One of the main challenges in nanoecotoxicological investigations is in the selection of the most suitable measurement methods and protocols for nanoparticle characterisation. Several parameters have been identified as being important as they govern nanotoxicological activity, with some parameters being better defined than others. For example, as a parameter, there is some ambiguity as to how to measure dispersion stability in the context of ecotoxicological investigations; indeed, there is disagreement over which are the best methods to measure nanoparticle dispersion stability. The purpose of this paper is to use various commercially available tools to measure dispersion stability and to understand the information given by each tool. By understanding the inherent strength and limitations of various techniques, we can thus identify suitable tools that yield complementary information. In this study, CeO2 was dispersed in two different types of media: de-ionised water and fish medium. Stability of these dispersions was monitored using various techniques, for a period of three-days. A visual sedimentation experiment showed that nanoparticle dispersion made in the fish medium was less stable compared to corresponding dispersion in de-ionised water. Techniques employed were shown to be sufficiently sensitive to differentiate the two-nanoparticle dispersions, with the exception of Nanoparticle Tracking Analysis, which is limited by its inability to accurately track the motion of large agglomerates found in the fish medium. The presence of large agglomerates in the fish medium were shown from Scanning Electron Microscopy analysis. Methods to measure dispersion stability should be selected on the basis that they provide complementary information. Suitable methods to assess dispersion stability should include the assessment of: a) sedimentation, b) surface charge (and subsequent influence on surface chemistry), c) monitoring the presence of agglomerates through time.
Citation: Journal of Nanoparticle Research
Pub Type: Journals
agglomeration, nanoparticle, nanomaterial, dispersion, fish media, ecotoxicology, particle size