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Open AccessArticle

The Effect of Composition of Different Ecotoxicological Test Media on Free and Bioavailable Copper from CuSO4 and CuO Nanoparticles: Comparative Evidence from a Cu-Selective Electrode and a Cu-Biosensor

by Aleksandr Käkinen 1,2,†, Olesja Bondarenko 1,3,†, Angela Ivask 1,* and Anne Kahru 1,*
1
Laboratory of Molecular Genetics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia
2
Department of Chemical and Materials Technology, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia
3
Department of Gene Technology, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia
*
Authors to whom correspondence should be addressed.
These authors contributed equally to this work.
Sensors 2011, 11(11), 10502-10521; https://doi.org/10.3390/s111110502
Received: 20 September 2011 / Revised: 20 October 2011 / Accepted: 31 October 2011 / Published: 3 November 2011
(This article belongs to the Special Issue Sensing of Toxic and Hazardous Metals in Various Environmental Media)
The analysis of (bio)available copper in complex environmental settings, including biological test media, is a challenging task. In this study, we demonstrated the potential of a recombinant Pseudomonas fluorescens-based biosensor for bioavailability analysis of CuSO4 and CuO nanoparticles (nano-CuO) in seventeen different ecotoxicological and microbiologial test media. In parallel, free Cu in these test media was analysed using Cu-ion selective electrode (Cu-ISE). In the case of CuSO4, both free and bioavailable Cu decreased greatly with increasing concentration of organics and phosphates in the tested media. A good correlation between free and bioavailable Cu was observed (r = 0.854, p < 0.01) indicating that the free Cu content in biological test media may be a reasonably good predictor for the toxicity of CuSO4. As a proof, it was demonstrated that when eleven EC50 values for CuSO4 from different organisms in different test media were normalized for the free Cu in these media, the difference in these EC50 values was decreased from 4 to 1.8 orders of magnitude. Thus, toxicity of CuSO4 to these organisms was attributed to the properties of the test media rather than to inherent differences in sensitivity between the test organisms. Differently from CuSO4, the amount of free and bioavailable Cu in nano-CuO spiked media was not significantly correlated with the concentration of organics in the test media. Thus, the speciation of nano-CuO in toxicological test systems was not only determined by the complexation of Cu ions but also by differential dissolution of nano-CuO in different test conditions leading to a new speciation equilibrium. In addition, a substantial fraction of nano-CuO that was not detectable by Cu-ISE (i.e., not present as free Cu-ions) was bioavailable to Cu-biosensor bacteria. Thus, in environmental hazard analysis of (nano) particulate materials, biosensor analysis may be more informative than other analytical techniques. Our results demonstrate that bacterial Cu-biosensors either in combination with other analytical/speciation techniques or on their own, may serve as a rapid (eco)toxicological screening method. View Full-Text
Keywords: copper-containing nanoparticles; bacteria; bioluminescent bioreporter; ion-selective electrode; speciation; toxicity; complexation copper-containing nanoparticles; bacteria; bioluminescent bioreporter; ion-selective electrode; speciation; toxicity; complexation
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MDPI and ACS Style

Käkinen, A.; Bondarenko, O.; Ivask, A.; Kahru, A. The Effect of Composition of Different Ecotoxicological Test Media on Free and Bioavailable Copper from CuSO4 and CuO Nanoparticles: Comparative Evidence from a Cu-Selective Electrode and a Cu-Biosensor. Sensors 2011, 11, 10502-10521.

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