| 1. |
- Fang, Zhao, 1986, et al.
(författare)
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TiO2 nanoparticle interactions with supported lipid membranes – an example of removal of membrane patches
- 2016
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Ingår i: RSC Advances. - 2046-2069. ; 6:94, s. 91102-91110
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for different levels of model systems for effect studies of engineered nanoparticles and the development of nanoparticle structure–activity relationships in biological systems. Descriptors for nanoparticles based on their interactions in molecular model systems may become useful to predict toxicological responses of the nanoparticles in cells. Towards this end, we report on nanoparticle-induced formation of holes in supported model membranes. Specifically, TiO2 nanoparticle – lipid membrane interactions were studied under low ionic strength, basic conditions (pH 8), using different membrane compositions and several surface-sensitive analytical techniques. It was found that for mixed POPC/POPG (PG fractions ≥ 35%) membranes on silica supports, under conditions where electrostatic repulsion was expected, the addition of TiO2 nanoparticles resulted in transient interaction curves, consistent with the removal of part of the lipid membrane. The formation of holes was inferred from quartz crystal microbalance with dissipation (QCM-D) monitoring, as well as from optical measurements by reflectometry, and also verified by atomic force microscopy (AFM) imaging. The interaction between the TiO2 nanoparticles and the PG-containing membranes was dependent on the presence of Ca2+ ions. A mechanism is suggested where TiO2 nanoparticles act as scavengers of Ca2+ ions associated with the supported membrane, leading to weakening of the interaction between the membrane and the support and subsequent removal of lipid mass as TiO2 nanoparticles spontaneously leave the surface. This mechanism is consistent with the observed formation of holes in the supported lipid membranes.
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| 2. |
- Hartmann, Nanna B., et al.
(författare)
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Are We Speaking the Same Language? Recommendations for a Definition and Categorization Framework for Plastic Debris
- 2019
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:3, s. 1039-1047
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Tidskriftsartikel (refereegranskat)abstract
- Copyright © 2019 American Chemical Society. The accumulation of plastic litter in natural environments is a global issue. Concerns over potential negative impacts on the economy, wildlife, and human health provide strong incentives for improving the sustainable use of plastics. Despite the many voices raised on the issue, we lack a consensus on how to define and categorize plastic debris. This is evident for microplastics, where inconsistent size classes are used and where the materials to be included are under debate. While this is inherent in an emerging research field, an ambiguous terminology results in confusion and miscommunication that may compromise progress in research and mitigation measures. Therefore, we need to be explicit on what exactly we consider plastic debris. Thus, we critically discuss the advantages and disadvantages of a unified terminology, propose a definition and categorization framework, and highlight areas of uncertainty. Going beyond size classes, our framework includes physicochemical properties (polymer composition, solid state, solubility) as defining criteria and size, shape, color, and origin as classifiers for categorization. Acknowledging the rapid evolution of our knowledge on plastic pollution, our framework will promote consensus building within the scientific and regulatory community based on a solid scientific foundation.
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| 3. |
- Zhao, Fang, et al.
(författare)
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TiO2 nanoparticle interactions with supported lipid membranes – an example of removal of membrane patches
- 2016
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:94, s. 91102-91110
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for different levels of model systems for effect studies of engineered nanoparticles and the development of nanoparticle structure–activity relationships in biological systems. Descriptors for nanoparticles based on their interactions in molecular model systems may become useful to predict toxicological responses of the nanoparticles in cells. Towards this end, we report on nanoparticle-induced formation of holes in supported model membranes. Specifically, TiO2 nanoparticle – lipid membrane interactions were studied under low ionic strength, basic conditions (pH 8), using different membrane compositions and several surface-sensitive analytical techniques. It was found that for mixed POPC/POPG (PG fractions ≥ 35%) membranes on silica supports, under conditions where electrostatic repulsion was expected, the addition of TiO2 nanoparticles resulted in transient interaction curves, consistent with the removal of part of the lipid membrane. The formation of holes was inferred from quartz crystal microbalance with dissipation (QCM-D) monitoring, as well as from optical measurements by reflectometry, and also verified by atomic force microscopy (AFM) imaging. The interaction between the TiO2 nanoparticles and the PG-containing membranes was dependent on the presence of Ca2+ ions. A mechanism is suggested where TiO2 nanoparticles act as scavengers of Ca2+ ions associated with the supported membrane, leading to weakening of the interaction between the membrane and the support and subsequent removal of lipid mass as TiO2 nanoparticles spontaneously leave the surface. This mechanism is consistent with the observed formation of holes in the supported lipid membranes.
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| 4. |
- Callegaro, S., et al.
(författare)
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Effects of alginate on stability and ecotoxicity of nano-TiO2 in artificial seawater LLER CL, 1993, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTSSYMP ON
- 2015
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513. ; 117, s. 107-114
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Tidskriftsartikel (refereegranskat)abstract
- The large-scale use of titanium dioxide nanoparticles (nano-TiO2) in consumer and industrial applications raised environmental health and safety concerns. Potentially impacted ecosystems include estuarine and coastal organisms. Results from ecotoxicological studies with nano-TiO2 dispersed in salt exposure media are difficult to interpret due to fast flocculation and sedimentation phenomena affecting the dispersion stability. The goal of this study was to investigate the stabilisation effect of alginate on uncoated nano-TiO2 in artificial seawater dispersions used in ecotoxicity bioassays. The most effective stabilisation was obtained at alginate concentration of 0.45 g/L after sonicating dispersions for 20 min (100 W). The size distribution remained constant after re-suspension, indicating that no agglomeration occurred after deposition. Ecotoxicity tests on Anemia franciscana and Phaeodactylum tricornutum did not show any adverse effects related to the presence of alginate in the exposure media, and provided evidence on possible reduced bioavailability of nano-TiO2. The suitable concentration of alginate is recommended to occur on a case-by-case basis. (C) 2015 Elsevier Inc. All rights reserved.
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| 5. |
- Danielsson, Karin, et al.
(författare)
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Influence of organic molecules on the aggregation of TiO2 nanoparticles in acidic conditions
- 2017
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Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- © 2017, The Author(s).Engineered nanoparticles released into the environment may interact with natural organic matter (NOM). Surface complexation affects the surface potential, which in turn may lead to aggregation of the particles. Aggregation of synthetic TiO2 (anatase) nanoparticles in aqueous suspension was investigated at pH 2.8 as a function of time in the presence of various organic molecules and Suwannee River fulvic acid (SRFA), using dynamic light scattering (DLS) and high-resolution transmission electron microscopy (TEM). Results showed that the average hydrodynamic diameter and ζ-potential were dependent on both concentration and molecular structure of the organic molecule. Results were also compared with those of quantitative batch adsorption experiments. Further, a time study of the aggregation of TiO2 nanoparticles in the presence of 2,3-dihydroxybenzoic acid (2,3-DHBA) and SRFA, respectively, was performed in order to observe changes in ζ-potential and particle size over a time period of 9months. In the 2,3-DHBA-TiO2 system, ζ-potentials decreased with time resulting in charge neutralization and/or inversion depending on ligand concentration. Aggregate sizes increased initially to the micrometer size range, followed by disaggregation after several months. No or very little interaction between SRFA and TiO2 occurred at the lowest concentrations tested. However, at the higher concentrations of SRFA, there was an increase in both aggregate size and the amount of SRFA adsorbed to the TiO2 surface. This was in correlation with the ζ-potential that decreased with increased SRFA concentration, leading to destabilization of the system. These results stress the importance of performing studies over both short and long time periods to better understand and predict the long-term effects of nanoparticles in the environment.
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| 6. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Coagulation and sedimentation of gold nanoparticles and illite in model natural waters: Influence of initial particle concentration
- 2016
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Ingår i: NanoImpact. - : Elsevier BV. - 2452-0748. ; 3-4, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- Gold nanoparticles (AuNP) possess unique characteristics that render them adequate for applications and also to be used as a model NP to evaluate the fate and behavior at low NP concentrations due to the ease of detection by modern analytical techniques. Moreover, AuNP may result in some negative effects in the environment and there is a necessity to predict their aquatic environmental concentrations by parameterizing the underlying transport and transformation processes. This study investigated the coagulation and sedimentation of 30 nm citrate-coated AuNP under enviro-mimicking conditions, i.e. model natural freshwaters (MNW) covering the range of European water chemistries relevant for colloids and NP (major ions, pH and dissolved organic matter) and artificial seawater (ASW). Firstly, the coagulation rates of AuNP at mg/L concentrations were evaluated using time-resolved dynamic light scattering which showed a decreased rate upon addition of Suwannee river natural organic matter (SRNOM) at low ionic strength (IS) but remained relatively high at high IS. Contrastingly, AuNP approaching environmental realistic concentrations (80 μg/L) in quiescent microcosms showed slow decline rates in all MNW and ASW regardless of the presence of SRNOM, as measured by nanoparticle tracking analysis and elemental Au spectrometry. When illite was added as model natural colloid the rates of decline of AuNP remained low as well. This is owing to limited collisions at low particle number concentrations. The results show that besides IS, pH, NOM concentration and type and the intrinsic surface charge of the particles, the particle number concentration and size distribution of both AuNP and natural colloids determine the extent of the large-scale fate of NP in aquatic environments.
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| 7. |
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| 8. |
- Gonçalves, Sandra F., et al.
(författare)
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Effects of silver nanoparticles to the freshwater snail Physa acuta: The role of test media and snails' life cycle stage
- 2017
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 36:1, s. 243-253
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Tidskriftsartikel (refereegranskat)abstract
- Silver nanoparticles (AgNP) are highly used worldwide, which will most likely lead to their release to the environment and subsequently increase environmental concentrations. Therefore studying AgNPs' deleterious effects to organisms is crucial to understand their environmental impacts. The freshwater snail Physa acuta was chosen to evaluate the potential deleterious effects of AgNP and counterpart AgNO3, through water only exposures. AgNPs' toxicity is greatly influenced by medium composition. Thus, two test media were tested: Artificial Pond Water (APW) and modified APW (modified by removing calcium chloride from medium). Acute tests (96h) were performed with juvenile and adult snails, in both media, to assess lethality, and egg mass chronic tests, with APW medium only, to assess embryo viability and mortality, carried out until reaching 90% hatching success in the control. Acute toxicity increased with decreasing shell length for both silver forms (ion and nanoparticle), i.e. juveniles where more sensitive than adults. Different test media led to dissimilar LC50 values, with chloride playing an important role in toxicity, most probably by complexation with silver ions and thus reducing silver's bioavailability, uptake and toxicity. Chronic tests showed that hatching success was more sensitive to silver in the ionic form than in the particulate form. Different forms of silver, exposure media and life cycle stages led to different patterns of toxicity, highlighting an impairment in the snails' life cycle.
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| 9. |
- Hassellöv, Martin, 1970, et al.
(författare)
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Marint mikroskopiskt skräp längs Bohuskusten 2015 - i jämförelse med tidigare studier 2013 och 2014
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Prover för mikroskopiskt skräp togs i november 2015 på 14 lokaler längs västkusten på uppdrag av Länsstyrelsen i Västra Götalands län och rapporteras här i detalj tillsammans med jämförelser från tidigare provtagningstillfällen (december 2013, april 2014 och december 2014) på samma lokaler. Syftet har varit att mäta halter och karaktärisera mikroskopiskt skräp samt undersöka lämpliga metodval för eventuella framtida övervakningsprogram. •Halter och karaktär av mikroskräp varierade stort beroende på vilken provtagnings- och filtreringsmetod som användes. Undersökningen 2015noterade ca 100 000 gånger högre halter av mikroskräpspartiklar frånytvattenprover på ett filter med storlek 10 μm (0,01 mm) jämfört med 300μm (0,3 mm) siktduk som användes vid trålning i havsytan. •Antalet antropogena (av mänskligt ursprung) partiklar som fastnade på 300μm filter varierade från ca. 0.1 till ca. 10 partiklar/m3 havsvatten oTill skillnad från tidigare provtagningar med 300μm som utförtsmed pump strax under havsytan så gav detta års trålprovtagning ejlika dominerande inslag av fibrer, utan plastpartiklar och fibreråterfanns i jämförbar förekomst. oHalterna 2015 var i samma storleksordning som tidigarerapporterats för svenska kustvatten. Dock hade fördelningen mellanplastpartiklar och syntetiska fibrer förskjutits mot plastpartiklarvilket kan förklaras mot systematiska skillnader i tidigareprovtagningsmetodik. •I proverna som togs med 10 μm filter återfanns i genomsnitt ca. 38mikroskräpspartiklar per liter (exkl. svarta och röda) vilket var en vissökning från tidigare provtagningar (18/l dec 2013 och april 2014 samt 9/ldec 2014). oEn högre förekomst av röda partiklar (58 partiklar/liter) uppmättes.Kemiska analyser visade dock att flertalet av de röda partiklarnabestod av järnoxider; dvs ej nödvändigtvis dominerat av partiklarfrån båtbottenfärg som tidigare antagits. Endast en mindre andelröda partiklar kan härröra från polymert ursprung. Därmed har rödapartiklar inte räknats in i samlingsbegreppet mikroskräp. oHalterna av potentiella förbränningspartiklar på 10 μm filter varmycket höga i Göteborgsområdet, Stenungsund samt Brofjorden.Genomsnittligt antal i Göteborgsområdet var ca. 3000 partiklar perliter. Medelhalten för alla stationer var cirka 1800 partiklar per liter. oSyntetfibrer och naturfibrer förekom i högst halter i Danafjord,Åstol, Galterön och Stretudden vilket troligtvis kan härledas tillutsläpp från avloppsreningsverk i närheten till provtagningspunkterna. • Resultaten pekar såväl i år som tidigare år på att stadsmiljön är en viktig källa till marint mikroskopiskt skräp. Källor kan vara från kommunala avlopp, dagvatten från vägar och stadsytor, industrier samt olika former av förbränning. • Förekomst av mikroskopiska skräppartiklar undersöktes i utgående vatten från fyra kommunala avloppsreningsverk (ARV): Uddevalla, Strömstad, Stenungsund och Skärhamn. För undersökningen kunde följande noteras; o Antalet uppmätta mikroskräppartiklar uppgick till mellan ca 10 och 80 partiklar per kubikmeter utgående vatten, med lägst antal partiklar i Skansverket (Uddevalla) och mest partiklar i Stenungsund. Dagarna innan provtagning i Stenungsund hade det regnat kraftigt vilket kan påverka resultatet. o Halterna var väsentligt lägre än de flesta tidigare mätningar avseende partiklar och syntetiska fibrer och kraftigt lägre avseende på ickesyntetiska fibrer. Största andelen (över 50% i vissa fall) av partiklarna bestod av fibrer (syntetiska och icke syntetiska), men det ska noteras att filter med storlek 300 μm förmodligen underskattar fiberhalten väsentligt
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| 10. |
- Hassellöv, Martin, 1970, et al.
(författare)
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Progress towards monitoring of microlitter in Scandinavian marine environments: State of knowledge and challenges
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Microlitter consists of minute particles of anthropogenic or processed natural material. The project brings together research groups to conduct specific case studies in gradients from near urban sources such as the traffic environment and cities to the coastal water and sediments in order to study the relative occurrence of specific sources and their environmental dispersion and distribution. The conclusion were first that in sediments from the road environment (tunnel runoff water), tire particles, asphalt and road markings could be identified, and in the urban creek sediments many black particles including elastomers, charcoal-like and oil and soot where in high abundance and decreased rapidly out in the recipient. The results emphasize the role of the cities as hotspot source functions for microlitter in the coastal environment and also where mitigating measures could be directed.
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