Freshwater dispersion stability of PAA-stabilised cerium oxide nanoparticles and toxicity towards Pseudokirchneriella subcapitataShow others and affiliations
2015 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 505, p. 596-605Article in journal (Refereed) Published
Abstract [en]
An aqueous dispersion of poly (acrylic acid)-stabilised cerium oxide (CeO2) nanoparticles (PAA-CeO2) was evaluated for its stability in a range of freshwater ecotoxicity media (MHRW, TG 201 and M7), with and without natural organic matter (NOM). In a 15day dispersion stability study, PAA-CeO2 did not undergo significant aggregation in any media type. Zeta potential varied between media types and was influenced by PAA-CeO2 concentration, but remained constant over 15days. NOM had no influence on PAA-CeO2 aggregation or zeta potential. The ecotoxicity of the PAA-CeO2 dispersion was investigated in 72h algal growth inhibition tests using the freshwater microalgae Pseudokirchneriella subcapitata. PAA-CeO2 EC50 values for growth inhibition (GI; 0.024mg/L) were 2-3 orders of magnitude lower than pristine CeO2 EC50 values reported in the literature. The concentration of dissolved cerium (Ce3+/Ce4+) in PAA-CeO2 exposure suspensions was very low, ranging between 0.5 and 5.6μg/L. Free PAA concentration in the exposure solutions (0.0096-0.0384mg/L) was significantly lower than the EC10 growth inhibition (47.7mg/L) value of pure PAA, indicating that free PAA did not contribute to the observed toxicity. Elemental analysis indicated that up to 38% of the total Cerium becomes directly associated with the algal cells during the 72h exposure. TOF-SIMS analysis of algal cell wall compounds indicated three different modes of action, including a significant oxidative stress response to PAA-CeO2 exposure. In contrast to pristine CeO2 nanoparticles, which rapidly aggregate in standard ecotoxicity media, PAA-stabilised CeO2 nanoparticles remain dispersed and available to water column species. Interaction of PAA with cell wall components, which could be responsible for the observed biomarker alterations, could not be excluded. This study indicates that the increased dispersion stability of PAA-CeO2 leads to an increase in toxicity compared to pristine non-stabilised forms.
Place, publisher, year, edition, pages
2015. Vol. 505, p. 596-605
Keywords [en]
CeO2, Dispersion stability, Ecotoxicity, Freshwater algae, Nanoparticles, Freshwater dispersion stability of PAA-stabilised cerium oxide nanoparticles and toxicity towards Pseudokirchneriella subcapitata
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:ri:diva-27469DOI: 10.1016/j.scitotenv.2014.10.010Scopus ID: 2-s2.0-84908333055OAI: oai:DiVA.org:ri-27469DiVA, id: diva2:1054474
Note
A3419
2016-12-082016-12-082023-05-09Bibliographically approved