Characterisation of nanoparticle size and state prior to nanotoxicological studies
Before commencing any nanotoxicological study, it is imperative to know the state of the nanoparticles to be used and in particular their size and size distribution in the appropriate test media is particularly important. Particles satisfying standards can be commercially purchased; however, these invariably cannot be used directly and need to be dispersed into the relevant biological media. Often such changes in the environment or ionic strength, or a change in the particle concentration, results in some aggregation or a shift in the particle size distribution. Such unexpected aggregation, dissolution or plating out, if unaccounted for, can have a significant effect on the available nanoparticle dose and on interpretation of any results obtained thereafter. Here, we demonstrate the application of characterisation instrumentation that sizes nanoparticles based on their Brownian motion in suspension. Unlike classical light-scattering techniques, the nanoparticle tracking and analysis (NTA) technique allows nanoparticles to be sized in suspension on a particle-by-particle basis allowing higher resolution and therefore better understanding of aggregation than ensemble methods (such as dynamic light scattering (DLS) and differential centrifugation sedimentation (DCS)). Results will be presented from gold (standard) nanoparticles in biologically relevant media that emphasise the importance of characterisation of the nanoparticle dispersion. It will be shown how the NTA technique can be extended to multi-parameter analysis, allowing for characterization of particle size and light scattering intensity on an individual basis. This multi-parameter measurement capability allows sub-populations of nanoparticles with varying characteristics to be resolved in a complex mixture. Changes in one or more of such properties can be followed both in real time and in situ.
KeywordsProtein corona Nanoparticles Dispersion NTA DLS Nanoparticle tracking and analysis Environment EHS
- Hackley V (2008) Enabling risk assessment, benchmarking, calibration and method validation, NanoImpactNet, Dublin 2008Google Scholar
- National Institute of Standards & Technology (2007) Report of investigation, Reference material 8013, Gold nanoparticles, Nominal 60 nm diameter 13/12/07Google Scholar
- Royal Society of Chemistry and Royal Academy of Engineering (2005) Nanoscience and Nanotechnologies: opportunities and uncertainties. Royal Society, LondonGoogle Scholar
- Saveyn H, De Baets B, Hole P, Smith J, Van der Meeren P (2008) Accurate particle size distribution determination by nanoparticle tracking analysis based on 2-D Brownian dynamics simulation. In Proceedings of the Particulate systems analysis, Stratford, 2008 Google Scholar