment. Both dispersed and settling NP can accumulate in benthic biofilms called periphyton that are essential to stream ecosystems. Periphytic organisms excrete extracellular polymeric substances (EPS) t...

This study aims to investigate effects of freshwater components in order to predict agglomeration behavior of silver nanoparticles coated with citrate (AgNP-Cit), polyvinylpyrrolidone (AgNP-PVP), and of TiO2 nanoparticles. Agglomeration studies were conducted in various media based on combinations of ions, natural organic matter (humic, fulvic acid...

When introduced into the aquatic environment, TiO2 NP are likely to settle from the water column, which results in increased exposure of benthic communities. Here, we show that the activity of two extracellular enzymes of intact heterotrophic biofilms, β - glucosidase (carbon - cycling) and L - leucin aminopeptidase (nitrogen - cycling), was reduce...

The intrinsic characteristics of nanom aterials im ply a m ulti-v ariable com plexity , which affects their toxicological potential. In m any aspects, this com plexity is related to their colloidal nature that distinguishes them radically from dissolv ed chem icals— whereas dissolv ed chem icals undergo chem ical speciation, colloids are affected b...

Carbon nanotubes (CNT) are strong sorbents for organic micropollutants, but changing environmental conditions may alter the distribution and bioavailability of the sorbed substances. Therefore, we investigated the effect of green algae (Chlorella vulgaris) on sorption of a model pollutant (diuron, synonyms: 3-(3,4-Dichlorophenyl)-1,1-dimethylurea,...

This supporting information contains 35 pages: 10 figures, 7 tables, and sections containing more details on the synthesis of the CNT, characterization of all materials and suspensions, preparation of the particle suspensions, quantification of diuron by high performance liquid chromatography-tandem mass spectrometry (HPLC-MSMS), quality assurance,...

The dissolution of Ag (citrate, gelatin, polyvinylpyrrolidone and chitosan coated), ZnO, CuO and carbon coated Cu nanoparticles (with two nominal sizes each) has been studied in artificial aqueous media, similar in chemistry to environmental waters, for up to 19 days. The dissolved fraction was determined using DGT (Diffusion Gradients in Thin film...

Cerium oxide nanoparticles (CeO2 NP) are increasingly used in industrial applications and may be released to the aquatic environment. The fate of CeO2 NP and effects on algae are largely unknown. In this study, the short term effects of CeO2 NP in two different agglomeration states on the green algae Chlamydomonas reinhardtii were examined. The rol...

Abstract In aqueous solutions, silver nanoparticle (AgNP) behavior is affected by a variety of factors which lead to altered AgNP size and toxicity. Our research aims to explore the effect of media composition on citrate-coated AgNP (cit-AgNP) behavior and toxicity to the cell line from rainbow trout (Oncorhynchus mykiss) gill, RTgill-W1. Three dif...

La chimie des milieux aquatiques étudie la nature des substances dissoutes et en suspension dans les eaux naturelles et autres systèmes aquatiques, les équilibres chimiques et les processus physico-chimiques dans lesquels ces substances sont impliquées. Cette discipline tient aussi compte des processus biologiques, géochimiques et physiques dans le...

Understanding mechanistic and cellular events underlying a toxicological outcome allows the prediction of impact of environmental stressors to organisms living in different habitats. A systems-based approach aids in characterizing molecular events, and thereby the cellular pathways that have been perturbed. However, mapping only adverse outcomes of...

Owing to their antimicrobial properties, silver nanoparticles (NPs) are the most commonly used engineered nanomaterial for use in a wide array of consumer and medical applications. Many discussions are currently ongoing as to whether or not exposure of silver NPs to the ecosystem (i.e. plants and animals) may be conceived as harmful or not. Metalli...

Carbon nanotubes (CNTs) are often processed in suspended form and therefore a release of CNT-suspensions into the aquatic environment is plausible. In this study, the behaviour of two physico-chemically very different CNT types in the presence of varying, environmentally relevant calcium-containing media was investigated, including the long-term co...

While seasonal variations in fluvial communities have been extensively investigated, effects of seasonality on community responses to environmental and/or chemical stress are poorly documented. The aim of this study was to describe antioxidant enzyme activity (AEA) variability in fluvial biofilms over an annual cycle, under multi-stress scenarios d...

Carbon nanotubes (CNT) are more and more likely to be present in the environment, where they will associate with organic micropollutants due to strong sorption. The toxic effects of these CNT-micropollutant mixtures on aquatic organisms are poorly characterized. Here, we systematically quantified the effects of the herbicide diuron on the photosynt...

A protocol was developed to extract, fractionate, and quantitatively analyze periphyton extracellular polymeric substances (EPS), which obtains both information on the molecular weight (Mr) distribution and protein and polysaccharide content. The EPS were extracted from freshwater periphyton between July and December 2011. Organic carbon (OC) compo...

The intracellular silver accumulation ({Ag}(in)) upon exposure to carbonate coated silver nanoparticles (AgNP, 0.5-10 μM, average diameter 29 nm) and silver nitrate (20-500 nM) was examined in the wild type and in the cell wall free mutant of the green alga Chlamydomonas reinhardtii at pH 7.5. The {Ag}(in) was measured over time up to 1 h after a w...

The role of phytochelatins (PC(n), metal-binding oligopeptides with the general structure (γGlu-Cys)(n)-Gly (n = 2-11) in metal detoxification is assumed to be based on immobilization of metals, which prevents binding of metals to important biomolecules. Although induction of phytochelatin synthesis has often been observed in algae upon exposure to...

To gain important information on fate, mobility, and bioavailability of silver nanoparticles (AgNP) in aquatic systems, the influence of pH, ionic strength, and humic substances on the stability of carbonate-coated AgNP (average diameter 29 nm) was systematically investigated in 10 mM carbonate and 10 mM MOPS buffer, and in filtered natural freshwa...

Accumulation of Pb and induction of phytochelatin synthesis were observed in Chlamydomonas reinhardtii upon Pb(II) exposure. Our aim was to examine whether Pb(II) is bound by phytochelatins (PCs) in C. reinhardtii and to examine formed complexes for their stoichiometry and composition. Metal-phytochelatin (Me-PC) complexes induced by Pb were isolat...

Due to growing production, carbon nanotubes (CNT) may soon be found in a broad range of products and thus in the environment. In this work, an algal growth test was developed to determine effects of pristine and oxidized CNT on the green algae Chlorella vulgaris and Pseudokirchneriella subcapitata. CNT suspensions were prepared in algal test medium...

Phytochelatins (PC) are metal-binding ligands synthesized by algae in response to elevated concentrations of various metals, such as Pb. Kinetics of PC synthesis and Pb accumulation in Chlamydomonas reinhardtii were investigated as a function of [Pb(2+)]=10(-11)-10(-7)M (pPb11-pPb7.1) in the exposure medium for up to 6h. The role of PC in Pb detoxi...

Carbon nanotubes (CNT) are one major building block of nanotechnologies and their environmental and health effects are currently under heavy investigation. There is general consent that a part of the CNT may eventually end up in the aqueous environment. CNT may thus have direct ecotoxicological effects on organisms. Moreover, they are also strong a...

The forecasted augmentation in the manufacture and use of engineered nanomaterials (ENM) makes it likely that increasing human and environmental exposure will occur. Carbon nanotubes (CNT) are one major building block of nanotechnologies and their environmental and health effects are currently under heavy investigation. CNT may have direct ecotoxic...

Due to the growing production, carbon nanotubes (CNTs) may soon be found in a broad range of products and as a result of that in the environment. The toxicity of CNTs to aquatic organisms is still largely unknown because no suitable test methods are available. Results are rarely reproducible due to difficulties in obtaining stable aqueous suspensio...

Carbon nanotubes (CNTs) may have direct ecotoxicological effects when incorporated into organisms. However, they are also strong adsorbents for organic compounds and may thus influence the bioavailability of other pollutants. The fate and the toxic effects of mixtures of CNTs and pollutants on organisms are currently only poorly characterised. To l...

Accumulation of cadmium in periphyton was investigated under field conditions while Cd concentration and speciation were dynamically varying in a small stream during rain events. Speciation in water was determined in situ by diffusion gradient in thin-films (DGT) and by modeling of complexation with fulvic acids. During the rain events, dissolved C...