Ag and TiO2 Nanoparticles: Effects on Model Aquatic Organisms A. Georgantzopoulou1, M. Dusinska2, M. Kruszewski3, YL. Balachandran4, J-N. Audinot1, L. Hoffmann1, A.C. Gutleb1
Background The increasing production scale and use of nanoparticles (NPs) in numerous products will unavoidably lead to their release in aquatic systems. There is a lack of knowledge on the effects of NPs on living systems as well as their interaction with other common environmental contaminants. Aim: assessment of effects of the widely used TiO2 (20 nm) and Ag (20 and 27 nm) NPs on the aquatic organism Daphnia magna and Desmodesmus subspicatus and validation of the use of Vibrio fischeri bioluminescence as a potential pre-screening assay.
Materials and Methods NPs: Characterised NPs and dispersion protocols were provided by the FP7 project NanoTEST, the PolishNorwegian Research Fund project PNRF122-AI-1/07 and the Bharathiar University, India. Bulky TiO2, Ag (200 nm), AgNO3 and reference compounds were used as positive controls. V. fischeri inhibition of luminescence: The ability of NPs to inhibit the natural bioluminescence of V. fischeri was assessed after exposure for 30 min (96-well plate format, adaptation from ISO 11348-1). D. subspicatus growth inhibition: Exponentially growing algae were exposed to NPs for 72 hrs and the inhibition of growth was calculated (manual count of cells, 12-well plate format, ISO 8692 adapted) D. magna immobilisation: Daphnids < 24 hrs old were exposed to NPs and their ability to move was evaluated after 48 hrs (6-well plate format, adaptation from OECD 202 guideline).
Results (A)
(B)
(C)
Figure 1. Effects of aqueous suspensions of Ag 27, 20 and 200 nm and AgNO3 on (A) V. fischeri, (B) D. subspicatus and (C) D. magna after 30 min, 72 hrs and 24 hrs exposure, respectively. Untreated organisms served as controls. Means with SD of two independent experiments are shown
Overview of results
Discussion
Table 1. Overview of the particles studied and the EC50s obtained in the assays with D. magna, D. subspicatus and V. fischeri.
Ag 20 nm Ag 200 nm Ag 27 nm AgNO3 Bulk-TiO2 Nano-TiO2
63.5 113.7
D. subspicatus D. magna 2.2 3.7
0.1 0.6
49.5
0.3
0.02
0.6 Increase in Lum > 200 mg/L Increase in Lum > 20 mg/L
0.04
0.001
No effect
No effect
No effect
No effect
Future Perspectives • Study effects on metabolic activity, oxidative stress, apoptosis and inflammatory markers in an intestinal coculture model • Proteomic studies in the co-culture model
WWW.LIPPMANN.LU
EC50s (mg/L) V. fischeri
• Ag size-dependent effects on daphnids’ mobility and algal growth • AgNO3 always more toxic than the NPs in all organisms • Daphnids were the most sensitive species • Ag NPs effects on V. fischeri >1 mg/L • TiO2: Size dependent increase in V. fischeri luminescence (Possibly TiO2 leads to increased O2 levels which could result in increase in light production. Alternatively, TiO2 particles may interfere with measurements)
1
Centre de Recherche Public – Gabriel Lippmann, Luxembourg (contact: gutleb@lippmann.lu) Norwegian Institute of Air Research, Kjeller, Norway 3 Institute of Nuclear Chemistry and Technology, Poland 4 School of Biotechnology and Genetic Engineering, Bharathiar University, Coimbatore, India 2
NanEAU is supported by within the “Core2008” program (C08/SR/07)